Physical Activity and Heart Rate Variability in Adolescents with Abdominal Obesity

Physical activity is a protective factor for autonomic dysfunction. However, whether this occurs in adolescents with abdominal obesity is still unclear. Thus, the aim of this study was to analyze the association between physical activity and heart rate variability (HRV) in adolescents with and without abdominal obesity. This cross-sectional study included 1152 boys (age: 17 ± 1 years). HRV measures of time (root mean square of the squared differences between adjacent normal RR intervals—RMSSD and the percentage of adjacent intervals over 50 ms—PNN50) and frequency domains (balance sympathetic–vagal—LF/HF) were evaluated, as well as total physical activity, commuting physical activity, leisure-time physical activity, and abdominal obesity. All physical activity domains were associated with better RMSSD, PNN50, and LF/HF in normal weight adolescents (p < 0.05), whereas in adolescents with abdominal obesity only leisure-time physical activity was associated with better PNN50 (b = 0.174, p = 0.035) independent of age, period of the day, body mass index, and blood pressure. In conclusion, higher leisure-time physical activity, but not total and commuting physical activity levels, was associated with improved HRV in adolescents with abdominal obesity.