| Summary: | 碩士 === 長庚大學 === 復健科學研究所 === 97 === Background: Pushing is a common movement in moving object, and it also related to about 9% to 20% low back injuries occurrence. Poor muscle endurance or muscle fatigue are a possibility cause of muscle injuries. The purpose of the present study was to examine the effect of fatigue on trunk muscle activity during treadmill walking with and without a pushing movement. Methods: Twenty healthy young adults were asked to walk with and without a simulated pushing movement. Volunteers first performed walking with simulating pushing by their maximum pushing force. Stopping criterion was reaching subjective assessment of trunk muscle fatigue by Borg CR-10 Scale, and return to carry out walking without pushing movement one week later. The electromyographic signal of erector spinea, multifidus, rectus abdominis and external oblique muscles at both sides were collected by surface electrodes. Median frequency(MF) and root-mean-square(RMS) which provide information of muscle fatigability and activity were calculated in the initial, middle and final periods of both walking with and without pushing movements. Repeated measure ANOVA was used to compare the differences of MF and RMS between the two conditions in three periods. Tukey HSD post hoc analysis was performed on all appropriate statistically significant main effects and interactions. Results: The mean time of walking with pushing was 19 min 32 sec±8 min 32 sec. MF of erector spinea, multifidus and rectus abdominis decreased in both walking with and without pushing conditions, but only significant in without pushing condition (p<0.05). The dominant side of trunk muscle showed the positive correlation with the non-dominant side in MF and RMS. MF and RMS between erector spinae and multifidus and between rectus abdominis and external oblique respectively showed positive correlation in simulating pushing condition (p<0.05). MF change showed negative correlation with RMS change during without pushing condition. Conclusion: Muscle fatigue was found in erector spinae, multifidus and rectus abdominis in both walking with and without pushing condition, but only showed significant fatigue in walking without pushing condition. Furthermore, significant muscle fatigue was found in the first half of the walking without pushing period.
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