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Swimming training for asthma in children and adolescents aged 18 years and under

  1. Sean Beggs1,
  2. Yi Chao Foong2,
  3. Hong Cecilia T Le2,
  4. Danial Noor2,
  5. Richard Wood-Baker3,
  6. Julia AE Walters2,*

Editorial Group: Cochrane Airways Group

Published Online: 30 APR 2013

Assessed as up-to-date: 12 JUL 2012

DOI: 10.1002/14651858.CD009607.pub2


How to Cite

Beggs S, Foong YC, Le HCT, Noor D, Wood-Baker R, Walters JAE. Swimming training for asthma in children and adolescents aged 18 years and under. Cochrane Database of Systematic Reviews 2013, Issue 4. Art. No.: CD009607. DOI: 10.1002/14651858.CD009607.pub2.

Author Information

  1. 1

    Royal Hobart Hospital, Department of Paediatrics, Hobart, Tasmania, Australia

  2. 2

    University of Tasmania, School of Medicine, Hobart, Tasmania, Australia

  3. 3

    University of Tasmania, Tasmanian School of Medicine, Hobart, Tasmania, Australia

*Julia AE Walters, School of Medicine, University of Tasmania, Hobart, Tasmania, 7000, Australia. Julia.Walters@utas.edu.au.

Publication History

  1. Publication Status: New
  2. Published Online: 30 APR 2013

SEARCH

 
Characteristics of included studies [ordered by study ID]
Altintas 2003

MethodsSTUDY DESIGN (parallel, cross-over): parallel

LOCATION, NUMBER OF CENTRES: 1 Adana, Turkey.

STUDY PERIOD: 6-week swimming training programme


ParticipantsN SCREENED: not known

N RANDOMISED:26

Intervention = 13, Control = 13

N COMPLETED: 26,

BASELINE DETAILS:

SWIM: M = 6, F = 7. CONTROL M = 7, F = 6

AGE SWIM: 9.8 SD 2.3 (range 5-13). CONTROL 10.4 SD 2.43 (range 6-14).

DIAGNOSIS ASTHMA: GINA criteria (author correspondence)

Lung function: FEV1 % predicted SWIM mean = 89.0 (SD 16); CONTROL mean = 88.2 (SD 13); PEF % predicted intervention mean = 83 (SD  11); Control mean = 82 (SD 14).

INCLUSION CRITERIA:

EXCLUSION CRITERIA:


InterventionsINTERVENTION: 6-week swimming training programme in an indoor non-chlorinated pool, 3 days per week for 90 minutes.

CONTROL: 6 weeks usual care

FOLLOW-UP PERIOD: not stated

CO-INTERVENTIONS: Permitted- ICS: 100-400 mcg daily


OutcomesPhysical Work Capacity (PWC) (watt), PEF, FEV1, FVC, 6-minute walking test


NotesStudy published as abstract. Author supplied study details and table of results pre-post for listed outcomes, June 2012. Study funding: not known.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low risk"We used random digit number to allocate them to the groups" from author correspondence.

Allocation concealment (selection bias)Low riskThird party allocation "Our statistic department randomised the patients into two groups" from author correspondence.

Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants were aware of group allocation owing to nature of intervention

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo details on outcome assessment

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo withdrawals noted in abstract or in author correspondence

Selective reporting (reporting bias)Low riskAuthor supplied results for study outcomes

Other biasUnclear riskNon identified

Matsumoto 1999

MethodsSTUDY DESIGN (parallel, cross-over): parallel

LOCATION, NUMBER OF CENTRES: 1 Japan. (Division of Pediatrics, Fukuoka Chest Hospital and Laboratory of Exercise Physiology, Fukuoka University)

STUDY PERIOD: 6-week swimming training programme during late autumn


ParticipantsN SCREENED: 16

N RANDOMISED:16

            Intervention = 8

            Control = 8

N COMPLETED: 16, M = 14, F = 2

AGE: 8-12 year-old

BASELINE DETAILS:

Age: 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

Lung function: FEV1 % predicted intervention mean = 84.0 (SD 9.6); Control mean = 83.2 (SD 22.4); PEF % predicted intervention mean = 114.2 (SD 22.7); Control mean = 93.6 (SD 21.9).

INCLUSION CRITERIA: Sixteen children with asthma diagnosed according to the ATS criteria who had been admitted to hospital for treatment participated in the study. All had severe asthma when admitted and the asthma attacks were controlled by treatment as an inpatient

EXCLUSION CRITERIA: None were prescribed oral steroids


InterventionsINTERVENTION: 6-week swimming programme in a heated (30 degrees C) indoor pool. 6 days per week for 30 minutes. Training intensity set at 125% of individual lactate threshold

CONTROL: 6 weeks usual care

RUN-IN PERIOD:         

TREATMENT PERIOD: 6 weeks (late autumn when allergic stimuli were minimal)

FOLLOW-UP PERIOD: not stated

CO-INTERVENTIONS: Permitted- theophylline: 7/8 intervention, 5/8 control. ICS: 4/8 intervention, 4/8 control. Disodium cromoglycate: 4/8 intervention, 2/8 control.


Outcomes
  1. Aerobic capacity- work load at lactate threshold (LT) calculated for each participant by visual inspection of a plot of blood lactate against work load (watts), tested using cycle ergometer and swimming ergometer separated by 1 day.
  2. Degree of exercise-induced bronchoconstriction (EIB)- exercise challenge tests on consecutive days using cycle ergometer and swimming ergometer work load set at 100% and 175% of lactate threshold.
  3. Bronchial responsiveness as Histamine PC20 mcg/mL.


NotesGraphs in figure 7 were used to estimate the values for exercise induced bronchoconstriction (% fall in FEV1)  and trialists were contacted to confirm the values for the time points and outcomes. No response was received at 29/07/12.

Study funding: supported by the Pollution-related Health Damage Compensation and Prevention Association of Japan.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskThey were randomly allocated to either a training group (n = 8) or a control group (n = 8)

Allocation concealment (selection bias)Unclear riskMethod not specified

Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants were aware of group allocation owing to nature of intervention

Blinding of outcome assessment (detection bias)
All outcomes
High riskOutcome assessment probably not blind

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo withdrawals reported

Selective reporting (reporting bias)Unclear riskPC20 histamine results reported as no changes during the training period in either training or control group. Graphs used to obtain % fall in FEV1 on swimming and cycle ergometry

Other biasUnclear riskNone identified

Varray 1991

MethodsSTUDY DESIGN: randomised controlled trial *

LOCATION, NUMBER OF CENTRES: 1. Hospital of Aiguelongue, Service d’exploration fonctionnelle respiratoire, Montpellier, France

STUDY PERIOD: 3 months of aerobic training and three months of high intensity training, 6 months in total.

