Hydration

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Experience From - Unknown , Karl King#1, Julie Arter, Karl King#2, Karl King#3, Ed Furtaw#1, Ed Furtaw#2, Stewart Dutfield, Karl King#4, Karl King #5, Brian McDonald , Mike , Karl King #6, Rich Schick #2, Ray K ,


Unknown

There's an old expression you've probably heard a countless times... "you are what you eat." While this may be true, ultra athletes see the other side. 60% of a person's body weight is water therefore "You are what you drink". Water serves two critical functions:

  1. Since water makes up most of our blood volume, it's an "energy supply line" that delivers oxygen to the muscles to allow them to do their essential work.

  2. At the same time, water is the body's cooling system - sort of human radiator. When you exercise, you generate heat - literally 8 to 10 times what you do at rest. Blood conducts the heat to the skin which, in turn, makes you flush and dissipates the heat. When this process is not enough, you perspire and are cooled off by evaporating sweat.

Properly hydrated, you feel great, perform at your peak, and speed your recovery for you next activity. The problem comes when the body doesn't have enough water to perform all these functions. You can easily loose two quarts of water per hour in hot weather by exercising. When you do, the blood volume diminishes and the body struggles to supply oxygen to muscles. You feel weaker and start to experience headaches, cramps and nausea. In fact, dehydration is a key factor in "bonking" or "hitting the wall".

By the time you're thirsty it's too late. The body has to do something, and what it does is shut down the sweating mechanism. The body's temperature starts climbing rapidly, and you begin to experience heat exhaustion and heatstroke, the latter of which can be fatal. So what should you do? It's simple. Make sure you don't run out of water, and keep drinking. Drink before, after, and most of all drink during the run. Medical and training experts advise drinking at least 8 oz every 15-20 minutes during exercise. Don't wait till you're thirst-by then it's too late and you're becoming dehydrated.


Karl King #1 the RD for the Ice Age 50

After a long cold Spring and no chance to acclimate to heat, runners should push a lot of water and sodium from the very start of an ultra.

  1. Drink water and take some salt BEFORE the race begins. Race Directors will please provide, water AND CUPS at the start line.

  2. You need 400 to 800 mgm of sodium per hour under hot conditions. The average small pretzel or saltine found at the aid stations has only 30 mgm of sodium. If you're drinking water only, you'd need 13 of those per hour to get in enough sodium. Even if you're taking a sportsdrink, one or two pretzels may not be enough. Most drinks are on the low side of the sodium requirement because the drinks would taste like sea water if they had sodium levels equivalent to 800 mgm/hour.

  3. Colas typically contain little or no sodium. A steady diet of half cola, half water could lead to inadequate sodium in a few hours of running.

  4. Don't be fooled by running in dry weather. Sweat may evaporate so fast that you think you're not sweating much when in fact you're sweating a great deal, and losing water through your lungs as you exhale.

  5. Don't assume that you are hydrated if you pee late in a run. If you are low on sodium, your body will be forced to dump water to keep you from going into a state of hyponatremia ( low sodium ). Thus it is possible to be dehydrated and peeing at the same time.

  6. If you do get dehyrated, take salt and water together. Your body will not properly re-hydrate if you don't have sodium on board. Therefore, avoid soda and sparkling waters unless you also take sodium.

  7. Don't trust your sense of thirst in an ultra. Most people are actually dehydrated by the time they register as thirsty.

  8. If you do get dehydrated, your blood pressure will be low. If you jump into a hot shower after the run, the blood vessels near the skin will dilate and your blood pressure will drop so low that your heart cannot push blood to the brain for a few seconds and you will pass out in the shower. If you need to clean up, use a wash cloth wet with tepid water.

  9. If you feel dizzy or have a queasy stomach, slow down or sit for a while. If it is really hot, you weren't going to have a PR anyway, so why kill yourself to finish a few minutes sooner?

  10. The runners most in danger of dehydration are not the speedsters at the front of the race, but those at the back of the pack who spend more hours out in the heat.

  11. If there is ice at the aid stations, consider wearing a white, mesh cap in which you can put ice cubes. It may look silly, but may also help cool your head a lot. It worked wonders for me at the hot, humid '94 Vermont 100.

I will echo the statement: it is just as stressful to be Race Director on a bad day as it is to run.


