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Re: Tim Noakes: we need you back for a moment [triguy42] [ In reply to ]
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I wonder if Dr. Noakes has ever raced an Ironman in hot, humid conditions?
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Re: Tim Noakes: we need you back for a moment [shacking] [ In reply to ]
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No but he has raced the Comrades Ultra multiple times if memory serves, that's a pretty hot one.

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Re: Tim Noakes: we need you back for a moment [shacking] [ In reply to ]
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shacking wrote:
now you are back pedalling a little, which is appropriate. If you studied scales, their use, with and without clothes, and all these other holes you are poking in the "use the scale" argument, you won't generally find a 22lb difference. Maybe a 5-10 lb difference. No piece of data in any equation is 100% reliable all the time. I am a doctor, I know that. I treat the patient, not the data. The point I want to make is-- the scale is probably the only useful piece of data in the field... we need to use it, albeit with the knowledge of some normal variation and also margin of error. DONT THROW AWAY THE SCALES!! I want to know how many people died in the hospital, who could have been saved if they hadnt been over-aggressively hydrated? That is the real MEAT of this story. And one we may never find out about.

There...instead of 'totally disagreeing' with everybody... ;-)
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Re: Tim Noakes: we need you back for a moment [devashish_paul] [ In reply to ]
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I found this... it appears that an immediate effect of altitude change is for your body to try to increase its oxygen carrying capacity by concentrating hemoglobin by the means of what is termed "altitude diuresis" and this is a normal physiologic response.


http://ismm.org/index.php/normal-acclimatization.html

Dramatic changes take place in the body's chemistry and fluid balance during acclimatization. The osmotic center, which detects the "concentration" of the blood, gets reset so that the blood is more concentrated. This results in analtitude diuresis as the kidneys excrete more fluid. The reason for this reset is not understood, though it has the effect of increasing the hematocrit (concentration of red blood cells) and perhaps improving the blood's oxygen-carrying ability somewhat; it also counteracts the tendency for edema formation. It is normal at altitude to be urinating more than usual. If you are not, you may be dehydrated, or you may not be acclimatizing well.
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Re: Tim Noakes: we need you back for a moment [shacking] [ In reply to ]
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shacking wrote:
I found this... it appears that an immediate effect of altitude change is for your body to try to increase its oxygen carrying capacity by concentrating hemoglobin by the means of what is termed "altitude diuresis" and this is a normal physiologic response.


http://ismm.org/index.php/normal-acclimatization.html

Dramatic changes take place in the body's chemistry and fluid balance during acclimatization. The osmotic center, which detects the "concentration" of the blood, gets reset so that the blood is more concentrated. This results in analtitude diuresis as the kidneys excrete more fluid. The reason for this reset is not understood, though it has the effect of increasing the hematocrit (concentration of red blood cells) and perhaps improving the blood's oxygen-carrying ability somewhat; it also counteracts the tendency for edema formation. It is normal at altitude to be urinating more than usual. If you are not, you may be dehydrated, or you may not be acclimatizing well.

If I remember correctly, the diuresis is a transient adaptation. By reducing plasma volume, Blood is effectively slowed through the pulmonary tissue increasing the time for it to become oxygenated. As EPO is stimulated and RBC #s increased, the blood volume rises as well.

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The above poster has eschewed traditional employment and is currently undertaking the ill-conceived task of launching his own hardgoods company. Statements are not made on behalf of nor reflective of anything in any manner... unless they're good, then they count.
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Re: Tim Noakes: we need you back for a moment [Bob Loblaw] [ In reply to ]
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Soldier: 12930ml total
Others: 9038ml
At ~300ml / hr more than the others, that means they were out around 13 hours.

Therefore:
Soldier 994 ml / hr (almost a liter)
Others: 695 ml / hr

a 20 oz water bottle (standard) is ~ 591ml.
a 24 ox bottle is ~710ml

The other soldiers drank approximately 1.15 bottles per hour.
The deceased soldier drank ~ 1.68 bottles per hour for 10 hours.

It seems like people end up in a bad spot when they drink ~1L an hour for an extended period of time.

It would be interesting to note his core temp and other things. I'll have to look for the full text.
Their equipment / sweat rate/ evaporative losses would also be interesting to know.

I still think a standard recommendation of " 1 bottle an hour" is a solid safe place to be.
I think we all agree that 1L per hour is over-doing it.

