The predictive relationship between physical activity and functional recovery in an acute low back pain population

Abstract

Advice to remain active and normalisation of activity are commonly prescribed in the management of low back pain (LBP). However, no research has assessed whether objective measurements of physical activity predict outcome and recovery in acute low back pain. The aims of this study were to assess the predictive relationship between activity and disability at 3 months in an acute LBP population. This prospective cohort study recruited 101 consenting patients with acute LBP (< 6 weeks) who completed the Roland Morris Disability Questionnaire (RMDQ), the Visual Analogue Scale (VAS), and resumption of full ‘normal’ activity question (Y/N), at baseline, 3 months and 1 year. Physical activity was measured for 7 days at both baseline and at 3 months with an RT3 accelerometer recall questionnaire and at 1 year with an activity recall questionnaire. Objective and non-objective measures of physical activity at baseline and change in activity from baseline to 3 months were not independent predictors of RMDQ (p > 0.05) or RMDQ change (p > 0.05) over 3 months or 1 year (p > 0.05). A self-report of a return to full ‘normal’ activities was significantly associated with greater RMDQ change at 3 months (p < 0.001). Paired t tests found no significant change in activity levels measured with the RT3 (p = 0.57) or the recall questionnaire (p = 0.38) from baseline to 3 months. At 1 year the only predictor of a lower RMDQ was a lower Fear Avoidance Belief Questionnaire- work component (FABQW) score at baseline. A number of measures of activity in univariate analyses predicted a report of LBP chronicity at 1 year including: a lower Baecke Sports Index score at 1 year, a lower change in activity from baseline to 1 year (BPAQ change), and a higher work activity score at baseline (p < 0.05). The report of not returning to full normal activities at 3 months explained 9.0% of the variance in chronic LBP at 1 year. However, none of the measures of activity either prior to the LBP episode, at baseline, 3 months, or at 1 year predicted RMDQ score at 1 year or a report of LBP chronicity in multiple regression analyses (p > 0.05). These results question the predictive role of physical activity in LBP recovery, and the assumption that activity levels change as LBP symptoms resolve. The importance of a patient’s perception of activity limitation in recovery from acute LBP was also highlighted.