Julie Arter

Subject: All Sport

Regarding Gordon Chase's questions about All Sport, I've never actually use the stuff although I've had a humorous experience with it. At Pueblo Nuevo 50, it was the only sports drink available at the aid stations. Since I had never used it, I assumed it was similar to Gatorade. At one of the aid stations, I poured it into my two fanny pack water bottles. Not 10 minutes out of the aid station, as I was running down the trail, I heard two loud pops. I soon feel liquid running down my legs. Unbeknownst to me, All Sport is slightly carbonated and my running shook the bottles which built up the carbonated gases until the explosion occurred. I could see the headlines in the papers the next day, "Woman Survived All Sport Bombing Blast at Pueblo Nuevo 50 Miler". Needless to say, I was covered with grape All Sport for the rest of the run. I dumped what was left in the bottles and used water the rest of the day. So, if you don't want to drink a carbonated sports drink, don't use All Sport.


Karl King #2

Can one run far on water only? Yes, if you call it running. The physiology and biochemistry of such a strategy is well known. Leg muscle glycogen will be exhausted, followed by liver glycogen. Because some carbohydrate is needed for efficient energy production via the Kreb's cycle, total lack of carbohydrate will slow the rate of energy production to a crawl, and that is just about what a runner will be doing in that condition.

The body's reaction to stress will cause elevation of the corticosteriod hormone cortisol, which will enable the body to start digesting itself for energy. Fat will supply most of the body's energy, but significant protein will be robbed from the body's own muscle tissue. This is essentially the early stages of starvation, and it is totally inconsistent with athletic performance.

The brain uses blood glucose for its fuel, and when the level of blood glucose falls below a critical level the brain will not allow sustained exercise.

Training with water only for ultra distances will improve one's ability to generate cortisol in response to stress, but that is a very destructive strategy if carried out for any length of time. It would be more of a tribute to the human body's ability to adapt to harsh conditions than a wise choice.

Running fast over long distances requires a good supply of carbohydrate. Since the legs muscles and liver can only store limited amounts, that implies eating during an ultra.

During a run of 50 to 100 miles, protein supplies 7 to 10% of the energy required. Experience shows that if you want to do well in a 100 miler, you should get some protein along the way.

Beyond the energy question, there is also the matter of electrolytes. If one ran with water ( tap water? ) only, sooner or later the critical electrolyte levels would fall because of depletion from sweating. That would cause a host of biochemical problems and eventual collapse.

Can you run on water only? Can you live on a diet of pickles only? Well, yes, but somewhere along the way, life is going to get pretty miserable if you try.


Karl King #3

Subject: Measuring Sweat Loss

Anstr asked about quantitative measures of sweat loss difference between runners who were and were not heat acclimated.

The amount of water lost in sweat is a bit complex and will vary from person to person. The common point is that it will be higher at higher temperatures.

As for sodium, there is a pertinent table ( 4.1 ) on page 119 of Noakes' Lore of Running. While potassium, magnesium and chloride don't differ much between the two, sodium loss is 33% greater in the unacclimated runner: 80 mmol/Liter vs 60 mmol/Liter.

As Anstr surmised, dehydration is not just a matter of absolute conditions; we sweat and lose sodium relative to our acclimation. Conditions that are typical, and no problem in late July, can be a killer at the end of Winter.


Ed Furtaw #1

Karl and others, The BRR was truly amazing. I have never seen such carnage. I only marked course, but it felt very warm. It was NOT however THAT hot. Only about 80 with high, but not oppressive, humidity. [SNIP]

I see only two possible explanations for all of the "need" for medical assistance. The most obvious is the lack of acclimation to warm weather. If that was it, then, lack of acclimation is a significant factor. Anyone have a quantification of how debilitating it can be? I have always recognized the importance of heat acclimation, but never realized it was THAT important.

The other possible explanation is that there was a psychological factor at work here. You don't feel well, you see paramedics, you worry that you will next be on the ground with needles in your arm, and bingo, there you are. [Other stuff deleted.]

I think Karl was right when he pointed to sodium as a major factor in the BRR "carnage". I looked through The Lore of Running by Tim Noakes thinking that there was some quantitative information in there about heat acclimation. There is. Heat acclimation (or acclimatization) takes 7 to 10 days of training in heat. Two of the main effects of heat acclimation are *increased* sweat rate but *decreased* sodium concentration in the sweat.

Table 4.1 in "..Lore.." contains data on sweat composition for unfit/unacclimated subjects, fit/unacclimated, and fit/acclimated. The sweat of fit/acclimated subjects contained 1.8 g/L of sodium and 0.1 g/L of potassium. The sweat of fit/unacclimated subjects contained 2.6 g/L of sodium and 0.15 g/L potassium. Note that these sodium levels are *much* greater than those of nearly all sports drinks. I think this is getting close to Karl King's point: inadequate sodium may have been the key to the BRR carnage.

