Why We All Need to Drink More During Hot Weather Exercise

Aug 08, 2018 · 87 comments
Eric T. (Portland, OR)
This just in: The Earth is round and revolves around the Sun.
hen3ry (Westchester, NY)
Drink water, not sports drinks, not soda, not juice. And don't do very strenuous workouts on very hot days.
Ron A (NJ)
@hen3ry I love water but why no hot weather workouts? I thrive on them. They're great character builders, both physically and mentally, as well as being a lot of fun.
Ny Surgeon (Ny)
Electrolyte drinks are better than water on a hot day, but they do not contain enough electrolyte to compensate for what is lost through sweat ounce-per-ounce. This means that if you replace all of your lost fluid with even a sport drink, you will become hyponatremic, meaning your sodium is too low (bad, potentially very bad). The lesson- do not exercise, at least hard, in intense heat unless you are very well acclimated to it, and decrease your effort. As a marathoner, I slow considerably for a marathon over 70 degrees. And races are now cancelled if the temps are in the 80s. A 3-5 mile run if you are trained in this heat, OK. More than that, there is no safe way to do it.
Yonder Hero (New Jersey)
I just moved to a new town and will begin bicycling again. Hydration isn't a problem. I have to map out bicycle routes with places to stop for urination.
SLP (Washington, DC)
@Yonder Hero In these Covid-times, it's really difficult for women to find safe places to urinate. Public toilets can be really dangerous, from the point of view of catching the virus. I've had to limit my rides to about 35 miles, so that I can get home in time to urinate. No matter how much we perspire, women still have to empty our bladders more frequently than men.
Tabs (Atlanta)
@SLP Agreed. I have to stop because I have to go! As a fairly fit 74-year-old who gave birth to 4 children way back when, I'd love to find a solution. If I'm out there more than an hour, I'm in trouble. I'm not a cyclist, but a speed-walker in the city and a hiker when I head for the hills. I used to hit the treadmill for longer sessions, but Covid is keeping me out of the gym. Ideas?
Pinktwig (North Potomac, MD)
Not only does one need to hydrate during exercise, one also needs to replace electrolytes. Generally speaking Gatorade is terrible for you with its sugar content. No argument can be made for kids or adults to drink it when they are just sitting around. However, with excessive sweating one requires more than just water. I have been fully hydrated with water and still suffered cramps. This situation was remedied and could have been avoided if I had been drinking Gatorade or any drink with electrolytes. My cardiologist now has me drinking water with electrolytes daily to control heart palpitations which were triggered by an electrolyte imbalance [ I add Gatorlyte powder to drinks as it has no sugar].
raspell (Memphis, TN)
@Pinktwig Actually Gatorade is sodium based whereas Powerade is Fructose based. I know this as studies were done on my body by Dr. Bergeron. i lose 8 pounds of water weight in 1 1/2 hours in 94 degree heat. solution: half water, half salt added Gatorade. the difference was amazing.
Erik Nordenson (Durango, CO)
What utter nonsense not to drink in hot weather. I used to train cyclocross in Moab Utah during the summer months, riding during he hottest part of the day, (that was my decision right or wrong) I had three frozen water bottles, and depending on the distance for that days ride a 50 ounce also frozen hydration mixture Camel back. Would consume every drop. Would return home to swamp cooler or A/C, relax and have a bite to eat. Never had any issues or cramps. Had I not done the above I would not be writing this today. BTW I was in my late 60 and early 70'S.
Douglas Ritter (Bassano Del grappa)
As a long distance cyclist all the research I have read says that if your body drops more than a few percentage points of hydration during a ride, which is possible even when drinking, your performance will suffer. I have a scale that measures my hydration level. Normally I am at 60%. At 56% after a ride is the danger zone. Not drinking for a 4 to 5 hour ride on a hot day would risk heat stroke.
Marc (Montreal)
Here's something you probably didn't think of: Drinking water (yes, even cold water) in cold environments is essential to keep you warm. As cross country skiers know, you often sweat in the winter doing this activity. But even if you don't sweat, but are walking out in the cold, being hydrated is still essential, because it helps with the digestion and breaking down of carbohydrates, which are then used to make energy to keep the body warm. So if you want to stay warm, avoid too much caffeine (a diuretic) and drink up before going out and especially if you will be eating energy bars and other foods.
