Water intake when running long

Krusty_Clown

Hi guys, long easy run today and I really messed it up, pushing the bounds of dehydration to nausea and near run-stopping levels. After completing the first 18 miles, I had consumed 2 x 500ml bottles of water (along with various energy products) and felt fine. I skipped a petrol station that looked too small to sell non-fuel products, and then didn't pass a shop until mile 25 at which point the damage was well and truly done.

Obviously I need to plan my routes a little better, but for future reference, is there some mechanism or approximate rule of thumb for how much water one should consume per hour, given an individuals body-weight? I'm aware of the process of weighing yourself after the run to see how much water-mass you have lost (2.2kgs in this case) but I'm looking for a more proactive rather than reactive suggestion. Thanks!

(and before the marathon bashers turn up, I'm not training for a marathon. )

RayCun

Does the rate of water loss increase over time? Could you weigh yourself after an hour's run, calculate the water lost there, and extrapolate?

BeepBeep67

In the nutrition booklet I posted, it talks about hydration and the best method is the before and after weighing method - however it does state that you can cope with up to 2% body weight loss - so a 70kg runner can cope with a 1.4kg loss.
I suppose that's why you experiement in training.

TFBubendorfer

Krusty_Clown wrote: »

Hi guys, long easy run today and I really messed it up, pushing the bounds of dehydration to nausea and near run-stopping levels. After completing the first 18 miles, I had consumed 2 x 500ml bottles of water (along with various energy products) and felt fine. I skipped a petrol station that looked too small to sell non-fuel products, and then didn't pass a shop until mile 25 at which point the damage was well and truly done.

Obviously I need to plan my routes a little better, but for future reference, is there some mechanism or approximate rule of thumb for how much water one should consume per hour, given an individuals body-weight? I'm aware of the process of weighing yourself after the run to see how much water-mass you have lost (2.2kgs in this case) but I'm looking for a more proactive rather than reactive suggestion. Thanks!

(and before the marathon bashers turn up, I'm not training for a marathon. )

Ok, on that very same day, today, I ran a long easy run myself, 20 miles, had exactly 0 ml of water and finished the run just fine. 2.2 pounds down is nothing and under normal circumstances I don't think you were particularly dehydrated.

Were you starting in a dehydrated state? Long drinking session the night before? The first long run in months perhaps? Taking loads of gels during the run?

On a more proactive basis, I always drink a lot of water immediately before the run (probably over 500ml, but I'm not actually measuring is), and hardly ever take any water during my training runs because I simply hate to carry anything heavy along with me. But since you're not exactly a novice yourself I presume you already do that.

aero2k

I tend to lose about 1kg per hour on long runs, perhaps a little more if it's hot. (measured by before and after weighing, and allowing for fluid intake on the run). I have lost over 3kg on hot days with no ill effects - that's assuming the heavy legs towards the end is down to distance rather than dehydration. In an ideal world I'd try to take in 500ml per hour during the run but it's actually difficult to drink that much, even in the heat of Edinburgh I doubt if I got much over a litre into me.

Like Thomas I try to be well hydrated the day before and the morning of a long run.

The only time I've had an experience like you describe was a couple of times when I "bonked" on the bike. (presumably due to low blood sugar levels as a mars bar / some fig rolls brought about a dramatic improvement).

heffsarmy

How often are you running the 25miles? The weather lately is very mild, I wouldn't take any water for on board for 20miles after that it would be a mouthful. If your well hydrated before a long run you shouldn't need too take on loads off water, your body will get used to it over time. Now if we lived in the Sahara desert it be different

Woundedknee.

For me I always make sure to be fully hydrated before a long run and wouldn't take any drinks during a training run except when doing a longer than usual session. This is something I've done over time and it's down to training in the same way as you train to run faster and longer.
The night before an early run I weigh myself and weigh myself again in the morning and would try to replace what was lost during the night before I head out with a liquid breakfast.

RacoonQueen

I'm the same as woundedknee. I don't bring water with me - at all. If it was a hot day I'd bring money just in case I needed to stop at a shop. I maintain good hydration levels throughout the day and never feel the need for it on a run, I've done this in training runs of up to 23 miles and never reached a point of feeling dizzy, weak or ill.

I'm not in posession of a weighing scales though so I don't know how much I sweat! :pac:

Enduro

An I'm also in-line with the above posts. I never bring water out with me on long runs, which can be up to 4 hours long. I reckon that like everything else, the body can adapt to deal with this.

