Cardiac autonomic activity in overweight and underweight young adults

Body mass has been associated with changes in the cardiac autonomic activity. The purpose of this study was to evaluate the cardiac autonomic activity by measuring heart rate variability (HRV) in underweight and overweight young adults. Frequency-domain HRV parameters (TP, LF/ HF ratio, LF and HF in absolute and normalized units, where TP - total power, LF - low frequency power and HF = high frequency power) were measured in 124 subjects (mean age 19 +/- 1 yr), grouped according to their BMI into underweight [UW, n = 12], normal weight [NW, n = 71] and overweight [OW, n = 41]. BP (blood pressure) and heart rate were recorded and total body fat was calculated. The groups were similar by age and significantly differed by BMI, body fat (kg), body fat %. OW found to have higher LF in normalised units compared to NW (P < 0.05). The OW had higher LF, lower HF when expressed in absolute units than NW with no statistical significance. Though not statistically significant, the LF/HF ratio, the index of sympathovagal balance was higher in OW. The UW had lower TP, LF, HF than NW with no statistical significance. The results indicate HRV is decreased in overweight young adults suggesting sympathovagal imbalance. HRV is unaltered in underweight group.