The influence of hydration status on heart rate variability after exercise heat stress

The influence of hydration status on heart rate variability after exercise heat stress

While exercise heat stress and hydration status are known to independently influence heart rate variability (HRV), the combined effect of these physiological stressors is unknown. Thus, heat-acclimated subjects ( n=5) performed exercise heat trials (40 °C, 20% relative humidity) in the euhydrated an...

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Bibliographic Details
Published in:Journal of thermal biology Vol. 30; no. 7; pp. 495 - 502
Main Authors: Carter, Robert, Cheuvront, Samuel N., Wray, D.Walter, Kolka, Margaret A., Stephenson, Lou A., Sawka, Michael N.
Format: Journal Article
Language:English
Published: Elsevier Ltd 01-10-2005
Subjects:
Autonomic nervous system
Exercise
Heart rate variability
Recovery
Exercise
Autonomic nervous system
Heart rate variability
Recovery
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Summary:While exercise heat stress and hydration status are known to independently influence heart rate variability (HRV), the combined effect of these physiological stressors is unknown. Thus, heat-acclimated subjects ( n=5) performed exercise heat trials (40 °C, 20% relative humidity) in the euhydrated and hypohydrated state (3.9±0.7% body weight loss). During each trial, cardiac cycle R–R interval data were collected for 45 min at rest (pre-) and after (post-) completing 90 min of cycle ergometer exercise. Pre- and post-exercise RRI data were analyzed by Fast Fourier Power Spectral analysis to determine the high-frequency (HF), low-frequency (LF), very low-frequency (VLF), and total power (TP) components of HRV. Overall HRV was decreased by both hypohydration and exercise heat stress. Hypohydration reduced TP, LF, VLF, and LF:HF ratio ( P < 0.05 ) while HF was significantly higher. The change in both LF and HF power (pre- vs. post-exercise) were blunted during hypohydration compared to euhydration. These data suggest that dehydration alone positively influences the parasympathetic (HF) control of HRV, but the reduction in overall HRV and the blunted oscillations in LF and HF power following exercise heat stress support an overall deleterious effect of dehydration on autonomic cardiac stability.
ISSN:0306-4565
1879-0992
DOI:10.1016/j.jtherbio.2005.05.006