Physical training for asthma

  • Conclusions changed
  • Review
  • Intervention

Authors


Abstract

Background

People with asthma may show less tolerance to exercise due to worsening asthma symptoms during exercise or other reasons such as deconditioning as a consequence of inactivity. Some may restrict activities as per medical advice or family influence and this might result in reduced physical fitness. Physical training programs aim to improve physical fitness, neuromuscular coordination and self confidence. Subjectively, many people with asthma report that they are symptomatically better when fit, but results from trials have varied and have been difficult to compare because of different designs and training protocols. Also, as exercise can induce asthma, the safety of exercise programmes needs to be considered.

Objectives

To gain a better understanding of the effect of physical training on the respiratory and general health of people with asthma, from randomised trials.

Search methods

We searched the Cochrane Airways Group Specialised Register of trials up to January 2013.

Selection criteria

We included randomised trials of people over eight years of age with asthma who were randomised to undertake physical training or not. Physical training had to be undertaken for at least 20 minutes, two times a week, over a minimum period of four weeks.

Data collection and analysis

Two review authors independently assessed eligibility for inclusion and undertook risk of bias assessment for the included studies.

Main results

Twenty-one studies (772 participants) were included in this review with two additional 2012 studies identified as 'awaiting classification'. Physical training was well tolerated with no adverse effects reported. None of the studies mentioned worsening of asthma symptoms following physical training. Physical training showed marked improvement in cardiopulmonary fitness as measured by a statistically and clinically significant increase in maximum oxygen uptake (mean difference (MD) 4.92 mL/kg/min; 95% confidence interval (CI) 3.98 to 5.87; P < 0.00001; 8 studies on 267 participants); however, no statistically significant effects were observed for forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), minute ventilation at maximal exercise (VEmax) or peak expiratory flow rate (PEFR). Meta-analysis of four studies detected a statistically significant increase in maximum heart rate, and following a sensitivity analysis and removal of two studies significance was maintained (MD 3.67 bpm; 95% CI 0.90 to 3.44; P = 0.01). Although there were insufficient data to pool results due to diverse reporting tools, there was some evidence to suggest that physical training may have positive effects on health-related quality of life, with four of five studies producing a statistically and clinically significant benefit.

Authors' conclusions

This review demonstrated that physical training showed significant improvement in maximum oxygen uptake, though no effects were observed in other measures of pulmonary function. Physical training was well tolerated among people with asthma in the included studies and, as such, people with stable asthma should be encouraged to participate in regular exercise training, without fear of symptom exacerbation. More research is needed to understand the mechanisms by which physical activity impacts asthma management.

Résumé scientifique

Exercice physique pour l'asthme

Contexte

Les personnes asthmatiques peuvent se montrer moins tolérantes à la pratique d'un exercice physique en raison d'une aggravation des symptômes asthmatiques lorsqu' elles font de l'exercice ou de motifs autres, comme le déconditionnement, suite à un manque d'activité. Certaines peuvent aussi limiter leur activité physique conformément à un avis médical ou à l'influence familiale et ainsi entraîner une baisse de la forme physique. Les programmes d'exercices physiques visent à améliorer la santé physique, la coordination neuromusculaire et la confiance en soi. D'un point de vue subjectif, de nombreuses personnes asthmatiques signalent être symptomatiquement en meilleure forme physique, mais les résultats issus des essais variaient et étaient difficilement comparables en raison des différences entre les protocoles d’étude et entre les programmes d’entrainement. De même, étant donné que l'exercice physique peut déclencher une crise d’asthme, la sécurité des programmes d'exercices doit être prise en compte.

Objectifs

Mieux comprendre les effets de l'exercice physique sur la santé respiratoire et générale des personnes asthmatiques à partir d'essais randomisés.

Stratégie de recherche documentaire

Nous avons effectué des recherches dans le registre des essais spécialisés du groupe Cochrane sur les voies respiratoires jusqu' à janvier 2013.

Critères de sélection

Nous avons inclus des essais randomisés composés de personnes asthmatiques âgées de plus de huit ans auxquelles la pratique d'un exercice physique a été proposée ou non de façon aléatoire. Cet exercice physique devait être pratiqué pendant au moins vingt minutes, deux fois par semaine, sur une période minimale de quatre semaines.

Recueil et analyse des données

Deux auteurs de la revue ont indépendamment évalué l'éligibilité et le risque de biais pour les études incluses.

Résultats principaux

Vingt-et-un études (772 participants) ont été inclus dans cette revue, dont deux autres 2012 études identifiées comme «en attente de classification». L'exercice physique était bien toléré sans aucun effet indésirable signalé. Aucune des études ne mentionnait une aggravation des symptômes asthmatiques suite à la pratique d'un exercice physique. L'entraînement physique a montré une amélioration marquée dans la santé cardio-pulmonaire, telle que mesurée par une augmentation statistiquement et cliniquement significative dans la consommation maximal d'oxygène (différence moyenne (DM) de 4,92 ml/kg/mn; intervalle de confiance (IC) 3,98 à 5,87, p < 0,00001; 8 études sur 267 participants); cependant, aucun effet statistiquement significatif n'était observée pour le volume expiratoire maximal en 1 seconde (VEMS), de la capacité vitale forcée (CVF), la ventilation minute au cours d'un exercice maximal (VEmax) ou le débit expiratoire de pointe (DEP). La méta-analyse de quatre études montraient une augmentation statistiquement significative de fréquence cardiaque maximum, et suite à une analyse de sensibilité et l'ablation des deux études, la signification statistique a été maintenue (DM 3,67 bpm; IC à 95% 0,90 à 3,44; P =0,01). Bien que les données étaient insuffisantes pour être regroupées en raison de divers outils de notification, il existe des preuves suggérant que l'exercice physique peut avoir des effets positifs sur la qualité de vie liée à la santé, avec quatre études sur cinq affichant des effets bénéfiques statistiquement et cliniquement significatifs.

Conclusions des auteurs

Cette revue a démontré que l'exercice physique a montré une amélioration significative de la consommation maximale d'oxygène, bien qu’aucun effet n'ait été observé dans les autres paramètres de la fonction pulmonaire. L'exercice physique était bien toléré chez les personnes souffrant d'asthme dans les études incluses et, par conséquent, les personnes présentant un asthme stable doivent être encouragées à pratiquer un exercice physique régulier, sans crainte d'une aggravation de leurs symptômes. Des recherches supplémentaires sont nécessaires pour comprendre les mécanismes par lesquels l'activité physique impacte la prise en charge de l'asthme.

Resumo

Treinamento físico para asma

Introdução

Algumas pessoas com asma podem ter menor tolerância ao exercício físico devido à piora dos sintomas respiratórios durante a pratica ou por outras razões, como a falta de condicionamento físico decorrente da inatividade. Alguns asmáticos podem limitar suas atividades por recomendação médica ou por influência da família, e isso pode levar à redução de sua aptidão física. Os programas de exercícios visam melhorar a aptidão física dos participantes, assim como sua coordenação neuromuscular e auto confiança. Subjetivamente, muitas pessoas com asma relatam que se sentem melhor em relação aos sintomas da doença quando estão fisicamente condicionadas. Porém, os resultados dos estudos variam e são difíceis de comparar devido aos diferentes tipos de desenho usados e diversos protocolos de treinamento. Como o exercício pode induzir a asma, também é importante avaliar a segurança dos programas de exercício.

Objetivos

Entender melhor os efeitos do treinamento físico para a saúde geral e respiratória de pessoas com asma, através da análise de ensaios clínicos randomizados.

Métodos de busca

Nós fizemos uma busca na Cochrane Airways Group Specialised Register of trials até Janeiro de 2013.

Critério de seleção

Nós incluímos ensaios clínicos randomizados que recrutaram indivíduos com asma com díade superior a oito anos e que foram randomizadas para realizar treinamento físico ou não. O treinamento físico deveria ser realizado por pelo menos 20 minutos, duas vezes por semana, por um período mínimo de quatro semanas.

Coleta dos dados e análises

Dois autores da revisão avaliaram de forma independente os estudos potencialmente elegíveis para inclusão e o risco de viés dos estudos incluídos.

Principais resultados

Foram incluídos 21 estudos (772 participantes) nesta revisão, sendo que dois estudos adicionais identificados em 2012 estão “aguardando classificação". O treinamento físico foi bem tolerado, sendo que não foi relatado nenhum caso de evento adverso. Nenhum dos estudos relatou piora dos sintomas da asma após o treinamento físico. O exercício produziu uma melhora significativa, tanto clínica como estatística, na aptidão cardiopulmonar avaliada pelo aumento do consumo máximo de oxigênio (diferença média (DM) 4.92mL/kg/min; intervalo de confiança (IC) 95% 3.98 – 5.87; P <0.00001; 8 estudos com 267 participantes). Porém, não foi detectado nenhum efeito significativo dos exercícios sobre o volume de ar expirado em 1 segundo (FEV1), a capacidade vital forçada (FVC), a ventilação por minuto no esforço máximo (Vemax) ou a taxa de pico de fluxo expiratório (PEFR). Uma metanálise de quatro estudos detectou um aumento estatisticamente significante na frequência cardíaca máxima. Mesmo após uma análise de sensibilidade que excluiu dois estudos, esta diferença continuou significativa (DM 3.67 bpm; IC 95% 0.90 – 3.44; P=0.01). Devido à diversidade dos instrumentos usados para avaliar a qualidade de vida, não foi possível fazer uma metanálises deste desfecho. Porém as evidências sugerem que o treinamento físico teria um efeito positivo na qualidade de vida relacionada com a saúde, já que quatro entre cinco estudos que avaliaram este desfecho relataram benefícios clinicamente e estatisticamente significativos.

Conclusão dos autores

Esta revisão demonstrou que o treinamento físico proporcionou uma melhora significativa no consumo máximo de oxigênio, sem outros efeitos sobre parâmetros da função pulmonar. O treinamento físico foi bem tolerado pelos indivíduos asmáticos que participaram dos estudos. Sendo assim, pessoas com asma estável devem ser encorajadas a participar de programas de treinamento físico regular sem medo de exacerbação dos sintomas. Mais pesquisas são necessárias para entender os mecanismos envolvidos nos efeitos do exercício sobre a asma.

Plain language summary

Physical training for asthma

Some people with asthma may show less tolerance to exercise due to worsening asthma symptoms when they exercise or other reasons such as deconditioning. This can prevent them playing sports or attempting to keep fit. Physical training programs for people with asthma have been designed to improve physical fitness, muscle coordination and confidence.

The review of trials found that exercise training (including running, gymnastics, cycling, swimming, weights and walking) was well tolerated among the study participants. This review also found that physical training improved cardiopulmonary fitness and showed some positive effects for health-related quality of life. However, physical training had no significant effect on resting lung function. In summary, people with stable asthma should be encouraged to participate in regular exercise training that is within their capacity without fear of worsening of their asthma symptoms.

Résumé simplifié

Exercice physique pour l'asthme

Certaines personnes asthmatiques peuvent se montrer moins tolérantes à la pratique d'un exercice physique en raison d'une aggravation des symptômes asthmatiques lorsqu' elles font de l'exercice ou de motifs autres, comme le déconditionnement. Ceci peut alors les empêcher de pratiquer un sport ou de se maintenir en bonne forme physique. Les programmes d'entraînement physique pour les personnes asthmatiques permettent d'améliorer la forme physique, la coordination musculaire et la confiance en soi.

La revue des essais a découvert que l'exercice physique (y compris la course, la gymnastique, le vélo, la natation, les haltères et la marche) était bien toléré chez les participants à ces études. Cette revue a également révélé que l'exercice physique améliore la santé cardio-pulmonaire et a des effets positifs sur la qualité de vie liée à la santé. Toutefois, l'exercice physique n'avait aucun effet significatif sur la fonction pulmonaire au repos. En résumé, les personnes présentant un asthme stable doivent être encouragées à pratiquer une activité physique régulière dans la mesure de leurs capacités sans crainte d'aggraver leurs symptômes asthmatiques.

Notes de traduction

Traduit par: French Cochrane Centre 9th January, 2014
Traduction financée par: Ministère du Travail, de l'Emploi et de la Santé Français

Resumo para leigos

Treinamento físico para asma

Algumas pessoas asmáticas podem ter menor tolerância aos exercícios devido à piora dos sintomas respiratórios quando se exercitam ou por outras razões, como a falta de condicionamento físico. Isto pode fazer com que evitem participar de atividades esportivas ou de se manter bem condicionados. Os programas de treinamento físico para pessoas asmáticas foram desenvolvidos para melhorar o condicionamento físico, a coordenação muscular e a confiança. Esta revisão concluiu que o treinamento físico (incluindo corrida, ginástica, ciclismo, natação, treinamento com pesos e caminhada) foi bem tolerado pelos participantes dos estudos. O treinamento físico também melhorou a aptidão cardiopulmonar e mostrou alguns efeitos positivos para a qualidade de vida relacionada à saúde. Porém, o treinamento físico não teve efeito significativo sobre a função pulmonar de repouso. Em resumo, pessoas com asma estável devem ser encorajadas a praticar exercícios regularmente, dentro de suas capacidades, sem medo de piorar seus sintomas.

Notas de tradução

Traduzido por: Brazilian Cochrane Centre

எளியமொழிச் சுருக்கம்

ஆஸ்துமாவிற்கான உடற்பயிற்சி

ஆஸ்துமா உடைய சில மக்கள் உடற்பயிற்சி செய்யும் போது, ஆஸ்துமாவின் ​ அறிகுறிகள் மோசமாகுதல் அல்லது நிலையகற்றல் போன்ற மற்ற காரணங்களால், உடற்பயிற்சிக்கு குறைந்தளவு சகிப்புத் தன்மையைக் காட்டக் கூடும். இது, அவர்கள் விளையாட்டுகளில் ஈடுபடுவதை அல்லது உடற்கட்டுடன் இருக்க முயற்சியெடுப்பதை தடுக்க முடியும். உடற் திறன், தசை ஒருங்கிணைப்பு மற்றும் நம்பிக்கையை மேம்படுத்த ஏற்றவாறு ஆஸ்துமா கொண்ட மக்களுக்கு உடற்பயிற்சி திட்டங்கள் வடிவமைக்கப்பட்டுள்ளது.

உடற்பயிற்சி (ஓடுதல், ஜிம்னாஸ்டிக்ஸ், சைக்கிள் ஓட்டுதல், நீச்சல், எடைகள் மற்றும் நடைபயிற்சி ஆகியவை உள்ளடங்கிய) ஆய்வு பங்கேற்பாளர்கள் மத்தியில் சிறப்பாக ஏற்றுக் கொள்ளப்பட்டது என்று இந்த சோதனைகளின் திறனாய்வு கண்டறிந்தது. உடற்பயிற்சி, இதயநுரையீரல் திறனை முன்னேற்றி மற்றும் ஆரோக்கியம்-தொடர்பான வாழ்க்கைத் தரத்தில் சில சாதகமான விளைவுகளை கண்டது என்றும் இந்த திறனாய்வு கண்டறிந்தது. எனினும், உடற்பயிற்சியால் நிலைப்பட்ட நுரையீரல் செயல்பாட்டின் மேல் எந்த குறிப்பிடத்தக்க விளைவும் இல்லை. சுருக்கமாக, நிலையான ஆஸ்துமா கொண்ட மக்கள் தங்களின் ஆஸ்துமா அறிகுறிகள் மோசமாகுகிற பயம் இல்லாமல் தங்கள் சக்திக்கு உட்பட்ட ஒழுங்கான உடற்பயிற்சியில் பங்கேற்க ஊக்குவிக்கப்பட வேண்டும்.

