Another interesting study has been reported at the American Physiological Society meeting held in New Orleans. A team of researchers has now examined the effects of oral contraceptives on female muscle mass, and found that oral contraceptive use impairs muscle gains in young women, and is associated with lower hormone levels. Many active young women use oral contraceptives (OC) yet this is the first time its effect on their body composition and exercise performance has been studied.
Dr. Chang-Woock Lee and Steven E. Riechman of Texas A&M University did this work, along with Mark A. Newman at the University of Pittsburgh. They studied seventy-three generally healthy women between the ages of 18-31 who completed a 10-week whole-body resistance exercise training program in two groups. Group 1 consisted of 34 women who used oral contraceptives (OC). Group 2 consisted of 39 women who did not take birth control pills (non-OC). The women 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.
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 at 75 percent of their maximum strength. Body composition was determined using hydrostatic weighing.
At the conclusion, researchers found that there were significant differences in lean mass gains. 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. In addition, those OC users had reduced DHEA hormone at the end of the training period. By contrast, the other participants’ levels did not change.
According to the researchers, “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.”