Researchers find link between oral contraceptive use, body composition and exercise performance

NEW ORLEANS Many active young women use oral contraceptives yet the contraceptives' effect on the womens' body composition and exercise performance has not been thoroughly studied, researchers presenting this weekend at the 122nd Annual Meeting of the American Physiological Society stated Friday.

A team of researchers has now examined the effects of OC on female muscle mass, and found that oral contraceptive use impairs muscle gains in young women, and is associated with lower hormone levels.

During the course of a 10-week study, researchers found that there were significant differences in lean mass gains for women on an OC regimen. However, other muscle responses such as strength gains and arm/leg circumferences were similar between the OC and non-OC users. Resting/fasting blood concentrations of the anabolic hormones were significantly lower in women taking OC vs. non-OC users throughout the study period.  At the same time, plasma concentrations of cortisol (catabolic hormone) were elevated. And those OC users had reduced DHEA hormone at the end of the training period. By contrast, the other participants’ levels did not change.

“We were surprised at the magnitude of differences in muscle gains between the two groups, with the non-OC women gaining more than 60% greater muscle mass than their OC counterpart,” stated Chang-Woock Lee of the Department of Health and Kinesiology, Texas A&M University. Even though the study has 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.”