மொழிபெயர்ப்பு குறிப்புகள்

மொழி பெயர்ப்பாளர்கள்: தங்கமணி ராமலிங்கம், ப்ளசிங்டா விஜய், சிந்தியா ஸ்வர்ணலதா ஸ்ரீகேசவன், ஸ்ரீகேசவன் சபாபதி.

Ringkasan bahasa mudah

Latihan fizikal untuk asma.

Sesetengah orang dengan asma boleh menunjukkan toleransi yang lebih rendah terhadap bersenam kerana gejala asma yang semakin teruk apabila mereka bersenam atau sebab-sebab lain seperti kurang kelaziman ('deconditioning'). Ini boleh menghalang mereka daripada bersukan atau cuba untuk menjaga kesihatan diri. Program latihan fizikal untuk pesakit asma telah direka untuk meningkatkan kecergasan fizikal, koordinasi otot dan keyakinan diri.

Ulasan kajian kajian ini mendapati bahawa latihan senaman (termasuk belari, gimnastik, berbasikal, berenang, mengangkat berat dan berjalan kaki) telah diterima baik dalam kalangan peserta kajian. Ulasan ini juga mendapati bahawa latihan fizikal menambah baik kecergasan kardiopulmonari dan menunjukkan beberapa kesan positif untuk kualiti kehidupan yang berkaitan dengan kesihatan. Walau bagaimanapun, latihan fizikal tidak mempunyai kesan yang besar atas fungsi paru-paru semasa rehat. Ringkasnya, orang dengan asma stabil perlu digalakkan untuk menyertai latihan senaman dalam keupayaan mereka tanpa berasa takut bahawa gejala asma akan menjadi lebih teruk.

Catatan terjemahan

Diterjemahkan oleh Ng Chia Shyn (International Medical University). Disunting oleh Tan May Loong (Penang Medical College). Untuk sebarang pertanyaan berkaitan terjemahan ini sila hubungi Ng.ChiaShyn@student.imu.edu.my.

Summary of findings(Explanation)

Summary of findings for the main comparison. Physical training for asthma
  1. 1 Methods of randomisation, allocation concealment and/or any attempts to blind outcome assessors were not described for the majority of studies assessing this outcome (limitations of design (-1))
    2 Significant heterogeneity (I² = 96%) (inconsistency (-1))
    3 Few participants in few studies (imprecision (-1))
    4 Moderate heterogeneity (I² = 45%)

    5 Single study
    6 Possible sources of clinical heterogeneity include swimming versus gymnasium activities and 6 versus 12 week intervention duration (inconsistency (-1))
    7 No results to pool (imprecision (-1))

    Abbreviations: 6MWD: six-minute walking distance; bpm: heart beats per minute; HRmax: maximum heart rate; PEFR: peak expiratory flow rate; VEmax: maximal expiratory volume (the maximum volume of air that can be breathed in 1 min during exercise); VOmax: maximal oxygen consumption (the maximum amount of oxygen in millilitres used while exercising).

Physical training for asthma
Patient or population: patients with asthma aged eight years or older
Settings: indoor or outdoor track, gymnasium and pool; university hospital, laboratory and physiotherapy department
Intervention: Physical training of whole body exercise lasting more than 20 minutes, twice a week, for at least four weeks
OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
Control Physical training

Asthma symptoms

measured using various techniques.

Follow-up: 6 to 24 weeks

See commentSee commentN/A

315

(9 studies)

⊕⊝⊝⊝
very low 1,6,7

We were unable to pool data for this outcome due to heterogeneity in the instruments used;

3 studies found symptoms lasted fewer days, 5 studies reported symptoms were unchanged; 1 study reported significant improvement.

Quality of life

Measured using various scales.

Follow-up: 12 to 18 weeks

See commentSee commentN/A

212

(5 studies)

⊕⊝⊝⊝
very low 1,6,7
We were unable to pool data for this outcome due to heterogeneity in the quality of life scales used. 4 studies found clinically significant improvement for total scores immediately after physical training,1 study found no significant difference.

Exercise tolerance

Measured using 6MWD

Follow-up: 18 weeks

See commentSee commentN/A

34

(1 study)

⊕⊕⊝⊝
low
3, 5
There was a statistically insignificant increase in the 6MWD in one study.
PEFR
L/min
Follow-up: 6 to 12 weeks
See commentSee commentN/A

77
(2 studies contributed data to meta analysis)

153

(4 studies in total)

⊕⊝⊝⊝
very low 1,2,3
We were unable to pool data for this outcome due to heterogeneity between study populations as per the I2 statistic; The results were originally analysed for two of the four studies assessing this outcome using the fixed-effect model, when the random-effects model was applied, the statistical significance disappeared. The minimally important difference is estimated to be a mean change of 11.9 (95% CI 7.3 to 16.1) (Karras 2000), which has been met in both these analyses. Data from two studies showed no change in PEFR, however, we were unable to combine data due to a high dropout rate in one study and unsuitable data for imputation in the other. Possible sources of clinical heterogeneity include swimming versus gymnasium activities and 6 versus 12 week intervention duration.
VEmax
Follow-up: 6 to 24 weeks
The mean VEmax ranged across control groups from
47.17 to 87.3 L/min
The mean VEmax in the intervention groups was
3.08 higher
(-0.63 to 6.79 higher)
 200
(5 studies)
⊕⊕⊝⊝
low 1,4
 
VOmax
Follow-up: 6 to 24 weeks
The mean VOmax ranged across control groups from
20.36 to 55.4 ml/kg/min
The mean VOmax in the intervention groups was
4.92 higher
(3.98 to 5.87 higher)
 267
(8 studies)
⊕⊕⊝⊝
low 1,4
 
HRmax
bpm
Follow-up: 3 to 6 months
The mean HRmax ranged across control groups from
185.46 to 187 bpm
The mean HRmax in the intervention groups was
3.67 higher
(0.90 to 6.44 higher)
 34
(2 studies)
⊕⊕⊝⊝
low 1,4
 
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

Background

Description of the condition

Asthma, a chronic respiratory condition affecting 300 million people globally (Masoli 2004), causes inflammation of the lungs as well as structural and functional remodelling of the airways. It is characterised by recurrent attacks of breathlessness and wheezing with varying degrees of frequency and severity, which is caused by swelling of the bronchial tubes resulting in airflow limitation (WHO 2011). Although the causes of asthma are not completely understood, risk factors are known to include inhaling asthma triggers such as allergens, tobacco smoke and chemical irritants. Asthma is incurable and the prevalence is increasing, particularly in children and young adults (Pawankar 2012), however appropriate management can control the disorder and enable people to enjoy a high quality of life (WHO 2011).

Asthma is estimated to account for one in every 250 deaths worldwide, many of which are preventable (Masoli 2004). The prevalence of asthma varies between countries, with prevalence estimates of 18.4% in Scotland, 15.3% in England, 15.1% in New Zealand, 14.1% in Canada, 11.4% in Brazil, 10.9% in the United States of America, 9% in Israel, 8.1% in South Africa, 6.9% in Germany, 6.7% in Japan, 4.5% in Italy, 3.8% in Bangladesh, 2.6% in Taiwan, 2.3% in Switzerland, 1.9% in Greece and 1.1% in Indonesia (EFA 2004; Masoli 2004). Asthma is reported to be the 10th leading contributor to the overall burden of disease in Australia (AIHW 2010), affecting 14.7% of all Australians (AIHW 2008; Braman 2006) and as such it has been a National Health Priority since 1996 (AIHW 2008). Globally, the healthcare costs associated with asthma management are significant and increasing (Bahadori 2009), with estimated costs in developed countries estimated at USD 300 to USD 1300 per patient per year (Braman 2006) and EUR 1583 per patient in Europe (Accordini 2013). With the healthcare burden of asthma increasing, confounding pressures are applied to healthcare systems, governments, families and the patients themselves (Masoli 2004) resulting in sub-optimal management (Kandane-Rathayake 2009).

Description of the intervention

Physical activity is comprised of bodily movements produced by the skeletal muscles that result in an increased metabolic rate over that of resting energy expenditure (Bouchard 2012). Physical training is defined by one 2012 publication as "... a form of leisure-time physical activity that is usually performed repeatedly over an extended period of time (exercise training) with a specific external objective such as the improvement of fitness, physical performance, or health" (Bouchard 2012). For the purpose of improving health outcomes the mode, intensity, frequency and duration of activities need to be considered (Bouchard 2012). Physical training programmes have been designed for people with asthma with the aim of improving physical fitness (Arandelovic 2007), neuromuscular coordination and self confidence, but the reported results have varied and have been difficult to compare because of different study designs and training protocols. Such protocols can include various types of aerobic exercise such as running, jogging, cycling, weight training, swimming, stretching and a combination of these activities amongst many other options (Avallone 2012).

How the intervention might work

A low level of habitual physical activity leads in turn to low levels of physical fitness. Thus a number of studies (Clark 1988; Garfinkel 1992), but not all (Santuz 1997), have reported people with asthma to have lower cardiorespiratory fitness when compared to their peers. For people with asthma, exercise can provoke bronchoconstriction in some individuals resulting in exercise-induced asthma (EIA). Research has also shown that inactivity as a result of breathlessness can lead to peripheral muscle deconditioning, which is an important factor limiting exercise capacity (Allard 1989; Laveneziana 2006).This is because deconditioning can result in further breathlessness, as atrophied leg muscles for example are more prone to fatigue (Swallow 2007), requiring increased ventilation for exercise to be maintained. Subsequently, this contributes to breathlessness in a spiraling cycle finally resulting in exercise avoidance and therefore further deconditioning of the skeletal muscles (Moxham 2009). Studies have shown that people with asthma are able to exercise and improve their fitness (Scichilone 2012), and that limitations in exercise capacity can sometimes relate more to lack of fitness than to air flow limitation (Sonna 2001). Habitual physical activity is associated with a reduction in asthma prevalence in children (Nystad 2001) and adults (Huovinen 2001), and may lower the minute ventilation of mild and moderate exercise thereby reducing the likelihood of provoking EIA; whilst physical inactivity has been associated with negative health consequences and an increase in asthma-related difficulties (Avallone 2012). Exercise training may also reduce the perception of breathlessness through a number of mechanisms including strengthening respiratory muscles. There are reports that exercise may have a protective effect against asthma development by reducing airway inflammation (Eijkemans 2012; Ford 2002) and increasing the patency of bronchioles (Eijkemans 2012).

Why it is important to do this review

Regular physical exercise and participation in sports are considered to be important components in the overall management of asthma, especially in children and adolescents (Orenstein 1996). There is some evidence to suggest that regular physical exercise improves asthma symptom management, lung function and mental health (Avallone 2012). However, there is evidence that some people with asthma may avoid participation in exercise and sports due to shortness of breath or worsening asthma symptoms during exercise, or fear of experiencing such symptoms (Avallone 2012; Scott 2013b). Some may have a negative attitude to exercise due to reasons including organisational policies, family beliefs, healthcare advice or inaccurate symptom perception (Williams 2008). Subjectively, many people with asthma report that they are symptomatically better when fit but the physiological basis of this perception has not been systematically investigated.

Objectives

To gain a better understanding of the effect of physical training on the respiratory and general health of people with asthma, from randomised trials.

Methods

Criteria for considering studies for this review

Types of studies

Randomised trials of people with asthma undertaking physical training.

Types of participants

We included people with asthma, aged eight years or older, with any degree of asthma severity. We included diagnoses of asthma made by a physician or the use of objective criteria (for example bronchodilator reversibility), or both. We excluded studies reporting results on patients with chronic obstructive pulmonary disease (COPD) but we did include data from studies of mixed populations where separate data were available for people with asthma.

Types of interventions

We included any type of physical training provided it was whole body aerobic exercise lasting at least 20 minutes, undertaken two times a week for a minimum duration of four weeks.

Control groups included no intervention, or co-interventions such as brief education only (as part of verbal consultations) or asthma medications providing the intervention group also received the same level of education or medication.

Types of outcome measures

Primary outcomes

Asthma symptoms, which included episodes of wheeze or shortness of breath, symptoms score, dyspnoea or number of symptom free days etc.

Secondary outcomes
  1. Bronchodilator usage

  2. Exercise endurance

  3. Work capacity

  4. Walking distance

  5. Quality of life

  6. Physiological measurements (i.e. peak expiratory flow rate (PEFR), forced expiratory volume (FEV), forced vital capacity (FVC), maximal oxygen uptake (VOmax), minute ventilation at maximal exercise (VEmax), maximal heart rate (HRmax), maximal voluntary ventilation (MVV))

Search methods for identification of studies

Electronic searches

We identified trials using the Cochrane Airways Group Specialised Register of trials, which is derived from systematic searches of bibliographic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL, AMED and PsycINFO, and handsearching of respiratory journals and meeting abstracts (please see Appendix 1 for further details). We searched all records in the Specialised Register coded as 'asthma' using the following terms:

"work capacity" OR physical* OR train* OR rehabilitat* OR fitness* or exercis* or aerobic*.

The World Health Organization International Clinical Trials Registry Platform (ICTRP) electronic search portal was also searched for studies using the terms: ['work capacity' OR 'physical' OR 'activit' OR 'train' OR 'rehabilitat' OR 'fitness' OR 'exercis'] AND asthma.

The most recent searches were conducted on the 25th January 2013.

Searching other resources

Two review authors reviewed the reference lists of all primary studies to identify trials not captured by electronic searches.

Data collection and analysis

Selection of studies

Two review authors (KC, MC) screened articles for potential relevance using the title, abstract or descriptors, or both. The same two review authors screened the full text articles from this second comprehensive list based on study design, populations, interventions and outcomes. A third review author checked through all the articles identified as potentially relevant for inclusion (JP).

Data extraction and management

A combination of two authors (KC, MC, MB and JP) independently extracted data for the trials using a standardised data extraction form prior to data entry into RevMan 5. Two review authors (MC and KC) entered data into RevMan 5, and the same two review authors corresponded with authors to obtain missing data and raw data.

Assessment of risk of bias in included studies

Two review authors assessed the risk of bias for all included studies as per the recommendations in the Cochrane Handbook of Systematic Reviews of Interventions, using a domain-based evaluation (Higgins 2008). We assessed each domain as either high, low or unclear risk of bias using the guidelines from table 8.5.c of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2008). Two review authors (KC and MC, JP or MB) independently assessed the included studies for risk of bias. We resolved conflicts by consensus or by referring to a third party (BS) when disagreement persisted.

Unit of analysis issues

In the case of cluster randomised trials, we planned to perform analyses at the level of individuals whilst accounting for the clustering in the data. We planned to do this using the statistical methods recommended in the Cochrane Handbook for Systematic Reviews of Interventions (chapter 16.3.3) (Higgins 2008) and to have our working checked by a statistician. However, no studies were found which used clusters as the unit of randomisation.

In the case of multi-arm trials where we deemed the studies similar enough to be pooled, we combined the groups using the appropriate formulas in the Cochrane Handbook for Systematic Reviews of Interventions (table 7.7.a for continuous data and chapter 16.5.4 for dichotomous data) (Higgins 2008). 

