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Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES

Objective

Patients with juvenile idiopathic arthritis (JIA) are less physically active than healthy peers. Therefore, we developed an Internet-based intervention to improve physical activity (PA). The aim of this study was to examine the effectiveness of the program in improving PA.

Methods

PA was determined by activity-related energy expenditure, PA level, time spent on moderate to vigorous PA, and the number of days with ≥1 hour of moderate to vigorous activity, and was assessed with a 7-day activity diary. Aerobic exercise capacity was assessed by means of a Bruce treadmill test and was recorded as maximum endurance time. Disease activity was assessed by using the JIA core set. Adherence was electronically monitored.

Results

Of 59 patients, 33 eligible patients were included and randomized in an intervention (n = 17, mean ± SD age 10.6 ± 1.5 years) or control waiting-list group (n = 16, mean ± SD age 10.8 ± 1.4 years). All patients completed baseline and T1 testing. PA significantly improved in both groups. Maximum endurance time significantly improved in the intervention group but not in the control group. In a subgroup analysis for patients with low PA (intervention: n = 7, control: n = 5), PA improved in the intervention group but not in the control group. The intervention was safe, feasible, and showed a good adherence.

Conclusion

An Internet-based program for children with JIA ages 8–12 years directed at promoting PA in daily life effectively improves PA in those patients with low PA levels. It is also able to improve endurance and it is safe, feasible, and has good adherence.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES

Children and adolescents with juvenile idiopathic arthritis (JIA) have reduced aerobic and anaerobic exercise capacity (1–3). There is also evidence that they are less physically active as compared with healthy peers (4, 5). As a result, they may perceive difficulties in joining regular sport activities and in social interaction. It is unclear if this is the cause of the low exercise capacity or the result of it. Physical activity (PA) and physical fitness are interrelated (6). PA can be described as all leisure and non-leisure body movements resulting in an increased energy output from the resting condition (7). To become and remain physically fit, it is necessary to become physically active and to adopt and maintain a physically active lifestyle (8).

Evidence is accumulating that PA is effective in the primary and secondary prevention of several chronic conditions (9–11). PA is also associated with a reduction in all-cause mortality (11). There is evidence that in youth ages 6–16 years, PA controls body weight; reduces blood pressure in hypertensive youth; improves aerobic capacity, muscular strength, endurance, and skeletal health; reduces anxiety and depression; and improves self-concept (12). PA also has a positive effect on academic performance, concentration, memory, and classroom behavior (12). For children with JIA and other chronic diseases, it is recognized that they could take advantage of the same health benefits (13, 14). Evidence supports the fact that PA is safe, feasible, and acceptable in patients with JIA with and without active disease (15). For these reasons, it is extremely important to encourage and improve PA in patients with JIA. To our knowledge, there are currently no published studies of successful interventions that have a positive effect on PA in JIA patients.

PA can be seen as a type of behavior that is multidimensionally determined by a mix of psychological and social factors such as perceived benefits, barriers, and self-efficacy toward PA; PA-related affect; norms and support from family, peers, school, and health providers; and PA options (16, 17). We observed that patients with JIA and their families are not always aware of the benefits of PA. Moreover, fear of the damaging effect of PA is not uncommon, barriers are often high, and self-efficacy toward PA is low. Improving PA by institutionalized training programs is not realistic for large groups and not desirable when children have to travel many kilometers to reach an institution. To overcome these problems, we developed an Internet-based intervention that is affordable and easily accessible for a large group of patients. A systematic review of Internet-based interventions to promote PA in adult populations showed that such an intervention is effective compared with a waiting-list group (18). An Internet-based PA intervention program showed high scores on satisfaction among adult patients with rheumatoid arthritis (19). Using Internet technology can be more effective when group sessions and individual tailored supervision are added (20). Group sessions provide the possibility of modeling, social support, and sharing experiences, which are all important factors to enhance self-efficacy and to adopt behavioral change (16). Therefore, 4 group sessions were added. The objective of the Internet-based program was to promote PA in daily life in children with JIA ages 8–12 years and, in particular, to promote moderate to vigorous PA. The aim of this study was to examine the effectiveness of the program in improving PA.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES

Patients.

