In a study of healthy older adults lifting weights regularly, for 3 months, taking recommended daily doses of ibuprofen or acetaminophen led to substantially greater increases over inactive placebo in quadriceps muscle mass and strength.
Dr Chad C. Carroll, a postdoctoral fellow working with Dr Todd Trappe in the Human Performance Laboratory at Ball State University, Muncie, Indiana, reported the study results this week during the annual meeting of the American Physiological Society, part of the Experimental Biology 2008 scientific conference in San Diego.
Taking ibuprofen or acetaminophen regularly during resistance training seems to induce changes within the muscle that enhance the metabolic response to resistance exercise, which promotes additional muscle building and strength gains in the elderly, the researchers found.
During 12 weeks of supervised knee-extensor weight training, performed three times per week for 15 to 20 minutes, 36 men and women, between 60 and 78 years old, were randomly assigned to ibuprofen, acetaminophen, or placebo in doses mimicking what chronic users of these pain relievers were likely to be taking on a daily basis.
"We used 1200 milligrams a day for ibuprofen and 4000 milligrams per day of acetaminophen, which is the maximum over-the-counter daily dose," Dr Trappe explained in an interview with Reuters Health.
As expected, resistance training alone (placebo group) increased quadriceps muscle mass and muscle strength. However, the increases were far greater in the ibuprofen and acetaminophen groups.
"The muscles of the ibuprofen and acetaminophen users got 40 to 60 percent bigger than the placebo group and their muscle strength also went up higher than the placebo group," Trappe said.
Specifically, muscle volume increased 11 percent in the ibuprofen group and 13 percent in the acetaminophen group, compared with 9 percent in the placebo group. Muscle strength increased 30 percent in the ibuprofen group and 28 percent in the acetaminophen group, compared with 23 percent in the placebo group.
These finding were somewhat surprising, Trappe said. In a prior study, his team measured muscle protein synthesis over a 24-hour period and found that ibuprofen and acetaminophen had a negative impact on muscle by blocking the COX enzyme.
Based on this acute study, "we figured that these drugs would actually get in the way of muscle building in the elderly - the group that seems to benefit the most from doing resistance exercises," Trappe explained.
The researchers are now examining muscle biopsies taken from the study subjects before and after the 3-month period of resistance training to better understand the metabolic mechanism behind the apparent beneficial effects of ibuprofen and acetaminophen during weight training. – (Megan Rauscher/Reuters Health)