This study investigated maximal voluntary muscular torque output and the time to peak torque contraction at three functional speeds during 50 reciprocal isokinetic contractions using the Cybex Ⅱ+ dynamometer. Flexor and extensor muscle groups of both knee were testes at 60, 120, and 240°/sec on 10 university long distance runners (5 men and 5 women) and 10 university sprinters (5 men and 5 women) between the age of 20 and 29. The Isokinetic endurance was measured by having each subject perform 50 maximal contractions of quadriceps and hamstring muscle groups of both knee at three speeds. When the peak torque values of contractions dropped below 60% of the maximum strength demonstrated in the nonfatigue condition, determined the maximum numbers of repetitions performed in excess of 60% of peak torque. The results indicate: 1) Torque decreased as the speed of exercise increased. 2) sprinters performed greater strength than long distance runners but there was significant difference between female runners. 3) The ratio of strength of hamstring and quadriceps muscle groups was increased as the speed of exercise increased. The ratio was between 48.8% and 84.2%. 4) Female long distance runners performed greater muscular endurance than female sprinters. 5) Sprinters were faster than long distance runners on the time to peak torque contraction.