Health status information and physical activity level will be collected longitudinally on a large group of individuals who are ultramarathon runners at the time of enrollment to determine if very high levels of physical activity alter health risks compared with sedentary or moderately active lifestyles.

The intent of this research is to longitudinally study the health of individuals who have run at least one ultramarathon (50K distance or greater) prior to enrollment.Longitudinal data will be collected through periodic (every 1-2 years) survey completion by enrolled subjects over the course of up to 20 years. All surveys will be collected through a secure web-based system used by Stanford University Qualtrics). Minor formatting adjustments will be required when placing into the on-line questionnaire format.

We anticipate that the follow-up surveys will be adjusted prior to use, so they will be submitted to the Institutional Review board as addendum or in continuing review. As indicated elsewhere, subjects will be recruited through an email exchange (referred to as the "Ultralist"), various ultramarathon-related web sites and blogs, and ultramarathon-related magazines. Initial recruitment will continue for up to 12 months or until we have reached our desired sample size. Recruitment material (attached) will include a link to the initial survey. For follow-up surveys, subjects will initially be sent an email (using the address they have provided with the initial survey) that contains a link to the survey and request that they complete the survey. Attempt to contact non-responders will be, in this order, through a second email, phone call, letter to their home, email to identified surrogate, phone call to identified surrogate, and letter to identified surrogate. Publicly available death records will be examined for cases where follow-up cannot be achieved.

Inclusion Criteria:Healthy adults, able to provide consent, able to do survey online, must have completed one ULTRA marathon prior to participating in this study.

Exclusion Criteria:Not meeting the inclusion criteria

Adult healthy volunteers who have completed at least one ULTRA marathon (50K distance or greater) prior to enrollment in the study.