Comparison of the effects of whole-body cooling during fatiguing exercise in males and females

The effects of cold stress on exercise performance and fatigue have been thoroughly investigated only in males, and thus the general understanding of these effects relates only to males. The aim of this study was to determine whether whole-body cooling has different effects on performance during fatiguing exercise in males and females. Thirty-two subjects (18 males and 14 females) were exposed to acute cold stress by intermittent immersion in 14 °C water until their rectal temperature reached 35.5 °C or for a maximum of 170 min. Thermal responses and motor performance were monitored before and after whole-body cooling. Whole-body cooling decreased rectal, muscle and mean skin temperatures in all subjects (p < 0.05), and these changes did not differ between males and females. Cold stress decreased the fatigue index (FI) of a sustained 2-min maximal voluntary contraction (MVC) only in males (p < 0.05). There were no sex differences in central and peripheral fatigability, or muscle electromyographic activity. This observed sex difference (i.e., body cooling-induced decrease in the FI of a sustained MVC in males but not in females) supports the view of sex effects on performance during fatiguing exercise after whole-body cooling.