Changes in muscle activation patterns and subjective low back pain ratings during prolonged standing in response to an exercise intervention

Background: Low back pain (LBP) development has been associated with occupational standing. Increased hip and trunk muscle co-activation is considered to be predisposing for LBP development during standing in previously asymptomatic individuals. The purpose of this work was to investigate muscle activation and LBP responses to a prescribed exercise program. Pain-developing (PD) individuals were expected to have decreased LBP and muscle co-activation following exercise intervention. Methods: Electromyography (EMG) data were recorded from trunk and hip muscle groups during 2-h of standing. An increase of >10 mm on visual analog scale (VAS) during standing was threshold for PD categorization. Participants were assigned to progressive exercise program with weekly supervision or control (usual activity) for 4 weeks then re-tested. Results: Forty percent were categorized as PD on day 1, VAS = 24.2 (+/- 4.0) mm. PD exercisers (PDEX) had lower VAS scores (8.93 +/- 3.66 mm) than PD control (PDCON) (16.5 +/- 6.3 mm) on day 2 (p = 0.007). Male PDEX had decreased gluteus medius co-activation levels (p < 0.05) on day 2. Discussion: The exercise program proved beneficial in reducing LBP during standing. There were changes in muscle activation patterns previously associated with LBP. Predisposing factors for LBP during standing were shown to change positively with appropriate exercise intervention. (C) 2010 Elsevier Ltd. All rights reserved.