All of the patients with JIA who were registered in our hospital and ages 8–12 years were selected for this study. Inclusion criteria consisted of a diagnosis of JIA, a good comprehension of the Dutch language, and the availability of a home-based computer with an Internet connection. Informed consent was obtained from parents and patients. Weight and height were determined using a mechanical scale and a stadiometer. Body mass index was calculated as body mass in kilograms/height in meters squared. Disease activity was measured and defined by a pediatric rheumatologist (WA) according to the response variables of the JIA core set (21). Of these 6, functional ability was modified and assessed by the revised Dutch version of the Childhood Health Assessment Questionnaire (C-HAQ) and using the alternative C-HAQ 38 score calculation method as described by Ouwerkerk et al (22). Ability was assessed using 30 questions in 8 domains covering major aspects of daily living: dressing, grooming, arising, eating, walking, hygiene, reach grip, and activities. Eight more challenging items were added to lessen the ceiling effect as described by Lam et al (23). These 8 extra items were grouped in one domain. Each question was rated on a 4-point scale (where 0 = no difficulty, 1 = some difficulty, 2 = much difficulty, and 3 = unable to do). The C-HAQ 38 was calculated as the mean of the 9 domains and yielded a score between 0 (no disability) and 3 (most severe disability). Erythrocyte sedimentation rate was not normally assessed.

Disease activity was classified according to the criteria by Wallace et al as active disease, inactive disease, clinical remission on medication, and clinical remission off medication (24). Active disease was defined as active arthritis being present in 1 or more joints, inactive disease was defined as no signs of disease with medication, and clinical remission on medication was defined as 6 continuous months without active disease on medication. Clinical remission off medication was defined as 12 months off of medication and no signs of active disease. The number of disease flares and improvement during the trial were recorded. A disease flare was defined as a minimum of 40% worsening in a minimum of 2 of 6 components, with no more than 1 component improving by >30% (25). Improvement was defined as a minimum of 30% improvement in a minimum of 3 of 6 components, with no more than 1 component worsening by >30% according to the American College of Rheumatology (ACR) Pediatric 30 (Pedi 30) criteria (21, 25).

Motivation for behavioral change was measured with a 100-mm visual analog scale (VAS) anchored on the left by “not willing to change” and on the right by “I am already changing.”

Intervention.

The intervention, “Rheumates @ Work,” was an Internet-based program lasting 17 weeks, combined with 4 group sessions. It contained the following elements: 1) health education: teaching the patient the fundamentals of cause and effect of JIA in order to improve disease management, 2) benefits of PA are explained and barriers toward PA are identified, 3) self-efficacy and perceived affect of PA are identified and reinforced, 4) influence of family and school is recognized and used to promote PA, 5) PA options in daily life are explored and encouraged, and 6) smart goals are set: patients have to better tune and define specific, measurable, attainable, realistic, and timely goals, such as “I am going to cycle to school 3 times a week instead of going by car, for the coming 2 months.” All of these elements are based on the health promotion model by Pender, which identifies moldable determinants of PA behavior (17). Films, animations, spoken texts, puzzles, brain twisters, and assignments were used and presented in dosed quantities. The program started with an interactive group session for patients and their parents, where an individual goal was set by the patient depending on their joint status and PA level. A contract expressing the will to participate was signed. Then the weekly Internet sessions started, and every week the patients worked on a specific theme: week 1 = what is JIA; week 2 = how to tackle problems; week 3 = energy and fitness; week 4 = benefits and barriers of PA; week 5 = pain and PA; week 6 = setting goals; week 7 = how to train; week 8 = second group session about barriers and benefits of PA; week 9 = taking responsibility; week 10 = chat box; week 11 = third group session about how to ask help from parents, friends, and school; week 12 = support and being physically active together; week 13 = how to be open over your JIA and ask for help; week 14 = how to deal with setbacks; week 15 = rewarding yourself; week 16 = retrospective; and week 17 = final group session: dealing with setbacks and adjusting goals. The patient received a reminder by e-mail when he/she did not complete the assignment. A feedback loop was built into the program to verify whether the patient had read the theory and made the assignment. During the entire week, the patient could ask questions by mail. After registration online, each patient had their own personal Web page that provided information about their current state of PA, fitness, and joint status. This information was measured at baseline. On this page, a small figure was depicted visualizing all of the joints by having 3 possible colors: green, orange, or red, depending on the physical examination of the rheumatologist. Green indicated that the joint could and should be normally used with respect to normal physical limitations. Orange indicated a joint with some degree of active arthritis, whereby light activities of daily life were encouraged but strenuous, and high-intensity activities were discouraged. Red indicated a joint with joint damage and therefore restricted function. During the intervention, the patient received the normal standard treatment for the JIA, which means that most patients were only seen at the beginning and at the end of the trial by a pediatric rheumatologist (WA). For those patients followed up in between, changed joint status was adapted at the personal Web page. The patients were free to perform their sport and leisure activities. Other physical training programs were allowed. Cognitive behavioral training focused on PA outside of the study was not permitted.

