Electrophysiological Function of the Lumbar Multifidus and Erector Spinae Muscles in Elderly Patients With Chronic Low Back Pain

STUDY DESIGN: This was a cross-sectional electrophysiological study. OBJECTIVE: The main objective of this study was to evaluate electrophysiological activation of lumbar multifidus (LM) and erector spinae (ES) in elderly patients with chronic low back pain (CLBP) classified by LBP developmental mechanisms. SUMMARY OF BACKGROUND DATA: Local and global muscles that function independently for stabilization and moment production, respectively, are crucial for stability and mobility of the lumbar spine. There is little research conducted on the electrophysiological functions of the LM as a local muscle and the ES as a global muscle in the lumbar spine, and their interrelation in patients with CLBP. MATERIALS AND METHODS: Elderly patients aged 65 years and above, with CLBP were assigned into motion-induced LBP (49 patients) or walking-induced LBP cohorts (57 patients), and compared with a control group (53 patients without LBP). Electrophysiological activation of the LM and ES was performed using surface electromyography (EMG) and mechanomyography (MMG) during lumbar extension and flexion. Electromechanical coupling efficiency (EMCE) was calculated using the ratio of MMG to EMG. RESULTS: EMG and MMG amplitudes in the LM tended to be lower in patients with LBP than in the control group. EMG and MMG amplitudes in the ES tended to be higher in patients with LBP than in the control group. EMCE was significantly higher in both the LM and ES during lumbar extension and flexion in the motion-induced LBP cohort than in the walking-induced LBP cohort; however, ES dominance was seen in the motion-induced LBP cohort, both in lumbar extension and flexion, according to the EMCE ratio. CONCLUSIONS: ES dominance was seen in the motion-induced LBP cohort, both in lumbar extension and flexion, according to the EMCE ratio. Subgrouping of patients according to the induction of LBP seems to be important for CLBP treatment, and the electrophysiological assessment for the deep and superficial back muscles may be beneficial to elderly patients.