Abstract
Muscular fatigue gradually progresses during long-time repetitive exercise in sports or rehabilitation, and in turn, it causes a higher risk of injury. Especially, the risk is higher than expected for skiing exercise because skiing exercise is alternately repeated all day long including ski-lift riding. Additionally, skiers must disembark from the ski lift after riding it to the top of the slope. In this study, we measured surface EMG at the tibialis anterior (TA) and the vastus lateralis (VL) muscles with respect to knee joint angles using a portable data acquisition system. For estimating muscular fatigue, we calculated the mean power frequency (MPF) of the surface EMG for selected intervals as determined by knee joint angles. The results showed that MPF at VL declined in the first half of the trial, and then plateaued in the latter half of the trial. The trend in decreasing MPF was steep in the afternoon compared to that in the morning. Therefore, the muscle activities during skiing can be evaluated by the MPF of EMG for selected intervals using knee joint angles.
