The aim of the present study was to investigate whether cycle training offers an effective and safe means for improving muscle strength in young people. Eighteen 10-year-old boys formed the training group and 17 age-matched boys participated as controls in the study. Participants took part in a strength-training program that included cycle training 3 times per week for a period of 12 weeks, whereas controls participated only in the school’s physical activities. Maximum knee extension and flexion was evaluated at various angular velocities using an isokinetic dynamometer. Significant increases (p < .001) were observed for both extensors and flexors in all angular velocities of the training group and only in the middle and high angular velocities of the control group (p < .05 to p < .001). The findings suggest that cycle training appears to be an effective means for improving muscle strength in prepubertal untrained males.