Geoffrey Baker (Oella, MD)
What about over drinking and hyponatremia?https://www.irunfar.com/2018/08/exercise-associated-hyponatremia-the-not...
Jailyn Colon (New York)
I agree with this article. When people do exercise outside in the hot weather with out drinking water it can be very dangerous. If you don’t drink water while exercising your body can over heat and that’s not good. People think that if they don’t drink any fluids when working out, they become stronger. But that is not true at all. So make sure when you work out drink all the fluids you can.
Miss Pae Attention (Caribbean)
Another reason to drink plenty of water-you avoid kidney stones! Trust me, you don't want them!
David (California)
I've read what seems to be virtually the same article many times over the years. But rarely anything about over hydration, which is a proven killer. According to one article I read, in recent years more athletes in the US have died from over hydration than under. Drink when you're thirsty is a good rule.
Gofry (Columbus, OH)
Hydration is important for performance at elite levels, but for most, sensible doses before training and some along the way for longer events are fine. I laugh when I see joggers who run 2-3 miles with belts full of water bottles or Camelback backpack bladders.
Expatico (Abroad)
Next in this groundbreaking column: why we need to eat when we're hungry.
Kiwi Kid (SoHem)
Drink before you're thirsty; eat before you're hungry. Two basic rules to follow if one is undertaking physical exercise.
Billy Baynew (.)
Decades ago the Israeli army subscribed to notion that withholding water during training would somehow make soldiers require less water. It didn’t go well.
Doc Who (Gallifrey)
But...but...I can't drink any more water!
DGL47 (Ontario, Canada)
As others have already said, mix your water intake with drinks that contain electrolytes (most sports drinks). This will save you from hyponatremia. I use this method when training for endurance bike races and marathons.
Edward Blau (WI)
Other comments have mentioned the need for salt replacement along with water. If you wait until you feel thirsty you are already dehydrated. Low glucose drinks like Gatorade have salts and the glucose needed to help the intestine absorb the salts. For the average person who spends their days and nights in air conditioning and then exercises outside in the summer staying hydrated is even more important for the body has had no chance to acclimatize in day to day living.
Charles Kantrow Jr (New Orleans LA)
Sweat contains both water and salt. When only water is replaced, the concentration of salt in the body can fall to dangerously low levels, producing a variety of symptoms, collectively called heat exhaustion. Articles such as this one should be fact checked for scientific accuracy and potential danger before publication.
R.S. (Boston)
Equally important is to not drink too much water. In endurance athletes, hyponatremia results in more injuries per year than dehydration, and yet all we every hear is to drink more water. To the author: It's simply irresponsible to caution against one without cautioning against the other.
Bill H (Champaign Illinois)
Doesn't salt also play a role especially when one sweats a lot. If you are drinking water and sweating aren't you losing sodium?
Ron A (NJ)
@Bill H Yes, you are but, in my personal experience, I eat so much stuff with salt in it that this just tends to counterbalance it.
Adrian (Brooklyn)
As usual many people miss the “informational” aspect of these articles. Are they Peer Reviewed? Do they have credible Validity & Reliability? Or is the article purely informational. Make what you like of it. The point being listen to your body and its needs. As someone who does morning Yoga 7 days a week plus 6 day a week gym workouts and maintains a very clean food intake with little to no Salt diet. I may have 1 alcoholic drink once a month, and drink about 4 litters of water a day. This type of article should be taken as informational only and without wanting then to be a Peer Reviewed Medical Study. Keep it positive People!
Doc Who (Gallifrey)
@Adrian It's infotainment.
DGL47 (Ontario, Canada)
@Adrian You sound like you are short of salt. Careful. With your workout schedule, you don't have to shun salt.
