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 4 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 degrees/s 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.