Dehydration

Much has been said and written about drinking and dehydration but unfortunately, nearly all of it is wrong or misguided. It is true that dehydration can be a serious problem, especially for individuals spending long hours wandering around in hot deserts or sitting on a life raft in the middle of the ocean. It can also be a problem in rare cases for well trained and determined athletes who push too hard in an endurance event.

However, most of the time and for most individuals it does not matter. What is more, overhydration and hyponatremia are much more prevalent and a whole lot more problematic.  Whereas dehydration in normal individuals under normal race conditions may lead to some loss of performance and maybe (maybe!) some cramping, hyponatremia can cause permanent brain damage and death. Even individuals who do not develop neurological symptoms will suffer more performance loss from gastro-intestinal ills due to overhydration (full stomach, fluid sloshing around, bloating) than they ever would from dehydration.

Sodium chloride, aka table salt or NaCl

Most of the ills attributed to dehydration have other causes. Cramping is a prime example. It is extremely common in marathon runners (40% according to one study) and its true cause is unknown. One thing is for sure: it has never been show to be caused by dehydration. Those who were dehydrated were no more likely to suffer cramps than those who were well hydrated. If anything cramping correlates better with training. Undertrained individuals are much more likely to suffer cramps than well trained athletes.

Eighteen percent (58) of the 330 finishers of the 1997 Ironman New Zealand were hyponatremic. A 2002 study in the Boston marathon found that 13% of non-elite competitors suffered from hyponatremia. That same year a Boston runner died of hyponatremia. Hyponatremia is so prevalent that the B.A.A. and W.T.C. started sending out flyers warning people of the dangers of hyponatremia.

BOSTON

Several symptoms of hyponatremia (i.e. overhydration) are similar to those of dehydration.

The best thing you can do to prevent dehydration in sunny locations is to cover your skin with clothing.

There is a strong belief out there that people need to drink before they feel thirsty. Many believe that poor performance can be fixed instantaneously by appropriate hydration. I have been with a lot of coaches in road races who yell at dropped athletes to drink more as if that would miraculously solve their problem.

Most people also believe that one needs to replace all the fluid (and calorie) losses sustained in a race, during that race. This notion is mistaken and makes no sense. One reason we developed a digestive system is so that we can interrupt our food and drink intake to take care of other matters -like running away from predators or searching for more food and water.

The longer the race the more modest your fluid needs (per unit time) will be as your body will adjust to initial losses and prevent further losses to the extent possible. The better trained you are the better it will work. Here are some things I learned about food and drink during a long race.

Drinking

When I first started cycling in the 1990's the mantra was, "you have to drink before you feel thirsty." Once you feel thirsty it is too late. The other common wisdom was that cramps were due to dehydration and that the best way to prevent cramps was to drink, a lot.

In the late 80's sports drinks started appearing on the scene. I remember the "introduction" of Cytomax and many cyclists asking how polylactate could prevent "the burn." Because another universally accepted truth was that lactate caused the burn. CytoMax was quickly followed by others and soon there are as many brands and types of sport drinks as there were sodas.

I quickly found out that I am a person who sweats a lot. I have rarely encountered people who sweat as much as I do, and I have found that people who complain that they sweat a lot, are often dry when I am dripping. It is quite possible that the sweating kept me from exercising when I was a teenager. I never liked exercise for some reason, and sweating may have had something to do with it. Esp. since I grew up in humid Belgium.

In any case, because I was essentially unprepared when I started cycling, I often experienced cramps. And because I sweat a lot, I quickly attributed these cramps to lack of fluids. And so started my drinking binge (drinking water and sports drinks that is). I would drink as much as my stomach would hold. Not right away, but over the course of three or four years. Then by 1994, I gave up on cycling.

A few years later, when I took up running, I was even more bothered by sweat. And again I often suffered cramps. Since I thought I was now "in better shape" the cramps had to be due to dehydration. What else was left? (Maybe not enough training?).

By then salt tablets had become universal too and I quickly got on the salt bandwagon. If I was drinking so much but still cramping, maybe the electrolytes were to blame? Many of my friends were so obsessed with electrolytes, and for some reason, with potassium (K+) that I finally started doubting the whole rationale. I can buy into Na+ losses, but K+? This did not jive with my training in human physiology and medicine.

I also noticed by reading bulletin boards and weblogs (another new thing) that I was not alone in this drink-as-much-as-you-can movement. Drinking and swallowing salt tablets became a way of life, not just for me but for others as well. And the more problems people experienced, the more prone they were to drink and eat salt.

But the running cramps persisted for quite a while. When I finally maxed out on salt tablets and even my friends started worrying about the health effects, it dawned on me that all this stuff was just hogwash. I had also heard more stories of runners who ran marathons without drinking and cyclists who would ride centuries on just one bottle. These were credible stories although the lead actors were mavericks of some sort. But if they could do it, it must be possible I thought. And it is.

Then I went to period of no drinking and no salt. That does not work too well either. It works for shorter runs (say less than 10 miles) or shorter rides (say less than 30) but that is it. If you go longer you need to drink something. But a whole lot less than most everyone recommends!

I also figured out that cramping has nothing to do with dehydration but everything with training. I was pleased to see that scientific studies support this idea. Sometimes I would be so dehydrated my voice changed and my face looked drawn, but no cramps. And then other times, it was quite chilly and I barely sweated but I did get cramps. 

I also noticed two other things: hyponatremia became a serious problem and even the media started picking it up. With all the emphasis on drinking, hyponatremia reared its ugly head. Hyponatremia is deadly. And drinking sports drinks does not cure it. The cure is to train and not to drink too much.

Hyponatremia is also an epidemic and the Boston Athletic Association (BAA) found that large numbers of Boston marathoners were in a state of subclinical hyponatremia. The more they looked at runners the more hyponatremia they found. They started issuing warnings.

I also noticed something else: less drinking and less salt works much better. My performance increased significantly. And perhaps more importantly, my comfort did too. No more upset stomachs, sloshing water, diarrhea bouts, potty breaks, and what have you. Also, no more time-robbing stops every mile. These days I barely drink for a marathon and never during the first half. The upshot? I don't have to stop for potty breaks, I don't have to stop to get drinks, I am no longer uncomfortable, and my finishing times have improved very significantly.

The take home message: think before you drink (and we are not talking alcohol here!)