| Keywords |
Spinal cord surface cooling ; Body temperature ; Heart rate variability ; Skin blood flow |
| Abstract |
The aim of this study was to investigate the effects of spinal cord partial surface cooling on body temperature, heart rate variability and peripheral blood flow following endurance exercise in the heat and to examine whether this influence was the change of blood fatigue factors. Eleven healthy men participated and were randomly assigned to both normal recovery(NR) and cooling recovery(CR) following bicycle exercise. After 10 min of rest at supine position they exercised on a bicycle ergometer at 50 ~ 55% VO2max for 48(± 6) min in a hot environment(36 ~ 37oC). We measured core (Tc) and mean skin (Tsk) temperature, the heart rate variability indices[very low frequency (VLF), low frequency (LF), high frequency (HF) and LF/HF] and skin blood flow of toe at 10 min prior to bicycle exercise and every 5 min during 30 min of recovery. Two-way repeated ANOVA was performed to determine main effect (time, condition) and interactions (time × condition) for all dependent variables. Analysis of variance showed no significant difference in Tre, Tsk, and HRV indices between NR and CR. Blood flow increased until 30 min recovery in NR, and 15 min recovery afterward it was not increased anymore in CR. However, there was no statistical significance. Significant difference was only observed for lactate between NR and CR (p < .01). Prolactin were not significantly different between NR and CR. The spinal cord partial surface cooling was not effective in reducing body temperature and skin blood flow during recovery. There are no interaction in heart rate variability indices between conditions. It seems that changes of VLF power are related to the activation of Renin-Angiotensin-Aldosterone system than thermoregulation and skin blood flow during recovery. |