Effects of acute endurance exercise on heart rate variability in young males with different body mass index

This study aimed to investigate the effects of acute endurance exercise on heart rate variability (HRV) in young males with different body mass index (BMI). 45 young males were selected as subjects, and they were divided into three groups according to the BMI: underweight (< 20.0 Kg/m ² ), normal weight (20.0-24.9 Kg/m ² ), overweight (25.0-29.9 Kg/m ² ). The subjects were tested on a treadmill (h/p/cosmos, Munich, Germany) using the Ellestad A protocol. HRV was recorded using the ActiGraph GT9-X+ (ActiGraph LLC, USA) for 5 min at two different time points, 5 min before and 5 min after exercise. HRV indicators were analyzed including SDNN (the standard deviation of all normal R-R intervals), HF (High Frequency Power), and LF (Low Frequency Power). There was no significant difference in each HRV indicator among the three groups at rest. Three groups experienced a significant decrease in each HRV indicator within a short time following exercise ( p  < 0.01). The underweight group did not display a significant difference in each HRV indicator compared to the normal weight group after exercise. Conversely, the overweight group exhibited significantly lower levels of SDNN and HF compared to the normal weight group ( p  < 0.05 or p  < 0.01). Within a short time after engaging in acute endurance exercise, HRV was inhibited in underweight, normal weight, and overweight males. Notably, HRV inhibition was more prominent in overweight males compared to normal weight males.