Design and randomization.

A randomized controlled trial was used with an intervention group and a control waiting-list group. Observers for the endurance test were blinded.

Outcome.

Physical activity.

PA was assessed with a 7-day activity diary filled in prior to randomization and immediately after the program finished (26, 27). After instruction, the patients were asked to record their activity level, and the assistance of parents was allowed. Every quarter of an hour, the dominant activity was scored using a number from 1 to 9, where 1 = sleeping, resting in bed, or watching television; 2 = sitting, eating, writing, etc.; 3 = standing, washing, combing, etc.; 4 = walking indoors (<4 km/hour), light home activities; 5 = walking outdoors (4–6 km/hour), cleaning the bedroom, easy outdoor playing; 6 = recreational sport and leisure time activities with low intensity; 7 = recreational sport and leisure time activities with moderate intensity; 8 = recreational sport and leisure time activities with high intensity; and 9 = competition sport. PA was expressed as PA level, activity-related energy expenditure (AEE), time spent on moderate to vigorous PA (from category 6 up to 9), and the number of days with 1 hour or more of moderate to vigorous activity. PA level and AEE were calculated as follows: a PA ratio was allotted to each of the different 9 categories following the modification by Bratteby et al (27). The PA ratio is the energy expended by an individual in a particular category as multiples of the basal metabolic rate (BMR). To calculate the total energy expenditure (TEE), all 15-minute periods of each category were summed up, divided by 96, and multiplied by the PA ratio value of each category and the predicted BMR, after which all of the categories were added up. The prediction formula according to Schofield was used: the predicted BMR for boys = 0.074 × body weight in kilograms + 2.754 megajoules (MJ)/day, and the predicted BMR for girls = 0.056 × body weight in kilograms + 2.898 MJ/day (28). PA level expresses the energy needed as multiples of the BMR, and is the TEE during a day divided by the predicted BMR. AEE is expressed as (0.9 × TEE) − BMR, assuming a diet-induced thermogenesis of 10% (29). One example is a female patient (weight 33 kg, predicted BMR 4.75 MJ/day). The first day of her activity diary showed 44 quarters of an hour with activities in category 1, 30 in category 2, 2 in category 3, 14 in category 4, 1 in category 5, and 5 in category 6: TEE = (44/96 × 0.95 + 30/96 × 1.5 + 2/96 × 2.0 + 14/96 × 2.8 + 1/96 × 3.3 + 5/96 × 4.4 + 0/96 × 6.5 + 0/96 × 10.0 + 0/96 × 15.0) × 4.75 MJ = 7.68 MJ; AEE = (0.9 × 7.68 MJ) − 4.75 MJ = 2.16 MJ; PA level = 7.68 MJ/4.75 MJ = 1.62.

Aerobic exercise capacity.

