Athletic performance, menstrual cycle


A NUMBER of old wives’ tales have survived and been retold down the years on this subject, with comments like: “My mother says I mustn’t have a bath or go swimming while I’m . . . ,”

“My mother says I mustn’t wash my hair during a period.” Even, “Women should not swim during menstruation because of the possibility of infection.”

As you read this article I want you to keep in mind the question: “An athlete qualifies for the final in the Olympics, out of the excitement her period starts. Should she forgo the chance of winning that Olympic medal, or go ahead and compete?”

What makes a female athlete different from a male athlete? As a group, female athletes, like their male counterparts, display co-ordination, strength, grace, speed, stamina and a bracing competitiveness.

But there is a signal difference between adult men and women, on and off the field. Women menstruate. And menstruation, with its accompanying fluctuating levels of the female sex hormone estrogen, can have a considerable effect on how a woman’s body responds to the demands of exercise and competition, as a range of provocative new science articles makes clear.

Many people, including coaches and athletes, have long contended that women’s endurance and overall performance may flag at certain times during the month although there is disagreement about when those times are.

Female athletes have been told, or have chosen, to start or discontinue using birth control pills to manipulate their hormone levels.

There is a school of thought that says: “Endurance performance is not influenced by the phase of the normal menstrual cycle” or “the synthetic menstrual cycle” of those on oral contraceptives.

Consequently, women should not be concerned about the timing of the menstrual cycle with regard to optimised, sport-specific performance.

There may, however, still be reasons for a woman to consider her period when planning training.

Estrogen, some researchers have concluded, had maintained the women’s hard-won strength and fitness gains better than men’s bodies had held on to theirs, for a simple evolutionary reason.

It was protecting the women “against fast muscle and collagen loss when she is inactive,” as during pregnancy, the study’s lead author, Mette Hansen, a researcher at the Institute of Sports Medicine in Copenhagen, told me in an e-mail.

Estrogen makes women stronger in adverse conditions, Dr Hansen concluded, a lesson that the fine, battle-hardened United States women’s soccer team can take solace in going forward.

While a man’s hormonal system remains relatively stable, a female’s hormonal system is constantly changing. According to Jason Karp, PhD, hormonal fluctuations can affect how women will respond and adapt to training.

“The phase of the menstrual cycle significantly affects a female runner’s hormonal environment and therefore her physiology,” Karp explains.

“Any physiological changes resulting from menstrual cycle-induced fluctuations in estrogen and progesterone are exacerbated during exercise, especially if it’s intense.”

In the book Running for Women (Human Kinetics, 2012), Karp and coauthor Carolyn Smith, MD, explain how various aspects of physiology are affected by the phase of the menstrual cycle, including oxygen consumption, body temperature and metabolism.

Jason Karp, PhD, is an exercise physiologist, a running and fitness expert. He offers science-based coaching to runners of all levels and consulting to coaches through his company

He is in demand as a presenter at numerous coaching, fitness, and academic conferences, including US Track and Field and Cross Country Coaches Association, American College of Sports Medicine, American Society of Exercise Physiologists and Idea World Fitness Convention.

Karp is also a prolific writer, with four books and more than 200 articles published in magazines, including Runner’s World, Running Times, Shape, Oxygen, Self, and Ultra-Fit.

Carolyn Smith, MD, is a family practice and sports medicine physician who serves as director of the student health service at Marquette University and head medical team physician for the department of intercollegiate athletics. She also maintains her teaching interests in her role as medical director for the athletic training education programme.

“Progesterone stimulates ventilation independent of the intensity of the run, which can increase the perception of effort since runners typically link their perception of effort to how much they’re breathing,” Karp explains.

“Breathing is greater during the luteal phase, when progesterone concentration is highest, making women feel more winded during luteal-phase workouts than in follicular-phase workouts.”

The increased breathing during the luteal phase may also increase the oxygen demand of breathing since the muscles responsible for breathing need oxygen to work just as leg muscles do.

More oxygen being used by breathing muscles means less oxygen is available for the leg muscles to aid with running.
Body temperature changes rhythmically throughout the menstrual cycle, peaking during the luteal phase in response to the surge in progesterone.

“A higher body temperature during the luteal phase makes it harder to run in the heat, because you don’t begin sweating to dissipate heat until you have reached a higher body temperature,” Karp says.

“Women also have a decreased ability to dilate the small blood vessels under the skin, which compromises their ability to release heat to the environment.”

Thus, long, intense workouts and races in the heat, such as half-marathons and marathons, can be more difficult during the luteal phase of the cycle.

“Menstrual-phase variations in running performance may largely be a consequence of changes to exercise metabolism stimulated by the fluctuations in estrogen and progesterone concentrations,” Karp says.

According to Karp, a woman’s responsiveness to strength training can also be influenced by the menstrual cycle.

“One study found that weight training every second day during the follicular phase and once per week during the luteal phase of the menstrual cycle increased maximal quadriceps strength by 32,6% compared to just 13,1% by training once every third day over the whole menstrual cycle.”

Running for Women presents guidelines for tailoring training to the menstrual cycle for maximum response and adaptation as well as determining the best times to perform the various types of training.

The book also contains recommendations for modifying workouts and training programmes for all stages of the life span, including pregnancy, menopause and post-menopause.

Janse de Jonge XA in an article entitled Effects of the menstrual cycle on exercise performance reviews the potential effects of the female steroid hormone fluctuations during the menstrual cycle on exercise performance.