LAUSR

OBJECTIVE To determine whether online exercise-associated collapse (EAC) prevention education decreases medical tent EAC visits among first-time marathoners. DESIGN A prospective controlled study, with age- and sex-stratified randomization, evaluated rates of medical tent diagnosed EAC among runners randomized to the intervention group and intervention participants, compared with a control group. SETTING Grandma's Marathon Medical Tent in Duluth, MN, June 2016. PARTICIPANTS Runners in the 2016 Grandma's Marathon who never previously ran a marathon (n = 2943), randomized into control (n = 1482) and intervention (n = 1461) groups. Intervention participants opened the EAC prevention video (n = 590). INTERVENTIONS Online EAC education included an introductory webpage and 5-minute professional video describing EAC and prevention. MAIN OUTCOME MEASURES Medical tent visit with EAC diagnosis. RESULTS Intervention participants had no decreased likelihood of EAC, compared with controls [odds ratio (OR), 0.88, 95% confidence interval (CI), 0.46-1.69]. Exercise-associated collapse occurred less frequently in those with longer race times (OR, 0.58, 95% CI, 0.43-0.79). Intervention participation was associated with longer race times (OR, 1.12, 95% CI, 1.10-1.23). CONCLUSIONS Those opening the EAC prevention video and controls had similar EAC rates. Slower running speed was associated with lower EAC rates. Video viewing was a predictor of slower running pace.