Here’s how running works on your menstrual cycles

Women's Running
Thursday, 05 November 2015 856 Views 0 Comments
Here’s how running works on your menstrual cycles

By Shailja Kaushik

Do most people advice you not to run during your period? Have you been repeatedly told that sports are a male forte? Here are the pros and cons of running on a woman’s body

With more and more women becoming involved in physical fitness and competitive endurance sports, there is an increased incidence of menstrual dysfunction.  This is due to changes in hormones such as gonadotropins, estrogen and progesterone which may lead to infertility or cessation of menstruation. According to the research study Menstrual Dysfunction and Hormonal Status in Athletic Women: A Review, disruption of the menstrual cycle, ranging from mild changes in flow, to amenorrhea, is a relatively common problem for the female athlete engaged in strenuous endurance sports; yet no evidence exists at present to indicate conclusively that this menstrual dysfunction is harmful to the female athlete’s reproductive system.[i]

Understanding the Menstrual Cycle

Let’s take a quick look at the different phases of the menstrual cycle:

Menstrual cycles start typically between the ages of 11-14, and go on until menopause, which is typically reached around 45-50 years of age. Generally, the length of the menstrual cycle is 28 days and it is divided into two phases with ovulation (release of egg from the ovary) occurring around the 14th day of the cycle. The first half of the cycle is known as the follicular phase and the second half is known as the luteal phase.

Throughout the menstrual cycle, there is a change in the concentration of two main hormones – estrogen and progesterone. Exercise causes fluctuations in the amount and timing of the secretion of these hormones which in turn manifests as physiological changes.

Follicular phase starts with the onset of the period and it goes on for 14 days; however, in many women the duration of follicular phase ranges from 11-21 days. Periods or menses last for 3-5 days. After the 5th day, the level of estrogen begins to rise and is highest on the 14th day. This surged estrogen level signals release of the luteinising hormone which triggers ovulation. Follicular phase corresponds with high estrogen levels and low progesterone levels.

Luteal Phase occurs for 14 days in all women. As the ovulation occurs on the 14th day, there is an increase in the progesterone level which causes a rise in the body temperature to prepare the right environment for the fertilisation of the released egg. As soon as ovulation occurs, estrogen levels begin to decrease. When there is no fertilisation, there is a sudden decrease in the levels of both estrogen and progesterone. Luteal phase ends, menses or periods start, marking the beginning of another menstrual cycle.

How running affects the menstrual cycle?

It has been observed that excessive intense exercise causes a decrease in the hormones such as gonadotropin-releasing hormones (GnRH) from the hypothalamus; the luteinising hormone (LH) from the pituitary gland, and the follicular stimulating hormone (FSH). These hormones in turn play an important role in controlling the menstrual cycle every month. As their concentration decreases or ratio changes, the menstrual cycle gets negatively hit. Exactly why this happens when women runners exercise is still not known; however it is presumed to be due to increase in the endorphins, especially ß-endorphins.

For a very long time now, doctors who have been treating women runners, have recognised the occurrence of irregularities in menstrual cycles.

Four most common menstrual irregularities diagnosed in women runners are[ii]:

  • Amenorrhea which is the absence of 3-12 consecutive menstrual periods
  • Oligomenorrhea which means irregular and infrequent menstrual cycles; 6-9 cycles every year
  • Anovulation or lack of ovulation. Even if their menstrual cycle is normal, they may not be releasing any egg. This may occur due to decrease in the levels of progesterone. No change in body temperature before and after menses, complete lack of pre-menstrual symptoms such as tenderness of breast and abdominal cramps may indicate lack of ovulation. If you fear any such abnormality, it is important to check with your physician for the course of action because it may lead to infertility and even, put the women athlete at the risk of endometrial cancer
  • Delayed onset of periods in girls nearing puberty

Exercise or running is also believed to interfere with the length of the phases of the menstrual cycle, especially the luteal phase which may be shortened due to an intense exercise regime.[iii]

Running or an intense training schedule is one piece of the complex puzzle that causes these menstrual irregularities. In the book Running Doc’s Guide to Healthy Running: How to Fix Injuries, Stay Active and Run Pain-Free, certain associated risk factors that are likely to result in irregular or absent periods among women runners are outlined as below[iv]:

  • Increased mileage and intensity
  • Pre-pubertal training
  • Delayed onset of initial period
  • Low body weight or weight loss
  • Low body fat or fat loss
  • Nulliparity (never having carried a pregnancy)
  • Never used oral contraceptive pills
  • Diet deficient in protein and total calories
  • History of a disordered eating pattern; bulimia or anorexia
  • Family history of amenorrhea and/or oligomenorrhea
  • Psychological stress

It has been seen that young runners training at an intense levels or those who have a history of menstrual irregularities are more prone to disturbances in their menstrual cycles while other women are able to train at high levels and never experience any menstrual problems. Too much exercise in women who have very little body fat can also reduce the levels of both estrogen and progesterone that control menstruation. Changes in the menstrual cycle due to excessive training can also affect fertility among women runners and athletes.

Positive effects of running on menstrual cycle

Surprisingly, research has shown that moderate exercise can alleviate physical pre-menstrual symptoms including breast tenderness, fluid retention and other mood disturbances.[v] Exercise is also believed to enhance the feelings of well-being before and during periods.

Treatment of menstrual dysfunction among women athletes and runners

Evaluation and treatment of menstrual dysfunction are important because if ignored as a routine consequence of running; it may lead to other medical complications such as osteoporosis, stress fractures and other soft tissue injuries, and increased growth of endometrial lining of the uterus which later results in heavier and painful periods or endometrial cancer.

References
[i] Baker ER. Menstrual dysfunction and hormonal status in athletic women: a review. Fertility and Sterility Journal. [1981, 36(6):691-696] [ii] Dagny Scott Barrios. Runner’s World Guide to Injury Prevention: How to identify problems, speed healing and run pain-free. Rodale, 2004.
[iii] Dagny Scott Barrios. Runner’s World Complete Book of Women’s Running: The Best Advice to Get Started, Stay Motivated, Lose Weight and Run Injury-Free, Be Safe and Train for Any Distance. Rodale, 2007.
[iv] G. Lewis; MD. Maharam. Running Doc’s Guide to Healthy Running: How to Fix Injuries, Stay Active and Run Pain-Free. Velopress, 2013.
[v] Dagny Scott Barrios. Runner’s World Complete Book of Women’s Running: The Best Advice to Get Started, Stay Motivated, Lose Weight and Run Injury-Free, Be Safe and Train for Any Distance. Rodale, 2007.

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