Aerobic exercise capacity was assessed by means of a Bruce treadmill test, which measures maximal endurance time. The Bruce treadmill protocol is suitable for young children. Although maximal endurance time depends on several factors like motivation of the child and aerobic as well as anaerobic exercise capacity, it may be used as the sole criterion of aerobic exercise capacity since the correlation coefficient of endurance time with maximal oxygen uptake is high (30). A treadmill was programmed for increases in grade and speed every 3 minutes as outlined by Bruce et al (31). After a general explanation of the exercise protocol and 5 minutes of rest, a polar chest belt was fixed on the chest of the patient. The resting heart rate was recorded. Patients were not permitted to hold the handlebar and they were vigorously encouraged to reach a level of maximal exertion. The test was terminated when the patient could not cope anymore with the speed and/or effort or at the observer's discretion. Maximal heart rate, maximal endurance time, and reasons for terminating were recorded. The Bruce test was accomplished by a blind observer. Outcomes were obtained at baseline and after completion of the program.

Adherence and safety.

Participation and progress were monitored by an administrator (IdG). Every week after login, the patient was guided through the theory, and after completion this was electronically registered. Results of weekly assignments were also electronically registered. Reminders were sent through e-mail in case of noncompliance and they were called after 1 week in case of nonresponse. Safety was monitored by a pediatric rheumatologist (WA) who kept record of disease activity and medication use. Adverse events during the program and test moments were registered.

Statistical analysis.

The Statistical Package for the Social Sciences, version 16 (SPSS), was used for statistical analysis. Descriptive statistics were used for patient characteristics. The Kolmogorov-Smirnov test was used to test variables for normality of distribution. A paired-samples t-test was used for within-group differences.

The Medical Ethics Research Board of the University Medical Center Groningen approved this study.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES

Patients and adverse events.

Fifty-nine patients with JIA who were ages 8–12 years and under treatment in the pediatric rheumatology department of the Beatrix Children's Hospital were identified, and through a mailing were informed and invited to participate. During outpatient visits, oral information was given as well. One patient was excluded for having to undergo major abdominal surgery during the trial period. Thirty-three patients and parents agreed to participate and informed consent was given (Figure 1). Twenty-five patients and their parents were not willing to participate. Eight parents did not see a necessity for the program since the disease was under control and they were satisfied with their child's functioning, 12 parents found the effort to participate too large, and 5 parents did not give a reason. All of the participating patients underwent baseline testing followed by blind randomizing in 2 groups. Seventeen patients were randomly selected for the intervention group and started the intervention within 1 month. Sixteen patients were selected for the control waiting-list group and they were invited to follow the intervention later. Patient characteristics are given in Table 1. There were no statistical differences between both groups at baseline. No adverse events were reported in both groups during the trial. One adverse event was reported at T0: a patient fell at the end of the treadmill test, causing minor scrapes. Of all those with active disease (5 in the intervention group and 8 in the control group), the physician's global assessment of disease activity was less than 20, except for 1 girl in the control group who had a physician's global assessment VAS score of 70. At baseline, 1 girl in the control group had active arthritis and joint limitations in both knees requiring intraarticular steroid deposits, which were administered followed by intensive physiotherapy. Both girls were in the control group and both improved according to ACR Pedi 30 criteria (21, 25). Three patients experienced a disease flare: 2 in the control group and 1 in the intervention group.

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Figure 1. Flow chart of recruitment and completion of the pilot study.

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Table 1. Patient characteristics at enrollment of the control waiting-list and intervention groups*
 Control group (n = 16)Intervention group (n = 17)Patients not included (n = 26)
  • *

    Values are the mean ± SD unless otherwise indicated. BMI = body mass index; VAS = visual analog scale; C-HAQ = Childhood Health Assessment Questionnaire; JIA = juvenile idiopathic arthritis.

  • Where 0 = a high level of well-being and 10 = a low level of well-being.

Men/women, no.2/142/156/20
Age, years10.8 ± 1.410.6 ± 1.510.9 ± 1.5
Height, cm145 ± 11145 ± 13 
Weight, kg35.6 ± 7.137.8 ± 10.0 
BMI, kg/m216.9 ± 2.117.6 ± 2.6 
Stages of change VAS (0–100 mm)5.4 ± 2.64.9 ± 2.6 
C-HAQ 38 score0.4 ± 0.30.6 ± 0.4 
Pain VAS (0–100 mm)2.0 ± 2.73.0 ± 3.0 
Overall well-being VAS (0–100 mm)1.9 ± 2.52.7 ± 2.6 
JIA subtype, no.   
 Persistent oligoarticular9910
 Extended oligoarticular020
 Polyarticular5413
 Enthesitis related001
 Systemic222
Disease activity, no.   
 Active disease85 
 Inactive disease11 
 Clinical remission on medication58 
 Clinical remission off medication23 

Adherence.

