Comparative analysis of heart rate variability parameters between athletes and sedentary individuals aged 18–25 years: A cross-sectional study

The present study aimed to compare heart rate variability (HRV) parameters between athletes and sedentary individuals aged 18–25 years. A cross-sectional comparative study was conducted among 80 healthy young adults divided into two groups: 40 athletes engaged in regular structured sports training and 40 sedentary individuals with minimal physical activity. Five-minute electrocardiogram (ECG) recordings were obtained in the supine position under controlled laboratory conditions. Total power was significantly higher in athletes than in sedentary individuals (2764.65 [standard deviation (SD)=656.17] ms² vs. 2156.60 [SD=713.11] ms², P<0.001). High-frequency (HF) power was also significantly higher in athletes compared with sedentary individuals (1118.42 [SD=379.79] ms² vs. 726.23 [SD=609.52] ms², P<0.001). In contrast, low-frequency (LF) power did not differ significantly between the two groups (1012.34 [SD=426.18] ms² vs. 1087.85 [SD=472.85] ms², P=0.455). LF normalized unit (LFnu) was lower in athletes than in sedentary individuals, although the difference was not statistically significant (55.47 [SD=11.50] vs. 60.88 [SD=16.15], P=0.088). HF normalized unit (HFnu) was significantly higher in athletes than in sedentary individuals (51.90 [SD=13.28] vs. 39.01 [SD=16.08], P<0.001). The LF/HF ratio was significantly lower in athletes compared with sedentary individuals (1.07 [SD=0.63] vs. 1.96 [SD=1.19], P<0.001). SD of normal-to-normal intervals (SDNNs) was significantly higher in athletes than in sedentary individuals (83.30 [SD=32.00] ms vs. 54.58 [SD=35.86] ms, P<0.001). Similarly, root mean square of successive differences (rMSSD) was significantly higher in athletes compared with sedentary individuals (64.86 [SD=23.78] ms vs. 42.67 [SD=35.46] ms, P<0.001). The percentage of normal-to-normal intervals that differ by more than 50 milliseconds (pNN50) value was also significantly higher in athletes than in sedentary individuals (33.35 [SD=13.16]% vs. 13.67 [SD=16.11]%, P<0.001). HRV assessment provides a reliable non-invasive marker for evaluating cardiovascular health and training effects in young adults.