Too much too early? An analysis of worldwide childhood ultramarathon participation and attrition in adulthood.

Background: Physical inactivity is associated with chronic disease and premature death, but excessive exercise can also lead to injury. Ultramarathon running is popular among adults but has not been assessed in children. To analyze ultramarathon participation in children and to determine if they continue running ultramarathons into adulthood provide some evidence of associated health risks.

Methods: Race results databases were used to identify ultramarathon finishers under the age of 19 between 1960-2017. Participation trends across calendar years, age groups and different race distances were analyzed and continued participation into adulthood examined.

Results: A total of 7775 finishes by 5418 individual children were recorded worldwide with an increase in ultramarathon finishers over time (P<0.0001), with the greatest number among older age groups (>16 years) and the 50 and 100 km race distances. Less than 25% of childhood ultramarathon runners continued running ultramarathons into adulthood and approximately 12% continued beyond 20 years.

Conclusions: Childhood participants has been growing exponentially over the last 20 years. While few of those children continue to complete ultramarathons into adulthood, the finding that some have continued well into adulthood suggests there is no obligate serious adverse physical impairment resulting from childhood ultramarathon participation.