Back pain, physical function, and estimates of aerobic capacity - What are the relationships among methods and measures?

Objectives: To establish the correlations of measures of self-reported disability, self-efficacy, physical performance, level of pain, and estimates of aerobic capacity (PVO2) in subjects with low back pain. Design: Fifty-one low back pain subjects, ranging in age from 26 to 65 yr, entered the study. Participants completed the Roland-Morris Disability Questionnaire and the self-efficacy questionnaire. Physical performance was evaluated by the loaded-reach test, sit/stand test, 5-min walk test, 50-foot walking test, and time to roll from right to left. Pain intensity and pain affect were measured using two visual analog scales. PVO2 was predicted from an equation. Results: The correlation coefficient among the physical performance outcomes ranged from 0.47 to 0.78. Pain measures had low correlations with measures of function but stronger correlations with other self-report measures. The disability measure correlated moderately with physical performance. Correlations between PVO2 and all other measurements were minimal, except for the 5-min walk test. Conclusion: Performance and disability were more consistent in evaluating low back pain. PVO2 failed to correlate with most other aspects of low back pain. This study suggests that aerobic capacity might not be a primary concern for patients with low back pain.