The title refers to the fact that I am now 2 weeks late for my period but am not pregnant. Am I sure about the fact that I'm not pregnant? Well, no, but I'm pretty convinced of it since I've had four negative pregnancy tests.
So, why is it that I am not ovulating? Is it due to running? Or in particular training hard? We all know that a very low body weight and/or a limited diet can lead to amenorrhea. But does running alone lead to an anovulatory syndrome? My intuition as a physician says no. Evolutionarily, women should not get pregnant if they lack nutrients or a bodily surplus. But humans are nomads and that is why exercise in itself is healthy for all of us. Interestingly, once women start running over 60 miles per week, about 25% don't get their period, but as their body weight increases, almost all ovulate normally. If they are below normal weight, up to 60% have amenorrhea (info from Ginny Ryan, University of Iowa). Just for comparison, about 5% of the female population suffers from amenorrhea at any given point time (this does not include pregnant women or those on hormonal birth control).
But let's look at a different study: Menstrual patterns in ultramarathon runners. S Afr Med J. 1987 Dec 5;72(11):788-93
70 female ultramarathoners; 9% suffered from oligo or amenorrhea, as compared to 7% of controls (I can't comment on the statistical significance of this as only the abtract is available). The study also showed that menstrual dysfunction was unchanged once they became ultra marathoners, i.e. the same 9% suffered from amenorrhea or oligomenorrhea BEFORE they started running ultramarathons. Allow me to directly quote one of the conclusions "Those likely to develop chronic menstrual dysfunction tended to be younger, had started running at a young age, trained over a long distance each week, had low body weight, had experienced previous menstrual irregularity and tended to be the better performers. In addition, there was frequently a past history of anorexia nervosa." Arrrggghhhh. These ALL apply to me. Well, "better performer" is questionable. They go on to say: "chronic menstrual dysfunction which is probably a reflection of a particular life-style, personality type, body build, and, possibly most importantly, nutritional status."
This study also found that 14% of the ultramarathoners suffered from temporary menstrual irregularity during times of increased stress and/or more intense training. Interesting that the day I was supposed to ovulate was the day of the Nike 15k and that I was training quite hard in the weeks leading up to it.
Am I surprised I am late for my period and not pregnant? No. Am I bummed out? A little, mostly because ovulation is a sign of good health.
Am I taking it bit easier in training as a result?
To answer this question: I went on an 8 mile tempo run today, now 8 days after the 50 miler, in 56:46, just 20 seconds slower than my fastest time ever on this route! I could still feel the 50 miler in my legs a little and pushed myself to the point of bubbling froth from my mouth, puking at about half-way point and completely collapsing at the end. I heard a car honk and looked up to see a 16 year old guy gesturing whether or not I was okay. I held my head up and smiled. I was more than okay!
But back to running's affect on menstruation. I am curious about my female readers. Feel free to participate in my very non-scientgific surveys in the column to the right (if you fill out one, please fill out the other as well).
Running Song of the Day: Waving Flag by K'naan (I love this whole album)