METHODS OF ANALYSIS: Used a electrically-braked cycle ergometer and a low resistance valve, with inspiratory airflow measured with a pneumotachograph and a pressure transducer. Expired air was sampled in a mixing chamber and analysed with a polarographic analyzor and for CO2 with an infrared analyzor.


ParticipantsRECRUITMENT MEANS: Not specified

TARGET PARTICIPANTS: Atopic children with asthma

N SCREENED: not available

N RANDOMISED: 14

N COMPLETED: 14

GENDER

M= 6 (intervention), 6 (control) Total: 12

F= 1 (intervention), 1 (control) Total: 2

AGE: 11.4 (+/-1.5) , 11.4 (+/-1.8), 9 – 13 years old (intervention and control group respectively)

ASTHMA DIAGNOSIS CRITERIA: At least 3 of 4 criteria: Clinical family history of asthma and/or personal history of eczema, conjunctivitis or rhinitis caused by a known allergen, Allergic (All the children presented a cutaneous hypersensitivity to one or several allergens, Immunologic (Blood IgE levels were determined by the paper radioimmunoabsorbent test (PRIST) where any levels above 150 UI/mL were considered abnormal), Functional (Improvement of at least 15% in FEV1 by inhaling a bronchodilator)

SEVERITY OF ASTHMA: Not specified

OTHER INCLUSION CRITERIA: Not specified

EXCLUSION CRITERIA: Not specified

OTHER

BASELINE DETAILS: Age, Height, Weight, Lean body mass, Airflows, Regular physical practice, Frequency of acute attacks, Initial cardiorespiratory fitness.


InterventionsSETTING OF INTERVENTION:  Not specified

DESCRIPTION OF INTERVENTION:  Aerobic training: 3 months- participants swam for 10 minutes at 3 times of their own VTh velocity. A session ran for an hour and there were two different sessions per week.

High intensity training 3-6 months- consists of a series of 25 m crawls performed at maximal speed, repeated 6 times in one series, with 1 minute break in between. A session consisted of 2 series for a total of 12 25m crawls. 2 sessions per week.

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

DURATION OF INTERVENTION: 2 x 3 months.

CONTROL: Not specified, assumed treatment as per normal with no further interventions

Cointerventions: Not specified


OutcomesPRE-SPECIFIED: Clinical benefit (measured via questionnaire), exercise testing (VO2 max, VTBW, VTh, Maximum heart rate), Lung function: FEV1, FVC, FEF 25% to 75% in litres and as % predicted

FOLLOW-UP PERIOD: 3 month and 6 months

 


Notes*Note: Method of randomisation not actually stated. Data for outcomes FEV1, FVC were supplied by authors of Varray 1991 to F Ram for first study stage 3 months. No data were used for month 3-6. Data published originally in Physical training for asthma 1999.

Study funding: not known.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskNot specified

Allocation concealment (selection bias)Unclear riskNot specified

Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants were aware of group allocation owing to nature of intervention

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo details on outcome assessment

Incomplete outcome data (attrition bias)
All outcomes
Low riskAlthough there was mention that all children completed the programme, the attendance rates were not specified. ‘All children completed the programme’

Selective reporting (reporting bias)Unclear riskIncomplete reporting of several outcomes, such as lung function. Also incomplete reporting of other data. ‘With regards to lung function we observed no significant differences between the 2 groups throughout the study’, Figure 3, 2, 1 where exact values not given.

Other biasUnclear riskBias may have occurred due to the effects of different training programs. ‘…cannot rule out the possibility that a bias occurred in the effects of the different training programs’

Varray 1995

MethodsSTUDY DESIGN (parallel, cross-over): Parallel

LOCATION, NUMBER OF CENTRES: Datalink Pulmochart, Montpellier, France

STUDY PERIOD: 3 months


ParticipantsN SCREENED: NS

N RANDOMISED: 18

N COMPLETED: 18

M = 14

F = 4

BASELINE DETAILS:

AGE: Age range in both groups 9-13 years

Intervention = 10.3 (1.3)

Control group = 11.7 (0.5)

Asthma diagnosis criteria: Participants included presented a functional improvement of 15% at least in FEV₁ by inhaling a bronchodilator; In addition all subjects were required to fulfil: clinical, allergic and immunological criteria 

INCLUSION CRITERIA:

  1. Improvement of at least 15% in FEV1 by inhaling bronchodilator
  2. Family history of asthma and/or personal history of eczema, conjunctivitis or rhinitis caused by a known allergen
  3. Allergic: all children showed a cutaneous hypersensitivity to one or several allergens
  4. Immunological blood IgE levels were determined by the paper radioabsorbent test (PRIST)


EXCLUSION CRITERIA: NS


InterventionsINTERVENTION: 2 supervised swimming sessions per week for a period of 3 months. Each session lasted 1 hour within which the children swam at least 3 times at their own ventilatory threshold (Vth) velocity for 10 minutes.

TREATMENT PERIOD: 3 months

CONTROL: usual care

FOLLOW-UP PERIOD: 3 months

CO-INTERVENTIONS: not stated


OutcomesAerobic physical fitness: Maximal Ventilatory O2 uptake (VO2max), Ventilatory threshold (VTh)

Ventilatory and breathing patterns: Resting pulmonary function, Rate of perceived dyspnoea (RPD)


NotesAuthors update: randomisation was ensured by drawing lots; Authors update: Age range in both groups was 9-13 years. Data for outcomes were supplied by authors of Varray 1995 to F Ram for review 'Physical training for asthma 1999'.

Study funding: not known.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskAuthors supplied details on randomisation method used: drawing lots

Allocation concealment (selection bias)Unclear riskNo details available

Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants were aware of group allocation owing to nature of intervention

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo details available

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo withdrawals from study

Selective reporting (reporting bias)Unclear riskInsufficient information

Other biasUnclear riskNone identified

Wang 2009

MethodsSTUDY DESIGN: Randomised controlled trial

LOCATION, NUMBER OF CENTRES: Taiwan, one centre (outdoor, non-chlorinated pool) study site not otherwise specified.

