Relationship of performance on the ERGOS work simulator to illness behavior in a workers' compensation population with low back versus limb injury.

A prospective blinded cohort study was performed to test for a difference in the pattern of physical activity factors measured with the ERGOS work simulator in subjects with low back injuries versus those with limb injuries. Also tested was the relationship between physical activity factors measured with the ERGOS and several psychological tests and measures of nonorganic pain behavior in subjects with low back pain. Subjects were 70 men, 22 to 64 years old, who attended a 2-week physical capacity assessment after undergoing rehabilitation for a work-related injury. In subjects with a complaint of low back pain, nonorganic pain behavior was measured with the Waddell score. In addition, two brief psychological tests, the Coopersmith Self-Esteem Inventory and analog self-rating of wellness, were administered. It was found that subjects with low back complaints underperformed globally in comparison with subjects with limb complaints. This underperformance was statistically significant (P < .05) for 7 of 13 strength variables and 2 of 7 dexterity variables. In the subjects with low back complaints, those who exhibited excessive illness behavior (Waddell score, 3 to 5) performed significantly worse on all 13 strength variables and on 3 of 7 dexterity variables. In the subjects with low back complaints, those with low self-assessment ratings were found to have a high Waddell score (P < .01) and to perform significantly worse (P < .05) on 12 of 13 strength variables and 6 of 7 dexterity variables. There were no significant relationships (P > .05) between Coopersmith Self-Esteem score and Waddell score or performance on ERGOS testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Pattern of performance in workers with low back pain during a comprehensive motor performance evaluation.

STUDY DESIGN: Tests of limb and back motor performance were administered to males with low back pain at the completion of a back-school program. OBJECTIVES: The objective of the study was to determine the relationship between such motor performance and the propensity for abnormal illness behavior as indicated by the Waddell score. SUMMARY OF BACKGROUND DATA: Previous studies in similar subjects had revealed a nonbiologic pattern of lumbar strength and movement in back-school patients, and correlations between lumbar variables, Waddell score, and 'global' psychologic measures. This suggested that psychologic factors might affect motor performance in body segments unrelated to the low back in such patients. RESULTS: Mean performance of the group with a high Waddell score (indicating a propensity for abnormal illness behavior) was lower on all tests, including those that did not involve the low back, in comparison to the group with a low Waddell score (P < .01, sign test). CONCLUSION: For all members of this population of patients, motor performance on dynamometry of any body segment does not necessarily reflect the maximum physical capacity.

Concurrent validity of the ERGOS work simulator versus conventional functional capacity evaluation techniques in a workers' compensation population.

A prospective blinded cohort study was performed in an interdisciplinary vocational evaluation program to investigate the concurrent validity of the ERGOS work simulator in comparison to current methods of evaluation. Seventy men and eight women, aged 22 to 64 years, who attended for a 2-week physical capacity assessment participated in the study. Physical activity factors as defined by the Canadian Classification and Dictionary of Occupations and the American Dictionary of Occupational Titles were assessed for all subjects under three evaluation conditions: the ERGOS work simulator, an exercise-oriented physical evaluation by a rehabilitation therapist, and performance of project-format industrial tasks. In addition, 17 men and 7 women were assessed with VALPAR standardized work sample tests. The statistical significance of the relationships between results obtained by the various evaluation methods was examined. There was a strong correlation between the ERGOS dynamometry and the clinical assessment of strength for all standard movements tested (P < .001). The Methods Time Measurement rating by the ERGOS for dexterity variables, according to industrial engineering standards, tended to rate subjects as more restricted than did the clinical evaluators. There was a significant relationship (P < .001) between the "overall physical activity rating" from ERGOS dynamometry, clinical evaluation, and performance in an industrial workshop setting. There was also a significant relationship (P < .001) between the "overall physical activity rating" for endurance of a full workday produced by the 4-hour ERGOS evaluation and by the 2-week functional capacity evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)

Serial lumbar dynamometry in low back pain.

To determine the significance of changes in motor performance as measured by lumbar dynamometry, serial lumbar dynamometry was performed on a group of 45 male Workers' Compensation patients with chronic "mechanical" low back pain and in a group of 20 healthy male volunteers. The patients were men aged 20-60 years, whose current episode of low back pain had lasted for at least 3 months (mean 19.5 weeks, range 12-47 weeks). Testing was performed at entry into a "back school" program of therapy and again 2 weeks and 4 weeks later. The control group showed a slight improvement in almost all variables of strength and range of motion between the first and second tests but no significant change between the second and third tests. This was consistent with a learning effect. The patient group was analyzed as a whole and also in two groups based on their response to the Waddell maneuvers at entry: Waddell score 0-2 (no excessive illness behavior) and 3-5 (excessive illness behavior). As a whole, the patients showed significant progressive improvement in most variables on successive tests. The group with the low Waddell score had significantly greater strength and range of motion than the group with the high Waddell score but the trend of improvement with time was similar in the two groups. The authors conclude that in this sample of patients with low back pain, serial lumbar dynamometry reveals a progressive improvement in performance, which is greater than the improvement expected from the natural history of physical recovery and greater than the improvement expected from an increase in strength and range of motion attributable to the therapeutic exercises performed and is much larger than any learning effect related to the test procedure.