A TIME-SERIES ANALYSIS OF THE RELATIONSHIP BETWEEN AMBULATORY EMG, PAIN, AND STRESS IN CHRONIC LOW-BACK-PAIN

Twenty-one subjects with chronic back pain (CBP) participated in an am bulatory electromyography (EMG) monitoring study to ascertain the rela tionships between muscle activity, physical activity, psychosocial str ess, and pain. A time-series analysis approach was adopted to investig ate both immediate and lagged associations between these variables in an attempt to determine potential causal relationships. Results for gr oup relationships showed a significant relationship between physical a ctivity and pain, self-report of stress and pain, but no relationship between EMG activity and pain. A lagged relationship between physical activity and pain was found, suggesting a causal relationship between physical activity and pain. However no time lag was observed between s tress and pain, hence no causal relationship can be elucidated. Analys is at the individual level indicated stronger relationships between. s everal combinations of these variables, highlighting the need to consi der the heterogeneity of the CBP population and etiology of CBI! The u se of ambulatory monitoring of pain, stress, and EMG is suggested as o ne avenue to further explore the population's heterogeneity.