Ibuprofen and acetaminophen: Effect on muscle inflammation after eccentric exercise

Purpose: We examined the influence of ibuprofen and acetaminophen on muscle neutrophil and macrophage concentrations after novel eccentric contractions. Methods: Twenty-four males (25+/-3 yr) were divided into three groups that received the maximal over-the-counter dose of either ibuprofen (1200 mg.d(-1)), acetaminophen (4000 mg.d(-1)), or a placebo after eccentric contractions of the knee extensors. Biopsies from the vastus lateralis were taken before and 24 h after exercise. Inflammatory cells were quantified in muscle cross-sections using immunohistochemistry. Results: Macrophage concentrations were elevated by 1.5- to 2.5-fold (P<0.05) at 24 h postexercise relative to preexercise concentrations, whereas neutrophil concentrations were not significantly elevated. Muscle inflammatory cell concentrations were unaffected by treatment with ibuprofen or acetaminophen when compared with placebo. Conclusions: Maximal over-the-counter doses of ibuprofen or acetaminophen, when administered therapeutically, do not affect muscle concentrations of neutrophils or macrophages 24 h after a novel bout of eccentric contractions.