Skinny hipster (World)
@DGL47 Actually, little is known about minimum salt intake. Apparently, hyponatremia (acute lack of sodium) is not observed by diet restriction only. Our body becomes very sodium efficient when on a sodium-restricted diet. Sodium is eliminated through urine and sweat, but the concentration is regulated by our body and can drop to very low levels. People on a very low sodium diet (say for congestive heart failure or Menyere syndrome) seem to do just fine on 500mg/day, even less. See salt-matters.org for more info (not fully scientific, as scientists are too busy working on drugs to chase funding to study salt restriction, but well-informed and rational).
Flyover Country (Akron, OH)
I don't believe this article at all. Obviously there is an extreme, but my experience is not along the lines of the article. Quite the opposite. There is an effieciency that develops that doesn't need constant hydration, the weight and imbalance of a water bottle full of water and water sloshing around in the stomach. And since when did a study of 8 people prove anything.
Jeff (California)
@Flyover Country: OTOH since when are your perceptions based on your own water use scientific?
Ignatius J. Reilly (N.C.)
Use a refillable bottle and/or recycle. Note Chesapeake Bay is full of trash this month. Mostly plastic bottles.
David (California)
Wasn't I reading an article on these pages a few days ago cautioning on the risks of over hydration, and complaining about football coaches who forced their teams to drink too much: "if your urine isn't clear, you're not a good teammate." According to that article, more athletes have died from over hydration than under hydration.
Ed (Wichita)
I luckily survived the 1960’s when hot city school yards and play fields had a single water fountain. There was no Gatorade. To top off the insanity of the day, Little League Baseball coaches (adults) warned us players that we should not drink any water during the game, else we’d get cramps and worse. While that silly idea is not in fashion today, there must be myriad other stupid ideas about sports fitness being foisted on minors.
Airborne (Philadelphia, Pa.)
A few years ago there was a sudden burst of articles in some popular newspapers and websites arguing that studies showed that we don't as much water as we'd been told. Stupid, and i've wondered how this came about. Shortly thereafter Vanguard Funds published an article by some fellow who had run a marathon or some such long distance race denying himself much liquid then used that as a metaphor for successful investing--didn't make much sense, but that's how these things spread.
Mike (Boulder, CO)
When we perspire during intense exercise, we not only lose water, but also minerals/salts. Remember to replace those in your hydration/sports nutrition strategy, too.
E Hinckley (Palo Alto, CA)
Should the subtitle be "deprivation" instead of "privation?" I've never seen privation used this way.
Karen (Phoenix)
I live in Phoenix, Arizona; this just seems so obvious. "Stay hydrated" is the mantra here (year round) for a reason.
allegedly (@home)
When in my 20s, in Toronto, when that humidex soared into the 40s Celsius, it was running time!(nicely hydrated, thank you) Now in my 60s, in Vancouver, my body simply does not approve of running temps over a measly 17! (still well hydrated but knowing that a ‘carrot’ consisting of one dry martini (gin) awaits). Hunh, maybe youth really is wasted on the young.
Jean (Cleary)
What kind of stress is put on the heart, when you exercise without hydration? Most health experts would tell you not to exercise in torrid temperatures, as would my mother, who was not a doctor. Common sense people, drink more water when temperatures sore. Forget the exercise. Or do it in a cool gym.
Dan88 (Long Island NY)
Really, not drinking water during hot-weather exercising is a thing? Reminds me of how the "trainers" at my gym are always coming up with new and strange ways to utilize the exercise equipment...
Doc Who (Gallifrey)
Thanks for the advice. I was wondering what to do when I get thirsty in hot weather.
David Godinez (Kansas City, MO)
45 years ago, my high school football coach withheld access to water during the our workouts in August as a way of making us tougher, and also to use water breaks as a reward for good performance. Although it seems mean-spirited, the goal essentially was the same as the modern-day reason given in this article. It's amusing how everything old is new again, even bad ideas!
Dan88 (Long Island NY)
@David Godinez Yes, and periodically you read about how one of these young, healthy high school or college students collapses and dies due to this antiquated, dangerous myth of withholding hydration in the name of "toughness."
