Electomyographic frequency changes in the erector spinae and multifidus muscles during isokinetic trunk movement with different speeds

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Electomyographic frequency changes in the erector spinae and multifidus muscles during isokinetic trunk movement with different speeds


Author: So, Man-lan Vienna
Title: Electomyographic frequency changes in the erector spinae and multifidus muscles during isokinetic trunk movement with different speeds
Degree: M.Sc.
Year: 2001
Subject: Backache -- Patients -- Rehabilitation
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Jockey Club Rehabilitation Engineering Centre
Pages: xi, 93 leaves : ill. (some col.) ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1578469
URI: http://theses.lib.polyu.edu.hk/handle/200/983
Abstract: Isokinetic approach has been extensively used for assessing or training back muscles strength and endurance for patients with low back pain (LBP). Lack of endurance in back muscles was the most conspicuous factor contributing to LBP occurrence or recurrence. The appropriate speed for isokinetic back muscles training was not yet clear. Selective training of the deep back muscle, i.e. multifidus, has been shown to have privilege in back exercise prescription according to its important role of spinal stabilization. This study investigated the dynamic fatigue patterns of two major back muscles multifidus and erector spinae with isokinetic speeds at 60, 90 and 120 /s by using the electromyographic (EMG) power spectrum analysis method. Twenty-three healthy normal volunteers, 11 males and 12 females, without LBP were recruited in this study. Their mean ages were 24.7 and 26.9 with standard deviation 5.1 and 4.8, respectively. The subjects were required to complete a three-day test with three different isokinetic speeds. Each test involved 30 repetitions of maximum effort of trunk flexion and extension by using a Trunk Extension/Flexion unit (Cybex Norm Testing & Rehabilitation System, New York). Surface EMG electrodes were used to record the activities of multifidus and erector spinae during each test. The median frequency (MDF) of the EMG signals was extracted from the power spectrum of EMG signals for determining the fatigue rates of the two back muscles. The main effects as well as the interaction of two factors, namely muscles (MF and ES) and speeds (60, 90 and 120 /s), on the fatigue rates were analyzed using repeated measures analyses of variance (ANOVA). The results showed that fatigue rates of the two muscles at the three testing speeds were different but with no interaction between the two factors. The main effects of Muscle factor (F (1,21)= 4.66; p=0.043) and Speed factor (F(2,42)=4.33; p=0.02) were statistically significant. The multifidus showed a higher fatigue rate compared with erector spinae at all testing speeds. There was a decreasing trend for the fatigue rates of both MF and ES with increasing speed. Exception was shown for the male subjects at testing speed of 90 /s. The findings implied that the fatigue patterns of both MF and ES were inversely proportional to the isokinetic speeds. Based on the results of this study, isokinetic test at slow to middle speeds load the MF more in compared with ES especially for male subjects. From the result of higher fatigue rate of multifidus, the slow speed was recommended for performing the isokinetic training or testing the endurance of deep muscle multifidus. Further study on the fatigue patterns of these back muscles with different speeds on the patients with LBP was indicated to reveal the endurance dysfunction of the back muscles under the condition of isokinetic trunk movement condition.

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