The effect of an ultra-endurance running race on heart rate variability.

PURPOSE: The aim of this study was to investigate the effect of an ultra-marathon on heart rate variability (HRV) and psychometric indices in endurance runners. In addition, we aimed to determine the magnitude of change and subsequent recovery for 7 days following the race.

METHODS

Recreationally trained runners (n = 13 (8M); age = 36.6 ± 7.6 years; height = 174 ± 9 cm; weight = 70.5 ± 9.3 kg) completed measures of HRV upon waking in the morning for 1 week prior to and 1 week following a 64-km running race. Profile of mood states, wellbeing, and muscular soreness were also measured throughout the study period to further contextualise recovery.

RESULTS

An increase in heart rate accompanied by decreased LnSDNN, LnRMSSD, LnLF, LnHF, and LnLF/HF from baseline were observed 1 day post-race (p < 0.05). Indices of HRV had returned to baseline on day 2 of recovery. Perceptual fatigue and muscle soreness increased post-race (immediately following and on day 1 of recovery) (p < 0.05) and took until day 5 of recovery to return to baseline.

CONCLUSION

The results indicate that cardiac autonomic control is significantly altered in response to a 64 km ultra-marathon. Specifically, parasympathetic activity is suppressed. The change in autonomic control was relatively short-lived, and parasympathetic-related indices had returned to baseline 2 days after the event. Subjective measures of fatigue and wellbeing suggest that athletes were not completely recovered until day 5 post-event, with muscular soreness remaining prominent during this period. A combination of physiological and psychological parameters is important to contextualise recovery in ultra-endurance runners.