Cardiac autonomic regulation after continuous and intermittent maximal exercise interventions

Aim. The aim of this study was to assess relationships between cardiac autonomic regulation after exercise and different types of single-bout exercise of a maximal intensity and of a similar duration. Methods. The study group consisted of 30 males (23 +/- 2 year old), which was separated into three subgroups. Groups A and B performed exercise interventions (continuous or intermittent), while group C represented the control group. Heart rate variability (HRV) was monitored continuously over 30 min after the exercise and consequently during a 6 h period following intervention. Spectral analysis parameters of HRV (total [PT], low- [PLF], high- [PHF] frequency power, LF/HF, and PLF in normalized units [LFnu]) were determined over 5 min intervals. Heart rate recovery (HRR) was also analysed. Results. There were not significant differences between groups A and B for the entire HRV monitoring (P<0.05) or in the relatively expressed HRR. The cardiac autonomic modulation expressed by PT, PLF, and PHF fully recovered in 120 min after exercise, whereas LF/HF and LFnu did not significantly differ (P<0.05) from the control group 60 min earlier. Conclusion. Cardiac autonomic recovery after all-out exercise is type non-dependent and sympathovagal balance restores faster than the absolute HRV magnitude.