A randomized controlled trial of the effect of naproxen on delayed onset muscle soreness and muscle strength

Objective: To determine the effect of naproxen in attenuating the symptoms (muscle soreness level) and signs (plasma creatine kinase [CK] activity and muscular strength decrement) of delayed onset muscle soreness (DOMS) induced by repeated bouts of eccentric exercise. Design: The design was a randomized, double-blind, placebo-controlled. crossover trial with two testing phases of 8 days duration that were separated by a;'washout'' period of 7 days. Setting: University-based sports science center. Participants: Twenty healthy male volunteers who responded to a notice in the university's athletic complex. Interventions: Eccentric single-leg exercises were performed on days 1, 3, and 3 to induce DOMS in the quadriceps muscles. Naproxen or placebo tablets (500 mg) were taken orally twice per day beginning on day 2 and continuing until the end of the testing phase. Main Outcome Measures: Perception of muscle soreness and knee extensor torque were evaluated daily throughout each phase. Plasma CK levels were evaluated on days 1, 3, 6, and 8 of each phase. Results: After the eccentric exercise, plasma CK levels were similarly elevated in both naproxen and placebo conditions (F = 1.42; p = 0.25). After DOMS developed, naproxen reduced the perception of soreness on day 3, when muscle soreness was highest (F = 2.20; p = 0.04). After treatments with naproxen, peak quadriceps torque during leg extension at 60% was higher than that after treatment with the placebo (F = 4.77; p = 0.04). There were no significant differences between the naproxen and placebo conditions for leg extension at 180 degrees/s (F = 1.66; p = 0.21) and 300 degrees/s (F = 0.71; p = 0.41). Conclusion: The data indicate that therapeutic doses of naproxen do not prevent CK release into the plasma but decrease the perception of muscle soreness and positively influence quadriceps peak torque.