Abstract
In order to reconcile contradictory results from previous studies on manual pushing, a study was conducted to examine the effect of trunk inclination on muscular activities, centre of pressure (COP) and force exertion during static pushing. Ten subjects pushed at 0o, 15°, 30°, and 45° body inclinations in parallel and staggered feet stances. Wall and ground force plates measured pushing force, wall COP, vertical ground reaction force (GRF) and ground COP. Electromyogram data were recorded at 10 trunk muscle sites. Pushing force was found to increase with body inclination. GRF peaked at 15° and reached its lowest level at the 45° inclination. The lowest wall force plate standard deviation of COP displacement was found at the 30° inclination. The lowest low back muscular activity was found at the 15° and 30° inclinations. Based on force exertion, muscular load, and stability, the 30° body inclination was found to be the best posture for static pushing. This study also showed asymmetry in muscular activity and force exertion which has been received less attention in manual pushing studies. These findings will require further study.
