Evaluation of Localized Muscle Fatigue Using Spectral and Nonlinear Time Series Analysis
Overview
The goal of this study is to investigate the effects of lower extremity muscle fatigue on a balance task. In order to facilitate lower extremity fatigue, a treadmill will be used to produce three different levels of muscle fatigue. Two techniques for assessing and quantifying fatigue level are currently being considered. These include the Borg RPE Scale, in which participants qualitatively assess fatigue level at regular time intervals; and an online monitor, in which the median frequency degradation of electromygraphic (EMG) signals is monitored in real-time and used to identify specific levels of fatigue. Between fatigue tasks, dynamic balance will be assessed using the forward lean and release technique described in the Step Length and Balance Recovery study. In addition to dynamic balance, a (static) sway technique is being considered to examine the effects of muscle fatigue on center of pressure (COP) characteristics. Specifically, this may be done by modeling COP trajectories as random walks and determining coefficients from the slopes of the resulting diffusion data.
Raw Data and Calculated Parameters
Raw Torque, SEMG data, and the calculated parameters. Notice the high variations in the spectral indices and how they increase towards the end of the trial. The CI seems to have an inverse relationship with the torque while the IEMG seems to be linear with torque.
Torque vs ISEMG
Log(CI) vs log(Torque)
