We evaluated whether the increased peripheral insulin sensitivity often reported after physical exercise is generalized or limited to the active musculature. Substrate exchange in leg (previously active) and forearm (previously inactive) were measured by catheterization technique basally and during a hyperinsulinaemic euglycaemic clamp (2 mU insulin kg-1 BW min-1) in nine healthy men before and 1 day after 3-h exercise (50% VO2max). One day after exercise basal glucose uptake was unchanged in the leg, while it was decreased in the forearm (-61%, P less than 0.01) compared with the pre-exercise condition. Glucose uptake during hyperinsulinaemia was increased in the leg (+31%, P less than 0.05), but not in the forearm. Basal lactate release by the leg was increased by the exercise, while lactate release by the forearm was decreased, significantly only during the clamp. These results indicate that local and not systemic factors are responsible for the changes in insulin sensitivity observed in the recovery from physical exercise.