Effects Of Upper Body Harness Tethering System On EMG Activity Of Low Back While Walking Under 25 % Traction

Abstract

The purpose of this study was to examine the effects of traction and 30 minutes of active traction on the EMG activity of the low back in adult males with chronic low back tightness. Ten adult males experiencing chronic low back tightness were administered either traction at 25% body weight or walked for 30 minutes at 2.5 miles per hour with traction of 25% of body weight while being supported in an active traction prototype (Conva-Lift). EMG activity of the low back was recorded after ten minutes of traction and after 30 minutes of walking. Standard EMG techniques were used with Motion Control pre-amplified electrodes to record eight seconds of EMG activity of the right longissimus (at lumbar 2-3 level) by an Ariel Performance Analysis System (APAS) at a sampling rate of 1000 hertz (Hz) after zeroing the AID board and AID range channels. A typical 2 second interval was selected for spike analysis and a spike threshold of .005 millivolts (mv) was utilized to identify an action potential. he mean peak EMG activity, mean action potential duration, and motor unit pulse frequency were analyzed for the interval. An ANOVA with repeated measures on the time factor was used to analyze the mean peak EMG, impulse duration, and stimulation frequency data. The ANOVA and subsequent post hoc analyses revealed that the 30 minute walking while under traction significantly reduced the peak EMG activity at a resting level of 3.691 mv to .038 mv (p=.OOl) and there were no significant differences between traction and walking with traction. The analysis found no significant changes occurred in the action potential duration between rest, traction, and walking with traction. The mean impulse frequency at rest was significantly reduced from 207.4 ± 86.9 Hz to a 43.6 ± 28.7 Hz pulse frequency after 30 minutes of walking with 25 % traction. Again, no differences in the pulse frequency existed between the traction and walking with traction conditions. In summary, walking 30 minutes at 2.5 miles per hour while having traction applied by the Conva-Lift equal to 25% of one's body weight resulted in significant decreases in peak EMG activity and impulse frequency of the low back, which would be indicative of inducing muscle relaxation in spastic muscle.