The influence of intense exercise-based physical therapy program on back pain anticipated before and induced by physical activities.

BACKGROUND CONTEXT: Pain anticipated before and induced by physical activities has been shown to influence the physical performance of patients with chronic back pain. Limited data exist as to the influence of treatment on this component of pain. PURPOSE: This study attempted to determine if pain anticipated before and induced by physical activities was altered during an exercise-oriented physical therapy program for chronic back pain. STUDY DESIGN/SETTING: Subjects were recruited from three physical therapy sites with similar spine rehabilitation programs that used intense exercise delivered in a group format. During the recruitment period, 70 subjects with chronic low back pain and disability agreed to participate and complied with recommended treatments. The primary outcome measures were anticipated and induced pain as assessed by visual analog scales (VAS) during six tests of back flexibility and strength. Additional outcome measures included the performance levels of these six tests (trunk flexion, extension, straight leg raising, back strength, lifting from floor to waist and waist to shoulder height), global back and leg VAS and Oswestry Low Back Pain Disability Questionnaire scores. METHODS: At evaluation for the spine rehabilitation programs, we recorded the anticipated and induced pain levels associated with the six tests of back function, the performance levels on each test and global pain and disability scores. Subjects then participated in the spine rehabilitation program that consisted of intense exercise delivered up to three times per week, for 2 hours over a period of 6 weeks. All outcome measures were reassessed at discharge. Pre- and posttreatment outcome scores were statistically compared using paired sample t tests and chi-squared test. Spearman correlation coefficients were used to compare anticipated and induced pain results with global back and leg pain VAS scores, Oswestry scores and physical performance levels for each physical test. RESULTS: Most measures of anticipated and induced pain improved between evaluation and discharge. Improvements were noted for global back pain (p<.001), leg pain (p=.001), disability (p<.001) and performance on each physical testing (p<.001) after treatment. Performances on all physical testing correlated with anticipated and induced pain for all tests at evaluation but only for measures of flexibility at discharge. Improvements in global pain and disability correlated with improvements in anticipated and induced pain with physical testing. CONCLUSION: Anticipated and induced pain with physical activities was lessened after physical therapy using exercise. Anticipated and induced pain with physical activities related to physical performance levels, global pain and disability ratings. These findings may help explain how exercise exerts a positive influence on chronic back pain and disability.