Dealing with missing data

We evaluated missing information about participants using an available case analysis as described in chapter 16.2.2 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2008). We addressed missing standard deviations by imputing data from the studies within the same meta-analysis or from a different meta-analysis providing these used the same measurement scale, had the same degree of measurement error and the same time periods between baseline and final value measurement (as per chapter 16.1.3.2 of the Cochrane Handbook for Systematic Reviews of Interventions) (Higgins 2008). Where statistics essential for analysis were missing (for example group means and standard deviations for both groups were not reported) and could not be calculated from other data, we attempted to contact the authors to obtain the data. We also asked study authors to provide data for unreported outcomes. We assumed that the loss of participants prior to performance of baseline measurements had no effect on the eventual outcome data for that study. We excluded studies reporting dropout rates higher than 30% from the meta-analysis and instead reported the results only in the text.

Assessment of heterogeneity

We expected to encounter some heterogeneity in factors such as baseline asthma severity, participant characteristics (for example age and physical state), intervention methods, time of measurement of results, and tools used to assess outcomes. We used the Chi² and I² statistics to quantify inconsistencies across studies (Higgins 2008). We also explored heterogeneity by visual inspection of the differences between studies (for example types of interventions, participants). We had planned to further explore heterogeneity using subgroup analysis (as per chapter 9.5.3 of the Cochrane Handbook for Systematic Reviews of Interventions), if there had been a sufficient number of studies (Higgins 2008).

Assessment of reporting biases

We had planned to assess reporting biases through visual inspection of a funnel plot, if we had been able to pool 10 or more studies in one meta-analysis. Although potential reporting, or publication, biases can be assessed using a funnel plot, asymmetry in a funnel plot may also occur due to true heterogeneity, poor methodological design or artefact. If we had found asymmetry in the funnel plots, we planned to include contour lines corresponding to perceived milestones of statistical significance (P = 0.01, 0.05, 0.1 etc), which may help to differentiate between asymmetry due to publication bias from that due to other factors (Higgins 2008).

Data synthesis

We entered data into RevMan 5 software. We pooled continuous data with a fixed-effect model, however in the presence of significant heterogeneity, as determined by a combination of the I² greater than 60% and Chi² P less than 0.01, we used a random-effects model to account for expected differences in the intervention and population etc.

We planned to pool dichotomous data using a Peto odds ratio (OR).

Subgroup analysis and investigation of heterogeneity

We had planned to perform subgroup analysis for each classification of intervention (for example swimming, running, cycling) if a sufficient number of included studies had been available.

Sensitivity analysis

We conducted sensitivity analyses by excluding studies with an unclear or high risk of bias for sequence generation or allocation concealment, or both. We also conducted sensitivity analysis by removing studies with participants with significant co-morbidities from the analyses.

Results

Description of studies

Results of the search

There were 1948 citations identified from the initial search of the pre-specified databases. Four additional articles were retrieved following handsearching of reference lists of potentially relevant studies and contacting authors, resulting in a total of 1939 citations after the duplicates were removed. From this list, 110 were identified as potentially relevant and full text articles were retrieved for closer inspection. Two review authors independently identified that 21 of these articles (29 citations) fulfilled the inclusion criteria of the review, of which two were newly included studies for the 2013 update (Boyd 2012; Wicher 2010). Two additional studies were also identified as awaiting classification as limited data were presented from scientific abstracts only (Pinto 2012; Pollart 2012). The remaining 79 citations were excluded, 20 of which were considered 'not relevant' to the review, leaving 54 studies (59 citations) that were relevant to the review topic. Reasons for exclusion are reported in the Characteristics of excluded studies table (also see Figure 1).

Figure 1.

Study flow diagram.

Included studies

See Characteristics of included studies. Twenty-one studies were identified as meeting the inclusion criteria, involving randomisation of 772 people. Two of these were new studies published since the previous review. The 21 trials were published between 1980 and 2012. Sample size ranged from 14 to 101 participants. All studies were randomised controlled trials of people with asthma undertaking physical training (whole body aerobic exercise) lasting for at least 20 to 30 minutes, two to three times a week, with a minimum duration of four weeks. The length of the physical training programs varied from six to 16 weeks.

Excluded studies

Fifty-four studies were excluded based on methodological grounds and we provided the reasons for exclusion in the Characteristics of excluded studies table. Thirty-four were not randomised, 14 included inadequately designed controls, three had intervention durations too short to meet the pre-specified criteria, and eight had other reasons for exclusion.

Risk of bias in included studies

Assessment of study quality was difficult due to either the limited availability of data or poor methodological reporting. All studies mentioned randomised allocation though only seven studies provided the exact methods (Fanelli 2007; Mendes 2010; Mendes 2011; Moreira 2008; Turner 2010; Varray 1991; Varray 1995). See the 'Risk of bias' tables (in Characteristics of included studies) for further information and Figure 2 and Figure 3. We did not ask for confirmation regarding 'Risk of bias' characteristics from all authors due to concerns about overburdening the authors with our requests as we were already asking for raw data for meta-analyses.

Figure 2.

Methodological quality graph: review authors' judgements about each methodological quality item presented as percentages across all included studies.

Figure 3.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Allocation

Allocation concealment was assessed as adequate in only two studies where we were able to obtain a copy of the protocol (Moreira 2008; Turner 2010). The remaining 19 studies were all unclear.

Blinding

Due to the nature of the study interventions it is understood that blinding of participants was not possible. However, one study (Swann 1983) did mention 'double blinding', though exactly who was part of that blinding process was not described; as such the bias for blinding of participants was unclear in this study. The remaining 20 studies all received a high risk of bias assessment for this domain.

Two studies reported blinding of outcome assessors and were therefore judged to be at low risk of bias (Ahmaidi 1980; Counil 2003), three other studies clearly stated that the outcome assessors were not blinded (Mendes 2010; Mendes 2011; Turner 2010), whilst the remaining 16 studies had an unclear risk of bias.

Incomplete outcome data

Incomplete outcome reporting of data was evident in two studies, which we judged to be at high risk of bias (Girodo 1992; Weisgerber 2003). The other trials were judged to be at low risk of bias (Counil 2003; Fanelli 2007; Gonçalves 2008; Matsumoto 1999; Moreira 2008; Turner 2010; Van Veldhoven 2001; Varray 1991) or unclear for the remaining 11 studies.

Selective reporting

Reporting biases were evident in nine studies (Ahmaidi 1980; Boyd 2012; Fanelli 2007; Girodo 1992; Matsumoto 1999; Mendes 2010; Varray 1991; Wang 2009; Wicher 2010), which included post hoc methods being used and the data presented pictorially or incompletely rather than reported as absolute values (that is the data could not be meta-analysed). We judged the remaining 12 studies as at unclear risk of selective reporting.

Other potential sources of bias

We identified other potential sources of bias in six studies (Boyd 2012; Fanelli 2007; Gonçalves 2008; Mendes 2010; Mendes 2011; Weisgerber 2003). Within the published abstract of the Boyd 2012 study the authors reported that 20 adults were to be recruited, yet only 19 were reported as being recruited in the primary manuscript with no explanation as to why the 20 participants were not recruited. The Weisgerber 2003 study had significant baseline imbalances (for height and FVC), with no mention of adjustments for these imbalances in the data analysis methods. In addition, the authors stated that the intervention may not have had sufficient intensity and duration to demonstrate a significant result. Similarly, the Fanelli 2007 study also had significant baseline imbalances between groups, which were not reported as being adjusted for in the data analysis methods (more intervention participants had peak VO values < 70% predicted than the controls at baseline, P < 0.05). In addition, the authors reported possible contamination in the control arm through the use of education and written action plans, which could lead to underestimation of the true effect of the intervention. Twenty-six of 68 participants enrolled into the Mendes 2011 study were simultaneously enrolled into the Mendes 2010 study, however the authors of the studies supplied the raw data excluding the overlapped participants and thus the trials were able to be included in the meta-analyses.

We identified two studies as having no other potential biases (Counil 2003; Silva 2006), whilst we could not be sure whether there were any other potential biases in the remaining 13 studies and we therefore judged these to be at unclear risk of bias.

Effects of interventions

See: Summary of findings for the main comparison Physical training for asthma

See also Summary of findings for the main comparison

Asthma symptoms

Nine studies reporting results for 315 participants measured asthma symptoms according to different methods (Boyd 2012; Gonçalves 2008; Mendes 2010; Mendes 2011; Swann 1983; Turner 2010; Varray 1991; Wang 2009; Wicher 2010). The Boyd 2012 study reported asthma control as a composite value according to the Juniper Asthma Control Questionnaire that integrates common indicators of asthma management including the use of bronchodilators, nocturnal symptoms, cough, activity level and pulmonary function. There was no significant difference in asthma control between the groups. One participant in the intervention group did experience an exacerbation during her 12 weeks of exercise, however the authors reported that the exacerbation did not appear to be triggered by the exercise program and that her study data were eventually discarded due to faulty heart rate monitor recordings. Three studies on 151 people (which excluded the known duplications between Mendes 2010 and Mendes 2011) reported on frequency of asthma symptoms, which was assessed by monthly sums of days free of asthma symptoms (Gonçalves 2008; Mendes 2010; Mendes 2011). The intervention groups in all three studies showed improvements in symptom free days over the controls; however, following attempts to meta-analyse the data, which suggested that it was not normally distributed, meta-analysis was deemed inappropriate (Gonçalves 2008: intervention 24.8 days (95% confidence interval (CI) 23 to 27) versus control 15.7 days (95% CI 9 to 21), P < 0.02; Mendes 2010, days without symptoms 30 days after study commencement: intervention 21.36 days (95% CI 7 to 27) versus control 14.47 days (95% CI 6 to 24); 60 days after study commencement: intervention 22.71 days (95% CI 11 to 29) versus control 15.51 days (95% CI 10 to 24); 90 days after study commencement: intervention 23.11 days (95% CI 11 to 27) versus control 15.84 days (95% CI 9 to 26), P < 0.001; Mendes 2011, days without symptoms 30 days after study commencement: intervention 23.17 days (95% CI 20 to 25) versus control 14.63 days (95% CI 10 to 18); 60 days after study commencement: intervention 24.33 days (95% CI 22 to 26) versus control 14.25 days (95% CI 10 to 18); 90 days after study commencement: intervention 24.83 days (95% CI 23 to 27) versus control 15.63 days (95% CI 9 to 21)). One study (Turner 2010) reported that asthma control (which was assessed by a six-point score, Ages and Stages Questionnaire (ASQ)) was unchanged in either group during the intervention period, or after three months follow-up post-intervention. Varray 1991 reported that there was no change in frequency of asthma attacks during the intervention period, and the Swann 1983 trial reported no difference between the two groups for the daily score of asthma symptoms during the study. In the study by Wang (Wang 2009), there was a statistically significant improvement in the severity of asthma in the experimental group compared with the control group (daily severity of asthma was monitored at the same time of the day based on National Heart, Lung and Blood Intitute Criteria (NHLBI 2011)). However, this outcome may have been biased by the fact that the intervention group had a greater compliance with controller medications. Authors of the Wicher 2010 study reported that the number of exacerbations for both groups was the same before and during the study, however no numerical data or P values were presented.

Peak expiratory flow rate (PEFR) (L/min)

Four studies reporting results for 153 people contributed data on PEFR (Mendes 2011; Van Veldhoven 2001; Wang 2009; Weisgerber 2003). Two of these studies (Van Veldhoven 2001; Wang 2009) were included in a meta-analysis, however due to significant heterogeneity as indicated by an I² statistic of 96% they were not able to be pooled (Analysis 1.1). The reason for this heterogeneity is unknown, although possible contributors included: population (Asian versus Dutch), intervention characteristics (swimming versus gymnasium activities) and duration of intervention (six weeks versus 12 weeks) for Wang 2009 and Van Veldhoven 2001 respectively. Better medication compliance in the intervention group of the Wang study may also have contributed. Weisgerber 2003 reported that there was no change in PEFR between the two groups post-intervention; these data were however excluded from the meta-analysis due to a dropout rate of over 30%. Data in the Mendes 2011 study showed no difference between groups, but were unable to be meta-analysed as they were reported as medians and inter-quartile ranges.

Forced expiratory volume in 1 sec (FEV1) (L)

Sixteen studies with results for 399 people reported on resting FEV1 at the endpoint. However, the results were reported in a number of different ways including: absolute values, per cent predicted, mean of absolute change, or change from baseline. Pooled data from nine studies which reported the absolute value of FEV1 at follow-up showed no significant effect of physical training on FEV1 (MD -0.00 L; 95% CI -0.10 to 0.10; Analysis 1.2). Another study (Weisgerber 2003) reported that physical training had no effect on FEV1, however these data could not be used in the analysis due to a dropout rate of greater than 30% (Weisgerber 2003).

Forced vital capacity (FVC) (L)

Thirteen studies reported follow-up data on resting FVC, however only seven trials involving 301 people provided data that could be pooled (Mendes 2010; Mendes 2011; Moreira 2008; Van Veldhoven 2001; Varray 1991; Wang 2009; Wicher 2010). The pooled results showed that physical training had no effect on FVC (MD 0.00 L; 95% CI -0.13 to 0.14; Analysis 1.3). Weisgerber 2003 also reported that physical training had no effect on FVC, however the data were excluded from the meta-analysis due to a dropout rate of more than 30%.

Minute ventilation at maximal exercise (VEmax) (L/min), maximal oxygen uptake (VOmax) (mL/kg/min), work capacity

Twelve studies performed cardiopulmonary assessment with an attempt to measure either VOmax, work capacity or VEmax post-intervention. According to the pooled data from five studies involving 200 people, physical training showed no evidence of improvement for VEmax (MD 3.08 L/min; 95% CI -0.63 to 6.79; Analysis 1.4). Tests for heterogeneity produced an I² = 64% presenting moderate levels of heterogeneity.

Four studies reported on the VOmax as change from baseline only and therefore could not be meta-analysed. Data from eight studies involving 267 people could be pooled. These trials compared endpoint VOmax for the two groups of participants and showed that physical training produced a statistically and clinically significant increase in VOmax (MD 4.92 mL; 95% CI 3.98 to 5.87; P < 0.00001; Analysis 1.5). Tests for heterogeneity were not significant (I² = 44%). According to data from four studies (Ahmaidi 1980; Boyd 2012; Matsumoto 1999; Van Veldhoven 2001), physical training resulted in an increase in work capacity, however these results could not be pooled as outcomes were reported using a mixture of change scores and absolute values. A statistically and clinically significant difference in work capacity was evident in two studies (Ahmaidi 1980; Matsumoto 1999), whereas another study showed no significant benefits between intervention and control (Van Veldhoven 2001).

Maximal heart rate (HRmax) (bpm)

Five studies with results for 97 people reported HRmax as an outcome measure with the overall pooled effect for four studies (81 people) being an increase in HRmax (MD 3.16 bpm; 95% CI 0.52 to 5.80). However, this overall mean effect contained significant heterogeneity as determined by a combination of the I² statistic (I² = 93%), visual inspection of the forest plot, and examination of study characteristics. Following a sensitivity analysis, elimination of the Counil 2003 and Van Veldhoven 2001 studies removed the heterogeneity (I² = 46%). There was still a significant increase in overall mean HRmax with two of the studies (MD 3.67 bpm; 95% CI 0.90 to 6.44; Analysis 1.6). Authors for the remaining study (Boyd 2012) reported that HRmax significantly increased in the exercise arm, however the data were not displayed in a way that could be meta-analysed.

