Abstract
Risk of occupational low-back disorders may be related to spinal stability achieved during manual materials handling. Stability is controlled and influenced by trunk muscle stiffness, antagonistic co-contraction and reflex response. Fatigue influences each of these factors, suggesting that fatigue may compromise spinal stability. A biomechanical model of spinal stability and experimental data were implemented to evaluate the effects of fatigue. EMG and trunk kinematics from 21 healthy subjects were recorded during static trunk extension exertions and sudden-load trials in fatigued and unfatigued states. The model predicted dramatic reduction in spinal stability associated with fatigue related decrement in paraspinal muscle stiffness and force generating capacity. Empirical data supported the model predictions, demonstrating increased antagonistic co-contraction during fatigued exertions. Results suggest risk of low-back injury from loss of spinal stability is increased during fatigue from manual materials handling.
Get full access to this article
View all access options for this article.