Objective: To compare the efficacy of acetaminophen extended release (ER) caplets to placebo in treating muscle soreness after a marathon.
Methods: This was a randomized, double-blind, placebo-controlled study of participants ≥ 18 years old, who completed a marathon and experienced muscle soreness rated at least 4 on a 0-to-10 numerical rating scale. The intent-to-treat efficacy analysis included 610 participants. Participants were screened for eligibility before the marathon, and reported to the study tent after the marathon. On confirming eligibility, participants were randomly assigned to 4 days of 3-times-daily treatment of either acetaminophen ER 1300 mg (n=307) or placebo (n=303).
Results: Participants treated with acetaminophen ER reported a significantly (P<0.0001) greater decrease in the primary endpoint of average change from baseline in muscle soreness on the day of the marathon (day 1) (-0.79) than did placebo (-0.36). In addition, the adjusted mean average interference with sleep was significantly lower for acetaminophen ER (2.14) than for placebo (2.52, P=0.0046). The adjusted mean overall satisfaction with treatment was significantly higher for acetaminophen ER (5.38) than for placebo (4.64, P=0.0060). Adverse events were reported by 3.7% of participants, with no clinically important difference between treatment groups. No serious adverse events were reported.
Conclusions: Acetaminophen ER 1300 mg, a nonprescription drug, was an effective treatment for post-race muscle soreness on the day of the marathon. In addition, acetaminophen ER provided benefit for interference with sleep and overall satisfaction with treatment, and was generally well tolerated.