Does body fat percentage predict post-exercise heart rate response in non-obese children & adolescents?

Abstract

Background: A correlation between adiposity and postexercise autonomic regulation has been established in overweight and obese children. However, little information exists about this link in non-obese youth. The main purpose of this cross-sectional study was to describe the relationship between body fat percentage (BFP) and heart rate recovery after exercise [post-exercise heart rate (PEHR)], a marker of autonomic regulation, in normalweight children and adolescents. Methods: We evaluated the body composition of 183 children and adolescents (age 15.0 ± 2.3 years; 132 boys and 51 girls) who performed a maximal graded exercise test on a treadmill, with the heart rate monitored during and immediately after exercise. Results: A strong positive trend was observed in the association between BFP and PEHR (r =0.14; p =0.06). Hierarchical multiple regression revealed that our model explained 18.3% of the variance in PEHR (p =0.00), yet BFP accounted for only 0.9% of the variability in PEHR (p =0.16). The evaluation of the contribution of each independent variable revealed that only two variables made a unique statistically significant contribution to our model (p <0.01), with age contributing 38.7% to our model (p =0.00) while gender accounted for an additional 25.5% (p 0.01). Neither BFP (14.4%; p =0.16) nor cardiorespiratory endurance (5.0%, p =0.60) made a significant unique contribution to the model. Conclusions: Body fatness seems to poorly predict PEHR in our sample of non-obese children and adolescents, while non-modifiable variables (age and gender) were demonstrated as strong predictors of heart rate recovery. The low amount of body fat reported in non-obese young participants was perhaps too small to cause disturbances in autonomic nervous system regulation.