Purpose: To examine the effects of prolonged systemic administration of diclofenac sodium (Voltaren), a nonsteroidal anti-inflammatory drug, on objective indices of exercise-induced muscle damage in humans.
Methods: Fifty-four volunteers (mean age, 26.4 yr; range, 18-35) participated in this randomized double-blind, placebo-controlled trial. To achieve steady-state tissue levels, either placebo or diclofenac was orally administered two times a day for 27 consecutive days. A strenuous 20-min stepping exercise program, about which the subjects were unfamiliar, was conducted on day 15. Creatine kinase (CK) activities were measured immediately before the exercise session and on days 16, 18, and 27. Vastus lateralis muscle samples were obtained immediately before exercise and on day 27 for subsequent histological characterization of muscle inflammation.
Results: The preexercise muscle samples revealed no difference in muscle damage between the two groups. However, the postexercise muscle samples showed that the diclofenac-treated group demonstrated less muscle tissue damage than placebo-treated subjects (P = 0.002). The administration of diclofenac also resulted in a significant lowering of post-/pre-exercise CK ratios on days 18 (P = 0.03) and 27 (P = 0.02) compared with the placebo group, an indirect finding that supports the possibility of diclofenac reducing exercise-induced muscle damage.
Conclusion: These findings demonstrate preadministration of diclofenac (in accordance with tissue half-life pharmacokinetics) significantly reduces quantitative indices of exercise-induced skeletal muscle damage in human muscle.