The effect of the phase of the menstrual cycle and the birth control pill on athletic performance.

Investigators are not in agreement on the effects of either the phase of the menstrual cycle, or the administration of OCAs on athletic performance. It appears, however, that apart from subtle changes in some variables, for most women there is no significant effect. Medals have been won and world records set in any phase of the menstrual cycle, and also by women taking OCAs. In terms of documentation of cycle phase, newer hormonal measurement techniques such as the levels of urinary luteinizing hormone (LH) to detect ovulation or salivary progesterone, should make it easier in the future to obviate the methodologic difficulties encountered in earlier studies. Further studies should also focus on the midcycle estradiol surge as well, in order to determine the relative contributions of estrogen and progesterone to any observed performance changes. Given the possibility that some cardiovascular, respiratory, and metabolic variables may change slightly during the course of a regular ovulatory menstrual cycle, it behooves researchers who are using women as subjects in other types of studies to standardize the menstrual cycle phase in which they are tested, in order to eliminate any possible confounding effects due to hormonal variation. Regarding the effects of oral contraceptives on performance, any conclusions from the studies to date are complicated by the proliferation of preparations currently on the market. Further studies are needed on monophasic, biphasic and triphasic formulations, including OCAs with the newer progestins (desogestrel, gestodene and norgestimate), as well as the progesterone-only agents (both oral and injectable). Prospective double blind randomized studies must be done, using a proper control group. The difficulty with this technique, however, is that women in the control group will inevitably be in various phases of the cycle, so accurate hormonal documentation is also essential in order to correctly interpret the findings. Just as the past few decades have seen a significant advancement in the participation of women in sports, future years should bring an enhanced scientific knowledge base about the interactions of the special hormonal considerations of the exercising woman throughout her reproductive life cycle.