Lower back muscle forces in pushing and pulling.
Lee-KS; Chaffin-DB; Waikar-AM; Chung-MK
Ergonomics 1989 Dec; 32(12):1551-1563
An assessment was performed of the effectiveness of a two dimensional, biomechanical model for predicting lower back muscle force during pushing and pulling (PP). The predicted muscle forces were compared with the experimental determination of the root mean square (RMS) electromyogram (EMG) values of the rectus abdominis (RA) and erector spinae (ES) muscles measured in PP tests with four male and two female subjects ranging from 20 to 30 years of age. This model allowed the computation of the reactive forces and movements at joints, the RA and ES muscle forces, and the compressive forces at the L5/S1 disc. Three different series of PP experiments were performed: isometric trunk PP in standing erect positions, with the thighs and hips braced; isometric hand PP in standing erect position, with the thighs and hips braced; and isometric hand PP in free postures at three different handle heights. Brief descriptions were provided of the equipment used to measure and record the myoelectrical signals, and the positions of electrodes on the subjects were provided. Cross correlations were computed between the measured RMS EMG values and the predicted muscle forces. Measured RMS EMG values were linear and highly correlated with the corresponding predicted forces in trunk and hand PP in erect posture. Measured RMS EMG values, however, were neither linear nor well correlated with the corresponding predicted forces in hand PP in free standing posture. A brief discussion was provided in an attempt to explain the low correlations between observed RMS EMG values and predicted muscle forces in the case of hand PP in free standing posture.
NIOSH-Publication; NIOSH-Grant; Musculoskeletal-system-disorders; Training; Ergonomics; Biomechanics; Mathematical-models; Muscle-tension; Muscle-stress; Muscle-physiology; Body-mechanics; Biodynamics; Physical-capacity; Physiological-measurements
Industrial & Operations Engr University of Michigan 2254 G G Brown Laboratory Ann Arbor, Mich 48109
University of Michigan at Ann Arbor, Ann Arbor, Michigan