STUDY PERIOD: 6 weeks

METHODS OF ANALYSIS: Used Microsoft Excel 2000. Calculated the means, SD and 95% CI for various variables. Two tailed Student’s t-test was used to assess the differences in continuous variables between groups, and a Chi-squared test was used to assess differences in categorical variables.


ParticipantsRECRUITMENT MEANS: Not specified

TARGET PARTICIPANTS: children with asthma from ages 7 to 12

N SCREENED: Not specified

N RANDOMISED: 30, 15 into treatment and control groups respectively

N COMPLETED: 30

GENDER

M = 10 (intervention), 10 (control)

F= 5 (intervention), 5 (control)

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

ASTHMA DIAGNOSIS CRITERIA: American Thoracic Society (ATS) criteria

SEVERITY OF ASTHMA: Accepted all severities, and classified into mild intermittent, mild persistent, moderate persistent or severe persistent based on National Heart, Lung and Blood Institute criteria.

OTHER INCLUSION CRITERIA: Not specified

EXCLUSION CRITERIA: Not specified

OTHER BASELINE DETAILS: Age, Height, Weight, BMI, Gender, Use of steroid inhaler, Family history of asthma, Atopy, Hay fever


InterventionsSETTING OF INTERVENTION:  Outdoor non-chlorinated pool

DESCRIPTION OF INTERVENTION:  10 minute warm up including breathing exercises in water, 30 minute swimming training and 10 minute cool down including breathing exercises in water. Beginners did kicking, experienced swimmers did freestyle or breaststroke, and physical work capacity was set at 65% of peak heart rate. 3 sessions per week

DURATION OF INTERVENTION: 6 weeks

DELIVERED BY: Supervised by certified swimming instructors                                                                            

CONTROL: No additional treatment received.

Cointerventions: regular treatment for asthma continued


OutcomesPRE-SPECIFIED: PFT – FVC, FEV1, FEV1%FVC, FEF50, FEF25-75. Daily PEF measures. Also daily assessment of asthma severity (as per NHLBI guidelines)

FOLLOW-UP PERIOD: None beyond end of 6 week intervention 


NotesStudy data supplied on 18 November 2010 to Kristin Carson, for Physical Training for Asthma review.

Study support from Taiwan Normal University


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskNot specified

‘Subjects were randomly assigned…’

Allocation concealment (selection bias)Unclear riskMethods for allocation concealment not described

Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants were aware of group allocation owing to nature of intervention

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo details on outcome assessment

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo withdrawals specified

Selective reporting (reporting bias)Unclear riskAuthor supplied some study data to previous Cochrane review

Other biasUnclear risk-Differences in medication use

-Hawthorn effect

-Greater compliance in swimming group

‘swimming group may have increased use of pre-exercise albuterol’, ‘affected parents’ or participants’ expectations of improvement if they were assigned to swimming group.’ Author states the swimming group may have greater compliance with controller medications leading to improvement

Weisgerber 2003

MethodsSTUDY DESIGN: Randomised controlled study

LOCATION, NUMBER OF CENTRES: Not specified

STUDY PERIOD: August 2001 to May 2002 (9 months)

METHODS OF ANALYSIS: Not specified


ParticipantsRECRUITMENT MEANS: From Medical College of Georgia Pediatric Pulmonary, Allergy/Immunology, and General Pediatric clinics.

TARGET PARTICIPANTS: children with asthma between 7-14

N SCREENED: not available

N RANDOMISED: 26

N COMPLETED: 5 SWIM, 5 CONTROL but 2 excluded due to change in asthma therapy during study period)

GENDER

M = 3 (intervention), 1 (control)

F = 2 (intervention), 2 (control)

MEAN AGE: 8.4 (intervention), 7.3 (control)

ASTHMA DIAGNOSIS CRITERIA: American Thoracic Society 1994 guidelines, Crapo 1981 and Polgar 1971 for predicted values.

SEVERITY OF ASTHMA: Moderate persistent (Excluded severe, mild intermittent and mild persistent asthma)

OTHER INCLUSION CRITERIA:

EXCLUSION CRITERIA: Severe, Mild intermittent, mild persistent asthma. Also other co morbidities making swimming unsafe or complicate the analysis of their performance. Other intervention in therapy during study period (2 children were placed on Advair). Exacerbations of asthma during study. At least 80% attendance for swimming lessons.


InterventionsSETTING OF INTERVENTION:  Not specified

DESCRIPTION OF INTERVENTION:  twice per week for 45 minutes. Beginner (3) – safety skills, front crawl, floating, and life jacket use. Advance Beginner (2) – Endurance swimming, rotary breathing, elementary backstroke, bobbing, treading

DURATION OF INTERVENTION: 5 or 6 weeks

CONTROL: Asthma treatment as per normal, no other interventions stated.

Cointerventions: Various other medications


OutcomesFEV1, FEV1%, FVC, FVC%, PEF, PEF%, FEF25-75, FEF25-75%. Asthma symptom questionnaire (made by authors).

PRE-SPECIFIED: 5-6 weeks

FOLLOW-UP PERIOD: 6-8 weeks 


NotesStudy support from: Avery Villenes, Augusta Family Y YMCA


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskUsed a random number table.

Allocation concealment (selection bias)Unclear riskNo details available for method used.

Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants were aware of group allocation owing to nature of intervention

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo details on outcome assessment

Incomplete outcome data (attrition bias)
All outcomes
High riskHigh dropout rates. 16 dropouts out of 26. Reasons were given clearly.

2 exclusions from control group analysis for change in their asthma therapy.

Selective reporting (reporting bias)Low riskIndividual patient data in Table 1 for lung function and symptoms, pre-and post intervention/control

Other biasUnclear riskSmall difference at baseline between groups in mean height and absolute FVC. No difference in percentage predicted lung function measures.

Small sample size, short duration.

