Sweating responses during activation of the muscle metaboreflex in humans is altered by time of day
The aim of the present study was to test for a time-of-day effect on sweating responses to activation of the muscle metaboreflex. Methods:
Eight male subjects each participated in two exercise sessions, one in the morning and one in the evening. Within each session there were two 60-s bouts of isometric handgrip (IHG) exercise at 50% maximal voluntary contraction. Prior to IHG, whole body warming by a water-perfused suit initiated mild sweating. The first bout of IHG exercise began at 06.00 hours (am) and 18.00 hours (pm). Blood circulation to the forearm was occluded for 120 s, beginning 5 s before the end of the second bout of IHG to activate the muscle metaboreflex. Results:
During both bouts of exercise, sweating rate (SR) on both the chest and right forearm significantly increased from the pre-exercise period in bothamandpmsessions. SR rapidly decreased during first minute of recovery after the first bout of IHG exercise. However, during post-exercise ischaemia (PEI) after the second bout of IHG exercise, SR was maintained significantly above the pre-exercise level only in thepmsession. The increases in SR on the chest and right forearm during PEI were significantly greater in thepm, than in theam, session. However, SR of the palm was not maintained during PEI. Conclusions:
We conclude that under mild hyperthermic conditions, the sweating response in non-glabrous skin to activation of the muscle metaboreflex exhibits a time-of-day effect.
Document Type: Research Article
Affiliations: 1: Department of Kinesiology, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan 2: Laboratory for Applied Human Physiology, Faculty of Human Development, Kobe University, Kobe, Japan 3: Ergonomics Section, Faculty of Engineering, Chiba University, Chiba, Japan 4: Division of Design Science, Graduate School of Science and Technology, Chiba University, Chiba, Japan
Publication date: 2004-01-01