An EMG fractal indicator having different sensitivities to changes in force and muscle fatigue during voluntary static muscle contractions

The EMGs partly show 1/fα spectral behaviours since their power spectral densities may experimentally fit with two linear segments in a log-log representation. The measured “right” slope produces variations of force as 20 times the variations of fatigue. 1/fα Behaviour may be related to stochastic fractals. This fractal indicator is a new frequency indicator that is thus complementary to other known classical frequency indicators when studying force during unknown fatigue states.