Overhydration and Endurance Running

http://www.irunfar.com/2012/07/waterlogged-a-dogma-shattering-book.html

by SeanDav • 11 years ago

93 28 11 years ago

nl5• 11 years ago

Tim Noakes has been talking about the over-hydration problem for a while.

It isn't clear to me how big a problem it really is. His recommendation of 400-800ml per hour for all endurance athletes isn't exactly controversial. In cycling lore the advice is 1 bidon/hour, which is around 600ml.

It's true that his advice against sodium supplementation doesn't suit sports drinks companies, but I don't think this is controversial from a sports-science point of view either. Sodium/electrolyte replacement drinks are unlikely to be harmful, and there is some evidence that some people find them easier to drink when exercising hard.

JshWright2• 11 years ago

I have a buddy who is an MD for various ultramarthons, and I've helped him with a few local 'nonultra' marathons (I'm a paramedic).

None of this is terribly earth-shattering, in my opinion... Regular oral hydration based on thirst, self-evaluation (Borg Scoring [1], etc), avoiding IV fluids (but using hypertonic solutions when necessary), etc... All stuff that has been talked about for quite some time now.

[1] https://en.wikipedia.org/wiki/Borg_scale

nether• 11 years ago

What about sports drinks vs pure water for endurance activities exceeding 2 hours? I used to only drink water, but switched to diluted Gatorade and found it to hydrate much better (less urination) and reduce soreness the next day.

nl5• 11 years ago

found it to hydrate much better (less urination)

Usually less urination is a sign of less hydration(?). There are studies that show that some people find it easier to drink the correct amount with a sports drink than with pure water.

reduce soreness the next day

Depending on which Gatorade drink you were using, you may have found some benefit from the carb content that some sports drinks have. There are some theories that easy-to-digest nutrition (which diluted sports drinks can be) help avoid hitting your fat or protein stores. Using fat or protein may cause muscle soreness in some people. I haven't seen any studies investigating this though.

JshWright2• 11 years ago

I don't have any actual data to back this up, but anecdotally, I find water and gatorade in a 2:1 ratio 'feels' better the next day (I don't mix it, I just drink two water bottles for every bottle of gatorade). However, my 'long term endurance' activity is firefighting, not running, so there may be some difference there.

bucketsofdirt• 11 years ago

I know you should be drinking water, but why avoid IV fluids? Are there certain ones that you should try to avoid more often; NS, LR?

I only ask because sometimes if I'm just not there- hydration wise- and I'm not thirsty I'll throw on 0.5 NS; often I cannot drink enough to replenish the fluids I'm losing.

AndrewKemendo• 11 years ago

Reading this makes me think that I did this on my first ultra. The general wisdom is eat/drink before you are hungry/thirsty and do it slowly. I ended up feeling bloated for the last 15 or so miles.

Race day eating is really one of the hardest parts about ultrarunning.

noir_lord• 11 years ago

Similar with cycling.

I did a 120 mile charity ride and was so worried about hitting the wall I over ate and felt nauseous for the last 20 miles.

outericky2• 11 years ago

I think eating is a separate matter. Plus, eating (particularly slightly more solid food) takes longer to absorb, so if you eat after you are hungry you are just extending that hunger longer.

That said - I've done many long (8-12hr cycling only or triathlon) events on liquids alone (I prefer infinit.us).

Liuser• 11 years ago

Same experience on my end for my first ultra distance race. However, feeling bloated is much better than bonking.

plorkyeran2• 11 years ago

"There is no relationship between fluid intake and hydration" is a very odd statement that doesn't appear to be ever followed up on and is on the surface utter nonsense. Is there a missing qualifier here ("fluid intake beyond 'drinking to thirst'"), or am I just missing something?

neaanopri• 11 years ago

Hydration and Thermoregulation
Dogma: We must drink water in order to prevent heat illness during exercise in hot conditions.
Science: There is no relationship between fluid intake and hydration, and the incidence of heat exhaustion or heatstroke. The only correlate to core temperature is running pace.

If I'm reading it correctly, there's no relationship between (fluid intake and hydration), and (the incidence of heat exhaustion or heat stroke).

It's a shame English isn't associative.

darkmighty• 11 years ago

How about:

There's no relationship between fluid intake and hydration versus the incidence of heat exhaustion or heat stroke.

Just use a different conjunction.

plorkyeran2• 11 years ago

Ah, that makes far more sense than how I'd parsed the sentence, and actually fits with the following text.

dbbolton2• 11 years ago

Urine frequency or color has nothing to do with hydration or kidney function.

That is not strictly true. They should have said "don't base your water intake on urine/urination".

Decreased urine volume and abnormally dark urine are both signs of dehydration (early and later stages respectively). They are also both associated with decreased kidney function. But a symptom alone never makes a diagnosis.

In other words, you can't assume you are dehydrated/your kidneys aren't working right based on those signs by themselves. As more an more signs/symptoms become apparent (esp. neuro/GI) then dehydration is likely.

electromagnetic3• 11 years ago

Dark urine is a sign of a lot of things, but also dehydration.

Frequent urination is a sign of a lot of things, and also over-hydration.

However, assuming either are related to your present hydration is dumb.

If you're regularly saying "my urine's dark, I must be dehydrated" you should probably be visiting a doctor.

niels_olson• 11 years ago

If you're regularly saying "my urine's dark, I must be dehydrated" you should probably be visiting a doctor.

um, well, maybe, but it is accurate (and interestingly, a bit more Bayesian) to say "Hmmm... my urine appears to be darker than it was previously. Without evidence supporting a competing hypothesis, this is most likely because I'm relatively closer to the lower end of normal total body volume". Competing hypotheses include rhabdomyolysis, acute renal injury, chronic renal injury, and all the many things that cause those sorts of end organ damage.

I know HN has at least on board-certified nephrologist lurking around. perhaps he'll chime in.

source: I'm a physician.

Also, I think Noekes raises some very interesting points. I'm a little concerned by the tone of this article, though overall I'm glad the author made the effort to write it. Things like saying Noekes only found 6 instances of heat exhaustion found in the setting of long-distance running are suspect. Doing a lit review is suspect, and in a case like heat exhaustion, it's very tricky to demonstrate the literature reflects the population. Do you really think every patient with heat exhaustion after a marathon got a case report written up? I don't.

dbbolton2• 11 years ago

I can't tell if you are agreeing with me or arguing against me because you didn't get the point of/read all of my comment. In case it's the latter:

However, assuming either are related to your present hydration is dumb.

That's exactly why I said "a symptom alone never makes a diagnosis" and "you can't assume you are dehydrated/your kidneys aren't working right based on those signs by themselves".

IgorPartola• 11 years ago

While this is interesting, I try to remind myself that I am by no means an ultra marathoner, so in my case I would likely not see any difference between one water protocol vs another.

Overhydration and Endurance Running

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