This study examines the relationship between marathon runners' performance and sexual activity plus four other health-related behaviors in the 48 hours prior to a marathon race. Results showed that marathon runners sexual activity was not related to their relative running performance. Those who slept more and took in more calories, compared to the amount they slept and the calories they consumed in previous events, performed better in this marathon, compared to their performance in previous events. Alcoholic drinking and cigarette smoking were not related to self-reported running success.