Do You Over-Hydrate in a Marathon?

This is a subject I am a little passionate about. I get worried for others when I see runners making hydration mistakes in training and in races. While this post is mostly written in my opinion and is written in all my own words.  I did however, take tips and suggestions from qualified sources to prove point. Sources are sited below for those interested.

Runner Type 1  I once met a guy during a marathon who made it a goal to not stop and drink at any of the water stops the entire 26.2 miles. I've also met a few runners who have told me in a marathon they may only stop 2-3 times the entire race to take a drink.

Runner Type 2 I have seen runners who are stopping to drink water every single mile during a marathon. And others who carry hydration packs and fill them at water stops so they can sip on their own drink in-between each of those water stops between the mile markers.

Let's test your knowledge. 

Whom of those two types of runners listed above are at greater risk of death or other serious problems?

If your an experienced runner, you probably already know the answer. But if you are newer to distance running let me tell you. 

It's the runners who stop at every water stop or who carry hydration packs and sip on them between water stops then also drinks at the stops who are far more likely to have health issues and risk death during a race.

It's true.

FACT: Did you know there is actually no known case of a runner in a US marathon ever dying due to dehydration in a race? BUT there are several cases where runners have died from over-hydration during a marathon. (Hyponatremia is the official term for over-hydration.)

Yup, in fact, more runners will over-hydrate in a marathon than under-hydrate and that is even in the hot races.

For this reason and the fact that many runners aren't using their marathon training schedules to learn how to hydrate properly. There is a push from the Road Race Medical Community for races to begin to decrease the number of aid stations, to ONE every 2-3 miles along a race course.  Since some runners can't teach themselves to drink correctly, having the water spaced out more correctly on a course can help teach them and help them out so they will have less chance of hurting themselves.

I personally think this is very wise, and I give a lot of props to the races whom have already conformed over to this.

Many think marathon training means getting in shape and learning to stay on your feet for 26.2 miles. Which is correct.

However, so much more should be put into your training.
One of those is learning how to hydrate properly and learning to teach yourself not to over drink. While it can be dangerous to become severely dehydrated. The risks apparently are far higher to start getting into over-hydration drinking habits in races and even in training.

A few interesting facts I learned while researching for this post:

* Studies have shown runners who are losing 1.5%-3% of their body weight during a race from dehydration have actually performed better in a race, than those who over-hydrate.
(In case your wondering, 1%-2% body weight loss they found was a fairly decent average for most runners in a marathon by the end.) 

* Some marathon runners will finish a marathon weighing more than they did when they started the race, purely because they are over-hydrating. This is extremely dangerous for some and those doing it probably don't even know how big the risks are!

* Always start a race fully hydrated, especially an endurance race.
If you do, hydrate properly you should never need to stop at a water stop in a 5K or shorter races around that distance. On a side note, not stopping to drink in shorter races can improve performance and your race times. As well as drinking correctly and not over-hydrating can improve performance in a marathon as well.

* 3-4 miles is the perfect distance between water stops even in hotter temperatures. However, you may find in winter or colder months you can easily go a few miles further between stops. 

If you are currently training to drink more frequently already, you can easily begin work on correcting this in your marathon training plans.

* Getting headaches after you run, or feeling lightheaded or dizzy towards the end of a run or in the hours following a run are possible signs your not hydrating enough. Additionally, if you find you are cramping up far too often in a run or after may also be signs you are not hydrating properly.

* Urine test. As a runner you should aim to have your urine looking like the color of lemonade. If it's too dark, your under hydrated for your daily training. If it's too clear, you may be over hydrating daily.

* Don't get into the, I'll drink a gallon of water a day fad. For most people, that could be way too much. While the 8 glasses or 8 oz. water a day is a pretty steady rule for most, even that rule of thought is outdated info. (FYI: 8 glasses at 8 oz. is only about half a liter.)

Want to know how much you really need? Take your total weight and then divide it by 2.
The answer you get, is how many ounces you should be drinking each day. (For your normal hydration purposes - See below to add your water for workout purposes.)

* If you work out, you obviously need more water than on days you don't. While most people can tell based on signs and thirst factor, not everyone is intuitive with their bodies actual needs. For those who fit this, you can use the sweat rate test. 

Weigh yourself before you go out for a (1 hour is a good one) training run, then when you return weigh yourself again. For each pound lost, example 1 pound means you should drink about 1 pint of water to recover from your sweat rate.
Granted this test isn't fool proof. Weather, temp, speed and distance may each play a role in this test, so you may need to adjust for different circumstances.

* You can't hydrate properly for a long run or a marathon in a day or two leading up to a race. In fact, leaving it to last minute won't help you much at all.
You should be fully hydrated 8-10 days leading up to any long run or marathon.

* If you are training for a marathon, especially when you get to the longer runs and months leading towards the race. It's best to cut out all alcohol consumption, as drinking alcohol can lead to dehydration.

* MARATHON DAY TIP If running a marathon, drink your morning water 2 hours before the race start, and try not to sip on anything while waiting for the race to start.  Some runners find doing this, and a quick swallow or two of water just before the gun goes off reduces the need to stop at one of those not so lovely port-o-potties during the race. 

