Several famous athletes have been affected by ALS, and some epidemiologic studies have indicated that vigorous physical activity (heavy labor or athletics) is a risk factor for the disease. In a case-control study of 279 patients with motor neuron diseases and 152 with other neurologic diseases, the authors found that subjects with motor neuron diseases were more likely than controls to report they had always been slim or they had been varsity athletes. For slimness, the odds ratio (OR) was 2.21; 95% CI, 1.40 to 3.47. For varsity athletics, the OR was 1.70; CI, 1.04 to 2.76.