Krusty_Clown

I am greatly surprised by the number of you who wouldn't bother with water on a 20 mile run. Certainly if I was running 17-18 miles I wouldn't bother, but for a 20 mile run, to ensure the quality of the run I'd stop at some stage for a bottle of water. I suppose two miles isn't a huge distinction though. Maybe it's something I should consider doing in future, to encourage the body to develop in that direction (though most of you are very long distance runners!).

No hangover, couple of bottles of beer the night before, nothing hectic. Porridge + coffee + 700ml of water before heading out. It was a 30 mile run (4 hours), and my third 26+ mile run of the year so far, so not the first long run in months. Definitely dehydration. Not sugar depletion.

Last week's 26 mile run with the same amount of water (but significantly faster) was a world apart from this run and I finished it strong, knowing another 3.5 miles would be easy. So I guess I'll rack this once down to an anomoly. But I was really looking for guidance on how much one should drink, rather than trying to identify the root cause.

Any guidance on how much water you would aim to consume in a race environment? Say 30-35 miles?

--amadeus--

I don't do the ultra thing so take or leave this as you see fit!

I don't think the issue is how much you drank, how much you sweated or how much you normally drink. I think the issue is that you didn't have water available when you needed it. I can't remember if you have read "The Lore of Running" but Noakes strongly recommends that you forget all about traditional teachings about running and dehydration. Instead he says that you should just drink to thirst (background blurb here and here). Dehydration is normal and your body will give you plenty of warning when it needs fluids. It seems in your case though it needed fluids that you couldn't give, hence the symptoms. As you say maybe just an anomaly where you happened no need more water today than usual.

I used to do the no carbs thing on long runs with nothing at all under 16 - 18ish and only water up to 22 - 24. In the last couple of training cycles though I have been a lot less regimented and structured about training and I bring gels and fluids on runs of 18+. Sometimes I take the gel, sometimes not, sometimes I empty the drink, sometimes I bring it back half full. It's developed into a cliché but your body will let you know what you need, it's up to us to have it to hand when required.

tunney

Most I have ever run in a day is 60km, didn't take any water on board during the runs but always started fully hydrated.

However then I was fit and lean. Now unfit and fatter I sweat more so I would, if I was going over 2 hours, like about 250ml an hour of water or light solution of energy drink.

I think it all depends on your sweat rate and the temperature.

Gringo78

The bottles of beer will have left you not in the mist hydrated state heading out. I used to not take water on long runs, 20 miles no prob, but if I had 2 drinks the night before I'd notice the effects of dehydration kicked in a lot faster. I now drink an extra pint of water fir every alcoholic drink to counteract it, preferably night before.

tunguska

Krusty_Clown wrote: »

I am greatly surprised by the number of you who wouldn't bother with water on a 20 mile run.

Im surprised aswell. Personally, on a 20 miler, I'd get through 2 litres. In colder weather anyway. In the summer I'd go through 3 litres for a 20miler. I run a 10mile loop which passes by the house, so I'll take a litre bottle with me at the start, throw it in a bush after 2miles and then grab when I need it as I go along. Then I'll have another litre bottle waiting for me on the porch after tha first 10miles is done, grab that quickly and throw it in the bushes again. So overall theres no stopping at all, I can rink and keep going no matter what.

Krusty_Clown

tunguska wrote: »

Im surprised aswell. Personally, on a 20 miler, I'd get through 2 litres. In colder weather anyway. In the summer I'd go through 3 litres for a 20miler. I run a 10mile loop which passes by the house, so I'll take a litre bottle with me at the start, throw it in a bush after 2miles and then grab when I need it as I go along. Then I'll have another litre bottle waiting for me on the porch after tha first 10miles is done, grab that quickly and throw it in the bushes again. So overall theres no stopping at all, I can rink and keep going no matter what.

And what would you drink during a race Tunguska? Similar amounts, or just take it as it comes?

Kangshung

RayCun wrote: »

Does the rate of water loss increase over time? Could you weigh yourself after an hour's run, calculate the water lost there, and extrapolate?

Totally unscientific but in my own experience the water loss wasn't linear when I weighed myself before/after a few runs in the evenings last Summer. Running a medium-slow pace for an hour I'd lose around 1.5kg (I seem to sweat more than most of the finely-tuned running machines here!). Next evening I'd run for 1.5hrs and not lose much more than that.

Similar pattern happened a few times but not enough to draw any definitive conclusions from, seems like it should be linearish really as it's not like one would stop sweating an hour into a two hour run. Weather makes a huge difference for me anyways, and no way I could run more than 2 hours without water in anything other than freezing temperatures.