Asymmetric trunk postures and trunk dynamics have been implicated as risk factors for occupational low back disorders. Muscle fatigue has also been cited as an ergonomic issue, though not directly linked to an increased risk of low back injury. This paper investigates the effect of trunk extensor muscle fatigue on muscle activity levels during symmetric and asymmetric trunk extension exertions. The results show that muscle fatigue alters both flexor and extensor muscle activity patterns in asymmetric trunk extensions earlier than in sagittally-symmetric trunk extensions. This quickened fatigue response to asymmetric trunk motions could be a contributor to the increased risk of low back injury seen in occupational tasks that include asymmetric trunk lifting.
Effect of Trunk Extensor Muscle Fatigue on Postural Stability in Healthy Young Adults