Effects of heart rate-based exercise group training on cardiorespiratory capacity, body composition and self- reported depression among adolescents with mild to moderate depression - a 12 week randomized intervention

Sammanfattning: Background: Physical activity (PA) brings several health benefits on different levels in the body. Many adolescents do not reach the daily recommendations for PA leading to negative health consequences, both physiological and psychological, eg. depression. PA has been shown to prevent depression and can be used as part of the treatment. Previous studies have found a link between PA and depression, but further research is still needed to confirm the effect of heart rate (HR)-based exercise and depression in adolescents.   Aim: The aim was to investigate the effects of either HR-based group exercise (EX group) or leisure group activities (LA group) in adolescents with mild to moderate depression on cardiorespiratory capacity (CRC), body composition, including skeletal muscle mass in percentage (SMM) and fat percentage (%), and self-reported depression after 12 weeks of intervention. A second aim was to compare the effects of the intervention between the groups.  Method: A randomized intervention pilot study including 14 adolescents in age between 13-17 years. CRC measured as maximal oxygen consumption (VO2max), body composition (body weight, SMM, fat%), and self-reported depression were measured before and after the intervention. The adolescents were randomized into either an HR-based EX group (n=4) or into a LA group (n=5) for 12 weeks, 3 times a week. The results were analyzed and compared within and between groups by non-parametric statistics.   Results: Nine participants, mean age (±SD) 15.7 (±1.3) completed the 12 week intervention, five in the EX group, and four in the LA group. A significant difference in relative VO2max was identified in the EX group, from 25.6 (±3.9) to 30.0 (±5.5), p=0.04, with no significant difference in the LA group. For the remaining measured variables, HR, body weight, SMM, fat% and self-reported depression, no significant difference could be found between or within the groups.  Conclusion: The study showed that the HR-based EX group, but not LA group, improved relative VO2max for adolescents with mild to moderate depression. Unfortunately, the groups were small. Further intervention studies with more participants need to be done to determine the importance of HR-based group exercise among adolescents with depression and the effects it has on health-related physiological and mental health in adolescents.