Coach Joel Friel talks about a change in philosophy regarding the amount of fluid you should drink during a race.
From the late ’70s through the ’90s, everyone, including me, believed athletes should drink as much as possible during a race, especially a hot one. Sport scientists and the American College of Sports Medicine supported the notion that any loss of weight due to dehydration caused endurance performance to decline. The old saw was that a 2 percent loss of body weight resulted in slowing down 2 percent.
The accumulating body of research in the past few years shows that drinking to maintain body weight was not beneficial to performance, and even dangerous. That advice has led to multiple exercise-related deaths in marathons in the past 20 years due to hyponatremia caused by diluting the body’s stores of sodium. Even drinking a product that contains sodium can still cause dilution. And symptoms in the early stages of hyponatremia, resulting from overdrinking, have also caused many a poor performance in long events such as Ironman triathlons, marathons and ultra-distance races. In fact, we now know that the most dehydrated person in a race is typically the winner—often experiencing as much as a 10 percent loss of body weight.
So I now advise athletes to drink when thirsty—not to some preconceived, artificial schedule which is as likely to be wrong as right. Thirst has worked quite well for our species for the past 2.6 million years. There’s no reason to believe that it has suddenly stopped being effective. Nor is there reason to believe that it is ever “too late” to start drinking. But it does require some changes in how an athlete thinks about fluids and how he or she trains. All workouts should, in part, be rehearsal sessions for paying attention to thirst. The same must then be done in races.
Joel Friel is the author of 12 books on training for endurance athletes, including his latest, The Power Meter Handbook: A User’s Guide For Cyclists and Triathletes (VeloPress, 2012).