Maximal ventilatory ventilation (MVV)

One study (Wicher 2010) reported MVV for participants of the intervention group only, with improvements observed between the pre- and post-test measurements (56.83 L/min + 18.25 to 66.81 L/min + 23.02; P = 0.001).

Six-minute walking distance (6MWD)

One study reporting results for 34 people (Turner 2010) measured the effect of physical training on functional exercise capacity as measured by the 6MWD post-intervention. There was an increase in 6MWD following exercise training of 36 + 37 metres in the exercise group and 6 + 38 metres in the control group, however this difference between the groups did not reach statistical significance.

Quality of life (QoL)

Five studies with results for 212 people reported health-related quality of life using four different scales: PAQLQ (Paediatric Asthma Quality of Life Questionnaire) (Fanelli 2007; Moreira 2008), AQLQ (Asthma Quality of Life Questionnaire) (Turner 2010), SF-36 (Short Form-36) (Turner 2010), and QOL-EPM (Quality Of Life - Escola Paulista de Medicina) (Gonçalves 2008; Mendes 2010). Four of these trials reported that physical training improved the quality of life scores of asthma participants. Two studies (Gonçalves 2008; Mendes 2010) reported statistically and clinically significant differences between the two groups (intervention and control) for QoL total scores and for physical limitation, symptom frequency and psychosocial subscores immediately following physical training. In the study by Turner (Turner 2010) there was statistically and clinically significant improvement in all domain scores of the health-related QoL (AQLQ) in the exercise group compared with the control group post-intervention. The Fanelli study (Fanelli 2007) also reported significant statistical and clinical improvements in health-related QoL (PAQLQ) total scores as well as all domain scores in the exercise group compared with the controls. In the study by Moreira (Moreira 2008) QoL scores were not statistically significantly different between the exercise and control groups. The authors reported that the number of participants achieving a clinically important improvement in the PAQLQ score from baseline did not differ between groups either (see also Characteristics of included studies).

Bronchodilator usage

There were no usable data available from any of the studies for bronchodilator usage.

Subgroup analyses

We could not perform subgroup analyses to compare different types of physical training because of the small study numbers and missing outcome data.

Discussion

Summary of main results

This systematic review examined the effects of physical training on people with asthma. Twenty-one randomised controlled trials satisfied the inclusion criteria, with the majority of the studies including small numbers of participants. Although all studies met the inclusion criteria they differed significantly in terms of intervention characteristics (including frequency, duration and type of intervention), reported outcomes and statistical presentation of data. The statistical presentation of results was a particular issue and limited the analysis as data were presented in such a way that they could not be meta-analysed without raw data being obtained (for example median values instead of means, change scores instead of total scores, and percentage predicted instead of absolute values). None of the studies evaluated longer term benefits of physical training in people with asthma.

According to the available data, physical training was well tolerated by the people with asthma with no adverse effects identified. Data from the available studies suggest that physical training improves asthma symptoms. None of the studies detected a worsening of asthma symptoms following physical training. Exercise-induced bronchoconstriction (EIB) was assessed in three studies. However, it was not one of our pre-specified outcomes for this review. Overall, physical training did not seem to change EIB severity.

Physical training improved cardiopulmonary fitness, as measured by an increase in maximum oxygen uptake (VOmax) and the work load achieved by a participant during exercise testing, without having a significant effect on resting lung function. Studies in healthy people have shown that VOmax may increase by up to 20% (Brooks 1996), the extent being dependent upon initial fitness level, type of training and age. Asthma patients respond to physical training in a similar manner and degree to non-asthma participants (Robinson 1992). Maximum heart rate (HRmax) significantly increased in the group that underwent physical training. A decrease in HRmax is the typical response to training (Brooks 1996). The present finding may indicate that a maximum effort was not achieved in the baseline test or that non-cardiac factors limited exercise capacity initially. For example, training may result in a decrease in the perception of breathlessness resulting in greater maximum exercise effort.

There were insufficient data to meta-analyse the effects of physical training on health-related quality of life. However, this review does provide some limited evidence from available studies that physical training has positive effects on the quality of life of asthma patients. This may also contribute to other health benefits and improved psychosocial well being. Although these positive effects on quality of life could be a translation of improved cardiopulmonary fitness, further studies are required to evaluate this aspect in detail.

Overall completeness and applicability of evidence

The intervention programs in studies which were successful in improving asthma symptoms included aerobic conditioning using a treadmill, other aerobic exercises or swimming. In three out of the four studies that were successful in improving asthma symptoms, exercise was coupled with an asthma education program and breathing exercises (Gonçalves 2008; Mendes 2010; Mendes 2011). Therefore, the effects seen may represent those of a package of care, rather than exercise alone, although this cannot be definitely proven.

Currently, Global Initiative for Asthma guidelines do not provide recommendations for physical training or exercise therapy for asthma management (GINA 2012). It may be appropriate for people with asthma who have stable disease to participate in regular aerobic exercise training programs provided they are educated about prevention and treatment of exercise-induced asthma. This may improve asthma management and reduce the health risks associated with a sedentary lifestyle.

Quality of the evidence

We were unable to assess reporting biases for outcomes in this review due to insufficient numbers of included studies for each outcome (minimum of 10 included studies required for each outcome). As such, the effect of reporting biases on the outcomes in this review are unknown.

Potential biases in the review process

Selecting only randomised controlled trials is a trade off, allowing higher quality evidence to be meta-analysed, on which to base future investigations and research. However, this does have the potential of introducing selection bias by excluding relevant studies which do not fulfil the strict criteria for inclusion within the review. In addition, this review, like all others, is potentially susceptible to publication bias, though attempts are made to reduce this as much as possible with the authors searching the relevant databases for published and non-published studies. Despite numerous attempts to contact study authors for raw data, the inability to obtain all relevant information might introduce a bias that has the potential to alter the outcome of the meta-analysis. Biases that occur due to poor reporting of trial methodology may not be adequately accounted for, despite the rigorous assessment by two independent review authors.

Agreements and disagreements with other studies or reviews

There are many studies (Dogra 2010; Mancuso 2013; Mendes 2010; Turner 2010) and reviews (Avallone 2012; Morton 2011) now reporting that physical activity does not exacerbate asthma symptoms or compromise asthma control, and associations with improvements in asthma are being observed. Likewise the review by Eijkemans 2012, focusing on longitudinal studies, indicated that physical activity may produce a protective effect against asthma development and that individuals with higher levels of physical activity may have a lower risk of developing asthma. A 2012 review of asthma and aerobic exercise produced similar findings to this review in that regular aerobic exercise improved asthma symptom management, lung function and mental health (Avallone 2012). This review included eight studies examining exercise habits, six examining exercise-related symptom perception and physiological responses, and nine looking at aerobic exercise as an intervention for asthma. Overall this empirical evidence also suggested that individuals with asthma are less likely to engage in physical activity than those without asthma; individuals with asthma are not biased in their subjective reporting of symptoms during aerobic exercise and physical inactivity among individuals with asthma has an association with negative health consequences and increased asthma-related difficulties. However, studies examining the mechanisms by which physical training may impact asthma outcomes are lacking (Eijkemans 2012; Scott 2013b). Some studies included in this review have examined several biological indicators (serum IgE, histamine responsiveness, sputum and serum eosinophil cell count, C-reactive protein (CRP) levels) suggesting that exercise may actually reduce airway inflammation (Boyd 2012; Matsumoto 1999; Mendes 2011; Moreira 2008; Wicher 2010). This paucity of data remains and needs to be addressed in order to advance the understanding of and ability to use physical activity to improve asthma care.

Authors' conclusions

Implications for practice

Physical training can improve cardiopulmonary fitness and may have positive effects on health-related quality of life in patients with asthma. These benefits are unrelated to effects on lung function. This review indicates that physical training is well tolerated in people with asthma. The intervention programmes that produced these benefits included aerobic conditioning using a treadmill, other aerobic exercises and swimming. In three of the four studies that were successful in improving asthma symptoms, exercise was coupled with an asthma education program and breathing exercises. There was no evidence of adverse effects caused by physical training on asthma symptoms. As such we found no reason for people with stable asthma to refrain from regular exercise.

Implications for research

There is a need for well conducted randomised controlled trials to assess clinical benefits of physical training in the management of bronchial asthma. The mechanisms by which physical activity impacts asthma remain broadly unknown and further research is required in this area to truly understand the role of exercise in asthma management. Trial sample sizes should be determined before the start of such studies. Specifically, there is a need for further assessment of effects of physical training on asthma symptoms, functional exercise capacity and health-related quality of life. It may also be beneficial to assess longer term effects (one year or more) of physical training and types of aerobic exercises that are more suitable and safer for people with asthma. The results of randomised trials should be reported following the CONSORT guidelines.

Acknowledgements

The authors of this review would like to thank members of the Cochrane Airways Group (St George's, UK), in particular Emma Welsh, Dr Christopher Cates and Elizabeth Stovold, for their support and assistance in formulating and updating this review. We would also like to thank Drs F Mendes, RC Gonçalves, A Varray, J Neder, S Turner, S Jenkins, S Basaran, C Carvalho, A Moreira and J Wang for providing raw or unpublished data relating to their studies.

We would also like to acknowledge the previous review authors FSF Ram, S Robinson and the late PN Black.

Data and analyses

Download statistical data

Comparison 1. Physical training versus control
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 PEFR (L/min) - Fixed effect model2 Mean Difference (IV, Fixed, 95% CI)Totals not selected
2 FEV1 (L)9383Mean Difference (IV, Fixed, 95% CI)-0.00 [-0.10, 0.10]
3 FVC (L)7301Mean Difference (IV, Fixed, 95% CI)0.00 [-0.13, 0.14]
4 VEmax (L/min)5200Mean Difference (IV, Fixed, 95% CI)3.08 [-0.63, 6.79]
5 VOmax (mL/kg/min)8267Mean Difference (IV, Fixed, 95% CI)4.92 [3.98, 5.87]
6 HRmax (bpm)234Mean Difference (IV, Fixed, 95% CI)3.67 [0.90, 6.44]
7 6MWD1 Mean Difference (IV, Fixed, 95% CI)Totals not selected
Analysis 1.1.

Comparison 1 Physical training versus control, Outcome 1 PEFR (L/min) - Fixed effect model.

Analysis 1.2.

Comparison 1 Physical training versus control, Outcome 2 FEV1 (L).

Analysis 1.3.

Comparison 1 Physical training versus control, Outcome 3 FVC (L).

Analysis 1.4.

Comparison 1 Physical training versus control, Outcome 4 VEmax (L/min).

Analysis 1.5.

Comparison 1 Physical training versus control, Outcome 5 VOmax (mL/kg/min).

Analysis 1.6.

Comparison 1 Physical training versus control, Outcome 6 HRmax (bpm).

Analysis 1.7.

Comparison 1 Physical training versus control, Outcome 7 6MWD.

Appendices

Appendix 1. Sources and search methods for the Cochrane Airways Group Specialised Register (CAGR)

Electronic searches: core databases

Database Frequency of search
CENTRAL (the Cochrane Library)Monthly
MEDLINE (Ovid)Weekly
EMBASE (Ovid)Weekly
PsycINFO (Ovid)Monthly
CINAHL (EBSCO)Monthly
AMED (EBSCO)Monthly

 

Handsearches: core respiratory conference abstracts

Conference Years searched
American Academy of Allergy, Asthma and Immunology (AAAAI)2001 onwards
American Thoracic Society (ATS)2001 onwards
Asia Pacific Society of Respirology (APSR)2004 onwards
British Thoracic Society Winter Meeting (BTS)2000 onwards
Chest Meeting2003 onwards
European Respiratory Society (ERS)1992, 1994, 2000 onwards
International Primary Care Respiratory Group Congress (IPCRG)2002 onwards
Thoracic Society of Australia and New Zealand (TSANZ)1999 onwards

 

MEDLINE search strategy used to identify trials for the CAGR

Asthma search

1. exp Asthma/

2. asthma$.mp.

3. (antiasthma$ or anti-asthma$).mp.

4. Respiratory Sounds/

5. wheez$.mp.

6. Bronchial Spasm/

7. bronchospas$.mp.

8. (bronch$ adj3 spasm$).mp.

9. bronchoconstrict$.mp.

10. exp Bronchoconstriction/

11. (bronch$ adj3 constrict$).mp.

12. Bronchial Hyperreactivity/

13. Respiratory Hypersensitivity/

14. ((bronchial$ or respiratory or airway$ or lung$) adj3 (hypersensitiv$ or hyperreactiv$ or allerg$ or insufficiency)).mp.

15. ((dust or mite$) adj3 (allerg$ or hypersensitiv$)).mp.

16. or/1-15

Filter to identify RCTs

1. exp "clinical trial [publication type]"/

2. (randomised or randomised).ab,ti.

3. placebo.ab,ti.

4. dt.fs.

5. randomly.ab,ti.

6. trial.ab,ti.

7. groups.ab,ti.

8. or/1-7

9. Animals/

10. Humans/

11. 9 not (9 and 10)

12. 8 not 11

The MEDLINE strategy and RCT filter are adapted to identify trials in other electronic databases.

What's new

DateEventDescription
25 January 2013New search has been performedLiterature search updated
25 January 2013New citation required and conclusions have changedTwo new included studies and two excluded but relevant studies identified; raw data obtained from Mendes and Goncalves as such meta-analyses re-run; expanded background and discussion into relevant subheadings, and sections re-written; added summary of findings table; updated results section

History

DateEventDescription
14 April 2011New search has been performedNew literature search run.
14 April 2011New citation required and conclusions have changedEight new included studies and 15 'excluded but relevant' studies added; Characteristics of included studies table reformatted and updated; risk of bias assessed for all studies; three previously included studies excluded following 'Risk of bias' assessment on the basis of inadequate reporting of randomisation.
18 August 2008AmendedConverted to new review format.
5 July 2005New citation required and conclusions have changedFive new studies added (Counil 2003 with 16 participants; Huang 1989 with 90 participants; Matsumoto 1999 with 16 participants; van Veldhoven 2001 with 47 participants; Weisgerber 2003 with eight participants). Twenty-five studies were added to the excluded studies list. Maximum expiratory ventilation is now significantly better with physical training. This is in line with the increases previously seen in cardiopulmonary fitness as measured by increases in maximum oxygen uptake. Although the results of the review now have narrower confidence intervals compared to the original review the conclusion remains unchanged.
2 May 2005New search has been performedLiterature searches re-run in May 2005.

Contributions of authors

KC and MC updated the protocol, reviewed the literature and identified studies for inclusion. MC and KC performed the majority of data extractions whilst second author data extraction was performed by a combination of KC, MC, JP and MB. Data were entered by KC and MC and analysed by KC who interpreted the data with the assistance of AE and BS. KC and MB extracted new study data for the 2013 update whilst KC re-wrote the background, results, discussion and conclusion for the 2013 update. KC and BS addressed peer and editorial reviewer comments. JP, KC and BS reviewed the manuscript. AE directed the data analysis and BS supervised the completion of the review.

Declarations of interest

None of the authors have any known conflicts of interest. No funding has been received for this review.

Sources of support

Internal sources

  • Respiratory Medicine Unit, The Queen Elizabeth Hospital, Adelaide, Australia.