Bag (Peekskill)
I played organized football from the late 60’s up until 1980 and saw the philosophical change from no water to yes water during practice. My completely un-scientific anecdotal observation is that water is a good thing to have before, during and after practice and games. Does anyone still drink water from their helmet? Yes, the helmet was filled from a spigot and we drank from it.
Muneer (NY)
This article incorporates multiple studies done on the effects of heat and cold on athletes. One exercise physiologist studying at the University of Portsmout, Joseph Costello, had noticed that the permissive dehydration would be stressful for athletes’ bodies, but not beneficial. So, he created a group of eight young men who completed two different courses of heat acclimation. Both of these heat acclimations were situated inside a physiology lab. The one difference between both sessions was that one group drank water as they exercised and the other group didn’t. After the testing, the scientists found out that levels of cortisol intensified when the men acclimated without hydrating. In other words, exercising without hydrating can lead to unnecessary physical stress. I chose this article because I wanted to learn more about the studies that are testing whether or not if drinking more during hot weather exercise is effective.
Iplod (USA)
Football coaches used to compel players to not drink on hot days. Add to that wearing uniforms with pads and excess body fat that many carry around and it's a recipe for tragedy. I hope this practice has given way to rationality.
dafog (Wisconsin)
@Iplod I agree completely, having played football in the 60s and 70s, high school and college. We were told to not drink water, to toughen us. What baloney! As if we were not being toughened enough in practice and games. Add concussions to that senseless dehydration ("you got your bell rung") and your have a good idea of that sport. I wouldn't do it again.
Natalie Gallegos (Los Alamos, NM)
As a three sport athlete, I understand the necessity of drinking water consistently. Every coach I have had always stresses on staying hydrated. A higher percentage of athletes know to drink water. "They settled on not drinking fluids during exercise in the heat as the way to increase efforts, since mild dehydration is known to be hard on the body." Most serious athletes would not believe this. If people are beginning to train, I could understand this quote more. The study that Joseph Costello did was accurate and productive. The study proves that you might feel yourself getting better. Yet, it doesn't benefit your running. Most athletes will know that when in hot weather, they should be drinking water. Past coaches have always told my team that we should be drinking water throughout the day. This article caught my attention because I am a serious athlete and I could relate to the article. While I know the importance of drinking water as an athlete, it was useful to know the benefits of it. Reading this article I have become more informed on the benefits of drinking water. People who do not drink water before and during their workout end up being more thirsty and "physically stressed." Athletes always want to keep improving, but, thinking that they don't have to drink water to get better is unhealthy. As a three sport athlete, I understand the need of drinking water consistently.
Scrumper (Savannah)
Come and run without hydration where I live in Savannah Ga right now and I can foretell without a crystal ball what will happen. It's the humidity that is detrimental and after two miles in early morning temps your feet will be sloshing around in your shoes. I read below the dangers of hyponatremia (low sodium level due to excess fluid) which is fine in more temperate climates but not in our Summer so down here we drink sports additive drinks when we run like Cytomax which delivers carbohydrates and sweated out electrolytes, amino acids and salt. It's quite easy to drink up to a gallon before during and after the run. Also no advil or aleve type pain relievers and decongestants that all contribute to dehydration. Several years ago I collapsed due to dehydration and since I've really upped the fluids and taken other precautions it's never happened again. Remember thirst is NOT a good indicator for hydration. At that point you are already dehydrated.
Hal (NYC)
Ninety minutes on a stationary Ike is the road bike equivalent of water boarding.
Iplod (USA)
Hal: I have to laugh, not at your comment, but at myself. I've been doing 1 to 1 1/2 hours on the elliptical most days this summer and I am totally drenched in sweat by the time I'm done. It's tough but not torture. If it was the latter I wouldn't do it!
Paul (Brooklyn)
This is another one of those "hello", this has been known since the Stone Age. However, you are right in the sense people should be reminded of the need for water in hot water. Never underestimate the ability of many people to do stupid things.
Jim Dwyer (Bisbee, AZ)
Do you mean that I have to raise my 3 Irish Ales to 4 before I walk my dogs? I'll give it a try and report back.
Joseph Baum, M.D. (Floyd, Virginia USA)
Medicine is becoming more like religion every day. We read the same books but come away with different conclusions. And the reasons for this is the same for both.
