Isokinetic strength of ankle plantarflexion (APF), knee extension (KE) and elbow extension (EE) was measured in male weight-trainers (6 power-lifters and 7 bodybuilders) and 25 untrained men of similar age and height. The weight-trainers exceeded control subjects by 21%, 25% and 73% in APF, KE and EE strength respectively. A similar pattern was obtained for limb girth, in which the weight-trainers exceeded control subjects by 6%, 13%, and 31% in calf, thigh and arm girth, respectively. Strength was similarly enhanced in the weight-trainers at the lower and higher velocities (APF 0.10, 0.63 rad X s-1, KE and EE 0.52, 3.14 rad X s-1) tested, and accounted for the positive correlation (r = 0.84) observed between low and high velocity strength. The powerlifters differed significantly from the bodybuilders only in their greater low velocity APF strength. The relatively greater enhancement of upper versus lower limb strength and muscle mass in the weight-trainers was considered in respect to training habits, trainability of different muscle groups and the state of training of muscle groups in untrained men.