External sources

  • No sources of support supplied

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Ahmaidi 1980

Methods

Country: France

Design: Randomised controlled trial

Objectives: To assess the validity of the 20-minute shuttle test (20-MST) to estimate maximal oxygen uptake (VO max) and its ability to register cardiorespiratory modifications over the course of an individualised aerobic training program for mild to moderately severe asthma in children acclimatised to moderate altitude

Study Site: Not stated

Methods of Analysis: Students paired t-test, linear regression analysis, Bland and Altman procedure to calculate bias, two-way analysis of variance

Participants

Randomised: 20 in total; Intervention n = 10; Control n = 10

Age: Intervention mean = 14.1 +1.8 years; Control mean = 13.8 + 2.1 years

Gender: Not given

Asthma diagnosis criteria: All were known to have had recurrent reversible wheezing episodes and were required to fulfil at least three of the following criteria (1) clinical: family history of asthma or personal history of eczema, conjunctivitis, or rhinitis caused by a known allergen or both; (2) allergic: all the children had a cutaneous hypersensitivity to one or several allergens; (3) immunologic: blood IgE levels were determined by the paper radio immunoabsorbent test (4) functional: improvement 15% at least in the FEV by inhaling bronchodilator

Recruitment means: Not stated

Co-morbidities included: None mentioned

Participant exclusion reasons: Not stated

Interventions

Setting: Outdoor track for intervention group

Intervention description: The training group participated in 36 sessions (3 d/wk for 3 months) of running on an outdoor track; each session lasted 1 hour during which the children ran for 10 min, 3 times, at their own predetermined ventilatory threshold

Control description: Served to determine whether testing had an effect on VO max values in the event that the training program was without effect

Duration of intervention: 36 sessions; 3 days per week for 3 months

Intervention delivered by: Not explicitly stated

Outcomes

Pre-specified outcomes: VOmax, Vth, HRmax, Wmax, maximum oxygen pulse

Follow-up period: 3 months

NotesLung function testing was done for the whole sample (of all possible 48 participants) after the run-in period and before training but not after training
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskMethods for allocation concealment not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Low riskDetermination of ventilatory threshold during maximal exercise test was done independently by two reviewers without knowledge of other results or participant identities, The shuttle test was accompanied and encouraged by an investigator who did not know to which group they belonged
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of yes or no
Selective reporting (reporting bias)High riskPost hoc methods of comparison for the intra- and inter-group comparisons were made when the analysis of variance-F ratio was significant
Other biasUnclear risk

Some potential concerns mentioned by the authors regarding outcome measurements (e.g. incidents of premature stopping of the laboratory test causing lower HR values; authors state “large number of participants performing the 20-MST at once may have made it difficult to evaluate accurately each individual”)

Baseline characteristics not given separately for the 2 groups (given together for the entire population), thus unable to assess for baseline imbalance

Boyd 2012

Methods

Country: United States of America

Design: Randomised Controlled Trial; Parallel group proof of concept study

Objective (Aim): To examine the effect of moderate intensity aerobic exercise on asthmatic responses in adult patients

Study Site: University of Alabama at Birmingham

Methods of analysis: Outcomes reported before and after protocol completion; Baseline characteristics compared, Paired comparisons were made using Fisher's exact test for nominal characteristics and Wilcoxon Rank Sum for continuous measures; Repeated measures analysis of variance techniques were applied to examine changes over time and to determine if the changes differed by group; Distributional properties of residuals from the repeated measures analysis of variance models were examined with only minor deviations observed for all outcomes

Participants

Randomised: 19 adults

Age: Intervention 53 (38-62) years; Control 54 (33-78) years

Gender: Males and females

Asthma diagnosis criteria: Mild-moderate persistent asthma defined by the NAEPP guidelines with at least a 12% FEV1 reversibility; Physician diagnosis of asthma was also documented with evidence of reversible airflow obstruction

Recruitment: By the study coordinator from the Universtiy of Alabama at Birmingham Lung Health Center's Asthma Clinical Research Database

Co-morbidities: None reported; Individuals with major illnesses were excluded

Subject exclusion criteria: Individuals who smoked within six months from the start of the exercise protocol or with greater than a 10 pack year smoking history were excluded to reduce the inclusion of patients with COPD; Individuals with major illnesses including coronary artery disease, congestive heart failure, stroke, severe hypertension, immunodeficiency states or other conditions that would have interfered with participation in the study or collection of proposed outcome measures were also excluded; Individuals who were unable or unwilling to provide consent, perform the exercise protocol, provide pre- and post-study measurements, be contacted via telephone or who intended to move out of the area within six months were also excluded

Interventions

Setting: University of Alabama at Birmingham clinical exercise facility

Intervention descriptions: 12-week protocol of moderate intensity aerobic exercise plus usual care with a frequency of three times per week, 30 minutes each session at a steady intensity that achieved 60-75% of maximum heart rate (HRmax); A mandated graded treadmill test was used to determine each subject's HRmax; Recommended exercise prescription included a five minute warm up, 30 minutes of steady state exercise via walking and a five minute cool-down; In addition, study subjects randomised to the moderate intensity aerobic exercise group received a three month free membership to a local exercise facility at the time of the initial visit

Control descriptions: Usual care alone (standard patient education); To control for interaction/attention within the exercise group, individuals receiving usual care also received weekly phone calls from the study coordinator; During these brief phone calls the study coordinator asked the subject how he/she was doing and if there was anything related to his/her respective program with which he/she needed assistance

Duration of intervention: 12 weeks

Intervention delivered by: Staff instructed subjects in the use of the heart rate monitor at the initial visit; No other information provided

Outcomes

Pre-specified outcomes: Asthma control (Juniper Asthma Control Questionniare ACQ), pro-inflammatory targets in peripheral blood and nasal lavage (eosinophilic cationic protein, serum cytokines, peripheral blood immune cell populations), lung function parameters (FEV, FEV/FVC,) and fitness measures (VO peak, HRmax, RER, total treadmill time)

Follow-up period: 12 weeks (post-intervention)

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomised mentioned as developed by a biostatistician, however methods not described
Allocation concealment (selection bias)Unclear riskBiostatistician developed permuted variable size block randomisation to allocate subjects to the two study arms, thus the block size prevented exact knowledge of the next randomisation assignment, however, no mention of specific allocation blinding or allocation methodology
Blinding (performance bias and detection bias)
For participants
High risk

Due to the nature of the intervention subjects were aware of their group assignment

 

Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskNo mention of blinding for outcome assessors
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of yes or no
Selective reporting (reporting bias)High riskData not reported in a way that can be meta-analysed, visual representation only; Attrition reported (19 to 16), however reasons not described
Other biasHigh riskAbstract states that twenty adults will be recruited, yet only 19 are reported as being recruited in the primary manuscript with no explanation as to why the 20 subjects were not recruited

Cochrane 1990

Methods

Country: Scotland

Design: Randomised controlled trial with a six-week run-in period

Objectives: To assess clinical and physiological effects of a medically supervised indoor physical training program for people with asthma

Study Site: Indoor facility not explicitly defined

Methods of Analysis: Students t-test; variables adjusted for; linear association between pairs of continuous variables measured with the Pearsons coefficient of correlation; paired t-test

Participants

Randomised: 36 adults

Age: Range 16 to 40 years

Gender: Total population only: n = 14 male n = 22 female

Asthma diagnosis criteria: Chronic asthma of mild to moderate severity as defined by a requirement for regular prophylactic treatment and reproducible airways obstruction when treatment withdrawn

Recruitment means: Following initial evaluation patients were randomly assigned to intervention and control. No further details provided

Co-morbidities included: Participants were free from any concomitant illness

Participant exclusion reasons: Not explicitly stated

Interventions

Setting: Indoor facility not explicitly defined

Intervention description: 30-minute training sessions, 3 times a week for 3 months; educational sessions separate from the control group

Control description: Attended similar but separate educational sessions to the intervention group only

Duration of intervention: 30-minute training sessions, 3 times a week for 3 months

Intervention delivered by: Medical supervision was provided during all hospital training sessions; Audio tape instructions for home use were available for patients unable to attend any of the hospital sessions

Outcomes

Pre-specified outcomes: FEV, VOmax, VEmax, maximum oxygen pulse, HRmax, RR, Vth and VE/VOmax

Follow-up period: 3 months

NotesThe mean number of training sessions undertaken by each patient was 36 (range was 19-42 sessions)
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskInformation not available
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskMethods not described
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of yes or no
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasUnclear riskOutcomes (particularly FEV) may have been affected in the 9 participants whom had their treatment altered during the study period

Counil 2003

Methods

Country: France

Design: Randomised controlled trial with no run-in period

Objectives: To assess the effect of a training protocol on aerobic and anaerobic fitness in children with asthma

Study Site: The study took place in a small city in the Pyrenees Mountains

Methods of Analysis: Mann-Whitney Wilcoxon rank test, 2-way analysis of variance, multiple regression models

Participants

Randomised: 16 total; 14 completed the study; Intervention n = 9 (completed n = 7); Control n = 7 (completed n = 7)

Age: Intervention mean = 14.0 + 0.6 years; Control mean = 13.9 + 0.8 years; Range 10 to 16 years

Gender: Only males in both arms

Asthma diagnosis criteria: 1) personal or familial history of allergy, 2) personal history of acute wheezing 3) reversible airway obstruction documented by lung function testing i.e. improvement of 15%, at least in FEV and/or 30% in forced expiratory flow 25-75 by inhaling a bronchodilator, 4) positive specific immunoglobulin E to inhaled allergens by a multi-allergen allergosorbent test and/or cutaneous hypersensitivity to one or several allergens, and 5) no evidence of other lung disease

Recruitment means: Through pulmonary rehabilitation clinics

Co-morbidities included: None mentioned

Participant exclusion reasons: Not stated

Interventions

Setting: A laboratory in France

Intervention description: The training group exercised by continuous cycling 3 times weekly for 6 weeks, 45 minutes each session; The target heart rate was individualised and corresponded to the anaerobic threshold level; Training sessions were supervised

Control description: Not explicitly defined

Duration of intervention: 6 weeks; 3 times a week

Intervention delivered by: Training instructor and a pulmonologist

Outcomes

Pre-specified outcomes: Chronic asthma of mild to moderate severity as defined by a requirement for regular prophylactic treatment and reproducible airways obstruction when treatment withdrawn

Follow-up period: Nothing beyond 6 weeks intervention period

PEFR, FEV, FVC, FRC, VEmax, HRmax, VO, episodes of wheeze (days), work capacity W, FRC%, maximal aerobic power, ventilatory reserve, aerobic threshold

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskInformation not available
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Low riskAuthors state "testing was done blindly"
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll incomplete outcome data adequately addressed
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasLow riskNo other sources of bias identified

Fanelli 2007

Methods

Country: Brazil

Design: Randomised controlled trial with a 2-week run-in period

Objective: Evaluate whether exercise training would improve HQoL and reduce EIB (exercise-induced bronchoconstriction) severity in children with moderate to severe persistent asthma. Secondly, assess the effects of training on aerobic fitness and daily use of inhaled steroids

Study site: Recruited from a tertiary centre specialising in paediatric asthma - study site not otherwise specified

Methods of Analysis: Kolmogorov-Smirnov test for normality; non-paired t-test or Mann-Whitney test for variables with parametric and non-parametric distributions for between group baseline comparisons. Chi² or Fisher test to evaluate between group changes in clinical and functional outcomes and response to training; Sign test to determine changes on categorical variables (e.g. level of aerobic impairment); Spearman's ranked correlation coefficient for associations between variables

Participants

Randomised: 38 in total; Intervention n = 21; Control n = 17

Age: Intervention mean= 11 + 2 years; Control mean = 10 + 2 years

Gender: Intervention n = 12 males/9 females; Control n = 11 males/6 females

Asthma diagnosis criteria: 1) Global Initiative for Asthma (GINA) guidelines 2) under medical treatment for at least 6 months before study 3) in a stable phase of the disease, that is, without any recent disease exacerbation or change in medication usage

Recruitment means: From a tertiary centre specialising in paediatric asthma

Co-morbidities included: Patients with other cardiopulmonary and/or musculoskeletal diseases were excluded

Participant exclusion reasons: Patients with other cardiopulmonary and/or musculoskeletal diseases; Under medical treatment <6 months before the study; recent (15 day) exacerbations or changes in medication usage

Interventions

Setting: Tertiary centre specialising in paediatric asthma (no further information provided)

Intervention description:

Education program: in asthma control; 2 once-a-week classes, each lasting 2 hours including: education video-tape, interactive classes to clarify doubts, lessons on disease pathophysiology, use of medication (relief and maintenance), WAP of action in case of worsening of symptoms

Physical training program: twice a week for 90 min during 16 wk; four parts: warm-up/stretching, aerobic exercise, upper- and lower-limb and abdomen endurance exercises, cooling down/stretching/relaxing

Initial 8 sessions of PT program were a build-up-period in which training intensity was gradually increased.

Control description: Non-exercising control group

Education program: in asthma control; 2 once-a-week classes, each lasting 2 hours including: education video-tape, interactive classes to clarify doubts, lessons on disease pathophysiology, use of Rx (relief and maintenance), WAP of action in case of worsening of symptoms

Duration of intervention: 16 weeks; Education program: twice a week for 2 hours; Physical training program: twice a week for 90 min

Intervention delivered by: Not explicitly stated

Outcomes

Pre-specified outcomes: QoL using Paediatric asthma quality-of-life questionnaire (PAQLQ); pulmonary function test; incremental cardiopulmonary exercise tests (CPET); exercise challenges with post-effort breathlessness measurements (Borg scale - Dyspnoea)

Follow-up period: Four months

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomly allocated by drawing lots
Allocation concealment (selection bias)Unclear riskAllocation concealment not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear risk“A single physician who was blinded to patient’s group allocation was in charge of the medical follow-up.” However, it is not clear if this is follow-up of outcomes or general follow-up
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll incomplete outcome data adequately addressed
Selective reporting (reporting bias)High riskResults for PQALQ and FEV are reported as change scores and graphically. Other results are only reported as baseline or change scores only and as such can not be meta-analysed.
Other biasHigh riskBaseline imbalances between groups - more intervention participants had peak VO values < 70% predicted than controls (15/21 versus 9/17, respectively P < 0.05); possible ineffective reporting mechanisms for observed reductions in corticosteroid use through increased use of rescue medication however, participants did not report increased use; possible contamination through education and written action plans in the control group which could underestimate the true effect of the intervention

Farid 2005

Methods

Country: Iran

Design: Randomised controlled trial

Objectives: To examine the effects of a course of aerobic exercise on pulmonary function and tolerance of activity in asthma patients

Study Site: Not explicitly stated

Methods of Analysis: Not reported

Participants

Randomised: 36 in total; Intervention n = 18; Control n = 18

Age: Intervention mean = 27 years; Control mean = 29 years

Gender: Intervention n = 8 males/10 females; Control n = 8 males/10 females

Asthma diagnosis criteria: Confirmation by investigator using clinical examinations, pulmonary function tests, skin prick test for aeroallergen and 6-minute walk test

Recruitment means: Allergy clinic

Co-morbidities included: None mentioned

Participant exclusion reasons: None explicitly stated

Interventions

Setting: Not explicitly stated

Intervention description: Aerobic exercise plan, 15 minutes of warming up and tensile exercise before 20 minutes of aerobic practice. No further description provided

Control description: No plan of exercise

Duration of intervention: Three sessions a week for 8 weeks

Intervention delivered by: Not reported

Outcomes

Pre-specified outcomes: Spirometry (FEV, FVC, FEV/FVC, PEF, FEF 25%-75%, MVV); RF (respiratory frequency) and 6-minute Walk Test (6MWT)

Follow-up period: Two months

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk Authors state "The patients were randomly put into two groups" but no further details provided
Allocation concealment (selection bias)Unclear riskDetails not provided
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskDetails not provided
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of yes or no
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasUnclear riskFew methodological details are reported which make it difficult to determine whether the study might have had other problems leading to bias

Girodo 1992

Methods

Country: Canada

Design: Randomised controlled trial with a run-in period

Objectives: To examine effects of deep diaphragmatic breathing in terms of symptomatic and behavioural characteristics of asthma patients

Study Site: Not explicitly stated

Methods of Analysis: ANOVA

Participants

Randomised: 67 were randomly allocated to one of three groups

Age: Mean age varied from 28-33 years

Gender: Not stated

Asthma diagnosis criteria: Doctor's diagnosis

Recruitment means: Media solicitations for people with asthma to volunteer for an experimental breathing study yielded 274 respondents; 150 eliminated, eventually 92 volunteers remained; of these 67 were randomly allocated to one of three groups

Co-morbidities included: Not explicitly stated

Participant exclusion reasons: history of allergies, asthma so severe as to preclude participation, chest disease or diabetes, or inability to make a 26-week commitment to the program

Interventions

Setting: Not explicitly stated

Intervention description: No details provided in published paper, written to author for information; Intensity level not mentioned

Control description: Wait-list control

Duration of intervention: 16 weeks

Intervention delivered by: Group DDB1 was led by a woman trainer; group DDB2 was taught by a 25-year-old man who had asthma and obtained significant therapeutic benefits from the use of the technique himself; group PE was led by a female medical student also experienced in physical education.

