Abstract:

Objective To explore the influence  of 8-week aerobic exercise in heart rate variability (HRV) in obese adolescents and to provide the evidence for form ulating special exercise prescription.Methods Forty male obese adolescents (BMI≥25 kg。m^-2) were randomly divided into exercise group (n=20) and control group (n=20).The  subjects in exercise group conducted a 8-week (five times/week,50-60 min) aerobic exercise while those in control group maintained their routine lifestyle.The body composition,hemodynamic parameters including heart rate(HR)  and blood pressure and HRV parameters including total power (TP),normalized low frequency (LFn),normalized high frequency (HFn) and LFn/HFn ratio were measured before and after experiment.Results There were no significant differences of the indicators of the subjects  between two groups before experiment (P>0.05).At the end of experiment,compared before experiment,the fat mass(FM),the  percentage of body fat(BF%),the rest HR,SBP and DBP were decreased (P<0.05 or P<0.01);the  TP  and HFn were increased(P<0.01);the LFn  and LFn/HFn ratio were  reduced (P<0.01) in exercise group after experiment;but the indexes of the subjects in control group showed no significant changes (P>0.05).Compared control group,the  FM,the BF%,the rest HR,SBP,DBP,LFn  and LFn/HFn ratio were decreased  while the TP  and HFn  were increased (P<0.01)  in exercise group after experiment.Conclusion Aerobic exercise may effectively reduce the  sympathetic activity and increase the  vagal tone in the  obese adolescents.

Key words: aerobic exercise, obese, heart rate variability, exercise prescription, adolescents