Overhydration and Endurance Running
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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.
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.
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.
I don't really think every patient with heat exhaustion after a marathon got a case report written up, but I don't care.
>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".
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.
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.
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.
So it's quite probable his decreased urination was from being able to retain more water due to the salt intake replacing what had been lost.
The evidence in this whole field is pretty scant really. For example, most people think electrolytes help with exercise induced cramps, and yet the only thing with any evidence to support its use is actually pickle juice (!)[1][2]. There is very little evidence to show electrolytes help with cramping in trained athletes.
[1] http://well.blogs.nytimes.com/2010/06/09/phys-ed-can-pickle-...
[2] http://www.ncbi.nlm.nih.gov/pubmed/19997012
[3] http://www.ausport.gov.au/ais/nutrition/factsheets/hydration... (read "What causes cramp")
Whilst you're right, the evidence is thin to suggest a lack of sodium is the cause of EAMCs, the recommended treatment is often fluids high in electrolytes.
> Notably, affected athletes often present with normal or somewhat elevated serum electrolyte levels, even if they are "salty sweaters," because of hypotonic sweat loss and a fall in intravascular volume. However, recovery and maintenance of water and sodium balance with oral or intravenous salt solutions is the proven effective strategy for resolving and averting exercise-associated muscle cramps that are prompted by extensive sweating and a sodium deficit. [1]
So whilst there might be a multitude of causes of EAMCs, there seems to be a singular treatment for it. The main hypothesised causes are dehydration, electrolyte depletion or altered neuromuscular control - which is likely caused by electrolyte imbalances.
The article authors claim "Science: There is no scientific evidence that shows sodium (or other electrolyte) deficits in those with muscle cramping." is patently false. There is evidence that sodium deficits increase EAMCs, but so does dehydration (meaning increased serum sodium concentrations), and the main risk indicator is over-exertion.
Yes there's contradictory evidence. However, if you did a generalized study trying to find out why hydraulic pistons seize you would find that there's contradictory evidence because too much and too little hydraulic fluid can seize it, and overworking it can too. Trying to claim there's only one cause is naive.
[1] http://journals.lww.com/acsm-csmr/Fulltext/2008/07001/Muscle...
As well as the increasingly popular "central governor" theory in sports science, he also "invented" the Paleo diet[1]. While I think the Paleo diet's benefits are overstated, there is little doubt that it set a trend towards diets that are more focused on choosing foods that have a high satiability index.
[1]http://en.wikipedia.org/wiki/Tim_Noakes#The_.22Noakes_diet.2...
The sports medicine perspective along the same lines with respect to all humans other than rich modern westerners would be interesting. Or primates in general.
There would seem to be an obvious life / reproduction advantage in not a body not suiciding by sweating out all the salt, which makes the doctor's argument intuitively appealing.
Infinite water bottles and infinite sugar and infinite salt might or might not help performance, but they're surely not natural, interesting for all non-creationists to consider that all our ancestors evolved specifically not to consume those commercial products... Even if it does help short term (maybe) the long term effects of poking the bear and informal screwing around with tightly coupled systems by consuming enormous doses of unnatural stuff in stressful situations does need to be looked into.
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.
> 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.
There's no relationship between fluid intake and hydration versus the incidence of heat exhaustion or heat stroke.
Just use a different conjunction.
Race day eating is really one of the hardest parts about ultrarunning.
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.
That said - I've done many long (8-12hr cycling only or triathlon) events on liquids alone (I prefer infinit.us).