We measured the knee joint angles and surface EMG signals during skiing, using a werable type measurement unit. Judging from every cycle of knee bending exercise, we analized only the most active intervals in measured EMG signals to evaluate muscle fatigue turn-by-turn. Then, we evaluated the time-series of muscle-activityrelated and knee-joint-angles-related indices within a trial and among trials during skiing exercise, comparing with the results during squat exercise. The results showed that the experts sustained the posture even through muscle fatigue occurred and that intermediate experts sometimes showed alternation of agonist muscles to prevent muscle fatigue. These features during skiing were also observed during repetitive squat exercise. Accordingly, study on several muscles with knee joint angles during squat exercise could be effective to evaluate the influence of muscle fatigue on performance during alpine skiing exercise.