All 33 enrolled patients completed baseline testing and testing after completion of the program (Figure 1). Fourteen patients (82%) completed the full Internet program. Three patients (18%) completed most of but not the entire Internet program. The first group session was attended by 16 patients, the second group session was attended by 15 patients, the third group session was attended by 16 patients, and the fourth and last group session was attended by 11 patients. Most nonattendees were absent because of other obligations.

PA outcome.

At T1, 2 patients in the intervention group did not return their 7-day activity diaries and 1 patient in the control group returned an incomplete diary. These patients were omitted from the PA analysis. All of the other patients returned complete and properly recorded activity diaries. AEE, PA level, time spent on moderate to vigorous activity, and the number of days with 1 hour or more of moderate to vigorous activity significantly improved in both the intervention and control groups (Table 2).

Table 2. Physical activity and aerobic exercise capacity at T0 and T1*
Outcome variableControl groupIntervention group
T0, mean ± SDT1, mean ± SDΔT1 − T0T0, mean ± SDT1, mean ± SDΔT1 − T0
  • *

    AEE = activity-related energy expenditure; NS = nonsignificant.

  • Significantly different (P < 0.01) based on paired-samples t-test.

  • Significantly different (P < 0.05) based on paired-samples t-test.

Physical activity      
 AEE, megajoules/day2.07 ± 0.592.95 ± 0.860.882.38 ± 0.853.62 ± 1.271.24
 Physical activity level1.57 ± 0.121.76 ± 0.170.191.63 ± 0.161.89 ± 0.250.26
 Moderate to vigorous activity,  hours/day1.19 ± 0.441.77 ± 0.790.581.30 ± 0.682.30 ± 1.041.00
 No. of days with ≥1 hour of  moderate to vigorous activity3.87 ± 1.514.87 ± 1.851.003.87 ± 1.645.07 ± 1.221.20
Aerobic exercise capacity      
 Resting heart beat/minute89 ± 1078 ± 10 90 ± 1389 ± 10 
 Maximum heart beat/minute200 ± 9193 ± 12 201 ± 11200 ± 8 
 Maximum endurance time, seconds608 ± 83603 ± 83−5 (NS)579 ± 74605 ± 6426

Since average PA levels at baseline were better than expected, we made a subgroup analysis for those patients with low PA levels (3 days or less of category 7, with 1 hour or more of moderate to vigorous activity). Those patients with a disease flare and the patients with a significant improvement in disease outcome were excluded. Twelve patients, 7 from the intervention group and 5 from the control group, were included (Table 3). AEE, PA level, time spent on moderate to vigorous activity, and the number of days with 1 hour or more of moderate to vigorous activity significantly improved in the intervention group but not in the control group.

Table 3. Physical activity at T0 and T1 of patients with low physical activity levels at baseline*
 Control group (n = 5)Intervention group (n = 7)
T0, mean ± SDT1, mean ± SDΔT1 − T0T0, mean ± SDT1, mean ± SDΔT1 − T0
  • *

    AEE = activity-related energy expenditure; NS = nonsignificant.

  • Significantly different (P < 0.05) based on paired-samples t-test.

AEE1.88 ± 0.392.45 ± 0.630.57 (NS)1.99 ± 0.923.39 ± 1.521.40
Physical activity level1.54 ± 0.111.65 ± 0.110.11 (NS)1.53 ± 0.121.82 ± 0.240.29
Moderate to vigorous activity, hours/day0.97 ± 0.431.22 ± 0.790.25 (NS)0.83 ± 0.242.07 ± 0.941.24
No. of days with ≥1 hour of moderate to vigorous activity2.20 ± 0.843.00 ± 1.60.80 (NS)2.43 ± 0.794.57 ± 1.402.14

Aerobic exercise capacity outcome.

Maximal endurance time on the treadmill significantly improved in the intervention group but not in the control group (Table 2).

