No abstract

The authors investigated differences in trunk muscle activation timing between patients with chronic nonspecific low back pain (NSLBP) and asymptomatic controls during a self-initiated postural challenge. The authors compared 30 participants with NSLBP to 30 controls. Surface electromyographic data were collected from bilateral trunk muscles. Dependent variables were trunk muscle onset and offset relative to extremity muscle activation and duration of the trunk muscle burst and abdominal-extensor cocontraction. Patients with NSLBP demonstrated significantly delayed trunk muscle onset latency (p< .01), and shorter burst (p = .02) and cocontraction durations (p < .01). Results suggest that patients with NSLBP may be inefficient in regulating trunk posture during voluntary extremity movements. These alterations could also represent a compensatory control pattern imposed by the CNS to avoid pain.

Trunk muscle timing impairment has been associated with non-specific low back pain (NSLBP), but this finding has not been consistent. This study investigated trunk muscle timing in a subgroup of patients with NSLBP attributed to movement coordination impairment (MCI) and matched asymptomatic controls in response to a rapid arm-raising task. Twenty-one NSLBP subjects and 21 matched controls had arm motion and surface EMG data collected from 7 bilateral trunk muscles. Muscle onset and offset relative to deltoid muscle activation and arm motion, duration of muscle burst and abdominal–extensor co-contraction time were derived. Trunk muscle onset and offset latencies, and burst and co-contraction durations were not different (p>0.05) between groups. Patterns of trunk muscle activation and deactivation relative to arm motion were not different. Task performance was similar between groups. Trunk muscle timing does not appear to be an underlying impairment in the subgroup of NSLBP with MCI.