Large proportion of participants who were beginners - most of the children were swimming at a beginner level’

Weisgerber 2008

MethodsSTUDY DESIGN (parallel, cross-over): parallel

LOCATION, NUMBER OF CENTRES: Milwaukee, Wisconsin (high asthma prevalence, low SES regions) from Children’s Hospital of Wisconsin Asthma/Allergy Clinic, Downtown Health Center, and 17 school-based clinics.

STUDY PERIOD: 3 intervention periods of 9-weeks in 2003 April/May, July/August, September/October.


ParticipantsN INVITED 850

SCREENED: 89

N RANDOMISED:78 46 SWIM/32 GOLF

N BEGAN PROGRAMME 35 SWIM/26 GOLF

N COMPLETED: 28 SWIM/17 GOLF

GENDER SWIM M = 13, F = 15; GOLF M = 7, F = 10

AGE: Range 7-14 year-old; SWIM 10.7 (1.9), GOLF 9.9(1.8)

BASELINE DETAILS: ASTHMA diagnosis: persistent asthma (according to NAEPP/NHLBI guidelines).

ASTHMA SEVERITY: MILD PERSISTENT SWIM 39%, GOLF 35%; SEVERE PERSISTENT SWIM 32%, GOLD 12%.

ICS USE: SWIM 52% ,GOLF 65%.

QOL participant: PAGQLQ SWIM 4.9 SD 1.5, GOLF 5.3 SD 1.1.

INCLUSION CRITERIA: children 7–14 years old with mild, moderate, or severe persistent asthma living in areas of high asthma prevalence and low socioeconomic status in Milwaukee

EXCLUSION CRITERIA: having mild intermittent asthma or co-morbidities making participation unsafe or confounding analyses


InterventionsINTERVENTION: 9-week high intensity swimming programme with 27 x 1-hr sessions (30 mins standardised swimming instruction using the American Red Cross format at participant’s swimming level + 30 min of vigorous swimming consisting of 4 phases: interval training (12-15 min periods swim 20 – 80 sec full-speed drills of flutter-kicking, water jumping, introductory front crawl, introductory back stroke, then rest for 20 – 80 sec), endurance training, relay races, and water games.

Swim pool setting - indoor , chlorinated

CONTROL: 9-week moderate intensity activity golf programme 27 x 1-hr sessions.

RUN-IN PERIOD: April – October 2003  

TREATMENT PERIOD: 9 weeks ( 3 intervention time periods (April/May, July/August, September/October)

FOLLOW-UP PERIOD: symptoms and quality of life measured on last day of class, Vo2 max within 2 weeks of finishing classes.

CO-INTERVENTIONS: ICS 52% SWIM, 65% GOLF. No significant pre- to post-intervention change in controller medication use, rescue medication use, pre-exercise medication use reported during the intervention


OutcomesPre- and post-intervention changes in:

-       Symptoms (PALQ symptoms domain, LWAQ index, )

-       Fitness (VO2 max, Coopers 12 min walk/run test, exercise time, peak heart rate)

-       Quality of life (QOL) PALQ total child, PACLQ total parent

-       Urgent asthma visits


NotesStudy author supplied allocation method, follow-up period and swimming pool details. Study data reported as pooled effects for swim and golf groups only. Study author supplied individual patient data for baseline and follow-up for all measures.

Fitness outcome data only measured on subgroup of participants swimming n =11, golf n=8 [CT12 results (meters), maximal oxygen consumption (V_ o2max) (mL/kg/min), and treadmill exercise time (minutes)].

Authors reported that as a marker of fitness change, Cooper’s test correlated poorly withVO2max (r = -0.01, P= 0.96) and therefore considered fitness change outcome using Cooper's test to be invalid.

Paediatric Asthma Quality of Life Questionnaire (PAQLQ) measures functional problems (physical, emotional and social) : 23 questions in 3 domains (symptoms, activity limitation and emotional function).

Living With Asthma Questionnaire (LWAQ): modified US version instrument has 27 items and five sub scales: Consequences (10 items);
Affect (6 items); Leisure (4 items); Seriousness (5 items) and Drugs (2 items).

Paediatric Asthma Caregiver’s Quality of Life Questionnaire (PACQLQ)

Study support: Helfaer Recreation Center; and the staff at the Bridging the Gap Golf Facility and the USGA’s First Tee Program. Speedo donated goggles, the Boys’ and Girls’ Clubs of Greater Milwaukee donated memberships to participants. Medical College of Wisconsin New Faculty Grant; Children’s Hospital Foundation of the Children’s Hospital of Wisconsin Small Studies Grant; and the National Research Service Award 2-T32-HP-10030-06 training grant.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low risk"We block-randomized in groups of six using SAS version 8.02, with the goal of obtaining relatively equal numbers in both intervention groups."

Participants were randomised to either swimming or golf, after parental informed consent was obtained

Allocation concealment (selection bias)Low riskAllocation by sealed envelopes

Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants were aware of group allocation owing to nature of intervention

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo details on outcome assessment

Incomplete outcome data (attrition bias)
All outcomes
High riskFor participants missing two sessions in a row, a researcher made at least three phone contact attempts on separate days. If contact was unsuccessful, a letter was mailed with a schedule and invitation to contact us to facilitate attendance. Withdrawals 7/35 swim (20%), 9/26 (35%) golf

Selective reporting (reporting bias)Low riskAll statistical analyses were performed using SAS software version 8.02. Trialist used paired t-tests to evaluate pre- to post-intervention changes in symptoms, fitness, QOL, and urgent asthma visits, and two-sample t-tests to evaluate inter-group differences. Author supplied individual patient data for all recruited participants.

Other biasUnclear riskAuthors reported that number of recruited participants (45) was below the minimum sample size (82) required to adequately power inter-group comparisons for the study outcomes. Theye did not report inter group comparisons in published paper. Individual patient data were supplied by the study author for all participants.

Wicher 2010

MethodsSTUDY DESIGN: parallel group randomised, prospective study

LOCATION, NUMBER OF CENTRES: Hospital de Clínicas of Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil.

STUDY PERIOD:  from November 2004 to August 2009.1-month run-in period and 3-month follow-up period.

