Monitoring of the Autonomic Nervous System Activity During Post-Marathon Recovery by Spectral Analysis of Heart Rate Variability: A Case Study

Abstract

Introduction: Vigorous physical exertion, such as a marathon, evokes long lasting changes in the autonomic cardiac regulation and peripheral fatigue. Aim of the study: We investigated changes in the autonomic nervous system (ANS) activity simultaneously with the subjective feeling of fatigue from the 67 hours following a race (42.195 km) in 31-year-old male amateur athlete. Methods: The ANS activity was assessed by spectral analysis of heart rate variability (SA HRV) during orto-clinostatics maneuvers. Both frequency-domain measures and age-dependent complex indexes of the SA HRV were used. Post-race ANS activity was assessed at the beginning of the 7 th , the 19 th , the 34 th , the 44 th , the 58 th , and the 67 th hour of the recovery period. Results: At the 19 th hour after the race, the overall spectral power had risen above the initial level, primarily owing to the prevailing sympathetic activity over the increasing vagal activity. By the 44 th hour, a further significant increase in ANS activity had occurred, this time due to the overriding vagal activity. A high level of subjectively perceived fatigue persisted throughout the entire recovery period monitored. Conclusion: This work demonstrated that the ANS activity was completely restored by the 44 th hour of post-marathon recovery. The high level of subjectively perceived fatigue persisted throughout the entire recovery period monitored and was not correlated to the ANS activity.