Ibuprofen Appears to Help Build Muscle

First, a study that measured muscle protein synthesis suggested to researchers in the Human Performance Laboratory at Ball State
University, Muncie, Indiana that ibuprofen and acetaminophen had a
negative impact on muscle by blocking the COX enzyme. So when the same researchers decided to measure the changes in muscle mass in a group of healthy older
adults lifting weights regularly, for 3 months, who were taking
recommended daily doses of ibuprofen (like that in Advil) or
acetaminophen (like that in Tylenol) they expected to see less muscle growth in the drug takers than in the control group. They were wrong.
The Scientific American reports on the surprising results of the Ball State study, which found that  taking
recommended daily doses of ibuprofen (like that in Advil) or
acetaminophen (like that in Tylenol) led to substantially
greater increases over inactive placebo in quadriceps muscle
mass and strength. In fact, Sciam reports that the muscles of the ibuprofen and acetaminophen users got
40 to 60 percent bigger than the placebo group and their muscle
strength also increased more than the placebo group.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.
                               
Read more in the Scientific American.