Krautman (Chapel Hill NC)
Beliefs = mythology (including religion) Evidence = science ( including Western medicine)
bauskern (new england)
I work with both high school and adult runners who train throughout the summer. I've never heard of *anyone* deliberately not drinking water so as to better acclimate to the heat. The vast majority of runners and athletes are well aware of the necessity of proper hydration. I'm not sure who this article is really aimed at, but it must be a tiny percentage of athletes.
michjas (phoenix)
When I was younger, I never skipped a workout on even the hottest days. And this is Phoenix. I did my normal 6 mile sub-8 training run when it was 120 degrees. I climbed Camelback Mountain, which has a 1,300 foot gain over 1,2 miles, at 116. I have never carried a water bottle when running -- it slows me down and feels awkward. But I never hike without an abundance of water, which I carry on my back. When I arrived at work planning a scorching weather run, I started drinking water. And I did not stop until I went down to the gym to change. I drank before climbing Camelback, but I paid more attention to keeping the water in my pack cold. A steep climb is anaerobic. A run at normal training pace tends more to be aerobic. When your workout is anaerobic, you burn water fast and have to have enough to immediately restore it. When your workout is aerobic, stored water is sufficient. So the rules of water consumption depend on the nature of your workout. But depriving yourself of water before and during hjot weather exercise is insane. It's extremely dangerous, it will generally cause you to slow down and stop and it is as foolish a strategy as I have ever heard anyone suggest.
Ny Surgeon (Ny)
@michjas Your workouts are frankly dangerous. You cannot replace your water loss without dangerously depleting your sodium, and that can kill you. Quickly. It is absurd to suggest that stored water is enough for aerobic exercise. You mean that with a temp of 100 degrees, I can run for 5 hours, say 30 miles, and not become dangerously dehydrated without water? That is ridiculous.
Jaque (Champaign, Illinois)
This is another ill conceived study on human physiology. Acclimatization requires living in the specific climatic conditions for a 2 to 10 days. That means you live in hot, cold or high altitude 24-hours a day for a few days. One hour exercise in heat followed by 23 hours of air conditioned living is not going acclimatize you to hot weather!
Still Waiting for a NBA Title (SL, UT)
@Jaque Agreed. The last few years we have decided not to use the A/C during the summer. Much of our house is in shade for most of the day as we and our neighbors have large trees and my neighbors houses are pretty close to mine. The main floor of my house gets to about 80's in the summer. The walk out basement stays in the low 70's. The upstairs, which only consists of the master suite, gets to the low 90's. We don't go upstairs very much during the day. At night when it drops to the 60's outside we open the windows and everything cools off pretty quickly. Even when we close the windows all but the window on the upper floor before bed. I do live in a dry climate so 80 degrees is a lot different here than 80 degrees with 70-80% humidity, Those temperatures are when it is in the high 90's to low 100's outside, which is typical here in the summer. Not only does it make going outside in the non-air conditioned world much more pleasant. But we save $100's a month in electricity and pollute the environment less. My friends and families who insist on keep their homes in the high 60's in the summer all complain insistently about the heat outside when I try to get them to do stuff before the sun goes down.
rockstarkate (California)
It's rather unbelievable that this needs to be said. What a world we live in, where people with unlimited access to fresh, clean water, deprive themselves of it in some kind of misguided quest for better "health." Our world is truly a mess.
Anon N 1 (Japan)
"Machiavellian style"? Which Machiavellian principle do you have in mind? "It is better to be feared than loved, if you cannot be both"? I can't think of any that apply.
Krautman (Chapel Hill NC)
Hydration and thermoregulation are two different physiological issues. When we are truly dehydrated, we become thirsty and we should drink water. How much? Until thirst is gone. Water intake beyond a quenched thirst only dilutes the urine , thus increasing urine volume. Excess water is not stored, even if you have a camel hump.If medication or pain causes inappropriate concentration of the urine ( SIADH) , drinking beyond thirst may lead to hyponatremia. Brain cells swell in a closed space. Thermoregulation requires evaporative sweat which is impaired by high humidity. Pour your water over your head in front of a fan!
