Effects of adaptive responses to heat exposure on exercise performance
To date few studies have been conducted on the effect of heat exposure to exercise performance in female athletes. With the publication of recent research, hopefully this will now change with the 2018 Commonwealth Games to be held in Queensland, Australia where athletes will have to compete in hot conditions.
A picture of the author Tze-Huan Lei and participant while taking part in the experiment. Credit: David Wiltshire, Massey University, New Zealand
During the luteal phase (post ovulation, when progesterone levels rise) of the menstrual cycle, body temperature rises. Hence the previous suggestion “that women should avoid competition or face a disadvantage when performing exercise with heat stress during their luteal phase”. However recent research demonstrates that in eumenorrheic athletes, autonomic regulation of body temperature (skin blood flow and sweating) either at rest or during exercise is not effected by the phase of the menstrual cycle. As yet there are no studies of females athletes taking the oral contraceptive pill with respect to body temperature regulation.
A recently published study, conducted on male athletes demonstrated that episodic heat exposure over 11 days had a positive effect on regulating body temperature in hot conditions, associated with rapid onset of sweating. This heat exposure also increased skeletal muscle contractility. These findings suggest that heat adaptation could maintain and improve sport performance. The mechanism of this improvement in skeletal muscle contractility with heat exposure could be an increase in transcription of oxidative phosphorylation-associated genes resulting in increases in synthesis of ATP, muscle mass and strength. This effect was recorded amongst men exposed to 10 weeks of periodic heat stress, without any training. In other words heat alone, even without exercise improved skeletal muscle function.
The interesting findings of these studies investigating the adaptive responses produced by exposure to heat will hopefully stimulate further research to include female athletes who compete in the same challenging environmental conditions as male athletes.
For further discussion on Endocrine and Metabolic aspects of SEM come to the BASEM annual conference 22/3/18: Health, Hormones and Human Performance
Amercian Journal of Physiology
European Journal of Applied Physiology