The aim of this study was to determine the change in isokinetic leg strength after static and dynamic squat burnout fatigues. Fifty four (37 male, 17 female) voluntary university students aged of 18-26 years (22.09 +/- 2.08) participated in this study. Two different burnout fatigue of static and dynamic squat exercise protocols were induced over an interval of 3 days. Strength measurements: After warm-up exercises, strength of the knee extensor and flexor muscles of the dominant leg was tested with 5 maximal repetitons at 60 degrees/sec using an isokinetic dynamometer. The decrease of the quadriceps muscle strength were -5.53% and 15.62% (p<0.00) respectively after static and dynamic squat fatigue exercises. Unlike this result, following static and dynamic burnout exercise fatigue, an increase in hamstring muscle strength were obtained significantly +3,31% ve +2,90% respectively (p<0.02). Furthermore, there were low negative relations between static exhaustion times with body weight (-.28) and thigh circumference (-.34), while there was no significant relationship between dynamic exhaustion times and any anthropometric measurements. The acute effect of the burnout fatigue in isokinetic strength were found surprising. There is a need to examine why muscles are activated more with acute response of burnout fatigue by the function of the working muscle. After burnout fatigue formed by static and dynamic exercises, isokinetic muscle strength of quadriceps muscle decreased and that of hamstring muscles increased. The possible reason of unexpected increase in the hamstring muscle strength after both of the fatigue types might be the increase in the participation of the total number of fibrils.