On the basis of this data, it appears that runners not acclimated to heat may lose about 50% more electrolytes per unit of sweat than those who are heat-acclimated. I could not find quantitative data on how much sweat rate is increased by heat acclimation. Apparently the decrease in sodium content of sweat with acclimation outweighs the increase in sweat rate, with a net result that the sodium losses are greater when not heat-acclimated.

Could anyone provide information on what drinks were provided at BRR, a the sodium content of those drinks?

Notice that the potassium concentration of sweat is very small compared to sodium concentration. The 2/1 ratio (sodium/potassium) mentioned by Dave&Lane Cooper is actually about 18/1 in sweat, so the amount of sodium to be replaced far exceeds the amount of potassium needed.

I am fascinated by Anstr's suggestion of a psychological factor in the relatively large number of runners receiving IVs or being transported to a hospital. In my field of work, I study indoor air pollution. It appears that there is a psychological component in the suffering of "sick building syndrome" symptoms. The symptoms are triggered by certain environmental conditions, but the psychological dimension is probably also a factor (of unknown magnitude) in establishing how much a given individual "suffers" from the conditions. As in the case of BRR, it is impossible to quantify how much the psychological factors (versus the physical environmental factors) contributed to the problems. This reminds me of the ultrarunners' quote: "Pain is mandatory; suffering is optional".


Ed Furtaw

Ed wrote:
Could anyone provide information on what drinks were provided at BRR, a the sodium content of those drinks?)

Anstr wrote:
We had Exceed at all of the aid stations. We also had the "normal" salty stuff like pretzels, saltine crackers, etc. We did not have plain table salt at each station (as maybe we should, by hindsight).

(Nobody gave us the Exceed--we paid for it--so feel free to trash it if you want. My perception is that it is about as good as any except for Gatorade which I personally dislike because it makes me puke. Of course, a lot of things make me puke.)

We also had water and Coke (though the Coke ran low at a couple of points).

I won't trash Exceed because I basically like the stuff pretty well. However, as I recall, it has maybe 200 mg/L (= 0.2 g/L) of sodium when mixed as recommended. (Could anyone provide more accurate information?) This is way below the 1.8 to 2.6 g/L of sodium in sweat noted in The Lore of Running. So even with Exceed, the BRR conditions and lack of heat acclimation of many of the runners could still have resulted in inadequate sodium for many. Were the runners who were hospitalized and/or received IVs tested for sodium in the blood? There have been some interesting data on blood sodium levels (and other chemicals) in finishers of Western States published over the years.

Perhaps under conditions like BRR this year, many runners would benefit by adopting an idea from Ultra Tracey: eat rock salt. Under certain conditions, it just may not be feasible to drink enough sodium from common drinks.

Any input from the physiologists out there?


Stewart Dutfield

The trouble with waiting until you want something is that the inclination can come too late. For example, "drink even if you're not thirsty" is widely accepted because runners know from experience that by the time you feel thirsty in a race you're already short of water, and you might have a lot of difficulty making up that shortage while continuing to run.

Running ultras makes considerable demands on the body; by the time the normal appetites have kicked in you might already be in trouble. Salt, in my experience, is a good example of this.


Karl King #4

Subject: Hydration & Carbo's

Ken Young raised some interesting points in the Jan/Feb issue of Ultra Running magazine (page 44 ). I'd like to add to that discussion.

  1. Super-hydration. There's not much doubt that many runners begin their long runs insufficiently hydrated. It is good practice to hydrate fully in the hour before a long run, and to drink regularly during the run, maintaining the best hydration possible under the circumstances. The most important water stop is the one just before the race begins.

    The typical runner will find it most effective to hydrate in the hour before the race begins, rather than trying to hydrate over the few days before. Also, studies show that the body stays cooler when one drinks regularly during the run rather than have just one big slug of water before the run starts. Your body loses water all during the run - replace it regularly during the run.

    If you would like to read more about drinking before a run, see the July-August issue of Running Research News, page 1. The science of drinking during a run has been covered exhaustively in Lore of Running by Tim Noakes, pages 115 - 131.

  2. Dehydrating pasta? Ken related how he would lose three pounds after eating pasta the night before the big run. I suspect that this was related to the sodium content of the meal and Ken's salt/water hydration routine, not the intrinsic nature of pasta. He loaded salt and water beforehand, gaining three pounds ( 1.36 liters of water ). Most pasta meals are low in sodium and high in potassium unless you add extra table salt. Having loaded sodium and water before, Ken's body may have dumped both after he ate a meal low in sodium. The Mexican-style food he ate before AR50 was probably fairly high in salt, and that extra sodium helped him retain the water he had previously loaded.

    Thus, runners need not fear eating pasta, provided they tend to their electrolyte needs.

