Heart rate variability (HRV) is a non-invasive tool for studying autonomic modulation of cardiovascular function. According to the specificity principle of training, each type of exercise causes specific adaptations. However, whether this concept also applies to HRV has not been established. The aim of this study was to compare the spectral components of HRV between endurance-trained and strength-trained young men.

Cross sectional analytical descriptive study. Spectral components of HRV at rest were analysed from short records in 12 runners, 10 weight lifters and 11 not physically active control subjects.

Endurance-trained subjects showed the lowest values in the low frequency component (LF) and the highest values at high frequency (HF), but these differences were not statistically significant. Total spectral power was similar in all groups (P=.103), as well as the ratio of low frequency components divided into high frequency (LF/HF) (P=.094). Heart rate at rest in aerobically trained group was significantly lower compared to strength-trained group (P<.01) and controls (P<.001).

The results showed no effect of long-term regular aerobic or anaerobic physical training, on spectral components of HRV. In our aerobically trained subjects, rest bradycardia was not explained by changes in the autonomic control of cardiovascular function.