Stride length, stance width and gait symmetry were measured as parameters of gait analysis in young (5 months) and old (28 months) Sprague-Dawley rats following 3 months of treadmill running as well as in sedentary controls. Stride length decreased significantly with age and increased significantly following training in both young and old rats. Means of stance width increased significantly with age, but were unaffected by training. Gait symmetry declined with age; however, treadmill running counteracted the decline of gait symmetry. It was concluded that treadmill running compensates for or prevents age-related changes in the neuromuscular function of rats, which lead to gait detoriation.