METHODS OF ANALYSIS: To analyse variables between two groups (pre-and post-treatment), used the Wilcoxon test for related samples. To analyse the comparison of the ages and anthropometric measurements, PC20 FEV1 and between groups swimming and control, used the Mann Whitney test. To analyse the relationship between numerical variables, used the Spearman correlation coefficient


ParticipantsRECRUITMENT MEANS: Not stated

TARGET PARTICIPANTS: children and adolescents (age 7-18 years)

N SCREENED: not known

N RANDOMISED: 71 patients randomised,

N COMPLETED: 61 completed swimming group (n = 30) and control group (n = 31),

GENDER

M = 27; INT 12, CONTROL 15

F = 34; INT 18, CONTROL 16

AGE: INT 10.35±3.13, CONTROL 10.90 ± 2.63

ASTHMA DIAGNOSIS CRITERIA:  moderate persistent asthma, diagnosed according to the criteria of the Global Initiative for Asthma (Global Initiative for Asthma, GINA)

SEVERITY OF ASTHMA: moderate persistent atopic asthma

OTHER INCLUSION CRITERIA: history of symptoms of reversible airway obstruction and recurrent, serum IgE with values ​​greater than or equal to the 97.5 percentile for age on at least one blood sample positive skin tests to at least one antigen tested , family history of allergy.

EXCLUSION CRITERIA: patients with a history of respiratory infection within 15 days. Systemic steroids, theophylline, or anti leukotrienes, oral beta2 adrenergic agents during one month before the study.

OTHER BASELINE DETAILS:

INT FEV1(L)* 1.88 ± 0.62, CONTROL FEV1 1.80 ± 0.59  (P = 0.74);

FEV1 % predicted INT 87.19 ± 13.24, CONTROL  74.73 ± 15.58 (P = 0.001)

PC20 (mg/mL)* INT 0.31 ± 0,25, CONTROL 0.30 ± 0.23 (P = 0.707)
WITHDRAWALS: 10 patients did not complete the study: 4 difficulty attending because they lived in other cities, 1 experienced aggravation of rhinitis, 2 attended baseline tests but did not attend swimming, 3 had less than 80% attendance during the swimming programme and were excluded.


InterventionsSETTING OF INTERVENTION:  Indoor, chlorinated pool with opening upper walls for ventilation.

DESCRIPTION OF INTERVENTION:  60 minutes session x twice weekly classes. Before swimming, PEF measured with warm up gentle stretching, postural and diaphragmatic breathing exercises performed lying on a mattress, for 15 minutes. 2 levels swimming training according to previous experience: Level I (n = 26) : adaptation to the water, breathing with full immersion, floating, swimming and basic diving, Level II (n = 4): children who had the skills described plus learning front and back crawl.

DURATION OF INTERVENTION: 12 weeks (24 sessions x 45 minutes)

CONTROL: No swimming training

Cointerventions: Both patient groups received inhaled fluticasone (dry powder, 250 mcg twice a day), formoterol (12 mcg two times a day) and salbutamol as needed.


OutcomesPRE-SPECIFIED: spirometric assessment FVC, FEV1, FEF 25-75%, methacholine challenge test: provocative concentration of methacholine causing a 20% fall in FEV1 (PC20).

TIME POINTS: before and after the study period.

FOLLOW-UP PERIOD: 3 months


NotesStudy was approved by the Ethics Committee Research at the University Hospital of UNICAMP # 529/2002, and all patients and their guardians signed informed consent before the baseline. Paper published in Portugese. PC20 result not given as geometric mean methacholine dose. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured only in the swimming group so results not used. Letter to author Wicher 25/05/12 re randomisation/allocation, table 3 results for FEV1 % predicted possible error transposing results for intervention/control group. Further request 26/07/12- no response received.

Study funding: not known.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskNo details given

Allocation concealment (selection bias)Unclear riskNo details given

Blinding of participants and personnel (performance bias)
All outcomes
High riskParticipants were aware of group allocation owing to nature of intervention

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo details given

Incomplete outcome data (attrition bias)
All outcomes
High risk10 withdrawals listed, 9 at least from intervention group

Selective reporting (reporting bias)Unclear riskProtocol not available. Results for outcomes specified in methods are available.

Other biasUnclear riskSignificant baseline imbalance in FEV1 % predicted between participant groups

 
Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Alison 2000Not a randomised-controlled trial

Arandelovic 2007Study participants are adults

Bernard 2006Not a randomised-controlled trial

Bonsignore 2008Not a randomised-controlled trial

Busfield 1982Not a randomised-controlled trial

Fitch 1971Not a randomised-controlled trial. Compared swimming, running, cycling in people with asthma. No control group

Fitch 1976Before versus after 5 months swimming training in people with asthma. Control group did not have asthma

Font-Ribera 2011UK longitudinal population-based birth cohort and no association between swimming and the risk of asthma or allergic symptoms. Not a randomised-controlled trial

Haluszka 1997Not swimming training

Huang 1989Swimming training in children with asthma. Control group selected prospectively and randomly. Not a randomised-controlled trial or quasi-randomised trial

Inbar 1980Comparison of swimming training in dry or humid air. No control group. Not RCT

Inbar 1991Not a study of swimming training. Not RCT

Inbar 1993No control group, Not a randomised-controlled trial

Kellie 2009Comment. Not a randomised-controlled trial

Lecheler 1988Compared interval and continuous physical training. Not swimming training

Mallinson 1981Epidemiological study and not a randomised-controlled trial

Moreira 2008Does not include swimming training

Nickmilder 2007Epidemiolgical association study of childhood asthma (ISAAC) and number of indoor chlorinated swimming pools per inhabitant in the studied centres. Not a randomised controlled trial

Nursing Standard 2010Not a randomised controlled trial

Paul 1989Not a randomised-controlled trial. Practice commentary.

Pelham 1999Pre- and postexercise pulmonary function comparison after controlled exercise in ice rink, gymnasium, and swimming pool. Not a randomised controlled trial.

Piacentini 2011Editorial for Font-Ribera 2011. Not a randomised controlled trial

Rothe 1990Children with asthma 'placed' into either a "free running group"swimming group" or a "control group." Not a randomised or quasi-randomised study.

Schaar 1999Comparison of inline skating and swimming groups. All participants did both activities in same order, no randomisation to group order.

Schmidt 1997Not swimming training

Silva 2006Not swimming training

Sly 1972Intervention not confined to swimming training (also callisthenics, tumbling, parallel bars, rope climbing, abdominal strengthening,wall ladder, running). Not a randomised-controlled trial.

