Pre-competitive overload period impairs parasympathetic modulation in athletes: A systematic review and meta-analysis

Abstract

Objective: The aim was to meta-analyze the effect of different type of overloads on parasympathetic modulation to the heart, assessed by root-mean-square difference of successive normal RR intervals (RMSSD) of athletes.

Methods: The analysis of the 14 studies selected (20 subgroups within studies), compared RMSSD of the same athletes before and after an overload period.

Results: RMSSD of athletes were lower at pre-competition compared to baseline (SMD = -0.50 [-0.83; -0.18], p = 0.002), while volume, volume plus intensity and post-competition overloads showed similar RMSSD than their respective normal load periods.

Conclusion: The lower RMSSD during pre-competition overload, characterize an loss of homeostasis, and could be explained by the presence of pre-competition anxiety, stress, and higher psychological challenges in addition to the same physical stress present in the other types of overloads (i.e.: higher volume or training intensity).

Keywords: Athletes; Autonomic nervous system; Biomarkers; Fatigue; Physiological; Stress.