Relationship between performance on lumbar dynamometry and Waddell score in a population with low-back pain

Physical and psychosocial correlates of test-retest isometric torque variability in patients with chronic low back pain

Variability in trunk torque production has been suggested as a means of detecting submaximal effort in the assessment of chronic low back pain. Several investigations question the validity of using torque variability to detect submaximal efforts in patients with back injuries. However, few investigations have studied the correlates of text-retest torque variability in clinical populations. The present study investigated psychological distress, disability/flexibility/pain, and symptom magnification correlates of test-retest torque variability in chronic low back pain patients. Contrary to previous studies, psychological distress, tendency to report symptoms, and pain were negatively correlated with measures of torque variability. The findings indicate the potential for psychological variables to influence torque production, but on the whole provide little strong support for the use of test-retest torque variability as a means of detecting submaximal performance.

Perceptions of disability and occupational stress as discriminators of work disability in patients with chronic pain

Pain-related work disability can be influenced by a number of medical, physical, and psychosocial factors. The present study investigated the role of perceived disability, occupational stress, pain, and distress in patients with chronic pain disorders who work despite pain and patients who are work disabled. A total of 165 patients referred to a multidisciplinary pain treatment center for chronic pain (> 6 months) were studied. The two groups were compared on age, gender, education, marital status, duration of pain problem, pain severity, psychological distress, perceived disability, and perception of the work environment. A discriminant function analysis was computed entering pain severity, distress, perceived disability (physical and psychosocial) and work environment variables. The two groups were equivalent on age, gender, education, marital status, and duration of pain problem. The groups differed on diagnosis and insurance coverage with the work-disabled group diagnosed with low back pain and receiving Workers Compensation coverage more frequently than working controls. Univariate analyses indicated that the work-disabled group reported higher pain severity, perceived physical and psychosocial disability, and job stress than their working cohorts. The discriminant function analysis indicated that the perception of physical disability, supervisor support, distress, and work pressure were capable of correctly classifying patients with chronic pain who continued to work from those who were work disabled. These findings indicate the importance of evaluating perceived disability and job stress, and if present, directing intervention effort at these factors in order to facilitate work re-entry.

A comparison of isometric strength and dynamic lifting capacity in men with work-related low back injuries

Job classification, return to work status, and job placement are determined by the results of lifting capacity tests. Lifting capacity is often assessed by maximum static or dynamic physical exertions. The purpose of this study was to compare maximum isometric lifting strength with maximum dynamic lifting capacity in subjects with work-related low back injury. Twenty-seven men performed five dynamic lifting tasks and two isometric strength tests. The mean Pearson product-moment correlation between maximum isometric lifting strength measurements and maximum dynamic lifting capacity measurements was .51 with a range of .30-.73. The results indicate low to moderate associations between isometric strength measurements and lifting capacity suggesting that estimates of functional lifting capacity should not be based on static measurements alone. Dynamic lift tests are often a better simulation of the task being assessed and may be more appropriate for a back-injured population.