Physical activity modifies the association between Magnesium Depletion Score and chronic pain: A cross-sectional...

Chronic pain is a common public health concern that substantially impairs quality of life. Magnesium is essential for neuromuscular and inflammatory regulation; yet, population-based evidence linking magnesium depletion to chronic pain remains limited. Moreover, whether physical activity modifies this association is unclear. This study examined the association between the Magnesium Depletion Score (MgDS) and chronic pain among US adults and evaluated the modifying role of physical activity. We conducted a cross-sectional analysis of adults aged ≥18 years from the National Health and Nutrition Examination Survey 1999 to 2004. Participants with complete data on MgDS, chronic pain, physical activity, and covariates were included (n = 1908). Chronic pain was defined as pain lasting at least 3 months, with sensitivity analyses using pain lasting more than 1 year. Survey-weighted logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for demographic, socioeconomic, lifestyle, and clinical factors. Physical activity, assessed as total metabolic equivalent task minutes per week, was categorized into tertiles, and interaction analyses were performed. Higher MgDS was significantly associated with increased odds of chronic pain. In fully adjusted models, each 1-unit increase in MgDS was associated with a 15% higher odds of chronic pain (OR: 1.15, 95% CI: 1.00-1.32; P = .047). Compared with participants with MgDS = 0, those with MgDS ≥ 2 had a higher likelihood of chronic pain (OR: 1.58, 95% CI: 1.14-2.18; P = .008). Results were consistent in sensitivity analyses. Subgroup analyses showed consistent associations across subgroups. Physical activity significantly modified the association between MgDS and chronic pain (P for interaction = .009), with stronger associations observed among individuals in the highest physical activity tertile. Magnesium depletion is independently associated with chronic pain among US adults, and this relationship is modified by physical activity. These findings highlight the importance of considering both nutritional status and physical activity in chronic pain management.