Effect of Endurance Training on the Autonomic Nervous System Function of Young Male

Abstract

In this study, healthy young males were randomized into groups with moderate intensity training (n = 24), high intensity training (n = 24) and utmost intensity training (n = 24). At the end of 8-week training period, HRV measurements demonstrated a marked increase of RMSSD ( P = 0.003), PNN 50 ( P = 0.002), HF ( P = 0.002), SDNN ( P = 0.002) and LF ( P = 0.003) in the moderate intensity group and a decreasing tendency in LFn and LF/HF; however, in the utmost intensity group HFn ( P = 0.012) decreased prominently while its LF ( P = 0.032), LFn ( P = 0.039) and LF/HF ( P = 0.015) increased significantly. Nevertheless marked changes were not found in the above indexes of the high intensity group. While resting HR of the three groups declined significantly at the end of 8 weeks ( P was 0.001, 0.0001 and 0.001 respectively); RMSSD, PNN 50 , HF, LF and SDNN were significantly higher in the moderate intensity group than in the other two groups ( P < 0.05 or 0.01). Compared with the moderate intensity group, HFn of the utmost-intensity group ( P = 0.012) was significantly lower but its LFn and LF/HF were markedly higher ( P was 0.025 and 0.015 respectively); LF/HF of both the high and utmost intensity group was significantly higher ( P was 0.033 and 0.037 respectively). Despite a significant reduction of plasma NE in all the three groups at the end of 8-week training period ( P was 0.016, 0, 0.031 respectively), plasma NE level of moderate and high intensity group was much lower than that of the utmost intensity group ( P was 0.001, 0 respectively). Utmost and moderate endurance training results in altered sympathetic and parasympathetic balance towards sympathetic dominance and parasympathetic dominance respectively; whereas high intensity endurance training almost has no effect on ANS function. CPT and HUTT reveal the potential danger posed by utmost intensity endurance training.