All sustained physical activities subject the body to various levels of fatigue. This is especially evident when running, which is one of the most popular forms of exercise and may be described as a reduction in maximum force production  and power output . the purpose of this study was to investigate the effect of running in an exerted state on knee muscles power absorption and work during the stance phase of running. Sixteen healthy physical education male students with an average age 22 and SD 2.27 years and height 177 and SD 5.47 cm and mass 72.6 and SD 8.4 kg participated in this study voluntary. Kinetic and kinematic data recorded by using of video camera and force plate. The negative and positive power and work of muscles operating on knee has calculated using inverse dynamic equations in MATLAB₂₀₁₀ Software. Paired sample T test was done to statistical analysis in SPSS 2010 software (p≤0.05). The results of this study indicated that negative peak power and work significantly decreased 33.78% and 22.6% respectively. Although the positive peak power significantly decreased (p≤0.05), positive work didn’t change significantly (p=0.644). The results of this research indicated that the absorbing function of the muscles is decreased following fatigue and may be led to increase the injury risk of running.