Post-exercise heart rate variability recovery after 800-m endurance run load among Cameroonian adolescent's males

The 800-m (m) run is part of Physical Education classes in Cameroon, after which arrhythmias may occur during recovery. Hence, this study aimed at determining relationship between 800-m run loads on cardiac autonomic recovery among school adolescents. Forty-two male adolescents (aged [17 ​± ​1] years) performed 800-m. Post-exercise heart rate variability (HRV) was recorded during 5-min (min) (HRV_5-min) and 15-min (HRV_15-min) in time: Standard deviation of normal to normal (SDNN); Root mean square of successive differences (RMSSD) and frequency domain (LH: Low frequency, HF: High frequency, TP: Total power). Rating of Perceived Exertion (RPE) and blood lactate concentration (BLa) were measured after exercise. In HRV_5-min, RPE was associated with SDNN (r ​= ​-0.44, p ​< ​0.01) and RMSSD (r ​= ​-0.38, p ​< ​0.05). BLa was correlated with SDNN (r ​= ​-0.38, p ​< ​0.05) and RMSSD (r ​= ​-0.56, p ​< ​0.001) in the time-domain, LF (r ​= ​-0.64, p ​< ​0.001), HF (r ​= ​-0.58, p ​< ​0.001) and TP (r ​= ​-0.61, p ​< ​0.001) in frequency-domain. Moreover, RPE was correlated with LF (r ​= ​-0.44, p ​< ​0.01), TP (r ​= ​-0.49, p ​< ​0.01) while exercise duration with HF (r ​= ​-0.38, p ​< ​0.05). In HRV_15-min, BLa was correlated with RMSSD (r ​= ​-0.53, p ​< ​0.001) and SDNN (r ​= ​-0.68, p ​< ​0.001). RPE was negatively correlated SDNN (r ​= ​-0.53, p ​< ​0.01) and RMSSD (r ​= ​-0.44, p ​< ​0.01). BLa was associated with HF (r ​= ​-0.55, p ​< ​0.001), TP (r ​= ​-0.50, p ​< ​0.01) and RPE with LF (r ​= ​-0.51, p ​< ​0.01), HF (r ​= ​-0.50, p ​< ​0.01), TP (r ​= ​-0.49, p ​< ​0.01). In addition, exercise duration was negatively linked to HF (r ​= ​-0.36, p ​< ​0.05). This study outlined that in untrained adolescents an increase of 800-m loads is associated with a slow vagal indexes of HRV during the recovery.