If you are using oral birth control, it may be, without you even realizing it.
A new study found that oral contraceptive use impairs muscle gains in young women, and is associated with lower hormone levels.
That’s a shocking find, especially for active young women, who are looking to improve their fitness performance while taking oral birth control.
Researchers at Texas A&M University and the University of Pittsburgh studied 73 healthy women between the ages of 18-31 for 10 weeks. During the study the women were broken up into two groups and completed whole-body resistance exercise training. The first group consisted of 34 women who used oral contraceptives, while the second group consisted of 39 women who did not take birth control pills. Both groups were encouraged to consume at least 0.5 grams of protein per pound of body weight per day (a third more than is called for by the U.S. government nutritional guidelines) to make sure they consumed enough calories and protein to promote muscle growth.
In addition, all the women were closely supervised as they exercised three times per week during the course of the 10-week study. The participants performed a variety of resistance exercises, including chest press, lat pull down, leg extensions, triceps extensions, arm curls and pull-ups.
At the end of 10 weeks researchers found that there were significant differences in lean mass gains between the women who used oral birth control and those who didn’t, with the non-oral contraceptive women gaining more than 60% greater muscle mass than their oral contraceptive counterparts. Researchers also found that oral contraceptive users had reduced anabolic hormone levels at the end of the training period. By contrast, the other participants’ levels did not change.
Despite the fact that researchers observed negative effects of oral contraceptive use on muscle gain in the context of resistance exercise training, “future studies are needed to help explain the reasons behind the results.”
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