• The average change from baseline in muscle soreness on Day 1
  

• Average change from baseline in muscle soreness for both morning and evening assessments, combined and separately; Average ratings of interference with 1) sleep, 2) daily activity, and 3) ability to go for a run
  

This is a randomized, double-blind, placebo-controlled study to compare the effectiveness and safety of acetaminophen and placebo in treating muscle aching and pain (soreness) that occurs in subjects who complete a marathon. Subjects are randomized to receive acetaminophen extended release caplets, 3900 mg/day (two 650 mg caplets taken three times a day, for four days) or placebo (two placebo caplets taken three times a day, for four days). The primary measurement of efficacy is the average change from baseline in muscle soreness, on Day 1, the day of the marathon. Safety assessments consist of monitoring adverse events, and a physical examination at the screening visit, including vital signs, weight, a medical history review, and a urine pregnancy test for females of childbearing potential. The hypothesis of the study is that acetaminophen is more effective than placebo in the relief of post-race muscle aching and pain (soreness) score on the evening of the race. Two acetaminophen 650 mg extended release caplets, taken by mouth, three times a day over a four day period or two placebo caplets, taken by mouth, three times a day over a four day period.