  3. Fat during ultras. While even the leanest runner has enough energy stored as fat to run an ultra, eating a small amount of fat during a long ultra has benefits. Most people who regularly run 100 milers will attest that "real food" helps the stomach avoid the nausea which would result from eating just energy bars and drinking ordinary sports drinks. What they are getting from the "real food" is fat and protein, both of which stabilize the acidity in the stomach and small intestine. In particular, the fat stabilizes the pH of the small intestine. While the fat is not needed for its calories, it is useful.

  4. Other thoughts. Much of what we've heard over the years on nutrition and physiology related to running is valid for the runner who does 10Ks and marathons, but not ultras. The subject becomes much more complex when you consider those who run 10 hours or more in an event. The "conventional wisdom" may not apply to the runs we do. Keep an open mind, and be prepared to learn from your own experiences.

    As for carbo loading, I don't load that much before a run because I've spent years training my body to load during the run, not the night before. The philosophy is that whatever my body is using on a regular basis as I run (air, water, energy ) I try to add in small amounts regularly during the run. Taking one big, deep breath and then trying to run far has never worked well for me.


Karl King #5

Jan wrote:

"Questions: Do I force myself to drink more when its colder or is less OK when it gets colder? Is this a normal transition everyone has to go through when the weather changes?"
The transition is normal, but it can lead to false sense of adequate hydration.

The amounts you drank for warm weather conditions sound typical. However, 30 ounces in 4 hours is probably too little. Remember, humans are very poor at accurately judging hydration status. It is more safe to drink more than you think you need. If you drink too much, it will simply be passed through. If you stay hydrated, your pace will be better and you will recover more quickly after your run.

As a rule of thumb, what works for me is:

hot weather30 ounces per hour
comfortable running temps 20 ounces per hour
cold weather15 ounces per hour

Remember too that during the first 20 miles of a run you are getting water that is released from the muscle's store of glycogen. That is an internal source of hydration. When that glycogen is nearly depleted, that source of water is gone, so you need to drink more after 20 miles than you did before.


Brian McDonald

Subject: Cold Water

As water absorption takes place in the intestines, the critical factor is the time from ingestion to when the stomach empties. While a group of us were training at the University of Alberta I posed the question of drink temperature to a couple of the sport physiologists. Their response was that cool drinks (cool, not cold) are absorbed the quickest. As was suggested in a previous post, cold drinks can cause spasms and slow down water absorption (I assume through increasing the time it takes the stomach to empty).


Mike

Subject Cold/Hot Water

I still think the temperatures of hot/cold beverages are neutralized en route to the stomach though...I'm no physiologist, can't even pretend to be, but intuition and common sense tells me that beverages ewill take on the ambient internal temps just like the air you breathe.


Karl King #6

Subject: Cold/Hot Water

An article in Running Research News stated ( in summary ) that cold drinks inhibit blood flow and reduce absorption rates. Hot drinks were less palatable and runners tended to drink less than they should. The best temperature range was from cool to tepid.

Of course you can adjust for ambient conditions, and the amount you drink. When I'm running at zero F a drink of warm water is appealing. When it is in the 90's cold water works fine for me. But then, I tend to drink small amounts frequently, and the cold water is quickly warmed. Drinking a quart of ice water would probably be a bad idea no matter how hot is.


Rich Schick

Subject: Cold/Hot Water

Seems the most important impact of fluid temperature is palatability(how you like it) kind of like sex. Some data seems to favor cool beverages over warm or hot, but the effect on gastric emptying would only impress a research scientist and would not be likely to have a noticable impact in the real world.

See citations below.

FLUID REPLACEMENT: THE AMERICAN COLLEGE OF SPORTS MEDICINE POSITION STAND

SSE#63-Volume 9 (1996), Number 4

It is recommended that ingested fluids be cooler than ambient temperature [between 15and 22C (59 and 72F)] and flavored to enhance palatability and promote fluid replacement. Fluids should be readily available and served in containers that allow adequate volumes to be ingested with ease and with minimal interruption of exercise."

GASTRIC EMPTYING DURING EXERCISE

SSE#46, Volume 6 (1993), Number 5

It now seems likely that several other factors which were formerly thought to be important, such as carbonation and the temperature of ingested drinks, do not have a major influence on the rate of emptying (Maughan, 1991). These factors may, however, be important in affecting the palatability of drinks, which will influence the volume consumed.


Ray K

Subject: Cold Beverages

Please understand that your son did not have leftover water in his stomach the next day that caused a sidestitch. Cold water is absorbed faster regardless of old wives or undereducated physicans tales to the contary. Any temp water is absorbed within very few hours. The side stitch was caused by improper breathing and or trying to run further faster than he was conditioned for.