Abstract
BACKGROUND: Manual material handling has been attributed as a major risk to human musculoskeletal system. Workers postural stability in these tasks is influenced by holding method, time and weight being handled.
OBJECTIVES: The study attempts to investigate postural balance in five different commonly adopted load handling methods amongst female volunteers.
METHODS: Ten women subjects performed manual material handling tasks by lifting 9 kg load in five different ways. Lifting tasks included (1) Upfront in palms (2) on head (3) sideways (left) (4) sideways (right) and (5) in bag at back. Normalized electromyography signals (back and leg) and center of pressure displacements parameters were investigated as measures of postural control.
RESULT: An increase in the medio-lateral and anterio-posterior center of pressure displacements and activity of back muscles was reported when subjects lifted the weight directionally.
CONCLUSION: There was a significant influence of load position on center of pressure displacements and muscle activity and thereby on postural stability. Keywords: Balance; center of pressure; electromyography.