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.

Motivational Effects of Stimuli Paired with Buildup of the Thirst Drive

Albino rats were adapted to a distinctive conditioning environment over a 4-day period and were then divided into experimental and control groups. The experimental group experienced 23 hr. of water privation in the conditioning environment on each of 14 successive days. The control group experienced only the first ½ hr. of privation in the conditioning environment and spent the rest of each privation period in a control environment. During subsequent tests in the conditioning environment, with Ss satiated, the experimental Ss consumed significantly more water than the control Ss. A replication produced similar results and indicated that the effect could be mediated by general, as well as specific, characteristics of the conditioning environment. The relation of the results to the conditioned drive hypothesis is discussed, and the direction of continuing research is indicated.

Irrelevant Thirst Drive and Light Aversion

In two experiments satiated female albino rats learned to press a bar to turn off a bright light, and performance was measured with 0 or 24 hours thirst added on two test days. The 28 Ss of Exp. I received extinction treatment on the test days; 14 Ss of Exp. II continued dark-rewarded bar pressing on the test days. Added thirst had no over-all effect in Exp. I and decreased performance in Exp. II. Ss extinguished with the light always on performed better than those with the light always off, and the amount of decrease from the first to the second extinction day depended in a complex manner on both lighting and thirst conditions. Thus, Hull's prediction of energization by irrelevant drives is not confirmed. The data were considered in relation to Estes' stimulus theory of drive.