State of the Science on Ultramarathon Running After a Half Century: A Systematic Analysis and Commentary.

Purpose: To systematically examine scientific publishing related to ultramarathon running.

Methods: PubMed-indexed publications through 2019 were identified in which the work involved data collection at or in association with an ultramarathon running event, included experimental running trials of ultramarathon duration using human subjects, focused on human ultramarathon runners as the study participants, or were directed at discussing some aspect of ultramarathon running or ultramarathon runners. The characteristics of each publication were tabulated.

Results: A total of 616 indexed publications were identified, with the first being in 1970. A rapid increase in publications was seen by 2010 in association with increased participation in ultramarathon running, followed by a plateauing at around 49 annual publications from 2014 to 2018. Most (83.3%) publications were observational, and the mean annual number of 1.6 experimental studies did not change (P = .20) from 1999 to 2019. Most of the publications were related to physiological issues, and race performance was the largest topic area (21.8%). The largest percentage of publications came from authors from the United States, followed by authors from Switzerland.

Conclusions: Research related to ultramarathon running has had a small presence in sport science and offers potential for further development. At present, publishing appears to be stable and without recent increased emphasis on experimental studies. Worthwhile research opportunities remain, particularly those where ultramarathons serve as a model for stress and could offer relevance to a wider population than ultramarathon runners, but such research appears challenged by relatively small participation in the activity and limited funding opportunities.