The predictive relationship of physical activity on the incidence of low back pain in an occupational cohort.

Objective: Quantify the relationship between physical activity and development of incident low back pain (LBP).
Methods: This nested prospective cohort study utilized an objective measure of physical activity in 68 participants with 30 incident cases of LBP. Physical activity was divided into tertiles and quartiles. Univariate and multivariate relative risks and hazard ratios were calculated.
Results: Comparing highest to middle tertile of light activity demonstrated a statistically significant relative risk of 3.68 for developing incident LBP. Lowest and highest tertile of minutes of moderate/vigorous activity yielded statistically significant relative risks of 4.60 and 6.14, respectively. Multivariate analyses demonstrated similar associations.
Conclusions: Moderate amounts of physical activity were protective for the development of LBP in this cohort, after adjustment for risk factors. This nonlinear relationship suggests higher levels of activity do not confer increased LBP prevention.