Obey your thirst!

Posted by James Greenwood | 9:45 AM | , , | View Comments



The topic of the hydration, dehydration and rehydration, both inside and outside of the competitive setting, has been a subject of intense debate over past few years.

There has been a huge amount of research done in labs around the world, in an effort to determine:
  1. Exactly what is means to remain be optimally hydrated
  2. How / if different levels of hydration levels can / do impact an athletic performance
  3. Whether current trends / guidelines are correct and necessary for athletes.
It is common knowledge that much of the research into the importance of remaining hydrated has been carried out by the manufacturers of rehydration products. Their conclusions almost always recommend we preemptively hydrate, before the body actually requires the fluids (and electrolytes), to avoid the "devastating" affects of becoming dehydrated.

This pre-hydration if you like, drinking even when not thirsty to avoid becoming dehydrated, has a number of real, even life threatening side effects, such as Hyper-hydration, and even Hyponatremia. which, over the years, has seen a number of athletes die.

As a side bar, there has never been a case where dehydration was proven to be the cause of an athletes death.

So as good consumers, we follow the hydration recommendations offered to us by the experts. I have been using these recommendations for years, and they seem to have worked pretty well.

However, over the past months, I have read a number of articles and a few studies that seem to fly in face of tradition.

The question one such article asks is who are the most dehydrated athletes in any given race (let's use an Ironman)? You might say the guy right at the back of the race, who has been out there of r 17 hours.

Well you would be wrong. The answer is actually the race winners.

Post race assessment of the hydration status of the top finishers showed that they had lost 10% - 12% of their body mass by the time they crossed the finish line. By the way, the ACSM recommends that no more than 2% - 3% should be lost during exercise, otherwise performance will drop, and you will have to deal with a number of physiological consequences, detrimental to your performance.

So how is it that the most dehydrated racers are able to perform at unimaginably high levels, for extended periods of time, without taking on enormous amounts of fluids (to replace those lost), and still not fall down, into a dehydrated heap?

Perhaps the body is more capable of dealing with being dehydrated for manageable periods of time, than we give it credit for. Perhaps we do not need to take in 800 - 12ooml of fluid per hour in order to keep our performance up.

After all, we use our hunger to guide us as to when we should to eat. We do not "graze" the whole day, in case we get hungry.

Perhaps contrary to popular belief, thirst is actually a good indicator of our bodies need for a top up of fluids (both in daily life, training and racing).

Broken down into very simple terms, the thirst mechanism looks something like this:

When our bodies' fluid levels begin to decrease, the concentration of Sodium relative to water increases.

The body is no longer in homeostasis, so a message is sent to the brain telling it about the imbalance.

The solution to the problem: make us thirsty, which leads to us taking in fluids (ideally water), thus returning the bodies water levels back to the ideal, and the body back to the desired concentration between Sodium and Water.

Finally, we are all aware that body mass and performance (especially in the bike and run legs) are intertwined, so perhaps a reduction in body weight, might well provide an indirect, and unforeseen, improvement in performance.

Surely having liters of fluids sloshing around inside the body, while trying to deliver the performance of a lifetime is not ideal.

From a personal perspective, I am not going to stop drinking fluids, in an effort to become a little lighter, and hope that my performance improves.

I am however, going to pay closer attention to what my body is telling me, afterall, it knows better than anyone what it needs, when it needs it and how much it needs.

James Greenwood is a competitive tri and multisport athlete currently training for Ironman Canada 2009. A level 1 Triathlon Coach, he holds a post graduate degree in Exercise Science, and is a Certified Strength and Conditioning Specialist through the NSCA. James is also currently the resident health and fitness programs expert at MyPypeline.com, and has starred in a number of multisport specific fitness videos.
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