The main purpose of this research was to examine the efficacy of naproxen sodium for the reduction of eccentric exercise-induced neuromuscular responses and gait alterations in healthy older individuals. To accomplish this purpose, 15 healthy, 54-64 year-olds performed 8 sets of 8 eccentric actions at 75% of their eccentric one repetition maximum (1RM) load with one leg in a double-blind, cross-over design. For 10 days immediately following exercise, they took either the non-steroidal anti-inflammatory drug (NSAID) or placebo, and after a 3-week washout, crossed over the drug or placebo and repeated the exercise with the other leg. During the 10 days following exercise, the following measurements were taken on days 3 and 10:​ 1RM strength, maximum isometric force, muscle injury and cross-sectional area (CSA) via magnetic resonance (MR) imaging, and soreness ratings. Also, at these same times participants were videotaped while walking down a 16% decline for 5 trials.

IRM strength and maximum isometric force were reduced (p < 0.05) more in the placebo (32% and 24%, respectively) than in the drug (6% and 12%, respectively) trial on days 3 and 10, respectively. Muscle CSA with an elevated T2 was 27% and 35% greater (p < 0.05) for the placebo than the drug trial on days 3 and 10, respectively. During the NSAID therapy trial on day 3 of recovery, less soreness was reported compared to the placebo trial (43 mm vs 26 mm, respectively). NSAID therapy was also effective in attenuating gait alterations. The placebo trial group displayed a 9% shorter step length, 7% less support time on the involved leg, and a 21% shifting back of the center of mass while walking downhill (p < 0.05) compared to the day 3 drug trial. In an attempt to understand these alterations, relationships between the gait changes and classical Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. neuromuscular responses were examined. It was found that step length was moderately related to strength and muscle soreness. Support time relative to stride time of the involved leg was related to maximum isometric force and T2 contrast shifts. Based on these results, the following conclusions were made regarding healthy older individuals:​ 1) novel eccentric exercise elicits strength loss, muscle damage, soreness, and altered functional performance reflected in downhill walking;​ 2) NSAID therapy is effective in attenuating the responses;​ and, 3) there are moderate relationships between downhill gait changes and classical neuromuscular responses to eccentric exercise.