Caffeine increases sweating sensitivity via changes in sudomotor activity during physical loading

Abstract

We assessed the effect of caffeine on sudomotor activity and sweating sensitivity during physical loading. Both physiological responses could occur due to energy expenditure. Subjects were 13 athletically trained males (22.1±3.7 years old, 174.2±5.4cm tall, and weighing 70.9±4.6kg, with maximal oxygen consumption [VO2max] of 53.6±4.4mL/kg/minute). The study involved a within-subject, random, crossover design. Tests were performed following the ingestion of 3mg/kg caffeine. The physical loading involved running for 30 minutes at 60% VO 2max (24.0±0.5°C, 40±3.0% relative humidity). Tympanic temperature (TYMP) was significantly higher in the caffeine-consuming group (Caffe-I) at pre-exercise (40 minutes after caffeine intake and immediately before running) (P