Fatigue Effects on Electromyography Signals on Resting Muscle

It is widely accepted that a resting muscle does not present detectable electromyographic signals at the skin surface (sEMG). For this reason, studies on resting muscle tone often focus on measuring mechanical properties, such as stiffness, tension, and elasticity, either through palpation or specific devices. In this study, the superficial flexor muscle of the fingers was analyzed. First, the Power Spectral Density (PSD) was obtained in a resting state (PSD_pre). Subsequently, the muscle was subjected to a fatigue protocol, and immediately, after returning to the resting state, the PSD was measured once again (PSD_pos). The results suggest that the muscle at rest presents detectable electromyographic signals. Furthermore, the Wilcoxon signed rank test indicates a statistically significant decrease in PSD_pre compared to PSD_pos, with a 95% confidence level (p-value = 0.00443). In other words, the resting muscle, after experiencing fatigue, shows a greater accumulation of power in its sEMG signal compared to the pre-fatigue state.