(FYI: This is what I learned to do, and it works amazingly, I rarely ever have to stop and use a bathroom along the course!)

* To keep you from getting too scared, One thing to note is, about 99% of the time most marathoners who finish a race are slightly dehydrated or slightly over-hydrated and they are perfectly fine and it is completely normal.

How do you know if your drinking too much water in a race?

* If you find you are stopping to have to pee often in a race.

* If you are stopping at every single water stop at a race that offers them each mile and you are drinking more than 2-3 oz. each stop. 

* If you finish a run and are weighting more than you did when you started the race/training run.

Informative resources I used as a guide for this post:
(Disclaimer, I was not asked by any of these news sites to promote their material. I purely used them as educational resources.)

Did you learn anything today?
If you train for marathons. Do you find you drink too much, or too little or just about right when you race?
Do you make sure to practice hydration training along with any race training?

Disclaimer: I wrote this based on research and my own opinion. I am not a doctor or trainer and information in my posts should only be taken as my opinion not be taken as advice. If you have further questions on this subject, I recommend asking your doctor or a skilled nutritionist/trainer on the subject.


  1. Great information! I'm not good at hydrating properly on a day to day basis but I'm working on getting better at that.

  2. OK - that freaks me out now that I'm over hydrating. But I get so dizzy & lightheaded with low blood sugar so am always trying to snack -which I need water. The 10 mile race I just did I wondered why the water stops were every 2 miles... makes more sense now. I have to look at my HM route now & see the water stops.

  3. The instructor who taught my coaching class was on the "people drink too much" side. He was an old school Olympic hopeful from the 70/80s and thinks it's a fad -- and not a good one. I can say I've never stopped in any race to tinkle. But, there are a lot of people who do. That's is an excellent indication you are drinking too much. I sweat anything I drink during the race right back out...and much more! (I even see people carrying fluids in a 5k. )

  4. I think it becomes a work in progress for all of us from time to time. For instance right now I am great with hydration daily, but 2 months ago, I was terrible at it. LOL

  5. Most races should be going back to water every 2-3 miles. I think even most marathons are already switching to water after mile 3, and then only every 2 miles thereafter. So according to what I have read, you'll see it more and more. But it's a good thing, to help runners.
    I read that for some people like to drink often, the key is just to drink less when you do. So for instance if you are snacking often in a race and need water with it, just drink 2oz so a swallow or two instead of a full cup. Very easy things to start practicing with in training especially as the warmer months start coming up!

  6. I think I tend to underhydrate, even tho I carry my own bottle. I never have to stop to pee during a marathon. I don't carry water, I carry Tailwind, which is an ultramarathon fuel with sugar and electrolytes. At last year's Chicago Marathon, I also stopped to drink water a few times. It was so hot. And I still was a little dry at the end.

  7. This is great information and a topic that's not talked about enough. My first year or two of running I used to overhydrate before doing 5k races. The result was a lot of stomach sloshing and side stitches. Since then I've learned to drink less before racing!

  8. It's so funny you said that. I was speaking to a local race director about this a while back and he also used the word "fad" to describe the over drinking craze. He thinks since most marathons especially larger ones are out for first timers and the money making they throw in extra water stops to make it look more appealing to those who don't understand less is more.
    I am like you, I rarely if ever need to stop to use the restroom. When I first started running them, I used to drink water up until the start and once I leaned to drink 1-2 hours before it made a world of difference and no more stopping:)
    Yeah, I never got the 5k fluid carriers, either.

  9. I only recently started hearing about Tailwind from a lot of ultra marathoners, and I hear good things about it!
    I'm like you a little. I myself find occasionally I tend to underhydrate a little as well in the later miles of a marathon, it's never hurt me, I think I just get to the point I'd rather finish than stop and drink, LOL

  10. I drink very little on race morning. Like you, what I do drink is long before the race. I make sure I'm well hydrated a few days leading up to it. Heck -- I can't run with all that sloshing around in my stomach!

  11. Thank you! One of the reasons I wanted to write this one is for exactly what you said, it's a topic not talked about enough and for some who get into risky habits in training it can actually become so dangerous.
    When I first started running marathons, I would drink right up until the start and I know exactly what you mean about the sloshy feeling. Once I figured out a better way, I haven't had the problem since. But yes oh that sloshy feeling an side stitches, not good memories, LOL

  12. LOL I am with you there! Nothing worse than a sloshing stomach!!!
    Good luck this weekend, #40 that's a huge amount of races, at this rate next year you'll be telling us your lining up for #100 :)

  13. Back in the day, in other words, when I used to be a serious sunner lol (late 1980s, early 1990s), I'm pretty sure there were fewer water stations/aid stations on the course. I seem to remember the last marathon I ran having a station at 3, 6, 9, 12, 15, 18, and then every mile from 20 on.