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES

The pilot study shows that an Internet-based program for children with JIA, ages 8–12 years, directed at promoting PA in daily life effectively improves PA in those patients with low PA levels. We also showed that this program improved aerobic exercise capacity expressed as endurance time and that the program is safe and feasible.

The objective of Rheumates @ Work is to promote PA in daily life and, in particular, to promote moderate to vigorous PA in children with JIA. The patients in the intervention group with low activity levels improved their daily moderate to vigorous activities with 1 hour compared with controls. This is a large and clinically relevant improvement, since public health guidelines for PA recommend 1 hour of moderate to vigorous PA per day. It shows that the intervention is effective for those patients who are most in need of it.

Although Rheumates @ Work is not a training program, we showed that it can improve aerobic exercise capacity, expressed as endurance time, in children with JIA. Patients in the intervention group significantly improved their endurance time. This is also a major finding because endurance is important for sustaining more strenuous daily activities. Studies on exercise training in healthy children ages 8–12 years showed that VO2max on average improved 7–8%, compared with 25–30% in healthy adults (32–34). Taking this into consideration, an improvement of 26 seconds in endurance time as shown in the intervention group is a clinically relevant finding.

Another important finding is that this program is safe, feasible, and has a good adherence among those who were willing to participate. In general, patients and their parents responded very positively on the program. Most of them enjoyed participating and declared the program to be meaningful.

Our study also showed that PA not only significantly improved in the intervention group but also in the control waiting-list group. The gain in PA levels in both groups might be a result of several contributing factors. The willingness to participate in this study and to join an Internet-based program directed at promoting PA is an indication of the willingness to change PA behavior. Both groups showed an equal and fair level of willingness to change, considering their equal stages of change VAS scores, indicating a selection bias toward those who are open for positive change in PA. Taking part in baseline testing could also evoke a positive change in PA levels in both groups. Patients were asked to fill in a 7-day activity diary, and by doing so, the awareness of an individual's level of PA might have increased. All of the patients received a 15-minute instruction on how to fill in the activity diary and they received an explanation of how to recognize the different PA categories. By filling in the diary day by day, they were forced to rethink and reconsider their daily activities. This process could possibly have induced a change in the control group. All of the patients had to perform an endurance test on a treadmill and an evaluation showed that although most children were a little bit nervous before performing the test, they enjoyed doing the test and for them it was a positive experience. This positive experience might increase the confidence of the patients in both groups in being able to perform more intense and strenuous activities. It is possible that increased PA is partly caused by seasonal influences, since baseline testing was in January and thus in the winter, whereas T1 was in June and thus in the summer (35). Failure to detect significant differences in PA between the groups as a whole may also have been the result of usual pediatric rheumatology care in our hospital, since PA in children with JIA has been encouraged now for many years. Baseline PA levels were better than expected, leaving less room for improvement.

This study has a number of limitations, some of which are already discussed above. Lack of power, a biased patient group, fair baseline levels of PA, and seasonal influences possibly influence outcome. To overcome these limitations, a multicenter randomized controlled trial is necessary. Another limitation is the relatively large group of patients who did not want to participate in this trial. It is important to assess and increase the motivation of patients and parents who primarily are not willing to participate to increase participation and feasibility.

We can conclude that Rheumates @ Work, an Internet-based program for children with JIA ages 8–12 years directed at promoting PA in daily life, effectively improves moderate to vigorous PA in those patients with low PA levels. It can also improve endurance and it is safe, feasible, and has good adherence.

AUTHOR CONTRIBUTIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES

All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Mr. Lelieveld had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study conception and design. Lelieveld, Armbrust, Geertzen, Sauer, van Weert, Bouma.

Acquisition of data. Lelieveld, Armbrust, de Graaf, Bouma.

Analysis and interpretation of data. Lelieveld, Armbrust, van Leeuwen, Bouma.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES

We would like to thank those who have contributed to the development of the intervention: Anke de Jong, Lennart de Vries, Davita Trip, Marije Kort, Rika Vennema, Eibert Tigchelaar, Alwin Bakema, Hans de Kleine, and students from the Noorderpoort College (Groningen, The Netherlands). We would also like to thank Meta van den Briel, PT, for accomplishment of all of the endurance tests.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES