Physiological, Biomechanical, and Medical Aspects of Lifting and Repetitive Lifting: A Review
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
Pagination or Media Count:
The literature relating to physiological and medical lifting and repetitive lifting is reviewed. Studies on maximal lifting capacity and maximal acceptable lift MAL, the amount of weight that can be lifted repetitively over and 8h period show that as the height to which the load is lifted increases, the amount of weight lifted decreases. As lifting frequency increases, MAL decreases but power output increases. MAL of females is 50 - 70 of male values. Cardiorespiratory and metabolic studies demonstrates that VO2, HR, VE, and ratings of perceived exertion increase in a linear manner with increases in the load or frequency of lifting. The mechanical efficiency of repetitive lifting is 6-7. MAL does not change with changes in the length or height of the load but as the load width increases, MAL decreases. VO2 and HR increase with increasing load length or width. A biomechanical model for estimation of forces and torques at various joints is presented. Compressive forces on the L551 spinal segment are less for the squat lift straight back, bent knees than the stoop lift straight back, bent knees. The free style and stoop techniques result in lower energy expenditures and higher power outputs than the squat.
- Stress Physiology