Dr. Anthracite (Scranton, PA)
Wait, there are people who think NOT drinking water on hot days makes their training BETTER? When I played H.S. football in the late 1970s, our coach thought that. He was 1) born in 1910 and 2) an idiot. I thought for sure that myth died a long time ago. To be sure, there are some people who overdo it (most of us don't need a liter of water for a half hour treadmill jog), but the idea that extreme heat is best battled by skipping water is old school training at its worse.
toddjm49 (austin tx)
It's insightful content like this that makes that $40/month subscription to the NY Times feel like money well-spent.
Ridem (Out of here...)
@toddjm49 I detect a whiff of sarcasm,perhaps?
Neil (Texas)
Why is this study even necessary?? And I am surprised that it does not mention dangers of fainting from dehydration. I lived in Houston at one time and worked downtown. I could never get over these professional young men and women - so called yuppies and millennials - pounding pavement during lunch hour. There should be a law against this stupidity - especially when downtown Houston is all connected underground with tunnels. And they let you jog.
Yirgster (SFO)
This study was based on a total of 8 (!!!) 'fit young men'. Not exactly a large number nor a cross section of those who exercise.
fsa (portland, or)
Like everything in life, correct hydration requires balancing bodily needs and good sense. Over-hydration leads to 'dilutional hyponatremia' and other electrolyte abnormalities, just as dehydration allows such electrolytes(potassium, sodium, etc.) to concentrate. Either state is dangerous, leading to cardiac irritability and potential sudden death, even in healthy young people. Don't forget Rhabdomyolosis, a sequela of vigorous excercise, complicated by inadequate hydration, among other causes. Muscle protein is broken down, clogs the kidneys and other organs, is life threatening- and kills. Good rule-Look at your urine. If too yellow, certainly if looking brown, drink immediately. Emergency Doctor Trauma Center
The Pooch (Wendell, MA)
Drink to thirst. Sure, don't dehydrate on purpose, but over-hydration during exercise is far more dangerous, having produced fatalities in marathons, triathlons, long football practices, etc. Over-hydration is specifically promoted as a sales gimmick by sports drink companies. See "Waterlogged" by Tim Noakes.
Katherine (Dallas TX)
I recommend Waterlogged to anyone who will listen. An article in CNN yesterday described the cases of two student athletes and others who died from drinking too much water. The most telling line in the article was this: "no football player has ever been known to die from dehydration, although seven died during this same four-year period from heatstroke, which may be related, but not always". Waterlogged explains this in detail. As always, it's follow the money - we didn't have these recommendations until the bottled water and sports drink industries were born...
BostonDoc (Boston)
Actually, the main danger during exercise in hot weather is OVERHYDRATION and resultant hyponatremia. Happens every year to participants in the Bosotn marathon and can reuslt in seizures or even death. This was a rare phenomenon before the dehydration phobia group gained ground. It is important to NOT drink too much.
Ron A (NJ)
If nothing else, I would think training in hot conditions without hydration would enable one to better withstand exercising in similar conditions when fluids were in short supply. They may also have an edge in races if they can make do with less pit stops.
MDB (Indiana)
@Ron A — You have to use common sense with this strategy. You have to sustain a good level of fluids in relation to your body weight, and pay close attention to that during the course of the activity, as well as your amount of perspiration. “Run by feel, not effort” is the runner’s mantra during hot weather. That means not worrying so much about pace or time, but paying attention to air temperature and dew point, and slowing down or stopping altogether if the latter gets too oppressive. It also means carrying your own supply of fluids, or placing them along your course for access. Your body works exponentially harder the warmer and more humid it is, and its toll creeps up on you. Dehydration is serious business. I have come close to sickness while running long distances a few times, and trust me, it is not a badge of courage or honor, or a testament to one’s fitness. It is scary and, in some cases, fatal. The body can adjust to hot weather exercise, which pays off when it cools, but you have to be careful in the meantime. (I use running as an example here, but I’m pretty sure it applies just as well to other physical activities in the heat.)
