Gender Differences in Low Back Pain and Self-Reported Muscle Strengthening Activity Among U.S. Adults

Objectives: We sought to examine the gender differences between low back pain (LBP) and muscle strengthening activity (MSA) in U.S. adults (≥20 years of age). Background: Low back pain is a well-known medical condition that has been shown to impact quality of life and professional productivity. It also adds to the financial burden of our healthcare system by augmenting medical treatment costs. Muscle strengthening activity is a recognized method to prevent and treat LBP. Studies analyzing the relationship between MSA and LBP by gender have produced mixed results. Methods: The sample (n=12,721) included participants in the 1999-2004 National Health and Nutrition Examination Survey (NHANES). Three categories of reported MSA participation were created: no MSA (referent group), some MSA (≥1 to/wk), and meeting the 2008 Department of Health and Human Services (DHHS) recommendation (\u3e2 d/wk). The dependent variable was LBP. Results: Gender stratified analysis revealed significantly lower odds ratio of reporting LBP for women (OR 0.82; 95% CI 0.70-0.96, P=0.03) and men (OR 0.86; 95% CI 0.70-0.96, P=0.01) reporting volumes of MSA meeting the DHHS recommendation. Following adjustment for smoking, the odds ratio remained significant in women (P=0.03) but not in men (P=0.21). Conclusions: Men and women reporting volumes of MSA meeting the current DHHS recommendation were found to have lower odds of reporting LBP when compared to those reporting no MSA prior to adjustment for smoking. After adjustment for smoking, the association between MSA and LBP continued to be significant in females but in males. These findings suggest that smoking may be an important mediating factor that should be considered in LBP research