Autonomic Nervous System Recovery After Various Exercises in Highly Trained Athletes

Introduction: Heart rate variability $(HRV)$ , expressed by the beat-to-beat variation in heart rate, offers a noninvasive indicator of autonomic nervous system (ANS) activity. Measurement of the ANS response is increasingly used to evaluate the effect of training load on the organism. Most authors compared only the impact of different types of running training sessions $(TS)$ (low-intensity training (LIT), high-intensity interval training (HIIT $))$ , $or$ separately plyometric $TS$ on $HRV$ In this study, $HRV$ was used to clarify how different types of running $TS$ and plyometric $TS$ influence post-exercise ANS response. Methods: 12 highly trained runners participated in this study. Each subject completed three types of TS - LIT running, HIIT running and plyometric. $5 - min$ pre-exercise ECGs were recorded just before $TS$ and $5-min$ postexercise ECGs were recorded 10 $min$ after $TS$ . Altogether 13 time-domain and frequency-domain HRV features were calculated. Finally, the changes between pre- and postexercise values of $HR$ V features were computed. Results: From 13 tested features, 9 and 10 features were statistically significant for distinguishing between plyometrics and $LIT$ and HIIT and $LIT$ respectively. There are no statistically significant differences in $HRV$ changes between plyometrics and HIIT. It could be assumed these two $TS$ affect ANS similarly.