Effect of a 24-h continuous walking race on cardiac autonomic control

Francois Cottin, Jean Slawinski, Philippe Lopes, Andry Van de Louw, Varonique Billat

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

This study investigated the relationships between walking speed and heart rate (HR) variability (HRV) in eleven subjects during a 24-h race. It was hypothesized that the nycthemeral rhythm on HR is preserved during the race. RR intervals and walking speed were measured. Fast Fourier transform was applied to samples of 1,024 successive RR intervals collected every hour from a HR monitor. Walking speed was averaged every hour and decreased (first lap: 8.8 ± 0.3 vs. last lap: 7.3 ± 0.8 km h-1, P < 0.001) with HR also decreasing (max at 19:00 h: 143 ± 9 vs. min at 7:00 h: 117 ± 14 beats min-1, P < 0.001) following a third order polynomial shape. HRV power spectral components followed distribution patterns similar to the mean RR during the race with a minimum in the early evening (19:00-20:00 h) and a maximum in the morning (5:00-8:00 h). Thus, as for mean RR, spectral components over time are also fitted to a third order polynomial regression. LF/HF ratio increased linearly (min = 0.5 ± 0.3, max = 2.8 ± 5.3, P = 0.02). Although mean HF peak did not decrease significantly over time, it was positively correlated with walking speed. In conclusion, this study showed that despite a constant decrease in walking speed, HR circadian rhythm is preserved during a continuous 24-h walking race. The short-term HRV components remain linked to HR whereas the LF/HF ratio increases linearly until the end of the race whatever HR is.

Original languageEnglish (US)
Pages (from-to)245-250
Number of pages6
JournalEuropean Journal of Applied Physiology
Volume99
Issue number3
DOIs
StatePublished - Feb 1 2007

All Science Journal Classification (ASJC) codes

  • Orthopedics and Sports Medicine
  • Public Health, Environmental and Occupational Health
  • Physiology (medical)

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