Effects of normal strength exercise on leukocyte accumulation were examined in 10 well-trained male subjects (27.2 ± 2.7 yr). The workout, consisting of 5 maximal sets of 3 reps in the leg press exercise and 5 maximal sets of 6 reps in knee extension exercise, was performed with the dominant leg and the other leg served as control. Maximal isokinetic knee extensions at 60°^.s^-1 were performed to evaluate neuromuscular fatigue and recovery. Accumulation of leukocytes was assessed with ^99mTc-labeled cells, and repeated images of the thighs were taken 1-24 h after the workout. Maximal force-generating capacity in the exercised leg was reduced by 17±2% (p<0.01) after the workout. The course of recovery followed a biphasic pattern characterized by halted recovery 10-23 h after exercise. The presence of leukocytes was ~10% higher in the exercised than in the control thigh 10 h after exercise (p<0.05). This difference increased to ~15% 20 h after exercise (p<0.05). The retarded recovery of maximal force-generating capacity observed 10-20 h after exercise, taken together with a significant infiltration of leukocytes in exercised muscle during the same time interval, shows a temporal relationship between leukocyte infiltration and impaired recovery.