Menstrual cycle phase affects temperature regulation during endurance exercise

Abstract

We investigated whether menstrual cycle phase would affect temperature regulation during an endurance exercise bout performed at room temperature (Ta) of 22 degrees C and 60% relative humidity. Nine eumenorrheic women [age 27.2 +/- 3.7 yr, peak O2 uptake (VO2) 2.52 +/- 0.35 l/min] performed 60 min of cycle exercise at 65% of peak VO2. Subjects were tested in both midfollicular (F) and midluteal (L) phases, although one woman did not show a rise in serum progesterone (P4) that is typically evident 1 wk after ovulation. VO2, rectal (Tre) and skin (Tsk) temperatures, heart rates (HR), and ratings of perceived exertion (RPE) were measured throughout exercise. Sweat loss (SL) was estimated from pre- and postexercise body weight differences. VO2, SL, and Tsk were not affected by menstrual cycle phase. Preexercise Tre was 0.3 degrees C higher during L than during F conditions, and this difference increased to 0.6 degrees C by the end of exercise (P less than 0.01). Compared with F, HRs during L were approximately 10 beats/min greater (P less than 0.001) at all times, whereas RPE responses were significantly greater (P less than 0.01) by 50 min of cycling. No differences in any measured values were found in the subject whose P4 was low in both test conditions. Results indicate that thermoregulation (specifically, regulation of Tre), as well as cardiovascular strain and perception of exercise, was adversely affected during the L phase.

Luteal phase of the menstrual cycle increases sweating rate during exercise

“…It is important to notice that, in our protocol, the women were maintained hydrated by appropriate water intake during exercise. This may have permitted the increase in sweating rate despite the already reduced urinary volume, contrasting with other studies in which the sweating rate was not altered and the core temperature increased (7,10).…”

“…Evidence about the possible effect of the menstrual cycle on thermoregulation during exercise is scarce and contradictory (6)(7)(8)(9)(10)(11), although the importance of controlling for the menstrual cycle in thermoregulation studies involving fertile women has been repeatedly emphasized (12)(13)(14).…”

“…Some studies have suggested that a higher core temperature (rectal or esophageal) can be maintained during exercise performed during the luteal phase, whereas the rate of sweating is unchanged (7,10) or is lower in the luteal than in the follicular phase of the menstrual cycle (11). Heart rate might be either altered (7,8,10) or not (11) depending on the phase of the menstrual cycle.…”

“…Heart rate might be either altered (7,8,10) or not (11) depending on the phase of the menstrual cycle. None of these studies, however, controlled fluid balance by measuring urinary parameters and providing water replacement during exercise.…”

Applied Physiology of Female Soccer: An Update

“…VO2max appears to be largely unaffected by the phase of the menstrual cycle [80,81]. However, some studies have shown increased minute ventilation [39,[82][83][84], heart rate [84][85][86] and rating of perceived exertion [84,85] during the luteal phase, which could be attributed to an increased core temperature (0.3 -0.5 °C) during this phase [84]. Lactate threshold findings are equivocal with some reports of stable values throughout the cycle [87,88], whilst others describe lower blood lactate concentrations in the luteal phase during moderate-intensity activity [89].…”