| The overall purpose of the present study was to examine EMG dynamics recorded during isoinertial exercise using recurrence quantification analysis (RQA) and fast Fourier transform (FFT). The physiological data were recorded from back muscles of patients experiencing low back pain.; Customized programs were used to calculate RQA percent determinism (%DET) and FFT central frequency (FC) episodically. During rhythmical muscle shortening and lengthening, EMG bursts exhibited increased %DET and decreased FC, both indicative of increased motor unit synchronization. Changes in %DET were found to be more sensitive than changes in FC indicating that RQA is more responsive than FFT to non stationary, high dimensional dynamics.; Linear correlation was found between %DET levels and decreased perceived pain following twelve weeks of therapy. Since %DET is an excellent marker for motor unit synchronization, following therapy the same exercise protocol did not bring motor units to their same pre-therapy levels of synchronization.; Cross-recurrence quantification (CRQ) was employed to test for these nonlinear synchronizations of motor units. (Abstract shortened by UMI.)... |
