| Sumario: | Study Design: Controlled laboratory study. Purpose: The aim of this study was to determine if there are any differences in hip and trunk muscle activation and firing patterns during 2 movement screening tests in individuals with low back pain (LBP) and control participants. Methods: Muscle activation for specific trunk and lower extremity muscles was examined by surface Electromyography (EMG). Twenty-two healthy active controls (mean age ± SD, 27.2 ± 4.6 years) and twelve subjects with LBP (mean age ± SD, 44.4 ± 14.6 years) participated in the study. The movement tests under investigation were the prone straight leg raise (PSLR) and sidelying hip abduction (SHA). Mean onset muscle timing and activation patterns were identified for each movement test. Separate one-way analyses of variance (ANOVAs) were used to determine differences in muscle onset times between groups. The influence of age was considered as a covariate in the analysis. Results: Significant between group differences were identified in muscle onset times. During the PSLR, subjects with LBP recruited muscles of the lower extremity before the trunk. This pattern was reversed for the controls. The onset time of the gluteus maximus was significantly greater for subjects with LBP (P=0.001). During SHA, the firing sequence was similar for both groups. Compared to healthy controls, subjects with LBP displayed a significant delay in onset times for all back muscles (Pd"0.002). Conclusions: Subjects with LBP were unable to effectively recruit/control their trunk musculature during these movement screening tests. A better understanding of this movement impairment and the restoration of trunk control may lead to a faster recovery.
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