Effect of cold water immersion on postexercise parasympathetic reactivation
American Physiological Society
Computing, Health and Science
Exercise, Biomedical and Health Science, Centre for Exercise and Sports Science Research
The aim of the present study was to assess the effect of cold water immersion (CWI) on postexercise parasympathetic reactivation. Ten male cyclists (age, 29 ± 6 yr) performed two repeated supramaximal cycling exercises (SE1 and SE2) interspersed with a 20-min passive recovery period, during which they were randomly assigned to either 5 min of CWI in 14°C or a control (N) condition where they sat in an environmental chamber (35.0 ± 0.3°C and 40.0 ± 3.0% relative humidity). Rectal temperature (Tre) and beat-to-beat heart rate (HR) were recorded continuously. The time constant of HR recovery (HRRτ) and a time (30-s) varying vagal-related HR variability (HRV) index (rMSSD30s) were assessed during the 6-min period immediately following exercise. Resting vagal-related HRV indexes were calculated during 3-min periods 2 min before and 3 min after SE1 and SE2. Results showed no effect of CWI on Tre (P = 0.29), SE performance (P = 0.76), and HRRτ (P = 0.61). In contrast, all vagal-related HRV indexes were decreased after SE1 (P < 0.001) and tended to decrease even further after SE2 under N condition but not with CWI. When compared with the N condition, CWI increased HRV indexes before (P < 0.05) and rMSSD30s after (P < 0.05) SE2. Our study shows that CWI can significantly restore the impaired vagal-related HRV indexes observed after supramaximal exercise. CWI may serve as a simple and effective means to accelerate parasympathetic reactivation during the immediate period following supramaximal exercise.