INSIDE SPORTS NUTRITION

Females have a reduced sweat gland activity compared to males, which limits evaporative heat loss and may cause additional heat stress during exercise. In addition, when progesterone is high (e.g. during the luteal phase of the menstrual cycle (MC) or post-ovulation), core temperature appears to increase by ~0.4 degrees C, compared to the follicular phase. Thus, combined with their reduced sweat gland activity, females may experience greater performance challenges during exercise in the heat, compared to males.

In hot conditions some physiological responses (e.g. skin blood flow and temperature, sweat sensitivity, and sweat rate) have also been suggested to change across the MC but findings are inconsistent. The physiological responses observed across the MC are likely more variable due to location of the temperature and sweat measurement on the body, effects of training status, hydration, and experimental protocols (e.g. duration and intensity). A recent meta analysis suggests greater pre- and post-exercise core temperature in females in the luteal phase compared to the follicular phase without any related change in skin temperature or sweat rate during exercise.

When examining endurance performance in the heat in the luteal vs. follicular phase, trained women appear to maintain performance despite the elevated core temperature; whereas recreationally active women have reduced exercise tolerance and shorter time to fatigue during the luteal phase. When comparing the pacing strategy of well-trained women in dry versus humid heat, there is evidence that athletes may self-select lower intensities/pace earlier and to a greater extent during humid conditions, independent of MC phase. For all athletes, beginning exercise in a well-hydrated state and replacing fluids can help to maintain the sweat response for cooling and mitigate perceived exhaustion.

Takeaways:
While core temp may be higher during the luteal phase compared to follicular, MC does not necessarily influence an athlete’s ability to dissipate heat.

Environmental heat stress has a bigger impact than phase of the MC on performance outcomes in females

Trained women have a better capacity to deal with heat stress during the luteal phase compared to recreationally active females

Though females may be less efficient at sweating compared to males, starting exercise well hydrated, hydrating during exercise, and using additional cooling strategies may help counteract any additional thermal stress or perceived strain during exercise in warm/hot conditions independent of MC phase

PMID: 32499153, 12141881, 33123618, 30377639