No details provided in published paper, Intensity level not mentioned

Outcomes

Pre-specified outcomes: Symptomatic and behavioural characteristics including medication use, frequency and intensity of asthma symptoms, asthma symptom checklist, physical activity inventory

Follow-up period: 6 months

No details provided in published paper

NotesWe ignored the deep diaphragmatic breathing data and only used the control and physical training data
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskDetails not provided
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskDetails not provided
Incomplete outcome data (attrition bias)
All outcomes
High riskNo details provided for attrition of participants, larger number of dropouts from the intervention group
Selective reporting (reporting bias)High riskPost hoc analysis was conducted for 'time spent in physical activities between groups'
Other biasUnclear riskNo mention of participant comparability between groups for characteristics or outcomes at baseline

Gonçalves 2008

Methods

Country: Brazil

Design: Randomised controlled trial

Objectives: To evaluate the role of an aerobic physical training program on psychosocial characteristics, QOL, symptoms and exhaled nitric oxide  in individuals moderate or severe asthma

Study Site: Not stated

Methods of Analysis: ANOVA, Student t-test, Kolmogorov-Smirnov test

Participants

Randomised: 23 total; 20 completed the study; Intervention n = 11 (completed n = 10); Control n = 12 (completed n = 10)

Age: (Only for those participants completing the study) Intervention median = 34.6 years (95% CI 21.0 - 47); Control median = 34.6 years (95% CI 21.0 - 47.0)

Gender: Intervention n = 3 males/7 females; Control n = 4 males/6 females

Asthma diagnosis criteria: Global Initiative for Asthma (GINA) guidelines

Recruitment means: Recruited after a medical consultation; no details provided

Co-morbidities included: None reported

Interventions

Setting: Not reported

Intervention description:

Education programme: Four hour education program which comprised of 2 interactive classes which aimed at explaining disease physiopathology, correct use of medications, and an action plan in case of worsening symptoms

Respiratory exercise program: Commenced the week after education program; 30 min bi-weekly yoga over 3 months.

Aerobic conditioning programme: The program started the week after the education program, 30 min bi-weekly aerobic training on a treadmill. The training intensity was 70% of maximum power obtained in the cardiopulmonary effort test carried out before the beginning of training

Control description: Same as for intervention for education program and respiratory exercise program only

Duration of intervention: 12 weeks; 30 min bi-weekly respiratory exercise program and 30 min bi-weekly aerobic conditioning program for 12 weeks

Intervention delivered by: Not reported

Outcomes

Pre-specified outcomes: Pulmonary function, Maximum aerobic capacity, QoL (used a 4 domain QoL Questionnaire, QQL-EPM), anxiety and depression levels, asthma symptoms, exhaled nitric oxide levels

Follow-up period: 12 weeks (nothing beyond 12-week intervention period)

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskMethods for allocation concealment not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskMethods not described
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll incomplete outcome data adequately addressed
Selective reporting (reporting bias)Unclear riskAll stated outcomes were addressed, however, protocol was not available to us
Other biasHigh riskParticipants within this study may be a subset of those participating in the Mendes 2010 and Mendes 2011 studies, for this reason outcomes reported across these three studies have not been pooled together in meta-analyses

Matsumoto 1999

Methods

Country: Japan

Design: Randomised controlled trial

Objectives: To assess effects of swimming training on aerobic capacity and exercise-induced bronchoconstriction and bronchial responsiveness to inhaled histamine in children with bronchial asthma

Study Site: Not explicitly stated

Methods of Analysis: Paired t-tests to detect differences within a group, Unpaired t-tests were used to detect differences between groups

Participants

Randomised: 16 in total; Intervention n = 8; Control n = 8

Age: Range 8 to 12 years; Intervention mean = 10.5 years; Control mean = 9.9 years

Gender: Intervention males n= 7, females n = 1; Control males n = 7, females n = 1

Asthma diagnosis criteria: ATS criteria

Recruitment means: Children admitted to hospital for treatment of asthma were recruited

Co-morbidities included: Not described

Participant exclusion reasons: Not explicitly stated

Interventions

Setting: Heated (30°C) indoor pool

Intervention description: Training took place for 6 weeks in a heated indoor pool for 2 periods of 15 minutes on 6 days each week; A 10 minute break was taken between the two 15 minute training periods; A swimming ergometer was used to assess work rate and corresponding heart rate at 125% of the lactate threshold; the training intensity was set to 125% of the lactate threshold for each participant individually.

Control description: Not explicitly defined; assumed no intervention

Duration of intervention: 6 weeks; 30 min each day for 6 days a week

Intervention delivered by: Not stated

A swimming ergometer was used to assess work rate and corresponding heart rate at 125% of the lactate threshold; The training intensity was set to 125% of the lactate threshold for each participant individually; Training took place for 6 weeks in a heated indoor pool for 2 periods of 15 minutes on 6 days each week; A 10 minute break was taken between the two 15 min training periods; Training intensity was increased as necessary to remain at 125% of the lactate threshold

Outcomes

Pre-specified outcomes: Aerobic capacity ( work load at LT), exercise-induced bronchoconstriction, histamine responsiveness

Follow-up period: 6 weeks

Aerobic capacity of the participants in both training and control groups was assessed again after the training period; Histamine responsiveness was also reassessed; Outcomes include change in work load during cycle test, % fall in FEV during swimming and cycle tests, changes in concentrations of histamine required to provoke a fall in FEV of 20% or more

NotesThe mean duration of swimming training was 31.4 days (SD 3.2) and the mean distance swum per day was 851.5m (SD 52.2). The mean total distance achieved during the entire training period was 26,675m (SD 2827.6).
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, methods not described
Allocation concealment (selection bias)Unclear riskInformation not available
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskInformation not available
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll incomplete outcome data adequately addressed
Selective reporting (reporting bias)High riskData presented in a way which cannot be meta-analysed
Other biasUnclear riskInsufficient information to permit judgement of yes or no

Mendes 2010

Methods

Country: Brazil

Design: Randomised controlled trial

Objectives: To evaluate the effects of an aerobic training programme on asthma-specific HRQoL and anxiety and depression scores and asthma symptoms in patients with moderate or severe asthma

Study Site: Hospital clinics, School of Medicine, University of Sao Paulo, Brazil

Methods of Analysis: Kolmogorov-Smirnov test to evaluate normality; Mann-Whitney U test to compare baseline nonparametric data; Chi2 test for gender and bronchodilator response at baseline. Two-way repeated measure analysis of variance followed by a Holm-Sidak post hoc test for HRQoL and asthma symptoms; McNemar test for anxiety and depression; Spearman test for linear correlation analysis

Participants

Randomised: 101 total; 89 completed the study; Intervention n = 50 (completed n = 44); Control n = 51 (completed n = 45)

Age: (Only for those participants completing the study) Intervention median = 39 years (95% CI 22.0 - 47.9); Control median = 39.5 years (95% CI 23.5 - 47.0)

Gender: Intervention n = 5 males/ 39 females; Control n = 10 males/35 females

Asthma diagnosis criteria: Global Initiative for Asthma (GINA) guideline (moderate or severe persistent asthma)

Recruitment means: Recruited at a University Hospital (University of Sao Paulo) after a medical consultation

Co-morbidities included: None reported

Participant exclusion reasons: Cardiovascular, pulmonary or musculoskeletal disease that would impair exercise training

Interventions

Setting: Not reported

Intervention description: Four-hour education program which included the teaching of breathing exercises.

Education programme: based on a videotape 'ABC of Asthma' which included information about asthma pathophysiology, medication skills, self-monitoring techniques, and environmental control and avoidance strategies. Patient doubts were elucidated with an interactive discussion. Breathing exercises: based on yoga. Included were Kapalabhati (fast expiratory breathing followed by passive inhalation); Uddhiyana (full exhalation followed by a forced inspiration performed without air inhalation (apnoea)) and Agnisara (full exhalation followed by a sequence of retractions and protrusions of the abdominal wall in apnoea)
Aerobic training programme: based on maximum oxygen consumption (VOmax). Aerobic exercise was initiated at 60% of VOmax for the first 2 weeks, increased to 70% VOmax; If the patient maintained two consecutive exercise sessions without symptoms the intensity was increased by a further 5%; Salbutamol (200ųg) was used 15 minutes before exercise if peak flow was < 70% of the patient's best value.

Control description: Four hour education program which included the teaching of breathing exercises described above for the intervention description. Did not take part in the aerobic training programme.

Duration of intervention: 12 weeks; Education programme: two classes held once a week, each 2 hours; Breathing exercise programme: 30 minute session performed twice a week for 3 months; Aerobic training programme: 30 minutes per session, twice a week for 12 weeks

Intervention delivered by: Not reported

Outcomes

Pre-specified outcomes: Asthma specific HRQoL (used a 4 domain QoL Questionnaire, QQL-EPM); anxiety and depression scores; asthma symptoms; spirometry FEV, FVC, VOMax

Follow-up period: Three months

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomised by drawing lots
Allocation concealment (selection bias)Unclear riskMethods of allocation not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
High riskRehabilitation program and evaluation of outcomes done by same investigators; No blinding of outcome assessors
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskReasons for missing data are described in general terms only. No mention of any missing outcome data or how they would be handled
Selective reporting (reporting bias)High riskData for VOMax given only in graphic forms, full data for asthma free days not presented, therefore, could not be meta-analysed
Other biasHigh riskParticipants within this study may be a subset of those participating in the Gonçalves 2008 and Mendes 2011 studies, for this reason outcomes reported across these three studies have not been pooled together in meta-analyses

Mendes 2011

Methods

Country: Brazil

Design: Randomised controlled trial

Objectives: To evaluate the effects of an aerobic training program on eosinophil inflammation (primary aim) and nitric oxide (secondary aim) in patients with moderate or severe persistent asthma

Study Site: University of Sao Paulo Hospital, Brazil

Methods of Analysis: Statistical power normality evaluated by Kolmogorov-Smirnov test and presented as medians and 95% confidence intervals. The Mann-Whitney test was used to compare non-parametric data and the Chi2 test to evaluate gender and bronchodilator response between groups at baseline. A two-way repeated measures ANOVA followed by a Holm-Sidak post hoc test used to measure induced sputum cellularity, FeNO and other outcomes

Participants

Randomised: n= 68; Intervention n = 34, Control n = 34; Completed: Intervention n = 27, Control n = 24.

Age: Range 20 to 50 years; Intervention median = 37.9 (25.7 - 47.3) years; Control median = 36.0 (22.0 - 47.5) years

Gender: Intervention n = 24 female, n = 3 male; Control n = 18 female, n = 6 male

Asthma diagnosis criteria: Global Initiative for Asthma (GINA) guidelines

Recruitment means: Recruited at a University hospital – no other information provided

Co-morbidities included: Not specified, though patients were under medical treatment for at least 6 months and were considered clinically stable

Participant exclusion reasons: Patients diagnosed with cardiovascular, pulmonary, or musculoskeletal diseases that would impair exercise training were excluded

Interventions

Setting: University hospital – Sao Paulo: between two medical consultants

Intervention description: Educational program: consisting of two classes (once a week) lasting 2 hours. The core activity was based on an educational videotape titled the ‘ABC of Asthma’. Interactive discussions to address patient’s doubts also occurred. Breathing exercises (yoga): including Kapalabhati (fast expiratory breathing followed by passive inhalation), Uddhiyana (full exhalation followed by forced inspiration without air inhalation (apnoea)) and Agnisara (full exhalation followed by a sequence of retractions and protrusions of the abdominal wall). This was performed as 30 minute sessions, twice a week for 3 months. Exercises were executed in sets of three with 2 minutes of exercise with 60 seconds of rest. Aerobic training program: involving indoor treadmill training for 30 minutes twice a week for 3 months. Exercises intensity started at 60% of VO2max and increased by 5% of cardiac frequency until a maximum of 80% maximal cardiac frequency

Control description: Same as the educational program and breathing exercise (yoga) above

Duration of intervention: 2 weeks; Education programme: two classes held once a week, each 2 hours; Breathing exercise programme: 30 minute session performed twice a week for 3 months; Aerobic training programme: 30 minutes per session, twice a week for 12 weeks

Intervention delivered by: Not specified

Outcomes

Pre-specified outcomes: Induced sputum for eosinophil cell count, fractional exhaled nitric oxide (FeNO), pulmonary function, cardiopulmonary exercise testing, asthma symptom-free days and asthma exacerbations

Follow-up period: Three months

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskParticipants randomised by drawing lots
Allocation concealment (selection bias)Unclear riskMethods not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
High riskSputum eosinophil counts and FeNO levels were determined by a blinded investigator but pulmonary function and cardiopulmonary tests were conducted by the same investigator in charge of aerobic training
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNo mention of how incomplete outcome data were addressed
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasHigh risk26 of 68 participants within this study are a subset of those participating in the Mendes 2010 study. In addition, there is a possibility that participants in the Gonçalves 2008 study are also a subset of those in Mendes 2010. For this reason outcomes reported across these three studies have not been pooled together in meta-analyses

Moreira 2008

Methods

Country: Portugal

Design: Randomised controlled trial

Objectives: To determine a rationale for exercise and sporting guidance for children and their parents

Study Site: Outpatient clinic of University Hospital Sao Joao, Porto, Portugal

Methods of Analysis: Fisher's exact test for categorical variables, unpaired t-test for numerical variables, changes within groups were compared using a paired t-test, differences between the exercise and control groups were compared by ANCOVA, with the baseline value as covariate

Participants

Randomised: 34 total; 32 completed the study; Intervention n = 17 (completed n = 16); control n = 17 (completed n = 16)

Age: Intervention mean = 12.9 + 3.4 years; Control mean = 12.5 + 3.5 years

Gender: Intervention n = 11 males/6 females; Control n = 9 males/8 females

Asthma diagnosis criteria: "...controlled asthma, treated with a small-to-moderate dose of inhaled corticosteroids (ICSs) for a period of > 1 yr and followed in the outpatient clinic University Hospital of Sao Joao..."