heavy sweater (Va)
@MDB You didn't get sick because you got dehydrated. You got sick because your temperature was too high because your workload was too high for the heat. Hydration does not equal cooling. I run in 90+ temps with high humidity all summer. I have lost as much as 15% of my bodyweight during long runs (during which I drank as much as I liked according to thirst). "Dehydration" is a bogus non-ailment. Heat exhaustion and heatstroke are real. When you feel awful when exercising in the heat, the solution isn't to drink, it's to cool down, by slowing or stopping exercise, getting to a cooler place. There's no magic to this. Drink when you're thirsty. Don't drink when you're not. Stop exercising when you're getting too hot.
Ron A (NJ)
@heavy sweater I do agree with you that heat exhaustion and heat stroke would be the medical conditions that would render a person ill. Still, being dehydrated can hasten those conditions. For one thing, you won't have enough extra fluids to sweat and keep yourself cool. I'm not sure I would accept your claim of losing 15% body weight in a day. For someone who's 150 lbs, that would be a reduction to 127.5! Are you sure you didn't mean 5%? As a reference, I do weigh 150. The most I ever lost in a long day in the mountains was 10 lbs or 7%. That was largely due to not eating. And, strictly for water loss, on a few occasions at the gym, after a particularly strenuous aerobics session, I lost 6 lbs or 4%.
Emergence (pdx)
The human body can adjust to stresses like dehydration to a point in an attempt to maintain or restore homeostasis, to a point. However, the insidious thing about losing 2, 3, or 4 percent body's water weight is that you can ignore it but beyond that, your kidneys can shut down to minimize water loss. That leads to kidney and other organ failure, severe electrolyte imbalance, shock and death. You cannot simply drink your way out of severe dehydration. Even intravenous fluids many not be effective because systemic rehydration is not immediate so it could be too late. There are too many stories of high school athletes collapsing and dying from too much physical exertion from insufficient water consumption in hot weather leading to death.
michjas (phoenix)
@Emergence Your scenario fits 70 year olds. But most young athletes dehydrate and start feeling cold and weak long before they go into shock and die. There are some very well known road racers who have badly dehydrated, become unsteady, and fallen to the ground. But if a top road racer dies from heat stress, it is almost always because of a genetic heart problem or a serious deficiency in some other organ.
Jaque (Champaign, Illinois)
@Emergence Reports of deaths are from "Heat Stroke" not "Dehydration"! Two are not related. Only treatment for Heat Exhaustion is to move the person in an air conditioned room. drinking water will not prevent Heat Stroke.
Krautman (Chapel Hill NC)
Correct. And small folks thermoregulate more efficiently than do large folks. Small people have relatively larger surface area/volume ratios than big people. This means smaller people have larger evaporative surface to cool their bodies. Bigger air conditioner. Who have I dialyzed in the ICU with heat -related rhabdomyolysis? : Large muscled football players and similar sized military recruits.Being " in shape"offers no protection from heat -related damage..
Menno Aartsen (Seattle, WA)
No, Ms Reynolds, we do not "generate internal heat more quickly than if the weather is cool" when the weather is hot. We just expend more energy cooling down. That energy does not come from "drinking". Sweat is one of the mechanisms the body uses to get rid of excess heat, but the path from fluid intake to sweating has little to do with "drinking during exercise". Drinking cold fluids during exercise - by cold I mean anything below body temperature - actually uses more energy than exercise without fluid intake.
michjas (phoenix)
@Menno Aartsen The notion that drinking uses too much energy when it's 110 out is novel. In fact, Mr. Aartsen is probably the only person in the world who subscribes to this theory. Things out of Seattle tend to be overrated. There's Mr. Aartsen's theory and Starbucks, the most bitter coffee in the world.
Still Waiting for a NBA Title (SL, UT)
@michjas Perhaps, but Grunge music was/is pretty awesome.
Janet (Oakland)
Gretchen, the article was great, until I came across your comment about "Machiavellian style" . It stopped me cold. I have no idea what you were trying to say - I don't think there was any advice that he gave to the Prince that would apply. I don't know if the NYT policy permits editing after publication, but it would help your article!