    I'm inclined to agree with some of those you have talked to regarding the fad thing. Races are all about getting the numbers these days, the "rookies," and it probably makes the race a little more attractive to the new crowd knowing there's an aid station every 50 feet :)

    I'm not surprised at all in this day and age that more people tend to be over-hydrating during a race. You get bombarded about how important it is to stay hydrated and then you throw a long distance run into the equation -- that must mean you have to really up the water intake! People don't realize that it's perfectly normal to be somewhat thirsty after a race :)

  14. I remember even 5-10 years ago we seemed to see fewer aid stations. I've noticed in races that are hosted or directed by runners or previous runners you still find the original methods of like you said 3, 6.. or the 3, 5, 7...
    Yeah, I think some races are too into the numbers these days, very much agree on that! They are far more into attracting anyone to run, I think that's why we now see finishers medals in 5k's and pretty much every race now.

    I agree with you on the bombard. I remember my last marathon the volunteers (even though they were awesomely trying to do their job.) were in every runners face, with "stop, here drink , take two if you need." If you don't take it, they sometimes say things that it worries them, not realizing you may have just taken water the mile before.
    While I know they have the best intentions, I think some race organizers should spend a little more time educating the volunteers.
    But you are right, it's perfectly normal to be thirsty after a race, that's when you can relax and take a nice long cold drink and it seems to taste so much better than too:)
    Thanks for visiting today and your comments!!!

  15. My cousin became huge into running a few years back and is always posting pictures on Facebook. Things that I always notice in those pictures that I never did back in the day -- earbuds and water bottles. I don't remember anyone carrying anything. Of course when I was doing this you didn't exactly have the digital music player/armband option (it would have been awesome).

  16. I've not done a full marathon so I don't really have any info to add but I have read a lot about over hydrating. I find it so interesting. I think that's why it's best to practice your strategies and find what works for you

  17. Ya, I am not sure when the carry a water bottle thing started. But if it makes them happy:)
    LOL sometimes listening to music in a race is overrated, you miss a lot of the casual runner chat. But on another hand ya sometimes it's awesome especially in training!

  18. I find it a interesting subject too, glad I am not the only one:) I very much agree, I think that's what training is for to learn how our bodies work and how to hydrate them to our best advantage, practice makes perfect (or close to it, LOL)

  19. Such a good tip. I was so worried about being dehydrated during my marathon traing that I was drinking water constantly. Then I read about over hydrating... and backed off! Hard to know that balance. And I also think every individual needs different amounts of water!

  20. Yes, I think it is one of those things that just comes with practice.
    But I agree with ya, each individual is different, just like all runners come in all shapes, sizes and speeds!

  21. This is so interesting. I definitely do not overhyrated. I make a point of that because I don't want to have to stop at the port o potty. All this time I thought I was doing it I also did not know how to calculate how much water I need by weight, so thank you for that tip!

  22. In my recent marathon, I drank a glass or so every 5K, it was so hot ! 70 degrees. I was worried about drinking too much water actually but the heat was crazy. And I didn't stop to pee once so I figured I wasn't taking in too much.
    I find I get injured when I am dehydrated... so I pay a lot of attention to how much I drink

  23. Great info :) I think working on being fully hydrated several days out from the race is the best advice! It gives you a much better chance on race day to just balance and take in what you need.
    I do a lot better these days with hydration than I used to. I never try to overdo. You can always drink after. I try to space out my intake after an event to get myself hydrated again:)

  24. Tricia MissSippiPiddlinMarch 8, 2017 at 6:32 PM

    I think I worry more about having to pee in a race than being thirsty. I hardly ever stop in a 5k and will stop for a few sips in a half. I'm always afraid of guzzling too fast in a race too. All great advice Kristy!

  25. Wow! I had no idea about this! If anything I am usually dehydrated by the end of a race especially if it's hot out. This was great to read! Thanks for sharing Kristy!

  26. I am guilty. So guilty. I tend to drink so much during a run that at the end of the run, I'm not thirsty, but I had no idea people have died from overhydrating at races. When I started out doing races, I would stop at every mile because I thought since they had it, it must mean I should be drinking but stopping so often made my time suck. That's what made me stop, not anything else.
    Great info here as always. Thanks for sharing.

  27. I'm same with you on disliking having to stop at a port o potty!
    Glad you found it useful!

  28. That's interesting about injuries and dehydration. That's awesome your good and in keyed into what your body needs!
    I'd say a drink every 5K was perfect for your marathon you just ran!

  29. Yes, I really do think being fully hydrated well in advance for a race does give you an edge and better balance!
    I'm the same way as you, I've gotten better with my hydration habits through the years!

  30. Thanks, glad you enjoyed it!
    One of my biggest things I hate to ever stop in a race to pee, so yeah I would rather drink less than have to stop and wait in line at a port-o-potty!

  31. When I did the research they said most people are slightly dehydrated, but those are usually the ones that perform better in the race.
    I am kinda like that too, I do try to drink correctly but when I finish I am usually ready for a big long drink!

  32. Ya, it's kinda scary. I was at a race once were I read about it happening to a gal after, that was the first time I learned that people can die from being too over-hydrated. I've been drawn to the subject ever since.
    I don't think your alone, I see so many in races stopping at each stop at every mile because they assume they have to. I think that is one of the reasons for the push to not do frequent water stops anymore. Glad you enjoyed it!


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