Sockrider 2007Not a randomised-controlled trial

Svenonius 1983Not a randomised-controlled trial

Turner 2011Study participants adults, not children/adolescents

Wardell 2006Letter to the editor. Not a randomised-controlled trial

Zipes 2003Comment. Not a randomised-controlled trial

 
Comparison 1. Swimming training versus control

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Quality of life1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    1.1 PAQLQ child
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

    1.2 PAQLQ symptom domain
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

    1.3 PACQLQ parent
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 2 Symptoms (change)2Mean Difference (IV, Fixed, 95% CI)Totals not selected

    2.1 LWAQ index (control golf)
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

    2.2 Composite score (control usual care)
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 3 Change in asthma symptoms (all)258Std. Mean Difference (IV, Fixed, 95% CI)-0.06 [-0.58, 0.47]

    3.1 Control usual care
18Std. Mean Difference (IV, Fixed, 95% CI)-0.29 [-1.73, 1.16]

    3.2 Control golf
150Std. Mean Difference (IV, Fixed, 95% CI)-0.02 [-0.58, 0.54]

 4 Urgent asthma physician visits1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    4.1 Control golf
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 5 Asthma consultation (1 or more) during intervention1Peto Odds Ratio (Peto, Fixed, 95% CI)Totals not selected

    5.1 Urgent asthma Physician visit (⋧1) during intervention
1Peto Odds Ratio (Peto, Fixed, 95% CI)0.0 [0.0, 0.0]

    5.2 Urgent asthma ED visit (⋧1) during intervention
1Peto Odds Ratio (Peto, Fixed, 95% CI)0.0 [0.0, 0.0]

 6 FEV1 L4113Mean Difference (IV, Fixed, 95% CI)0.10 [-0.00, 0.20]

    6.1 Absolute
114Mean Difference (IV, Fixed, 95% CI)-0.08 [-0.44, 0.28]

    6.2 Change
399Mean Difference (IV, Fixed, 95% CI)0.11 [0.01, 0.22]

 7 FEV1 % predicted (change)483Mean Difference (IV, Fixed, 95% CI)8.07 [3.59, 12.54]

    7.1 Control usual care
364Mean Difference (IV, Fixed, 95% CI)6.55 [1.24, 11.85]

    7.2 Control golf
119Mean Difference (IV, Fixed, 95% CI)11.82 [3.48, 20.16]

 8 FVC L4113Mean Difference (IV, Random, 95% CI)0.10 [-0.07, 0.26]

    8.1 Absolute
114Mean Difference (IV, Random, 95% CI)-0.19 [-0.95, 0.57]

    8.2 Change
399Mean Difference (IV, Random, 95% CI)0.11 [-0.06, 0.28]

 9 FVC % predicted (change)5144Mean Difference (IV, Random, 95% CI)3.85 [-0.58, 8.28]

    9.1 Control usual care
4125Mean Difference (IV, Random, 95% CI)2.00 [-1.84, 5.84]

    9.2 Control golf
119Mean Difference (IV, Random, 95% CI)8.89 [2.65, 15.12]

 10 FEF 25% to 75 % predicted (change)4118Mean Difference (IV, Random, 95% CI)12.63 [2.73, 22.53]

    10.1 Control usual care
399Mean Difference (IV, Random, 95% CI)11.07 [-1.17, 23.30]

    10.2 Control golf
119Mean Difference (IV, Random, 95% CI)19.02 [3.26, 34.78]

 11 FEF 25% to 75% L1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    11.1 Absolute
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 12 FEF 50 % predicted1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    12.1 Absolute
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 13 PEF L/min238Mean Difference (IV, Random, 95% CI)62.07 [22.84, 101.30]

    13.1 Absolute
238Mean Difference (IV, Random, 95% CI)62.07 [22.84, 101.30]

 14 Exercise capacity: VO2 max (mL/kg/min)3Mean Difference (IV, Fixed, 95% CI)Subtotals only

    14.1 Control: usual care
232Mean Difference (IV, Fixed, 95% CI)9.67 [5.84, 13.51]

    14.2 Control: golf
119Mean Difference (IV, Fixed, 95% CI)-7.00 [-14.57, 0.57]

 15 Exercise Capacity: other measures (control: usual care)2Mean Difference (IV, Fixed, 95% CI)Totals not selected

    15.1 Physical Work Capacity (PWC170 watts)
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

    15.2 Swimming ergometry at lactic threshold (change kp)
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

    15.3 Cycle ergometry at lactic threshold (change watts)
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 16 Exercise Capacity: Any measure (control: usual care)474Std. Mean Difference (IV, Fixed, 95% CI)1.34 [0.82, 1.86]

    16.1 VO₂max (mL/kg/min)
232Std. Mean Difference (IV, Fixed, 95% CI)1.65 [0.82, 2.49]

    16.2 Physical Work Capacity (PWC170 watts)
126Std. Mean Difference (IV, Fixed, 95% CI)1.05 [0.22, 1.88]

    16.3 Cycle ergometry at lactic threshold (change watts)
116Std. Mean Difference (IV, Fixed, 95% CI)1.32 [0.21, 2.44]

 17 Distance fitness tests-all (m)2Mean Difference (IV, Fixed, 95% CI)Totals not selected

    17.1 Coopers 12min walk-run distance (control usual care)
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

    17.2 6min walk distance (control golf)
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 18 Distance fitness tests-all (m)270Std. Mean Difference (IV, Fixed, 95% CI)0.15 [-0.34, 0.63]

    18.1 Coopers 12-minute walk-run distance (control usual care)
126Std. Mean Difference (IV, Fixed, 95% CI)0.60 [-0.19, 1.39]

    18.2 6min walk distance (control golf)
144Std. Mean Difference (IV, Fixed, 95% CI)-0.14 [-0.77, 0.48]

 19 Bronchial hyper-responsiveness: ln PC20 methacholine1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    19.1 Children and adolescents
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 20 Exercise induced bronchoconstriction (maximum fall in FEV1 (%)1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    20.1 Swimming ergometry
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

    20.2 Cycling ergometry
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 
Summary of findings for the main comparison. Swimming training for asthma in children and adolescents aged 18 years and under

Swimming training for asthma in children and adolescents aged 18 years and under

Patient or population: children and adolescents aged 18 years and under studies with asthma
Settings: Recruited from asthma clinics. Asthma diagnosis by recognised criteria.
Intervention: Swimming training programme- meeting minimum intensity criteria (> Weekly, > 20 minutes, > 4 weeks)

OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments

Assumed riskCorresponding risk

ControlSwimming training

Quality of life 1
Paediatric Asthma Quality of Life Questionnaire (PAQLQ). Scale from: 1 (worse) to 7 (better).
Follow-up: mean 9 weeks
The mean change in quality of life in the control group was -1.87The mean change in quality of life in the intervention group was
0.26 (1.05 lower to 1.58 higher)
50
(1 study1)
⊕⊕⊝⊝
low2,3

Asthma symptoms
Different scales in different studies (lower scores mean fewer symptoms)
Follow-up: 6-9 weeks
The mean change in asthma symptoms ranged across control groups from
0 to -2.14 standard deviations
The mean asthma symptoms in the intervention groups was
0.06 standard deviations less
(0.58 lower to 0.47 higher) see comment
58
(2 studies)
⊕⊕⊝⊝
low3,4,5
The difference of 0.06 standard deviations would equate to a small difference on Living with Asthma Questionnaire (LWAQ) or a composite 12-point scale of < 0.5 units. The effect size is < 0.2 representing a small effect.

Exacerbations requiring hospital admissionsee commentsee commentsee commentsee comment-Outcome not reported

Exacerbations requiring a course of oral corticosteroidssee commentsee commentsee commentsee comment-Outcome not reported

Urgent asthma physician visits1
Number of times the child visited a physician's office/clinic for an asthma flare up
Follow-up: mean 2 months
The mean urgent asthma physician visits in the control group was
0.17 visits in 2 months
The mean urgent asthma physician visits in the intervention groups was
0.08 higher
(0.25 lower to 0.42 higher)
44
(1 study1)
⊕⊕⊕⊝
moderate3

Resting lung function
Forced expiratory volume (FEV1) in 1 second (litres)
Follow-up: 6-12 weeks
The mean change in resting FEV1 ranged across control groups from
0.05-0.15 litres
The mean difference in FEV1 in the intervention groups was
0.10 L higher
(0 to 0.2 higher)
113
(4 studies)
⊕⊕⊕⊝
moderate3
The mean difference is comparable to the difference in FEV1 in children with asthma (N = 4, n = 719 7) comparing low dose fluticasone propionate (100 mcg) daily with placebo mean difference (MD) 0.1 L [0.15, 0.36] (Adams 2008)

Fitness6
Maximal oxygen consumption (VO2 max)
Follow-up: mean 12 weeks
The mean VO2 max in usual care control groups was
39 mL/kg/min
The mean fitness in the swimming intervention groups was
9.67 mL/kg/min higher
(5.84 to 13.51 higher)
32
(2 studies)
⊕⊕⊕⊕
high
The 25% difference for swimming compared to control in VO2 max is clinically meaningful. It is larger than the differences seen in physical activity studies in children without asthma, range 5% to 15% (Armstrong 2011) and that seen in children with asthma undertaking physical training 9% (Counil 2003).

*The basis for the assumed risk is provided in the table. 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; FEV1 forced expiratory volume in one second; L: litres;

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.

 1 Control group: golf
2 High risk of attrition bias assessed in study
3 The confidence interval does not rule out a null effect or harm
4 Comparison groups differed; usual care or golf
5 Effect size < 0.2 represents small effect
6 Pooled studies with non-active usual care control group only
7 N= number of studies; n= number of participant
 
Table 1. Correlation coefficients: from studies for imputing standard deviation of mean changes

Weisgerber 2008Swimming groupGolf group

FEV1 % predicted0.64910.9179

FVC % predicted0.87220.9064

FEF 25% to 75% % predicted0.38230.9234

Coopers test0.76550.8588

Peak heart rate0.92590.3264

Exercise time0.82000.8584

Weisgerber 2003Swimming groupUsual care group

FEV1 L0.59830.9433

FEV1 % predicted0.55850.8495

FVC (L)0.77790.9781

FVC % predicted0.92290.4247

PEF (L/s)0.51150.7406

PEF % predicted0.03190.9062

FEF 25% to 75% % predicted0.86340.8904

 FEF = forced expiratory flow; FEV1= forced expiratory volume in 1 second; FVC = forced vital capacity; PEF = peak expiratory flow
 
Table 2. Sensitivity analyses

OutcomeNSD calculation methodEffect size [95% CI]

Quality of life (PAQLQ)1Change (no imputation)MD 0.26 [-1.05, 1.58]

1AbsoluteMD 0.16 [-1.17, 1.50]

Symptoms (PAQLQ)1Change (no imputation)MD 0.07 [-1.12, 1.26]

1AbsoluteMD 0.12 [-1.20, 1.43]

Caregiver quality of life (PACQLQ)1Change (no imputation)MD 0.71 [-0.83, 2.25]

1AbsoluteMD 0.61 [-0.86, 2.07]

Asthma symptoms (LWAQ index)1Change (no imputation)MD -0.10 [-2.55, 2.36]

1AbsoluteMD 0.83 [-1.44, 3.11]

Exercise Capacity: Any measure (control: usual care)4Cycle ergometry (Watts)MD 1.34 [0.82, 1.86]

4Swimming  ergometry (kp)MD 1.41 [0.88, 1.94]

 LWAQ = Living with Asthma Questionnaire; MD = mean difference; N= number of studies; PACQLQ = Paediatric Asthma Caregiver’s Quality of Life Questionnaire; PAQLQ = Paediatric Asthma Quality of Life Questionnaire; SD = standard deviation
 
Table 3. Subgroup and sensitivity analyses

Outcome N SD calculation method  All studiesNon-chlorinated

/ ventilated chlorinated pool
Chlorinated poolUnknown chlorination status




Effect size [95% CI]NEffect size [95% CI]NEffect size [95% CI]NEffect size [95% CI]

MD FEV1 L3Change (Correlation from Weisgerber 2003)MD 0.11 [0.01, 0.22]20.16 [0.02, 0.30]010.05 [-0.12, 0.21]

4AbsoluteMD 0.20 [0.05, 0.35]20.24 [0.04, 0.44]020.15 [-0.08, 0.37]

