Sunday, August 30, 2009

my first blog post is a doozy

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 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):

  1. 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.

  2. Were they all on oral contraceptives with the same hormone composition? Again, something I haven’t seen anything about. Triphasic versus monophasic, the type of hormones in the pill – all of these could affect the outcomes.

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:

Weightlifting: you're doing it wrong.


  1. Becky- Great commentary on this study.. I agree completely that this research seems to have some significant flaws, including you point about the nonrandom sample selection. If they were not randomly assigned to OC vs non-OC, then there would be many variables that would have to be controlled for in the data analysis. I am definitely interested in reading the full publication to hear more about the specifics! And-what type of scientific study/researcher uses the publication of their results (with questionable validity)as a platform on which to voice their personal opinions?

  2. I'm glad you wrote about this. I hadn't read the article until now, but Bea mentioned it to me last night and I've been irked by it ever since. I'm not sure I even understand the point of the if women who are trying not to have children will actually weigh the potential for greater muscle gains against the chance of having an unwanted pregnancy. I personally think the study is bogus and for all the reasons you mentioned, I don't feel the study is very scientific. My favorite part of the article was this quote:

    “Numerous health and performance benefits including improved exercise/athletic performance, body composition, esthetic beauty, and self-image can be attained from the increased muscle mass and strength associated with resistance exercise training. OC users may not be able to fully enjoy those benefits ...."

    I love that three of the four "health and peformance benefits" refer to your physical appearance.

  3. Dori - that quote is AMAZING...

    I actually was just encouraged to dig a little harder than my initial search and uncovered this:

    It's a more straightforward article and actually goes into a some detail about methodology and the findings. It looks like these are press releases based on a paper presented at a conference in April and the manuscript isn't readily available online yet. While it doesn't address sample selection or the small sample size, it does mention that the type of birth control moderates the overall effect and is definitely much more reasonable with its conclusions.

    After doing some more research it seems the authors were trying to address differences in muscle building among women and chose to examine oral contraceptives. They have some interesting, but limited, findings that require much more rigorous future research to make any big conclusions (and even then would probably not deter women from using OCs!)...the big issue here are how the media then takes these findings and interprets them...making it a lot harder for us to ferret out what is really going on!

  4. don't many women aovid weight training because they they have a (unfounded) fear they will wake up looking like a bodybiulder?

    seems this article would sell OC to some ppl rather than scare them away "Get Strong without the Bulk! (and stay un-pregnant too!)"

  5. go me with the triple post. i accidentally deleted my last post in an attempt to add to it.

    that picture is friggin' hilarious becky. what are those, 2.5lb weights? did they use those in the study?

    and that quote is priceless dori. :)

  6. It seems a little silly for me to post a comment now after so many people have weighed in, but oh well. As Becky has said the study itself does not warrant the response from "media". I use quotes because the worst of it comes from blogs. What I find interesting is that their is no significant difference in strength gain. Becky made a very good point by questioning the dose of birth control used. When you think about it, the lack of muscle gain mass makes sense. What is one way body builders attempt to aid in their bulking up? They do what they can to lower their estrogen levels and raise their testosterone levels. What is the major component of birth control? Estrogen. Don't get me wrong, estrogen is great. It promotes the formation of female secondary sex characteristics, and who doesn't love those? For those who do not know, the study was conducted at Texas A&M. In fact they found that certain pills made muscle gain less likely, such as medium and high androgenic progestins, whose users achieved less than .5 percent gain during the study.

    My absolute favorite quote from one of the blogs was this: "The young women were on a very aggressive muscle-building campaign; participants exercised three times per week for ten weeks under the supervision of exercise physiologists. They performed a variety of exercises to include chest press, lat pull down, leg extension, triceps extension, arm curl and abdominal crunch. Exercise was done using standard exercise machines and each volunteer performed three sets of 6-10 repetitions per exercise." I do not call that "a very aggressive muscle-building campaign".

    So, if any of you ladies plan on being in a muscle magazine, you might want to make sure you are on a low dose pill. Otherwise enjoy the fact that you are going to get stronger but not bulk up (I am joking Mandy)

  7. Studies such as this one that have obvious flaws but are written in a way that is pallatable to the public are a thinly vailed attempt to chip away at a womans right to choose. This is MORE than just an annoying article that plays on stereotypes of womens negative body image. This is one way to get women to "choose" to stop taking birth control. There are many bogus studies such as this one put out by researchers that are funded by pro-life organizations. I bet if you look into who funded this study you would find a direct link to an anti-choice organization.

    I know this is a very political and heated point to bring up, but I can't let this go unnoticed.