Dehydrated and Dominant?

By Emily Beers

In ExPhysiology

June 09, 2015

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New study shows mild dehydration has no effects on athletic performance.

Researchers from Brock University in St. Catharines, Ontario, have discovered new evidence that suggests being dehydrated doesn’t hinder athletic performance.

Stephen Cheung is the lead author of “Separate and Combined Effects of Dehydration and Thirst Sensation on Exercise Performance in the Heat,” published in the June 2015 volume of the Scandinavian Journal of Medicine and Science in Sports. The study analyzed the performances of 11 experienced long-distance cyclists under different hydration conditions.

Obscuring their actual hydration status from the athletes to ensure valid results, Cheung and his team compared performance data between hydrated and dehydrated rides. On the days participants became dehydrated, they lost up to 3 percent of their pre-race body weight, Cheung said. However, results showed hydration status had no effect on performance.

Cheung is hoping the results of his study can help change the information presented to the public about hydration and performance—information he believes is flawed.

“We’re bombarded by public messages saying you need to drink all the time and any bit of dehydration is bad for your health and performance,” Cheung said. “There’s a disconnect between the public message and what elite performers are doing.”

Despite the potentially serious consequences of drinking too much, Cheung believes most people continue to listen to the dehydration message. It’s much harder to send out a message that you can drink too much, Cheung explained. He’s hoping his research can help change common perception.

“The message from my study is that if you’re peaking for a performance, like a half marathon, you don’t need to overemphasize or obsess about hydration, and you can drink way less fluid than you think,” Cheung said.

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16 Comments on “Dehydrated and Dominant?”


wrote …

Any ideas what the correlation is to recovery as it pertains to hydration? I understand that performance "in the now" may not be affected, but how did those cyclists that were dehydrated fare in their recovery? Were they able to get back on the cycle and perform adequately in two hours, 8 hours, or even the next day? Was their recovery prolonged or affected in any way?

I know fighters that rely on cutting massive amounts of water weight before a match usually (though anecdotal) often report feeling weaker, and many have lost fights due to the inability to recover from such severe weight loss. These are athletes that dehydrate on a regular basis, and are used to it. In the interest of the big picture and after effects I think it would be unwise to discourage hydrating while working out (which I don't think is the purpose of the article), but for everyday athletes with regular jobs it may be beneficial to stay hydrated without overdoing it.

Just some thoughts, and for the record I hate Gatorade. I believe it to be one of the biggest shams in the sports world. I don't believe the weekend warrior or everyday Crossfitter is going to ever lose enough electrolytes to warrant putting that much sugar into the body. Perhaps extreme endurance athletes or the Crossfit games might warrant it, but I think there are better ways to recover.


wrote …


Thanks for your comment. You stated,

"I don't believe the weekend warrior or everyday Crossfitter is going to ever lose enough electrolytes to warrant putting that much sugar into the body"

Despite your antipathy towards Gatorade, you have fallen for another Gatorade myth. Gatorade doesn't actually replenish electrolytes.

In fact, Gatorade lowers blood electrolyte concentration levels:

Tim Noakes' magnum opus "Waterlogged" is essential reading. Athletes have died due to Gatorade's negative effect on electrolyte levels.


replied to comment from Russ Greene

C'mon Russ.
Tim Noakes' magnum opus is called 'The Lore of Running'.



replied to comment from Russ Greene

Interesting study for sure, but not really the point of my comment/questions. I'm on board with the overhydrating aspect and the fallacies of sports drinks, but I want to know how operating without replenishment affects recovery.


wrote …

Hey Dave,
I had the same feelings. I'm guessing he's not willing to speculate on the recovery process that the dehydrated experienced. And from my experience with his postings, if he doesn't have a tongue-in-cheek come back, he either disallows the question, or will not respond. Through this he maintains his 'reputation'.



wrote …

David, I have seen no evidence that waiting until post-exercise (when it is safe) to fully restore hydration delays the recovery process. If you have, I'd be interested in seeing it.

Neither this article nor Noakes' work is advocating for permanent dehydration, but rather talking about a healthy level of dehydration induced during exercise while drinking to thirst. The point is that trying to fully replace fluids lost during exercise, beyond thirst, risks hyponatremia. For this reason, not even the ACSM still recommends fully replacing fluids lost while exercising.

The stress of exercise causes the Syndrome of Inappropriate Antidiuretic Hormone (SIADH), which causes the body to retain more water than usual. So hyperhydration is a greater risk for athletes during exercise.

Ian, if you have comments to add beyond personal aspersions and disputing which book is Noakes' greatest, I eagerly await them.


wrote …

I take a disliking to the way CrossFit has recently incorporated traditional exercise science research to support their modalities of exercise while trashing some of the biggest institutions affiliated with traditional exercise science. CrossFit have tried so hard to separate themselves from the mainstream sports medicine and strength and fitness communities to a point where they were in danger of ostracizing themselves from the entire scientific community. In order to support their new fitness business model with science beyond the cool college speak of Mr. Glassman, they have been forced to correlate modern exercise science issues with their new exercise regime through research not affiliated with the long-standing fitness institutions against which they currently have lawsuits filed. you still there?

I don't see how dehydration factors into the CrossFit equation. I admire HQ's ardor in digging up current science but to my knowledge there hasn't been any big humdrum about dehyration in the community - ever. The only time it has ever even come to public light was during the 2008 (I think) trail run when Khalipa almost passed out. What I mean is, there is no real threat to dehydration or even over hydration during a CrossFit event. Guys and gals exercise on average for 15 minutes at about 70%. With this new fangled exercise modality should come it's own separate research if it's to be relevant.