Recruitment means: Outpatient clinic of University Hospital Sao Joao, Porto, Portugal

Co-morbidities included: Not specified

Participant exclusion reasons: Not explicitly stated

Interventions

Setting: Indoor gymnasium

Intervention description: Twelve week, bi-weekly 50 minute sessions of submaximal aerobic exercise designed as moderately intensive training programme including both lower and upper extremity activities. Typical session consisted of warm-up (10 minutes) with arm and leg exercise, submaximal training (30-35 minutes) including aerobic exercises, strength training, and some balance and coordination exercises, and a cool-down period (7-10 minutes)

Control description: Continued usual daily routine

Duration of intervention: Twelve weeks; bi-weekly for 50 minutes

Intervention delivered by: Not specified in methods through in discussion it states "...supervised by health professional..."

Outcomes

Pre-specified outcomes: Lung volumes (PEF) and bronchial responsiveness to methacholine, Paediatric Asthma Quality-of-Life Questionnaire and Paediatric Asthma Caregiver's Quality of Life Questionnaire (PAQLQ and PACQLQ), Exhaled nitric oxide (eNO), CRP levels (C-reactive protein), Physical activity measure using an Actigraph monitor

Follow-up period: Three months

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskBlinded computer-generated randomisation schedule
Allocation concealment (selection bias)Low riskAllocation numbers were encoded on labels placed in each case report form by an outside researcher, and patients were assigned the next available allocation number in sequence
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskNo mention of attempted blinding for outcome assessors
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll incomplete outcome data adequately addressed
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasUnclear riskInsufficient information to permit judgement of yes or no

Silva 2006

Methods

Country: Brazil

Design: Randomised controlled study with three arms (2 intervention arms combined for this analysis)

Objectives: To investigate whether time of the day influences the effects of physical exercise training for children with asthma

Study Site: Not explicitly stated, but included an outdoor swimming pool

Methods of Analysis: Normality of data distribution determined by Kolmogorov-Smirnov test, Intra-group and between group comparisons made by ANOVA followed by the Tukey-Kramer multiple comparisons test

Participants

Randomised: 69 in total; Morning intervention n = 23; Afternoon intervention n = 23; Control n = 23.

Age: Morning intervention mean = 9.5 + 0.2 years; Afternoon intervention n = 9.2 + 0.2 years Control mean = 9.5 + 0.2 years

Gender: Morning intervention n = 12 males/11 females; Afternoon intervention n = 12 males/11 females; Control n = 11 males/12 females

Asthma diagnosis criteria: Physician diagnosed asthma according to GINA guidelines

Recruitment means: Not reported

Co-morbidities included: None mentioned

Participant exclusion reasons: Use of oral steroids in the previous 8 weeks, physical disability, and other pulmonary or systemic disease

Interventions

Setting: Not reported other than for the swimming which took place in an outdoor pool

Intervention description: Twice-weekly 90 min sessions over 4 months, morning training group and the afternoon training group followed the same training program

Circuit training 45 min: first 5 min no running allowed (to avoid triggering EIB). Tasks were walking for 5 min, running for 10-15 min, Upper and lower limb exercises, training on a bar, Individual and team games, postural and stretching exercises followed by swimming pool exercises 45 min

Control description: Non training group received regular asthma treatment and education

Duration of intervention: Twice-weekly 90 min sessions for 4 months

Intervention delivered by: A physical educator and a physiotherapist

Outcomes

Pre-specified outcomes: 9 min running distance, resting heart rate, spirometry, exercise challenge tests, abdominal muscle strength (number of sit-ups in 60 seconds)

Follow-up period: Nothing beyond the 4 months intervention period

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskMethods for allocation concealment not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskMethods not described
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of yes or no
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasLow riskNo other biases identified

Swann 1983

Methods

Country: United Kingdom

Design: Randomised controlled trial with a run-in period

Objectives: To assess the effect of a physical training program on children with asthma, known to have exercise-induced bronchoconstriction

Study Site: An asthma clinic, no other details provided

Methods of Analysis: Not stated

Participants

Randomised: n = 27 children; only n = 21 completed the study

Age: Control range: 7-14 years (mean 10.3); Intervention range 8-13 years (mean 11.1)

Gender: Not stated

Asthma diagnosis criteria: Not explicitly defined; assumed doctor diagnosis

Recruitment means: Children attending the asthma clinic with proven exercise-induced bronchospasm (> 20% fall in PEFR after exercise)

Co-morbidities included: None stated

Participant exclusion reasons: n = 5 children dropped out of the relaxation group; details not provided

Interventions

Setting: Not explicitly stated

Intervention description: Graduated physical training program twice per week and repeated daily at home: warm-ups, squat thrusts, star jumps, sit-ups and press-ups; exercise loads were increased at each session

Control description: Relaxation classes supervised by the same physiotherapist once per week for three months

Duration of intervention: Twice a week for 3 months

Intervention delivered by: Sessions were supervised twice weekly by paediatric physiotherapist

Outcomes

Pre-specified outcomes: Daily PEFR, % fall in PEFR after exercise, asthma symptom scores

Follow-up period: 3 months

NotesAll children were given sodium cromoglycate by Spinhaler, 15 minutes before exercise. Wrote to author to find out the duration of the training, received no reply to date
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskAllocation concealment not described
Blinding (performance bias and detection bias)
For participants
Unclear riskDouble-blind study mentioned, however who was actually blinded was not stated
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskDouble-blind study mentioned, however who was actually blinded was not stated
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskLarger number of drop-outs from the control group (5/12), no characteristics or results provided for attrition
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasUnclear riskStatistical methods not described

Turner 2010

Methods

Country: Australia

Design: Randomised controlled trial with 3 week run-in period

Objectives: To investigate whether exercise training improves functional capacity and QOL in middle-aged and older adults with fixed airway obstruction asthma

Study Site: Physiotherapy department of Sir Charles Gairdner Hospital

Methods of Analysis: Unpaired t-tests, Mann-Whitney tests, chi squared analysis, ANOVA

Participants

Randomised: 35 in total; Intervention n = 20; Control n = 15

Age: Intervention mean= 65.3 + 10.8 years; Control mean = 71.0 + 9.7 years

Gender: Intervention n= 8 males, n = 11 females; Control n = 7 males, n = 8 females

Asthma diagnosis criteria: Diagnosed by respiratory physician based upon reported patterns of disease variability, trigger factors, atopy and responsiveness to medications. In addition moderate/severe asthma with fixed airflow obstruction was defined by at least two of the following criteria; FEV < 80% predicted, FEV/FVC < 80% of predicted or RV > 120% predicted

Recruitment means: Through a metropolitan hospital and private clinic where patients were managed by either of 2 respiratory physicians

Co-morbidities included: None reported

Participant exclusion reasons: Co-existing respiratory conditions, respiratory tract infection in the previous 4 weeks, current smoker or ex-smokers who ceased within the previous 2 yrs, smoking history > 15 yrs, co-morbid conditions likely to reduce exercise capacity, current participation in a > 30 min/day of moderate or vigorous exercise, participation in a Pulmonary Rehabilitation Program in the previous 12 months

Interventions

Setting: Physiotherapy Department

Intervention description: Three 80-90 min exercise classes each week for 6 weeks, this consisted of 10-15 min warm-up, 20 min walking training, 5-10 min cool-down period followed by exercise circuit comprising 10 min cycle ergometry training, approximately 45 min step-ups, wall squats, and upper limb endurance training

Control description: Standard medical care only

Duration of intervention: Three 80-90 min sessions a week for 6 weeks

Intervention delivered by: Supervised by physiotherapists

Outcomes

Pre-specified outcomes: Health-related QOL (self complete version of the AQLQ), functional exercise capacity, health status (SF-36), (6MWT), health status (SF-36), anxiety and depression, peripheral muscle strength, asthma control

Follow-up period: 3 months post-6 weeks intervention period

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomised using http://www.randomizer.org into the two groups
Allocation concealment (selection bias)Low riskAn independent researcher allocated participants at time of consent; investigators and patients were blinded to allocation until after the 3 weeks run-in period
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
High riskAuthor states blinding was not possible for outcome assessors
Incomplete outcome data (attrition bias)
All outcomes
Low riskIncomplete or missing outcome data were replaced using the last observation carried forward method
Selective reporting (reporting bias)Unclear riskSome post hoc analysis was performed
Other biasUnclear riskAuthors mention some potential contamination of control groups as some individuals stated they had been exercising more than regularly, however the effect of this is unknown

Van Veldhoven 2001

Methods

Country: the Netherlands

Design: Randomised controlled trial

Objectives: To evaluate the effects of a physical exercise programme for children with asthma on an outpatient basis

Study Site: Heideheuvel Asthma Centre in Hilversum

Methods of Analysis: Chi2 test, analysis of variance (ANOVA), multivariate analysis of variance (MANOVA)

Participants

Randomised: 47 in total; Intervention n = 23; Control n = 24

Age: Range 8 to 13 years

Gender: Intervention male n = 16, female n = 7; Control male n = 18, female n = 6

Asthma diagnosis criteria: Severity of asthma was diagnosed using the questionnaire of the classification of the Dutch Central Advisory Committee for Peer Review

Recruitment means: Through an asthma centre (n = 9), following an advertisement in a local paper (n = 19), and from a special school (n = 20)

Co-morbidities included: None mentioned

Participant exclusion reasons: One child in the experimental group dropped out because of a physical problem not related to asthma and was omitted from further analysis

Interventions

Setting: Not explicitly stated.

Intervention description: The 3 month exercise programme consisted of group exercises twice a week for one hour in a gymnasium and one 20 minute exercise session per week at home. The gym sessions started with 10 minutes warming up, 20 minutes of fitness training then 15-20 minutes different physical activities followed. The training group also received information about asthma and exercise to improve coping behaviour with asthma

Control description: Children in the control group did not receive an extra care or treatment

Duration of intervention: 3 months

Intervention delivered by: Not stated

Outcomes

Pre-specified outcomes: Exercise test (Wmax, VE, VO, Vco, O pulse), Psychosocial indices (Self Perception Profile for children - CBCK), Asthma Coping Test (ACBT), PEFR, FEV, FVC, EIB; A maximum incremental exercise test was used to determine maximum workload, HR, minute ventilation, oxygen uptake, CO production and a treadmill endurance test at submaximal heart rate was also taken; A translated version of the Self-Perception Profile for Children was used to measure perceived competence and the Asthma Coping Test was also administered

Follow-up period: 3 months

NotesAssessments took place immediately before and after the intervention
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskMethods for allocation concealment not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskMethods not described
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll incomplete outcome data adequately addressed
Selective reporting (reporting bias)Unclear riskAll stated outcomes were addressed, however protocol was not available
Other biasUnclear riskInsufficient information to permit judgement of yes or no

Varray 1991

Methods

Country: France

Design: Randomised controlled trial

Objectives: To determine the impact of different individualised training intensities on cardiorespiratory fitness, and beyond that, on the underlying disease in children with asthma

Study Site: Not explicitly stated

Methods of Analysis: Unpaired and paired Student t-test, two way and one way analysis of variance, Hortogonal contrast method

Randomised controlled trial with no run-in period. Authors update: randomisation was ensured by drawing lots

Participants

Randomised: 14 in total; Intervention n = 7; Control n = 7

Age: Intervention mean 11.4 + 1.8 years; Control mean 11.4 + 1.5

Gender: Intervention male n = 6, female n = 1; Control male n = 6, female n = 1

Asthma diagnosis criteria: All 14 participants were known to have recurrent reversible wheezing episodes and were required to fulfil at least 3 of the 4: clinical, allergic, immunological or functional (improvement of > 15% in FEV after bronchodilator) criteria

Recruitment means: Not stated

Co-morbidities included: None mentioned

Participant exclusion reasons: None mentioned

Interventions

Setting: Indoor swimming pool for intervention group

Intervention description: Indoor swimming pool training, twice a week for 3 months. Each session lasted for an hour (i.e. 10 minutes on and 10 minutes off)

Control description: Not explicitly stated, assumed no intervention

Duration of intervention: 3 months; twice a week 1 hour sessions

Intervention delivered by: Training was supervised by a physical education teacher

Outcomes

Pre-specified outcomes: Clinical benefit (wheezing attack frequency, any modification observed by the parents), exercise test (VOmax, ventilatory  threshold Vth), FEV, FVC

Follow-up period: 6 months

NotesStudy had 2 stages and went for 6 months but we only used the first 3 months data, because the second 3 months was specialised high intensity training
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomisation was ensured by drawing lots as per author update
Allocation concealment (selection bias)Unclear riskMethods for allocation concealment not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskMethods not described
Incomplete outcome data (attrition bias)
All outcomes
Low riskAll incomplete outcome data adequately addressed
Selective reporting (reporting bias)High riskIncomplete reporting of outcome data (exercise testing outcome), data reported incompletely and could not be meta-analysed
Other biasUnclear riskPotential bias with the study design. Unsure if intervention program could have different effects due to the different training programs

Varray 1995

Methods

Country: France

Design: Randomised controlled trial

Objectives: To determine whether individualised aerobic training at ventilatory threshold decreases the  exercise hyperventilation and modifies breathing pattern at all exercise intensities

Study Site: Not stated

Methods of Analysis: ANOVA, contrast method, stepwise regression with a ridge procedure, Bland and Altman procedure

Participants

Randomised: 18 in total; Intervention n = 9; Control n = 9

Age: Intervention mean=1 0.3 years; Control mean = 11.7 years

Gender: Intervention males n = 7, females n = 2; Control males n = 7, females n = 2

Asthma diagnosis criteria: Participants included presented a functional improvement of 15% at least in FEV by inhaling a bronchodilator. In addition all participants were required to fulfil: clinical, allergic and immunological criteria

Recruitment means: Not reported

Co-morbidities included: None mentioned

Participant exclusion reasons: None mentioned

Interventions

Setting: Indoor swimming pool for the intervention group

Intervention description: Twice a week for 3 months with each session lasting for total 30 minutes for an hour (i.e. 10 minutes on and 10 minutes off). Individualised training intensity used during study for each participant

Control description: Not explicitly stated, assumed no intervention

Duration of intervention: 3 months

Intervention delivered by: Physical education teacher

Outcomes

Pre-specified outcomes: Exercise testing (VOmax and Vth)

Follow-up period: 3 months

NotesAuthors update: randomisation was ensured by drawing lots. Authors update: age range in both groups was 9-13 years
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandomisation ensured by drawing lots (according to contact with authors by original review authors)
Allocation concealment (selection bias)Unclear riskMethods for allocation concealment not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskMethods not described
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of yes or no
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasUnclear riskInsufficient information to permit judgement of yes or no

Wang 2009

Methods

Country: Taiwan

Design: Randomised controlled trial

Objectives: To investigate the benefits of a 6 week swimming intervention on pulmonary function tests and severity of asthma in children

Study Site: Intervention in outdoor swimming pool, study site not otherwise specified

