Menstrual Cycle

A female athlete's performance may depend on the phase of the menstrual cycle she is in. The menstrual cycle ranges from 24 to 35 days and comprises of three phases: menstrual phase (menses), preovulatory phase and the postovulatory phase. The menstrual phase is the periodic discharge of 25 to 65ml of blood, tissue fluid etc. and lasts for approximately 3 to 7 days.

Example of the phases of 28 day menstrual cycle:

The effect of sport

Physically active women increase their chances of changes to their menstrual cycle. These include irregular cycles (oligomenorrhea) or complete cessation of the cycle (amenorrhea). In the general population, amenorrhea occurs in 2 to 5% of women of reproductive age, whereas for women participating in sport it can be as high as 40%.

Other factors

All women need to be aware that exercise is not the only factor that can result in oligomenorrhea or amenorrhea. The other factors are a high stress level, body weight and body composition (% body fat level below 20%).

Athletes are prime candidates for oligomenorrhea or amenorrhea as they are likely to experience:

• heavy training loads
• high stress levels from trying to manage the training program with work and family life and the pressures of competition
• as a result of the training, body weight may reduce and the fat level may fall below 20% for some months

Consequences

Amenorrhea reduces the body's capacity to absorb calcium, decreases bone density and increases the risk of musculoskeletal injury in vigorous exercise.

Impact on training

The hardest time to race efficiently, for athletes experiencing a menstrual cycle, is during the week before menstruation and a week after ovulation (Williams 1997)^[1]. At these times increased levels of progesterone simulate the brain's respiratory centre increasing ventilation rates (progesterone is also linked to the mood swings). Athletes use breathing rate as an indicator of exercise intensity so exercise can tend to feel harder at these times.

The time of maximum efficiency for athletes experiencing a 28 day menstrual cycle might be pre-ovulation (days 9 to 12) or post-ovulation (days 17 to 20).

Referenced Material

1. WILLIAMS. T. (1997) Menstrual Cycle Phase and Running Economy. Medicine and Science in Sports and Exercise, 29(12), p. 1609-1618

Page Reference

The reference for this page is:

• MACKENZIE, B. (2007) Menstrual Cycle [WWW] Available from: http://www.brianmac.co.uk/menstrual.htm [Accessed

Associated Pages

The following Sports Coach pages should be read in conjunction with this page:

• Articles on Physiology
• Blood Pressure
• Body Fat
• Body Type
• Energy Pathways
• Ideal Weight
• Lactic Acid
• Maximum Heart Rate
• Movement Analysis
• Muscle Types
• Protein
• Range of Movement
• Vitamins
• VO2 max