There is a growing interest in the physical training possibilities of children with juvenile arthritis. In the first Chapter a brief introduction on physical fitness and physical training is given including an overview of the existing studies in juvenile arthritis patients. In Chapter 2, we described the findings of our pilot study with 10 JIA patients. We developed our aquatic fitness training program using the experiences of this pilot study. During this pilot study found a high willingness of parents and JIA patients to participate in a training study. Chapter 3 deals with the reliability of the assessment of the maximum oxygen uptake (VO_2peak; the gold standard for physical fitness) and gives a description of our experiences of exercise testing in this patient group. We found an impaired VO_2peak especially in the more severe diseased patents. The comparison of the exercise capacity of JIA patients with healthy peers is systematically reviewed in Chapter 4. A meta-analysis showed that the VO_2peak of JIA patients was 21.8 % lower (95 % confidence interval: 13.7 %, 29.9 %) compared to healthy controls (p < 0.0001).
The relationship between functional ability and different indices of both aerobic and anaerobic physical fitness is described in Chapter 5. A low relationship between aerobic fitness and functional ability was found (r = 0.0 to 0.4, p > 0.05, except for eating r = 0.46, p<0.05). The correlations between anaerobic physical fitness and functional ability in JIA patients were strong (r = 0.5 to 0.75, p<0.05). This is indicated a good relationship between anaerobic fitness and functional ability.
The association between physical activity and physical fitness are described in Chapter 6. Partial correlation coefficients (to control for age) between physical activity and indices of health related physical fitness showed significant relationships between Caltrac^tm motion counts and absolute VO_2peak (r=0.31) and relative VO_2peak (r=0.34), but not with the indices of body composition. There was also a significant correlation between PAL and relative VO_2peak (r=0.33). Physical activity was significantly related to cardio-respiratory fitness but not with body composition in children with JIA.
The effects of our physical training study provided in Chapter 7. Fifty-four patients with JIA (age 5 to13 years) participated in this study and were randomised into an experimental (N = 27) and a control (N = 27) group. The children in the experimental group received a training program consisting of a 1 hour a week supervised training program in a local pool of approximately 20 sessions. Effects were analysed on the following domains: functional ability, health-related quality of life, Joint status and physical fitness. Although all measures improved more in the experimental group compared to the control group, none of the differences became statistically significant. The current research found no significant effect of an aquatic fitness-training program in children with JIA. Since there were no signs for worsening in health status, one can conclude that this was a safe exercise program.