Physical activity and amyotrophic lateral sclerosis : a European population-based case-control study

Objective To assess whether physical activity is a risk factor for amyotrophic lateral sclerosis (ALS). Methods From February 2008 to April 2012, 652 patients with ALS from European population-based registries (France, Ireland, Italy, United Kingdom, Serbia) and 1,166 population controls (matched for age, sex, and residency) were assessed. Upon direct interview, data were collected on occupation and history of sport and leisure activities, physical activity, and accidental injuries. Physical exercise was defined as having spent time doing activities that caused an individual to breath hard at least once per month and was coded as none, job-related, and/or sport-related. Sport-related and work-related physical exercise were quantified using metabolic equivalents (METs). Risks were calculated using conditional logistic regression models (adjusting for age, country, trauma, and job-related physical activity) and expressed as odds ratios (ORs) and adjusted ORs (Adj ORs) with 95% confidence intervals (CIs). Results Overall physical activity was associated with reduced odds of having ALS (Adj OR = 0.65, 95% CI = 0.48-0.89) as were work-related physical activity (Adj OR = 0.56, 95% CI = 0.36-0.87) and organized sports (Adj OR = 0.49, 95% CI = 0.32-0.75). An inverse correlation was observed between ALS, the duration of physical activity (p = 0.0041), and the cumulative MET scores, which became significant for the highest exposure (Adj OR = 0.34, 95% CI = 0.21-0.54). An inverse correlation between ALS and sport was found in women but not in men, and in subjects with repeated traumatic events. Interpretation Physical activity is not a risk factor for ALS and may eventually be protective against the disease.