April 24, 2020
New study on women’s menstrual cycle shows no impact on exercise performance
Findings may increase the number of women participating in sport science research studies
Does the menstrual cycle impact sport performance? This is something Anmol Mattu wondered when she was playing basketball with the Dinos at the University of Calgary. Now Mattu, as a Master of Science student in the Faculty of Kinesiology, is exploring how the menstrual cycle and oral contraceptives affect exercise.
“Most researchers are unsure about how hormonal changes influence their findings, but it’s important that we understand how women differ in their physiology by studying these changes,” says Mattu.
Women remain significantly under-represented in sport and exercise research. They tend to be excluded from exercise studies because of the unknown effects of fluctuations in natural reproductive hormones, estrogen and progesterone, across the menstrual cycle. Hormones are known to have many effects on the body, such as increased blood supply, which may impact research outcomes.
“However, what we have demonstrated is that both the menstrual cycle and oral contraceptive cycle phases have little impact on exercise performance,” says Mattu. This finding is published in the Scandinavian Journal of Medicine and Science in Sports. Co-authors on the study include Drs. Danilo Iannetta, Martin J. MacInnis, Patricia K. Doyle‐Baker and Juan M. Murias, from Faculty of Kinesiology at the University of Calgary.
“Based on these findings, exercise researchers should at least question the idea of not testing women solely because their cycle might act as a confounding factor for the outcome measures. In many cases, women can and should be included in exercise studies.”
Oral contraceptives and sport performance
The study included 15 women who were not taking hormonal contraceptives and 15 women who were taking an oral contraceptive pill. Each participant performed several cycling exercises to submaximal (i.e., can normally last for at least 20 minutes) and maximal (until you are exhausted) exercise tests before and after ovulation.
Both groups of participants had no detectable effects on exercise performance across their respective hormonal cycles; however, researchers found that prior to ovulation, the participants who were not taking contraceptives perceived their exertion to be greater toward the end of submaximal effort as opposed to after ovulation.
It’s important to apply an evidence-based approach to optimize an athlete’s health and performance, says Dr. Patricia Doyle-Baker, Dr. PH/PhD, a kinesiology researcher and a co-author on the study.
“This study adds to the growing body of literature that shows hormonal fluctuations between the menstrual and oral contraceptive cycle phases do not affect oxygen capacity. Although the menstrual cycle may cause discomfort in some, their exercise performance is not impacted,” says Doyle-Baker.
The study has some limitations. “We didn’t test at every day of the cycle, we didn’t test during menstruation and we didn’t test during that small window of time when estrogen peaks as this was not possible given the length and intensity of the study protocol. Also we stopped testing aerobic activity at 30 minutes, so we can’t generalize beyond that,” says Mattu.
“Some women athletes who track their cycles say their performance peaks at certain times, but it may be based on their perception rather than actual performance. This would be an area for further research,” she adds.
The research was funded by the Natural Sciences and Engineering Research Council of Canada and the Heart and Stroke Foundation of Canada.