MD FEV1 % predicted4Change (Correlation from Weisgerber 2003)MD 8.47 [3.60, 13.33]26.40 [0.29, 12.50]111.82 [3.48, 20.16]115.70 [-15.48, 46.88]

4AbsoluteMD 2.39 [-3.90, 8.69]2-0.38 [-8.08, 7.32]110.97 [-3.35, 25.29]13.80 [-13.11, 20.71]

MD FVC L3Change (Correlation from Weisgerber 2008)MD 0.11 [-0.06, 0.28]

3Change (Correlation from Weisgerber 2003)MD 0.09 [-0.00, 0.19]20.20 [0.07, 0.33]01-0.05 [-0.19, 0.10]

4Absolute0.31 [0.12, 0.50]20.33 [0.07, 0.59]020.28 [-0.00, 0.56]

MD FVC% predicted5Change (Correlation from Weisgerber 2008)MD 3.85 [-0.58, 8.28]32.00 [-2.13, 6.14]18.89 [2.65, 15.12]116.80 [-27.63, 61.23]

5Change (Correlation from Weisgerber 2003)MD 4.53 [0.26, 8.80]32.89 [-2.00, 7.78]18.89 [2.65, 15.12]116.80 [-27.63, 61.23]

5AbsoluteMD 6.76 [-0.93, 14.46]35.28 [-6.96, 17.52]19.27 [-4.34, 22.89]18.20 [-6.84, 23.24]

MD FEF 25-75 % predicted4Change (Correlation from Weisgerber 2008)12.63 [2.73, 22.53]28.75 [-7.61, 25.10]119.02 [3.26, 34.78]118.07 [0.52, 35.62]

4Change (Correlation from Weisgerber 2003)12.47 [1.12, 23.82]28.59 [-7.76, 24.95]119.02 [3.26, 34.78]118.07 [0.52, 35.62]

4Absolute12.40 [5.30, 19.49]

 FEV1= forced expiratory volume in 1 second; FVC = forced vital capacity; MD = mean difference; N= number of studies; SD = standard deviation
 
Table 4. Comparison of baseline characteristics of included studies

ID/Location/ full publicationn randomised/ Withdrawals% maleMean age (range)Asthma diagnosisAsthma severity

Varray 1991 /France/ yes14/086%11  (9-13)Atopy, BDR, clinicalNot  known

Varray 1995/ France/ yes18/078%11 (9-13)Atopy, BDR, clinicalNot  known

Matsumoto 1999/ Japan/ yes16/088%11 (8-12)ATS criteria + hospital admissionSevere

Altintas 2003/ Turkey/ no26/050%10 (5-14)GINA criteriamoderate

Weisgerber 2003/ USA/ yes26/1650%8(7-14)ATS criteriaModerate persistent

Weisgerber 2008/ USA/ yes78 recruited /61 commenced intervention/ 16 withdrawals44%10 (7-14)NAEPP/NHLBI criteriaMild, moderate, or severe persistent

Wang 2009/ Taiwan/ yes30/067%10 (7-12)ATS criteriaMild, moderate, or severe persistent

Wicher 2010/ Brazil/ yes71/1044%10 (7-18)GINA criteriamoderate persistent

 ATS = American Thoracic Society; BDR = bronchodilator response; EIB = exercise induced bronchoconstriction; FEF = forced expiratory flow; FEV1= forced expiratory volume in 1 second; FVC = forced vital capacity; GINA = Global Initiative for Asthma; hr = hour, ICS = inhaled corticosteroids; NAEPP = National Asthma Education and Prevention Program; NHLBI = National Heart, Lung, and Blood Institute; PEF = peak expiratory flow; QOL = quality of life; Tx = treatment;
 
Table 5. Comparision of intervention characteristics of included studies

ID/Location/ full publicationAsthma treatmentSwimming time/frequency per week/n weeks/ pool type. Swimming supervision.Comparison groupFollow-up point in weeks/

outcomes in meta-analysis

Varray 1991 /France/ yesnot known60 minutes/ 2/12/ indoor. Supervisor: physical education teacher.usual care12 / FEV1, FVC, FVC%pr, VO2max, VEmax, 

Varray 1995/ France/ yesregular Tx60 minutes/2/ 12/ indoor. Supervisor: physical education teacher.usual care12/ VO2 max,

Matsumoto 1999/ Japan/ yesregular Tx/ 50% ICS, 75% theophylline, 38% cromoglycate30 minutes/6/6/ indoor heated. Supervisor: unknown.usual care6/ aerobic capacity, EIB

Altintas 2003/ Turkey/ no100-400mcg ICS90/3/ 6/ indoor non-chlorinated. Supervisor: unknown.usual care6/ physical work capacity, walk test, PEF % pred, FEV1 % pred, FVC % pred.

Weisgerber 2003/ USA/ yesregular Tx45 minutes/2/6/ indoor. Supervisor: certified swim instructor unaware of study participation.usual care6-8 / FEV1, FEV1 % pred, FVC, FVC % pred, FEF25-75%, PEF, Symptoms 

Weisgerber 2008/ USA/ yesRegular Tx, ICS 52% swim, 65% golf60 minutes/3/9/ indoor, chlorinated. Supervisors: certified swim instructors who had attended 1-hr training seminar outlining asthma safety.Golf sessions 60 minutes/ 3/ 99 /QOL, symptoms, exercise capacity,healthcare utilisation,  FEV1, FEV1% pred, FVC, FVC% pred, FEF 25-75%,

Wang 2009/ Taiwan/ yesregular Tx30 minutes/ 3/ 6/ outdoor non-chlorinated. supervisor: certified swimming instructors not aware of involvement in the study.usual care6/ FEV1, FEV1% pred, FVC, FVC% pred, FEF50%, FEF 25-75%, PEF, 

Wicher 2010/ Brazil/ yesall ICS 1000mcg/day, LABA BD60 minutes/ 2/ 12/ indoor, ventilated, chlorinated. Supervisor: unknown.usual care12/ FEV1, FEV1% pred, FVC. FEF 25-75%, 

 BDR = bronchodilator response; EIB = exercise induced bronchoconstriction; FEF = forced expiratory flow; FEV1= forced expiratory volume in 1 second; FVC = forced vital capacity; hr = hour, ICS = inhaled corticosteroids; PEF = peak expiratory flow; QOL = quality of life; Tx = treatment;