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.