Acute biomechanical responses to a prolonged standing exposure in a simulated occupational setting.

Prolonged occupational standing has previously been associated with low back pain (LBP) development. The immediate effects of a bout of prolonged standing on subsequent functional movement performance have not been investigated. It is possible that including a period of prolonged standing may have acute, detrimental effects. The purpose of the study is to investigate the impact of a prolonged standing exposure on biomechanical profiles (trunk muscle activation, joint stiffness and kinematics) during three functional movements. A total of 23 volunteers without history of LBP performed lumbar flexion, single-leg stance and unloaded squat movements pre- and post 2 h of standing exposure. It was found that 40% of the participants developed LBP during the standing exposure. There was a decrease in vertebral joint rotation stiffness in lateral bending and increased centre of pressure excursion during unilateral stance following standing exposure. There may be adverse effects to prolonged standing if followed by activities requiring precise balance or resistance of side loads. STATEMENT OF RELEVANCE: Prolonged standing may result in decreases in balance reactions during narrow base conditions as well as in the capacity to effectively resist side-loads at the trunk. Consideration should be given when prolonged standing is included in the workplace.