HIP-SPINE MOVEMENT INTERACTION AND MUSCLE ACTIVATION PATTERNS DURING SAGITTAL TRUNK MOVEMENTS IN LOW-BACK-PAIN PATIENTS

Profiles of hip-spine movement interaction and muscle activations were characterized in 10 low back pain patients and in 10 normal subjects during trunk forward bending and extension. Electrogoniometric recordi ngs showed that patients performed the movements significantly more sl owly than normal subjects when asked to choose a comfortable cadence. For movements performed at the same velocity and amplitude, only the m ovement profiles at the spine and activation patterns of the erector s pinae (ES) muscle during flexion were found to be significantly differ ent between the two groups. A detailed analysis revealed that a subgro up of six patients (SG2) with an abnormal hip-spine movement interacti on showed a significant (P < 0.01) lack of relaxation in ES muscle at the end of flexion. Patients from SG2 had pain for a longer time (P < 0.01) compared to patients from SG1 with normal movement and electromy ographic profiles. Given the small sample size, these results are not conclusive, but they suggest that the lack of relaxation of the ES mus cle may be associated with perturbation of movement patterns and the d uration of the symptoms.