In brief:In a preliminary study to evaluate possible causes of exhaustion, 48 runners who collapsed during or after an ultramarathon race were questioned about their training methods. The training profiles were compared with those of matched controls who had finished the same race without collapsing. Possible contributing factors found among the collapsed runners included inadequate training, failing to carbohydrate load, not eating a prerace breakfast, prerace illness, and hypothermia (during one race, which was run in cold, wet, windy conditions). The authors suggest that regardless of athletic ability or previous racing experience, runners may be prone to collapse during or after ultramarathon races if their prerace training and preparation are inadequate.