But hey, it's another opportunity to one-up the traditional way of thinking among the fitness community and CrossFit is all about undercutting the competition so why not throw it up on the Journal? And this, I feel is the main driver behind the recent dehydration articles - not the pursuit of science. Any athlete who's worth his salt has know about these issues for a long time.


replied to comment from Ian Liebold


Let me make sure I understand your complaint. You stated no objection to the accuracy of the article, but rather "take a disliking" to the information presented because of a larger problem you have with CrossFit?

In that case, we will continue spreading the truth about hydration in order to prevent further cases of hyponatremia and heat stroke. If this displeases you, that's unfortunate, but we think that no more athletes should have to die from an entirely preventable illness.

For more information, please read this article:

It states, "The recent preventable deaths should serve as a tragic reminder that medical personnel, professional societies and industry must strive harder to translate evolving scientific recommendations and guidelines to practical use by athletes and those who train them."

As for your point that hydration unrelated to CrossFit, that's not true. Here's one example. Aggressive hydration is frequently recommended to prevent and/or treat rhabdomyolysis. Through our research into hydration, we've found that this advice is misguided. Hyperhydration can actually cause rhabdomyolysis. It is important to verify blood sodium concentration prior to administering an IV or advising an athlete to drink aggressively. Unfortunately even doctors still can mess this up.

Thank you for your comments.


replied to comment from Russ Greene

Well I guess that settles it!
My displeasure is not unfortunate at all but thanks for your concern. In fact it's opposing opinions that you so desperately try to scrub from the pages of your blogs that advance the discussion. But you, (just like my ex-wife) attempt to quash all opposition at it probably seems threatening to your little crusade.

I understand your points about hyperhyrdation however, the science article as posted to the Journal relates to dehydration. So, I stand behind my comments that the Journal is subversively trying to undermine traditional exercise science while 'advancing' its agenda. So now you're telling me that the problem in CrossFit is not dehydration affecting performance but hyperhydration. My head is spinning trying to understand what exactly it is you want me to understand.

Thank you for YOUR comments.

PS, no need for further research articles. It seems like we're having trouble dealing with one as it is. And I'm already sufficiently well read.


wrote …


The scientists at CrossFit's conference presented their findings at the ACSM annual meeting this year. I suppose you think that this was all part of Drs. Rosner and Verbalis' "subversive" plot to undermine traditional exercise science. And when the CrossFit Conference's findings are published in several journals this year, or CrossFit funds hydration research to prevent hyponatremia, that's all just more subversion.

Second, you don't seem to recognize that the hyped up fear surrounding dehydration has promoted hyperhydration and thus hyponatremia. See page four of this article. It draws that connection explicitly.


replied to comment from Russ Greene

No, I guess I don't understand any hype surrounding dehydration and subsequent hyperhydration aside from the hype that CrossFit inc is currently producing. The issue of over hydration and hyponatremia has been studied for decades now and as I said in a previous comment, most every formidable athlete understands the issues involved. The deaths that have recently occurred, according to the doctors in the football article have been 'freak accidents' which tells me that most if not all of the endurance community has a solid grasp on how to handle their intake during exercise.

"In his book “Waterlogged: The Serious Problem With Overhydration in Endurance Sports,” Dr. Tim Noakes noted 12 deaths from EAH or EAHE between 1981 and 2009. In August 2014, two high-school football players were killed by EAHE after drinking too much water and Gatorade." - Beers' article.

Is this the consequence from what you call the 'promotion of hyperhydration'?

It's your money, you can research whatever you want. But is it just a coincidence that while presenting your 'new' research you can, at the same time, bad-mouth Gatorade and any other sport-drink brand name or company? Seems to Inc's MO.


wrote …

And BTW. There is no dispute about Noakes' greatest book but the way you tried to sell 'Waterlogged' as his magnum opus says it all.


wrote …


Hyponatremia is far more common than you portray. As recently as 2009 there was a 30% rate found at Western States:

NEJM found a rate 22% among women at the Boston Marathon:

In 2012, a study in the Clinical Journal of Sports Medicine reported that runners in the Boston Marathon, "lack knowledge about appropriate fluid intake to prevent hyponatremia on race day."

An article in the European Journal of Applied physiology reported in 2012 that in a ultraendurance swim event, "two males (8%) and four females (36%) developed EAH"

If we conservatively assumed a 10% rate of hyponatremia in endurance athletes, this would represent hundreds of thousands of cases worldwide, each year. And that's not counting training cases!


wrote …

All of my points stand here. Move on Russ.


wrote …

I found the article interesting. As a new member to CrossFit I was told to make sure I drink enough water. Prior to joining CrossFit my old routine was to drink about a gallon of water a day. I'm now questioning that advice. After my WODs I notice my joints swelling especially in my fingers. Is that normal? Am I over hydrated or dehydrated? Working out in a warm climate I definitely lose a lot of water through perspiration.


replied to comment from Russ Greene

Well I stand corrected. I was simply quoting from the original Beers' article. As I read more, I am agreeing more with CFs campaign to bring the issue to the forefront. I would bet that with each documented case there are two more undocumented cases which didn't necessarily end with such acute symptoms or even death.

Forgive my a-hole comment above. not warranted and very embarrassing. My apologies.

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