A method for real-time estimation of local muscular fatigue in exercise using redundant discrete wavelet coefficients

In this paper, we propose a method to estimate muscular fatigue in exercises with load fluctuations. Muscular fatigue is an important property when evaluating the state of a muscle. However, it is extremely difficult to apply general methods, which depend on the relative changes in the signal power or frequency characteristics of a surface EMG, during exercise. We define two qualitative factors of muscular and neural activity, and by compounding these factors, we define a fatigue coefficient to estimate muscular fatigue. These values can be calculated in real-time. The fatigue coefficient quantifies the influence of the muscular fatigue and is not affected by changes in the load amount. Therefore, it can be used to estimate muscular fatigue, even for non-repetitive actions and unknown load amounts.