If you’re debating your fueling strategy for an upcoming half marathon, a new study suggests that the two most recommended approaches—drinking when you’re thirsty and following a set hydration plan—are both effective.
Canadian researchers had 10 trained runners complete two half marathons on a treadmill in hot conditions (86 degrees, 42 percent humidity). During one half marathon, they drank when they felt thirsty. During the other, the runners followed a set fluid program designed to prevent them from losing more than 1 percent of their body weight through sweat. Previous research suggests that performance falters if you lose 2 percent or more of your body weight.
The runners' times and pace throughout the distance were similar under both conditions, despite the fact that during the drink-to-thirst experiment the runners lost 3 percent of their body weight, according to the study.
Drinking less, however, did result in greater physiological stress. Runners' body temperatures and heart rates were higher when they followed the thirst-based approach, but the difference didn’t impact their time, leading the researchers to conclude that drinking more offers no performance benefit during a half marathon in hot conditions.
The study is the latest in the ongoing debate about how much fluid endurance athletes need both to perform well and stay safe under hot condition.
This Gear Tip will help you navigate the water stops at your race: