Are any of you other ladies not sure what to make of this flap about oral contraceptives reducing gains in lean muscle? While the initial study came out sometime in mid-April, links to articles about it continue to crop up (I’ve seen it a lot recently, in places other than just crossfitdurham.com) and I’ve always struggled a bit to figure out the take home message. There is something about the whole business and the implications that some article authors are trying to make that really bugs me, so here comes a mini-rant complete with some dorking out. You’ve been warned.
The general gist of the study is as follows: Researchers took a small sample of “relatively healthy” 18-31 year old women and looked at how oral contraceptive users (OC) and non oral contraceptive users (non-OC) compared when exposed to a “whole body resistance program” (I’m thinking Nautilus machines here). After 10 weeks, OC users saw statistically significant smaller gains in lean muscle mass in comparison to non-OC users but overall strength gains weren’t significantly different.
There is something about the massive proliferation of these findings that is bugging me, though, and it is partly that I can’t find the full study online and there are some general research issues that aren’t addressed (I’ll list the 2 main ones for the sake of brevity):
- Sample selection (my impression is that the sample was NOT random assignment, e.g., “you go on OC, you do not go on OC” and that instead they found current users and non-users to test) – oral contraceptives are not for everyone. Many women try OC and find that, no matter the formulation, the hormones in OC and their bodies are just not friendly, so they switch to a different method of birth control. If there are underlying physiological differences that influence the decision to use a certain form of birth control, these might also influence how the body responds to exercise.
Where I really start to get irked, however, is the generally implicit, but at times explicit*, message that women who are interested in improving their fitness performance might consider switching birth control methods…because nothing helps you meet your fitness goals like an unintended pregnancy. While this might ultimately be something to think about for women who are pursuing sport as a career, it's extreme for those of us who just want to improve our levels of fitness in general. When I think of “fitness” it is more than just “how big are my muscles?” – it is a general quality of life issue, and I know a lot of women who would take a little less muscle mass for the overall improvement in quality of life that they get from oral contraceptives (hormonal control that reduces mood swings, acne, pain, etc.).
From a Crossfit perspective in which strength is more important than body composition—we aren’t trying to win physique contests (or at least I’m not) but we ARE trying to lift heavy things—this suggests that maybe oral contraception doesn’t have a huge influence on overall performance, or at least not the type of performance we are measuring. And even if it does hinder performance slightly, those of us on OCs can at least take solace in research that finds that oral contraceptives significantly reduce exercise-induced delayed onset muscle soreness (aka DOMS).
* The best part of the summary that noted “…young women who are trying to build muscle mass may want to choose another form of contraception” was the accompanying photo: