[Sports practice is related to parasympathetic activity in adolescents]. / Prática esportiva está relacionada à atividade parassimpática em adolescentes.

OBJECTIVE: To analyze the relationship among sports practice, physical education class, habitual physical activity and cardiovascular risk in adolescents. METHODS: Cross-sectional study with 120 schoolchildren (mean: 11.7±0.7 years old), with no regular use of medicines. Sports practice and physical education classes were assessed through face-to-face interview, while habitual physical activity was assessed by pedometers. Body weight, height and height-cephalic trunk were used to estimate maturation. The following variables were measured: body fatness, blood pressure, resting heart rate, blood flow velocity, intima-media thickness (carotid and femoral) and heart rate variability (mean between consecutive heartbeats and statistical index in the time domain that show the autonomic parasympathetic nervous system activity root-mean by the square of differences between adjacent normal R-R intervals in a time interval. Statistical treatment used Spearman correlation adjusted by sex, ethnicity, age, body fatness and maturation. RESULTS: Independently of potential confounders, sports practice was positively related to autonomic parasympathetic nervous system activity (ß=0.039 [0.01; 0.76]). On the other hand, the relationship between sport practice and mean between consecutive heartbeats (ß=0,031 [-0.01; 0.07]) was significantly mediated by biological maturation. CONCLUSIONS: Sport practice was related to higher heart rate variability at rest.