CeMCOR

To blame women‘s "funny" periods on too much exercise is usually just prejudice. Far apart periods are called "oligomenorrhea' if cycles are farther apart than 36 days. Absent menstruation for six or more months is called "amenorrhea." The notion that exercise causes bad changes in menstruation persists in our culture where it is men who are free to exercise.

The idea that exercise causes oligomenorrhea or amenorrhea is wrong and has been proven so by three different studies (1-3). But the question still remains-what is going on with your cycle if it is not exercise?

First, we have to understand the complex control of women's menstruation and ovulation. Women's reproduction is carefully controlled in favour of an individual woman's survival and secondly in terms of the safety of the baby should we get pregnant. It requires energy to menstruate, to ovulate and make progesterone (which requires more calories because it increases our core temperature) and finally because getting pregnant is an even further drain on our body's resources.

Women's menstrual cycles and ovulation are carefully controlled by our hypothalamus in the brain. The part that is the "mastermind" gets information about how much we are eating, how much energy we are expending, how stressed we are and whether or not we are ill. Also, it takes at least and likely more than 12 years after the first period for the coordination of this complex reproductive system to "grow up" and our menstrual cycles to become regularly ovulatory.

I suspect that the stress of training programme and your relatively young gynecological age (meaning how many years it has been since your menarche) are enough reason for your current menstrual cycles to be far apart. After all, if your first period was at 12 or 13 years old, as is average, you have had only 6-7 years for this essential maturation of reproduction.

Another possible reason for your far apart periods is that your weight is slightly lower than normal (BMI 18.5-24.9 is ideal). It also sounds like you may be concerned about gaining weight. Although I totally agree that over-eating can make you feel sluggish and fat, being too careful can also be another kind of stress called "cognitive dietary restraint." Dr. Susan Barr, a professor of nutrition at UBC, and I have shown in multiple studies that this kind of concern about "over-eating" is likely to cause irregular cycles in younger women, and regular cycles with not enough progesterone (ovulatory disturbances) in those who are gynecologically mature (4). In a past study we showed that those with "eating restraint" had higher stress hormone (cortisol) levels indicating that making decisions about what to eat or avoid eating was a kind of stress. We also have shown that not ovulating normally, even if the menstrual cycle seems to be normal, is a risk for more rapid bone loss (3;5;6).

Ok-the bottom line about what you can do. First of all, you need to get to know yourself a bit better by tracking your menstrual cycle. You can go to the CeMCOR website www.cemcor.ca and see links to U-Tube video clips about how important it is to understand and value your own menstrual cycle. You can download the Menstrual Cycle Diary and track your own experiences. Your period is likely to be on the way when you notice some breast tenderness or stretchy vaginal mucus. Just keeping this kind of a record and being able to discuss what you're learning with someone else (a friend, your mom, your family doctor) appears to help your cycles improve.

Secondly, I'd continue to do your exercise for the same amount of time but substitute some weight training for a few of your running sessions a week. And gradually become aware of whether you are eating more when you do more exercise-if you are not, your hypothalamus will be warning your reproductive system that it isn't getting enough calories to be regular and ovulatory.

In the mean time, I'm a bit concerned because your low weight and irregular periods mean you're not building optimal, strong bones right now. To compensate, I'd make sure to get enough calcium (from milk, yogurt, cheese or fortified soy or rice beverages) so that you have a serving with at least two meals plus take a multiple vitamin and a calcium pill (say 500 mg elemental calcium) at bedtime (7). Also, for now, I'd suggest that you take a 1000-unit vitamin D pill a day. For more information about the things that prevent osteoporosis in young women see 'The ABC's of Adolescent Bone Health' remembering that the extra vitamin D and calcium are needed until your periods are regular and ovulatory.

Finally, when you are ready (and by eating healthy food), I'd gradually let your weight increase by a pound or two. As you gain confidence, you will see that you don't need to have such a low weight to feel and look good.

Hope this is helpful for you,
All the best,

Jerilynn

Reference List

1. Rogol AD, Weltman A, Weltman JY, Serp RI, Snead DB, Levine S et al. Durability of the reproductive axis in eumenorrheic women during 1 yr of endurance training. J.Appl.Physiol. 1992;72:1571.

2. Bonen A. Recreational exercise does not impair menstrual cycles: a prospective study. Int.J.Sports Med. 1992;13:110-20.

3. Prior JC, Vigna YM, Schechter MT, Burgess AE. Spinal bone loss and ovulatory disturbances. N Engl J Med 1990;323:1221-7.

4. McLean JA, Barr SI, Prior JC. Cognitive dietary restraint is associated with higher urinary cortisol excretion in healthy premenopausal women. Am.J.Clin.Nutr. 2001;73:7-12.

5. Waugh EJ, Polivy J, Ridout R, Hawker GA. A prospective investigation of the relations among cognitive dietary restraint, subclinical ovulatory disturbances, physical activity, and bone mass in healthy young women. Am.J Clin.Nutr. 2007;86(6):1791-801.

6. Bedford JL, Prior JC, Barr SI, . A prospective exploration of cognitive dietary restraint, subclinical ovulatory disturbances, cortisol and change in bone density over two years in healthy young women. JCEM 2010;95(7):3291-9.

7. Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. Dietary Reference Intakes for Calcium and Vitamin D. November 2010, 1-4. 2010.