Methods of Analysis: Two-tailed students t-test for differences in continuous variables between groups Chi2 test for differences in categorical variables between groups

Participants

Randomised: 30 in total; Intervention n = 15; Control n = 15

Age: Intervention mean = 10 (range 9 - 11) years; Control mean = 10 (range 9-11) years

Gender: Intervention n = 10 males/5 females; Control n = 10 males/5 females

Asthma diagnosis criteria: ATS criteria

Recruitment means: Not stated

Co-morbidities included: None mentioned

Participant exclusion reasons: Not stated

Interventions

Setting: Outdoor swimming pool for intervention group

Intervention description: 10 min warm-up including breathing exercise in water, 30 min swimming training (beginners - kicking, experienced swimmers - freestyle and breaststroke); Physical work capacity was set at 65% of peak heart rate, 10 min cool-down; Regular treatment for asthma continued unchanged

Control description: Received no specific treatment, regular treatment for asthma continued unchanged

Duration of intervention: Three 50 min sessions a week for 6 weeks

Intervention delivered by: Supervised by certified swimming instructors

Outcomes

Pre-specified outcomes: PFT (FEV, FVC, FEV/FVC, FEF50,FEF25-75), daily PEF, daily assessment of severity of asthma (NHLBI criteria)

Follow-up period: Nothing beyond the 6 week intervention period

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, but methods not described
Allocation concealment (selection bias)Unclear riskMethods for allocation concealment not described
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskMethods not described
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to permit judgement of yes or no
Selective reporting (reporting bias)High riskNumerical outcome data for severity of asthma not presented, only P values provided, therefore, cannot be meta-analysed
Other biasUnclear riskAuthor states the swimming group may have greater compliance with controller medications leading to improvement

Weisgerber 2003

Methods

Country: USA

Design: Randomised controlled trial

Objectives: To determine whether swimming improved symptoms and PFTs in children with asthma

Study Site: Not stated

Methods of Analysis: Not stated

Participants

Randomised: 26 children; Completed intervention n = 5, control n = 3

Age: Total population only: range 7 to 14 years

Gender: Intervention male n = 3, female n = 2; Control male n = 1, female n = 2

Asthma diagnosis criteria: Criteria for inclusion was moderate persistent asthma according to symptom criteria and a need for preventive daily asthma therapy

Recruitment means: From the Medical College of Georgia Pediatric Pulmonary, Allergy/Immunology, and General Pediatric clinics

Co-morbidities included: Participants excluded for other co-morbidities that would make swimming unsafe or complicate the analysis of their performance

Participant exclusion reasons: Eight children could not be reached after consent because of disconnected phones and never began the study. Two children performed initial PFTs and completed swim lessons but missed follow-up PFTs and could not be reached to reschedule. One child in the control group performed initial PFTs and was then lost to follow-up. One child withdrew because of a conflict with a school sport. Three children withdrew secondary to transportation difficulties. One child had to reschedule his swimming lessons to a date that would not be finished in time to be included in this analysis. Two in the control group were excluded from analysis due to a change in their asthma therapy. Presence of other co-morbidities that would make training unsafe or difficult, asthma therapy changed during trial duration or if an exacerbation occurred during the trial period. Children were also excluded from the study if they did not attend at least 80% of the lessons. However, all children assigned to the swim group met this attendance requirement.

Interventions

Setting: Family swimming school

Intervention description: Swimming training according to the child's ability. Lessons were conducted twice per week for 5 to 6 weeks, depending on the time of the year, for 45 minutes each

Control description: Not explicitly stated; "...an equivalent observation period for the control group"

Duration of intervention: 6 weeks

Intervention delivered by: Certified swimming instructors

Swimming training according to the child's ability; Lessons were conducted twice per week for 5 to 6 weeks, depending on the time of the year, for 45 minutes each; Lessons were taught by certified swimming lesson instructors who were not aware of the child's involvement in the study. Children were excluded from the study if the did not attend at least 80% of the lessons, however, all children assigned to the swim group met this attendance requirement

Outcomes

Pre-specified outcomes: FEV, FVC, PEFR, child's asthma score

Follow-up period: 6 weeks

NotesRandomisation was conducted using random number table
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation conducted using a random numbers table
Allocation concealment (selection bias)Unclear riskInvestigators unaware as to order of randomisation
Blinding (performance bias and detection bias)
For participants
High riskDue to the nature of the intervention it is not possible to blind participants
Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskMethods not described
Incomplete outcome data (attrition bias)
All outcomes
High riskSignificantly large number of dropouts for total population (12/26)
Selective reporting (reporting bias)Unclear riskInsufficient information to permit judgement of yes or no
Other biasHigh riskBaseline imbalances (for height and FVC); Methods of analysis not disclosed; authors state intervention may not have had the intensity and duration to demonstrate a significant result

Wicher 2010

Methods

Country: Brazil

Design: Randomised prospective controlled trial

Objectives: To investigate the medium-term benefits of a swimming program in school children and adolescents with moderate persistent atopic asthma and to assess and compare spirometric parameters and bronchial hyper-responsiveness in two groups of children and adolescents

Study Site: Pulmonary physiology laboratory (Laboratrio de Fisiologia Pulmonar, LAFIP) of the Hospital de Clínicas da Universidade Estadual de Campinas (UNICAMP) Division of Pediatric Pulmonology

Methods of Analysis: Chi2, Wilcoxon, Mann-Whitney and Spearman’s rank correlation tests were performed; Categorical study variables for sample profiles were presented in frequency tables (absolute values and percentages) and as descriptive statistics (mean, standard deviation, minimum, maximum and medial vales) for continuous data; Progression of variables in both groups pre and post-treatment were analysed using the Wilcoxon signed-rank test; Mann-Whitney U test was used for comparing participant ages, anthropometric parameters, FEV1 and PC20 between the groups; Spearman’s rank correlation coefficient was used for analysis of the relationship between numeric variables

Participants

Randomised: 71 in total with 61 completing (30 in the swimming group and 31 in the control)

Age: Intervention group mean 10.35 years + 3.13; Control group mean 10.90 years + 2.63

Gender: Intervention group 18 females and 12 males; Control group 16 females and 15 males

Asthma diagnosis criteria: All participants had moderate persistent atopic asthmas diagnosed according to Global Initiative for Asthma (GINA) criteria and a clinical history of reversible, recurrent symptoms of airway obstruction

Recruitment means: Patients from the Hospital de Clínicas da Universidade Estadual de Campinas (UNICAMP) Division of Pediatric Pulmonology

Co-morbidities included: None reported

Participant exclusion reasons: Children who did not attend at least 80% of the classes were excluded

Interventions

Setting: Swimming pool and hospital

Intervention description: Swimming sessions lasted 60 minutes over a period of three months, twice weekly producing a maximum of 24 lessons; Before exercise children underwent peak expiratory flow to detect any possible bronchial obstruction at time of swimming; This was followed by light stretching exercises, lower and upper limb warm-ups with global postural exercises and awareness of diaphragmatic breathing whilst subjects were lying on mats (approximately 15 minutes); Subjects were then taken to the pool where training was divided by skill level being: Level 1 – adaptation to the water environment, total immersion breathing, floating/treading water, moving underwater and elementary diving; Level 2 – Where children had already acquired the aforementioned skills and mastered body control in the water; Lessons included mastering the front crawl and backstroke

Control description: Control group of non-swimmers

Duration of intervention: 12 weeks

Intervention delivered by: Trained by an instructor however details not reported

Outcomes

Pre-specified outcomes: Demographics, spirometry, bronchial challenge with methacholine, allergy skin testing and serum IgE measurement

Follow-up period: Post-test 12 weeks

Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation mentioned, however, methods not described
Allocation concealment (selection bias)Unclear riskAllocation concealment not reported
Blinding (performance bias and detection bias)
For participants
High risk

Due to the nature of the intervention it was not possible to blind participants

 

Blinding (performance bias and detection bias)
For outcome assessors
Unclear riskNo mention of attempted blinding for outcome assessors
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskAttrition with reasons reported, however, it is unclear if there was any missing data and if so how it was addressed
Selective reporting (reporting bias)High riskPre-specified protocol not available; Data reported in a way that cannot be meta-analysed such as number of exacerbations in each group
Other biasLow riskNo other biases identified

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
Altintas 2003Quasi-experimental study only; not randomised
Arandelovic 2007Intervention group had swimming plus education through an asthma school that the control group did not receive
Basaran 2006Quasi-experimental study only; not randomised - participants were 'randomised' based on admission order
Bauer 2002Study does not included physical training using whole body
Belanyi 2007Quasi-experimental study only; not randomised
Bonsignore 2006Inadequate control group - both groups received physical exercise
Bundgaard 1983Inadequate control group - both the groups were trained and the only difference was the intensity of training with no difference in duration or frequency of training
Cambach 1997Study included a composite intervention and included both participants with asthma and COPD. A physiotherapist run program included breathing retraining, mucus evacuation and exercise
Cox 1989Quasi-experimental study only; not randomised
Cox 1993Data for asthma patients not separately reported
Dean 1988Intervention duration too short, being only for 5 days
Didour 2002Quasi-experimental study only; not randomised
Dogra 2010Quasi-experimental study only; not randomised
Edenbrandt 1990Intervention duration too short, participants only exercised once per week
Emtner 1998Inadequate control group - follow-up analysis where either all groups had physical training or where study was a before & after assessment; also includes retrospective interview results
Emtner 1999Review of physical training evaluations - not an investigational intervention
Fesharaki 2010Inadequate control group - two intervention arms only
Fitch 1986Original inclusion now excluded; Authors state volunteers "...were selected to participate in the study." Quasi-experimental study only; not randomised
Foglio 2001All patients had already undergone an 8 week rehabilitation program training prior to being included in the current trial
Graff-Lonnevig 1980Quasi-experimental study only; not randomised - allocation was based on who lived closer to the gymnasium and this group being included in the exercise training arm
Hallstrand 2000Inadequate control group - health control participants used, not participants with asthma
Henriksen 1983Quasi-experimental study only; not randomised - participants are said to be randomly chosen but the intervention group of 28 were chosen from a total of 42 because they were inactive in sports and related physical games and had poor physical fitness. Control groups were more physically active than the participants in the intervention group
Hildenbrand 2010Inadequate control group - aquatic training program only
Hirt 1964Quasi-experimental study only; not randomised - mentioned as randomised, but all patients who were in hospital were assigned to the control group; participants who had severe asthma were assigned to the control group
Huang 1989Quasi-experimental study only; not randomised - original inclusion now excluded. Control group "...randomly but prospectively selected..." No randomisation mentioned for the intervention group
Kendrick 2000Quasi-experimental study only; not randomised
Kennedy 2002Quasi-experimental study only; not randomised
Kriegel 1998Quasi-experimental study only; not randomised - but a long term observational study
Lecheler 1988Inadequate control group - comparison of two types of intervention (interval and continuous running training)
Malkia 1998Quasi-experimental study only; not randomised, but a questionnaire-based study
Meyer 1999Quasi-experimental study only; not randomised
Meyer 2002Quasi-experimental study only; not randomised, but a questionnaire-based study
Muzembo 2001Quasi-experimental study only; not randomised. Composite patient group and not able to obtain data for asthma patients only
Neder 1999Quasi-experimental study only; not randomised. Participants were consecutively allocated to the training and placebo groups, where the first 26 participants were allocated to the training group and the next 16 to the placebo group
Orenstein 1985Quasi-experimental study only; not randomised, participants were assigned to groups according to the availability of transport
Pin 1993Inadequate control group - both study groups underwent physical training. One had intermittent training and the other group had aerobic training
Postolache 2002Quasi-experimental study only; not randomised
Riegels-Nielsen 2000Quasi-experimental study only; not randomised
Rosimini 2003Quasi-experimental study only; not randomised
Rothe 1990Exercise prescription is of too short a duration
Satta 2000Quasi-experimental study only; not randomised
Schaar 1999Quasi-experimental study only; not randomised - comparison of two intervention groups (swimming and inline skating)
Schmidt 1997Quasi-experimental study only; not randomised - participants were randomised on the basis of distance from training centre
Scott 2013aInadequate control group - three arm trial: exercise intervention, dietary intervention or combination of the two
Sly 1972Quasi-experimental study only; not randomised - original inclusion now excluded due to insufficient randomisation. Participants were 'selected' for the study. No mention of randomisation
Stiefelhagen 2003Not an investigational intervention - recommendations for sports training in asthma
Svenonius 1983Quasi-experimental study only; not randomised - not randomised since the participants could choose which one of the four groups they would like to be in
Turchetta 2002Quasi-experimental study only; not randomised
Van Veldhoven 2000Quasi-experimental study only; not randomised, but a before-and-after study
Weisgerber 2004Inadequate control group - comparison of two intervention groups (swimming and golf)
Weller 1999Quasi-experimental study only; not randomised
Worth 2000Quasi-experimental study only; not randomised
Yüksel 2009Quasi-experimental study only; not randomised - participants randomly arranged according to admission order
Zaid 2008No outcomes related to asthma patients reported

Characteristics of studies awaiting assessment [ordered by study ID]

Pinto 2012

Methods

Country: Brazil (Sao Paulo)

Design: Randomised controlled trial

Objective (Aim): To evaluate the effects of aerobic training on bronchial hyper-responsiveness, airway inflammation and health-related quality of life in patients with moderate and severe asthma

Study Site: Not reported

Methods of analysis: Two-way ANOVA test was used and a significance level of 5% was set (P<0.05)

Participants

Randomised: Twenty-five subjects

Completed to date: Twenty-five subjects

Age: 41.6 + 10.5 years

Gender: Not reported

Asthma diagnosis criteria: Not reported; only described as asthmatic patients

Recruitment: Not reported

Co-morbidities: Not reported

Subject exclusion criteria: Not reported

Interventions

Setting: Patients were studied between two medical consultations, no other information provided

Intervention descriptions: Aerobic training performed twice a week over three months; In addition to intervention arm performed an educational program and received placebo treatment

Control descriptions: Performed an educational program and received placebo treatment

Duration of intervention: 12 weeks

Intervention delivered by: Not reported

Outcomes

Pre-specified outcomes: Health-related quality of life (AQLQ), histamine and airway inflammation by exhaled nitric oxide levels

Follow-up period: 12 weeks (post-intervention)

Notes 

Pollart 2012

Methods

Country: United States of America

Design: Randomised controlled trial

Objective (Aim): To examine if non-exercising asthmatic subjects enrolled in a structured exercise program will have better quality of life than non-exercising asthmatic subjects enrolled in an education program only

Study Site: Not reported

Methods of analysis: Binary data were analysed using random permutation procedures to examine the presence of imbalances at baseline between groups

Participants

Randomised: Fourteen subjects

Completed to date: Fourteen subjects

Age: Not reported

Gender: Not reported

Asthma diagnosis criteria: Not reported; only described as asthmatic subjects

Recruitment: Not reported

Co-morbidities: Not reported

Subject exclusion criteria: Not reported

Interventions

Setting: Not reported

Intervention descriptions: Structured four month exercise program or exercise education (it is unclear from the abstract if the intervention group also received exercise education)

Control descriptions: Exercise education

Duration of intervention: 16 weeks

Intervention delivered by: Not reported

Outcomes

Pre-specified outcomes: Asthma quality of life

Follow-up period: 16 weeks (post-intervention) in addition to four, eight and 12 weeks

Notes 

Ancillary