The Truth about Hydration - a la Noakes

The timelapserunner has been reading his copy of Waterlogged which arrived last week. This work is impressive, and not just for the fact that it's 400+ pages. Dr. Tim Noakes' work is clearly the definitive word on what the best research has to say about hydration during intense exercise. And it is also clearly at odds with a lot of advice given to recreational runners over the last forty years or so. It is not entirely coincidental, Noakes points out, that some of the advice to 'hydrate, hydrate, hydrate' started up in earnest about the time that sports drinks were coming onto the market. Noakes points more than just a single finger in that direction, in any case. So, what is the right piece of advice to follow? What should we recreational-but-still-serious runners do regarding in-race hydration?


Apparently impatient to find the punchline, the timelapserunner searched the Table of Contents to find the 'bottom line' chapter and quickly read the advice given there. In the briefest of assertions in Chapter 11, here's the advice that Noakes gives:

"Athletes should drink to thirst during the race and not more than 800 mL/hr."

OK. In layman's terms that sounds to me like: if you're thirsty, drink; if not, don't - at least don't drink a lot. Yep, it's that simple. Dr. Noakes contends that all the best research shows that the intensely exercising human will know when to drink by recognizing thirst. Then drink only to satisfy that thirst, and not more than 800 mL/hr - which is 27 ounces per hour. On top of that, Noakes dispels the myth that the 800 mL/hr figure is univeral - it's not, he says. The 800 mL/hr figure would typically be for a heavier athlete working very intensely on a hot day. A figure of 400 mL/hr (13.5 ounces per hour) would be a more appropriate maximum for a lighter weight athlete working less intensely on a cool day. In this latter case, think the average January woman marathoner. For the former, think overweight Florida Gator football players during August practices (i.e., the athletic situation that inspired the invention of Gatorade).

An interesting fact in all of this is that serious marathoners prior to the 70s were pretty much counseled not to drink at all during the race. From that extreme, the common recommendation from the 90s on was to advice runners to drink as much as tolerable - the other extreme. The ancient wisdom, if practiced by amateurs, would be an invitation to heat-related illnesses. The more modern wisdom - again, if practiced by amateurs - would generate an increased risk of 'water poisoning' or exercise-associated hyponatremia (EAH), Noakes explains in his book.

So, in essence, the best advice based on the best research today is rather simple: if you're thirsty in a race, drink. If you're not, don't force a lot of water down because you heard you should. Unless, maybe, you're an overweight Florida Gator football player running in a summer marathon.

DISCLAIMER: The timelapserunner may be completely out in the broccoli on this one, may not have understood a single thing he read, and may have completely misstated Noakes' science and conclusions. DO NOT FOLLOW any of the advice given here. We don't know what we're talking about. See your doctor before beginning any intense exercise program and ask for her advice on hydration. Amen.

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Tomorrow's post will show what the timelapserunner has in mind for dealing with hydration during the upcoming longer and longer Saturday runs.

TODAY'S WORKOUT: Walking, three miles, averaging 15:57 per mile. Stretching afterwards. No problems.