In this issue of Neurology ® , Vaage et al. 1 publish a study in which they used a prospective analysis to address the role of physical activity (PA) and fitness in the later development of amyotrophic lateral sclerosis (ALS). This is a controversial area that has been the subject of significant interest in the field, 1 especially given the number of high-profile athletes who have been reported to develop ALS.This study aims to address this question using a large prospective Norwegian cohort (n = 373,696) focused on cardiovascular health. Out of the total cohort, 504 individuals developed ALS during a follow-up period of ;27 years. Prospective analyses are a powerful means of avoiding some of the potential confounders within case-control comparisons. The key conclusions of this study are that in male and not female participants, higher levels of PA at age 40-45 years were inversely related to the probability of a later diagnosis of ALS. Impressively, the authors supported this with an objective measure of physical fitness-resting heart rate-where a lower heart rate at this time point was associated with a lower future risk of ALS. 1