Effect of fatigue on torque output and electromyographic measures of trunk muscles during isometric axial rotation.

Abstract

OBJECTIVES: To examine the changes in torque output resulting from fatigue, as well as changes in electromyographic measures of trunk muscles during isometric axial rotation and to compare these changes between directions of axial rotation. DESIGN: Subjects performed fatiguing right and left isometric axial rotation of the trunk at 80% of maximum voluntary contraction while standing upright. SETTING: A rehabilitation center. PARTICIPANTS: Twenty-three men with no history of back pain. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Surface electromyographic signals were recorded from 6 trunk muscles bilaterally. The primary torque in the transverse plane and the coupling torques in sag..