Belief in the need for sodium supplementation during ultramarathons remains strong: findings from the Ultrarunners Longitudinal TRAcking (ULTRA) study.

In the past, ultramarathon runners have commonly believed that consuming sodium supplements, as capsules or tablets, will prevent exercise-associated hyponatremia (EAH), dehydration, muscle cramping, and nausea, but accumulating evidence indicates that sodium supplementation during ultramarathons is not necessary and may be potentially dangerous. In this work, beliefs about whether sodium supplements should be made available at ultramarathons were assessed during 2018 among 1152 participants of the Ultrarunners Longitudinal TRAcking (ULTRA) study, of which 85.2% had completed an ultramarathon during 2014-2018. Two-thirds (66.4%) of study participants indicated that sodium supplements should be made available at ultramarathons, supported by beliefs that they prevent EAH (65.5%) and muscle cramping (59.1%). Of those indicating that sodium supplements should not be made available, 85.0% indicated it is because runners can provide their own, 27.9% indicated it is because they are not necessary, and 12.1% indicated they could increase thirst drive and cause overhydration. In general, there was a tendency for those who were older, less active in running ultramarathons in recent years, and with a longer history of ultramarathon running to be less likely to know that sodium supplements do not help prevent EAH, muscle cramping, and nausea. Novelty Ultramarathon runners continue to have misunderstandings about the need for sodium supplementation during ultramarathons. Few ultramarathon runners recognize that supplementing sodium intake beyond that in food and drink is generally not necessary during ultramarathons or that it could result in overhydration. Continued educational efforts are warranted to help ensure safe participation in the sport.