In elite endurance athletes, the 'fatigue' state was associated with a significantly higher supine heart rate (+6.27 bpm) and lower heart rate variability compared to the 'no-fatigue' state.
Observational (n=57)
No
Does a state of fatigue alter heart rate variability in elite endurance athletes?
Fatigue in elite endurance athletes is associated with significantly lower heart rate variability and greater intra-individual variance, suggesting altered autonomic regulation.
Effect estimate: Mean difference +6.27 bpm
Absolute Event Rate: 63.3% vs 55.3%
p-value: p=<0.0001
PURPOSE: This longitudinal study aimed at comparing heart rate variability (HRV) in elite athletes identified either in 'fatigue' or in 'no-fatigue' state in 'real life' conditions. METHODS: 57 elite Nordic-skiers were surveyed over 4 years. R-R intervals were recorded supine (SU) and standing (ST). A fatigue state was quoted with a validated questionnaire. A multilevel linear regression model was used to analyze relationships between heart rate (HR) and HRV descriptors total spectral power (TP), power in low (LF) and high frequency (HF) ranges expressed in ms(2) and normalized units (nu) and the status without and with fatigue. The variables not distributed normally were transformed by taking their common logarithm (log10). RESULTS: 172 trials were identified as in a 'fatigue' and 891 as in 'no-fatigue' state. All supine HR and HRV parameters (Beta±SE) were significantly different (P<0.0001) between 'fatigue' and 'no-fatigue': HRSU (+6.27±0.61 bpm), logTPSU (-0.36±0.04), logLFSU (-0.27±0.04), logHFSU (-0.46±0.05), logLF/HFSU (+0.19±0.03), HFSU(nu) (-9.55±1.33). Differences were also significant (P<0.0001) in standing: HRST (+8.83±0.89), logTPST (-0.28±0.03), logLFST (-0.29±0.03), logHFST (-0.32±0.04). Also, intra-individual variance of HRV parameters was larger (P<0.05) in the 'fatigue' state (logTPSU: 0.26 vs. 0.07, logLFSU: 0.28 vs. 0.11, logHFSU: 0.32 vs. 0.08, logTPST: 0.13 vs. 0.07, logLFST: 0.16 vs. 0.07, logHFST: 0.25 vs. 0.14). CONCLUSION: HRV was significantly lower in 'fatigue' vs. 'no-fatigue' but accompanied with larger intra-individual variance of HRV parameters in 'fatigue'. The broader intra-individual variance of HRV parameters might encompass different changes from no-fatigue state, possibly reflecting different fatigue-induced alterations of HRV pattern.
Schmitt et al. (Mon,) conducted a observational in Fatigue (n=57). Fatigue state vs. No-fatigue state was evaluated on Supine Heart Rate (HR SU) (Mean difference +6.27 bpm, p=<0.0001). In elite endurance athletes, the 'fatigue' state was associated with a significantly higher supine heart rate (+6.27 bpm) and lower heart rate variability compared to the 'no-fatigue' state.