• Average change in muscle soreness from baseline for both morning and evening assessments.
  

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

The objective of this randomized, double-blind study is to compare the effectiveness and safety of acetaminophen extended release caplets and ibuprofen in relieving the muscle 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 five days) or ibuprofen caplets, 1200 mg/day (two 200 mg caplets taken three times a day, for five days). The primary measurement of efficacy is the average change in muscle soreness from baseline for both the morning and evening assessments. Safety assessments consist of monitoring adverse events, and a physical examination including vital signs, weight, a review of concomitant medications, and a urine pregnancy test for female subjects. Two hypotheses are examined in a step-down approach. The first hypothesis is that acetaminophen extended release is not inferior to ibuprofen in relieving the muscle soreness that occurs after a marathon. If acetaminophen extended release is not inferior to ibuprofen in relieving the muscle soreness that occurs after a marathon, the second hypothesis is that acetaminophen extended release (3900 mg/day) is superior to ibuprofen (1200 mg/day) in relieving the muscle soreness that occurs after a marathon. Two acetaminophen 650 mg extended release caplets, taken by mouth, three times a day for five days or two ibuprofen 200 mg caplets, taken by mouth, three times a day for five days.