Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In



Hydration And Running: How Much Should You Drink?

A new book and a new online tool help runners rehydrate properly.

A new book and a new online tool help runners rehydrate properly.

In the first half of the 20th century most runners avoided drinking during races and training runs. Back then it was widely believed that the small benefit of a briefly quenched thirst was not worth the hassle and discomfort of trying to drink and hold down fluid while running. Some runners also felt that giving in to one’s thirst made one mentally soft.

In the last part of the 20th century and the first part of the present one runners were encouraged to drink as much as possible during longer races and to drink at least enough to completely offset weight loss resulting from perspiration during training runs. These recommendations were based on research that demonstrated a clear performance-enhancing effect of drinking on the run as well as on other studies which seemed to suggest that drinking reduced the risk of heat illness.

Within the past few years a new philosophy of running hydration has gained ascendance. This philosophy advises moderate drinking during prolonged running. It is based in part on a reconsideration of earlier research on hydration and in part on newer, more carefully designed studies, including field studies conducted in real-world race environments. Such scrutiny has led many experts to conclude that in fact hydration plays a minimal role in thermoregulation, that drinking too much is as problematic as drinking too little, and that athletes don’t perform any better when they force themselves to drink as much as possible than they do when they drink instinctively.

The original champion of the new hydration philosophy was Tim Noakes, a renowned South African exercise scientist who has authored a new book on the subject. In Waterlogged: The Serious Problem of Overhydration in Endurance Sports (Human Kinetics, $24.95), Noakes advises runners and other endurance athletes to trust their thirst and simply drink by feel in competition and in training.

I know what you’re thinking: Does it really take a whole book to teach athletes to drink according to their thirst? Heck, a single Tweet would seem sufficient to do the job. But Noakes has not only written an entire book whose single recommendation is to drink by thirst—he’s written a really interesting book that offers a lot more than just its practical utility.

Waterlogged provides nothing short of a complete education on thirst, exercise thermoregulation, hydration, dehydration, and yes, overhydration. Its author wasn’t thorough for the mere sake of thoroughness, having long dealt with sports drink industry pushback against his ideas about hydration, Noakes wished to make an ironclad case in support of these ideas. As such, his book covers everything from the evolutionary history that made our species uniquely well adapted to running for prolonged periods of time in the heat (without drinking) to the flaws in the original studies that started the overhydration trend in the 1960s.

If you’re the kind of runner who enjoys learning about how the human body works, especially in relation to running, you will find Noakes’s book as hard to put down as his previous Lore of Running. (Did you know that the most dehydrated finisher in any given race is usually the winner?) But even if you’re the “Just give me the news I can use” type of runner, there is plenty of information in the pages of Waterlogged that you can apply to your training.

For example, Noakes explains how the sodium concentration of sweat is greater than that of the body’s internal fluids, so the more we sweat, the saltier we become internally. For this reason there is—contrary to popular belief—no risk of becoming “salt depleted” in events such as marathons—unless we drink too much water or sports drink, whose sodium concentrations are much lower than that of the body’s internal fluids.

While I believe that Noakes’s advice to drink according to one’s thirst is valid, I also believe that there is some important fine print to consider. For example, some runners don’t do a very good job of paying attention to their thirst and consequently tend not to drink enough. Such runners can benefit from having a hydration plan for workouts and races that keeps them on track.

Indeed, it’s helpful for all runners to have some kind of hydration and overall nutrition plan for each race. It reduces the chances of screwing up one’s race by taking in too much, too little, or the wrong thing. Robert Portman, PhD, a sports nutrition expert and author of Hardwired for Fitness, has created a new exercise hydration and nutrition calculator that enables runners and other athletes to create an appropriate plan for workouts and competitions very easily.

What makes the Portman Calculator different from previous calculators is that it represents the new, moderate philosophy of hydration. Portman considered not only the benefits of consuming adequate amounts of fluid (and carbohydrate) during exercise but also the limits to gastrointestinal absorption of these substances. The result is a calculator whose results are actually applicable to the real world.

I tested the calculator recently by entering an activity (running), the intensity of that activity (6:00/mile, or the approximate pace of my best marathon), the duration of that activity (157 minutes, or the amount of time it would take me to complete a marathon at that pace), and my current body weight (163 pounds). Based on this information, the Portman calculator recommends that I consume a total of 50 ounces of fluid during the race, which works out to a couple of ounces at each aid station, which is almost exactly what works best for me. The calculator supplied recommendations for carbohydrate and protein intake that were equally sensible.

The Portman Calculator has the potential to help a lot of runners and other athletes avoid the race hydration and nutrition errors that are so common. Try it yourself:


About The Author:

Matt Fitzgerald is the author of RUN: The Mind-Body Method of Running by Feel (VeloPress, 2010) and a Coach and Training Intelligence Specialist for PEAR Sports. Find out more at