Abstract
Manual lifting was studied using a six axis force platform. Subjects (6 male, 6 female) lifted and lowered boxes at eight variations of location and direction. For each of the eight, there were three weights (5, 10 and 15 kg for males, 5, 7.5 and 10 for females), three volumes (150, 225 and 300 mm cubes), and two techniques (bend and squat); 144 conditions in all. Peak force or torque was recorded for the vertical, lateral and frontal forces and the somersault, twist and cartwheel torques.
In general, male forces and torques are 25–40% higher than for females. Object weight had different effects on males and females. Forces and torques tend to be smaller for lowering (than lifting), for smaller containers (than larger), and for objects close to the body (than away). Forces and torques for straight ahead (vs 45°) and squat (vs bend) had mixed results so one simple rule is not always best.
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