OBJECTIVES: Regular exercise is a key component of obesity prevention and 48% of Americans do not meet minimum guidelines for weekly exercise. Social support has been shown to help individuals start and maintain exercise programmes. We evaluated social support among endurance athletes and explored the relationship between social support for exercise, health behaviours and health status. DESIGN: Survey. SETTING: The largest Nordic ski race in North America. PARTICIPANTS: 5433 past participants responded to an online questionnaire. OUTCOME MEASURES: Social support, health behaviours and health status. RESULTS: The mean overall support score was 32.1 (SD=16.5; possible range=-16.0 to 88.0). The most common forms of social support were verbal such as discussing exercise, invitations to exercise and celebrating the enjoyment of exercise. We found that an increase of 10 points in the social support score was associated with a 5 min increase in weekly self-reported exercise (5.02, 95% CI 3.63 to 6.41). CONCLUSIONS: Physical activity recommendations should incorporate the importance of participation in group activities, especially those connected to strong fitness cultures created by community and competitive events.