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Tuesday, 9 November 2010

Exercise and Fertility

I am writing this in response to Cynthia's comment:

"Not sure that hiring a coach is entirely consistent with your desire to get pregnant again."

Which is along the lines of what I was hoping someone would write. Because it is an important topic, often misunderstood and the above statement is, under most circumstances, not true.

Exercise/training does not decrease a woman's fertility. Loss of menstruation, however, obviously does. But these are two different things. Many elite athletes train beyond what they feed themselves. This is especially true for young elite athletes. They train hard, are thin, don't eat right and become amenorrheic. Think female athlete triad. BUT there is no evidence that training hard or for many hours negatively affects a woman's fertility, assuming she is still menstruating.

Bente Klarlund Pedersen, in her book "Motion og Graviditet" has an entire chapter on this subject in which she discusses and provides evidence that exercise does not negatively affect fertility. The one exception to this she cites is intense exercise on the day of implantation makes implantation less likely. Let's call this the exception that proves the rule. Beyond this, exercise also significantly decreases the chance of miscarriage. (Have to point out that I have a chance to meet Bente this coming Sunday at the Rudersdal Social Marathon. I'm actually hoping to ask her for permission to translate her book into English).

But since the above book is still only in Danish (and I had to return it to the library, so I don't have any citations), I will also refer to a large Norwegian study of almost 4000 women from the journal Human Reproduction from 2009 (Gudmondsdottir, et al).

They found that women who exercise greater than 60 minutes at a time had a decreased odds ratio of infertility compared to those who did not exercise. 0.6 adjusted OR (0.3-1.5 CI) - which was not significant, but at least did not show an increased odds compared to controls. Also those with a high level of perceived exertion did not have significantly significant increased odds of infertility.

However, there were two subgoups with slightly increased odds of infertility, those who exercise daily and those who exercise to the point of "exhaustion". The problem with these two groups is they are both likely to have more women with a lower than normal BMI and/or amenorrhea, which they did not control for. Interestingly, the women in these groups who had children, actually had MORE children than women who didn't exercise - so it points to a dichotomy: there is a group of normal, menstruating women who are fertile and a group of non- menstuating women who are not fertile.

Another study looked at eumenorrheic women and found no correlation between increased intensity of training or endurance training and abnormalities in levels of various reproductive hormones, though I can only read the abstract (Rogol, et al. 1992 Appl. Journal of Physiology).

There has not to this date been any evidence I am aware of that strenuous exercise in itself negatively affects fertility. It can sometimes cause irregular periods. But if you time things right, and are aware of when you ovulate (think fertility awareness method; FAM) you can have the same chance of getting pregnant as a woman with a clockwork cycle. The big problems happen when exercise combined with inadequate nutrition creates amenorrhea. And that is a different ball of wax - and not a ball you want to be stuck in - that is if you are interested in getting pregnant or in having bones that don't break easily.

I know I am an n of 1, but I got pregnant after trying for 2 months with The Lorax while running between 80 and 90 miles a week. I then got pregnant, with the subsequent miscarriage, while training for an Ironman after only 4 months of trying (and 1 month after a 50 mile race).

I personally have no evidence that strenuous exercise affects fertility and I have not seen any convincing evidence to back up the theory either. Though any opposition to this is welcome...

In other news, I have had two AWESOME days of training (and am still hoping for a pregnancy btw)

Monday: swim training record! - 35 laps in 41 minutes! Yes!
Tuesday (today): 8 mile tempo run in 56:48 (only 28 seconds slower than my fastest 8 mile tempo time ever last March) and with a negative split. The time from today is also nearly 6 minutes faster than my 8 mile tempo time from last November. Yipee!

Running Songs of the day:

I have mentioned this song before, but it is just so good for running fast, that I have to post the video:

"Come with me" by CEO

CEO Come With Me.
Uploaded by divisionparis. - Music videos, artist interviews, concerts and more.

And this is a good one for running or walknig or whatever
"Winter Weeds" by Liam Singer (not a bad last name for him)

10 comments:

Ellen said...

I'm no expert, but it makes sense to me to have a coach who will plan a program for you to prevent over- or under-training. Good luck with everything!

cherelli said...

If Bente were to get her book translated to English it would be a huge seller; there hasn't really been anything on the market here since James Clapp's book. You know I am pretty poor at sitting on the fence about this; i am still running though, my run sessions are shorter, lots more strength work. It makes sense to avoid the intense exercise around implantation (as the month I did get pregnant was the time I was on a roadtrip just after ovulation and getting exercise was harder)...but thanks again for this post. Good luck with the getting pregnant and training bit!!

SteveQ said...

I have a great comment about coaches and getting pregnant, but it's WAY too dirty for this blog.

sea legs girl said...

Ha ha, Steve. Just write the comment on Glaven's blog - I'm sure it'll fit right in.

sea legs girl said...

Ellen - yeah, training right is definitely healthier than simply training hard. -agreed.

Cherelli - totally agree with you about the book.

Regarding your running less - A woman's beliefs about her own fertility are so complex. I admit a lot of my own beliefs simply come from what worked before and intuition. I could never tell you what to do: there is no real solid evidence saying running is good or bad for fertility. I don't want to tell anyone what to do or believe - I simply like presenting studies, evidence, theories, etc. and dicussing.

SteveQ said...

re: Chippewa date - Vacation Sports is notorious for being disorganized; don't trust any date for the race they state until close to race time.

Stefanie Schocke said...

Love the research you post!

Marathon Princess said...

When I was TTC the specialist I was working with said there is no magic weight or exercise that is good/bad for fertility, every woman's body is different and the trick is figuring out what your body "likes". After about 1 year I finally got pregnant a month before a marathon.
Good luck with the training, finding a coach is a great idea to help find the good balance.

Drs. Cynthia and David said...

The crossfit people allege that women starting their protocol show increased fertility. Just anecdotal perhaps, but consistent with hormone normalization (perhaps resolving PCOS issues). They exercise pretty intensely, but usually only for short times.

In my comment I meant only that you may need to control your urge to train excessively, but a coach would probably help with that.

Anyway, good luck.

Cynthia

Anonymous said...

I have been trying to get pregnant for many months now. Really glad to hear that you have no issue of conceiving despite intense training. I think i'm not doing enough of exercise that's why haha!