EMG responses resulting from transient and steady-state dynamic isometric loading of the human biceps can be distinguished

Abstract

In order to determine if differences in human muscle EMG response to steady-state (STD) dynamic load and transient (TRN) load could be detected, two distinct sinusoidal loads having identical amplitude and frequency were applied to the forearm, which was held in a fixed posture. The first condition used application of a constant amplitude, constant frequency, STD sinusoid, and the second condition used application of a single sinusoid of identical amplitude and frequency as the STD load. Time-domain parameters of Half-Mass, Dispersion Moments, Asymmetry Moments, Peak Ratio (ratio of cycle peak RMS EMG to cycle mean RMS EMG) and Time-to-Peak Ratio (ratio of cycle time to reach peak RMS EMG to cycle time duration) were used to quantify responses in the time domain. A single frequency-domain parameter, Dispersion Moments, was used to quantify responses in the frequency domain. Individual ANOVA's of the time domain parameter results revealed that p=0.689 for Dispersion Moments, p=0.111 for Half-Mass, p=0.007 for Asymmetry Moments, p=0.001 for Peak Ratio, and p=0.001 for Time-to-Peak Ratio. The time-domain MANOVA and frequency-domain ANOVA revealed that EMG responses resulting from STD and TRN applied loads were statistically different in the time domain ( p=0.001), but not in the frequency domain ( p=0.810). Thus, use of Asymmetry Moments, Peak Ratio, and Time-to-Peak Ratio parameters can distinguish EMG responses to STD and TRN loads.