Bob Loblaw wrote:
DrTriKat wrote:
[

Exercise-associated hyponatremic encephalopathy and exertional heatstroke in a soldier: High rates of fluid intake during exercise caused rather than prevented a fatal outcome.

http://www.ncbi.nlm.nih.gov/pubmed/25586818


wow - brutal abstract:
Abstract Athletes are often advised to drink in order to "fully replace bodyweight losses" in order to prevent exertional heatstroke (EHS) during exercise in the heat. There is little evidence that "dehydration" in the range experienced by athletes adversely affects thermoregulation or is the exclusive cause of EHS. In contrast it is established that excess fluid intake can cause exercise-associated hyponatremia (EAH) sometimes associated with encephalopathy (EAHE). As part of a series of experiments to determine optimal fluid replacement during exercise in the heat, we studied a group of exceptionally well-conditioned and heat-adapted members of the South African National Defence Force. A 20 year old male started a time restricted 50 km route-march in a dry bulb temperature that reached 37.5°C (WBGT of 33.6°C, relative humidity of 85%). Pre-march plasma osmolality, serum [Na(+)] and total body water measures indicated euhydration. Fluid was available ad libitum and isotonic sports drinks at 5 km intervals. Fluid intake and core body temperature (Tc) were recorded throughout while he was tracked by a global positioning system measuring distance travelled, position and speed. Comparing the total fluid intake of the soldier (12930 mL) to the rest of the participants (mean intake of 9 038 mL) up to 40 km, it is evident that his intake was 3892 mL (approximately 300 mL h(-1)) more than the mean for group. At approximately 17h14 the soldier was found lying by himself at the side of the route, 2.24 km from the finish point. He passed away the next day in a medical care facility. This tragic event provides the valuable opportunity to present data on the pacing, temperature regulation and fluid consumption of an exceptional athlete during the development of a fatal case of combined EAHE and EHS. Pacing, fluid intake, Tc and environmental condition data are presented for 5km intervals throughout the march. We propose a novel hypothesis on the possible contribution of EAHE to the development of EHS.

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The above poster has eschewed traditional employment and is currently undertaking the ill-conceived task of launching his own hardgoods company. Statements are not made on behalf of nor reflective of anything in any manner... unless they're good, then they count.
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Last edited by: xtrpickels: Jul 15, 15 8:47
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Re: Tim Noakes: we need you back for a moment [xtrpickels] [ In reply to ]
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xtrpickels wrote:
Soldier: 12930ml total
Others: 9038ml
At ~300ml / hr more than the others, that means they were out around 13 hours.

Therefore:
Soldier 994 ml / hr (almost a liter)
Others: 695 ml / hr

a 20 oz water bottle (standard) is ~ 591ml.
a 24 ox bottle is ~710ml

The other soldiers drank approximately 1.15 bottles per hour.
The deceased soldier drank ~ 1.68 bottles per hour for 10 hours.

It seems like people end up in a bad spot when they drink ~1L an hour for an extended period of time.

It would be interesting to note his core temp and other things. I'll have to look for the full text.
They're equipment / sweat rate/ evaporative losses would also be interesting to know.

I still think a standard recommendation of " 1 bottle an hour" is a solid safe place to be.
I think we all agree that 1L per hour is over-doing it.

Bob Loblaw wrote:
DrTriKat wrote:
[

Exercise-associated hyponatremic encephalopathy and exertional heatstroke in a soldier: High rates of fluid intake during exercise caused rather than prevented a fatal outcome.

http://www.ncbi.nlm.nih.gov/pubmed/25586818


wow - brutal abstract:
Abstract Athletes are often advised to drink in order to "fully replace bodyweight losses" in order to prevent exertional heatstroke (EHS) during exercise in the heat. There is little evidence that "dehydration" in the range experienced by athletes adversely affects thermoregulation or is the exclusive cause of EHS. In contrast it is established that excess fluid intake can cause exercise-associated hyponatremia (EAH) sometimes associated with encephalopathy (EAHE). As part of a series of experiments to determine optimal fluid replacement during exercise in the heat, we studied a group of exceptionally well-conditioned and heat-adapted members of the South African National Defence Force. A 20 year old male started a time restricted 50 km route-march in a dry bulb temperature that reached 37.5°C (WBGT of 33.6°C, relative humidity of 85%). Pre-march plasma osmolality, serum [Na(+)] and total body water measures indicated euhydration. Fluid was available ad libitum and isotonic sports drinks at 5 km intervals. Fluid intake and core body temperature (Tc) were recorded throughout while he was tracked by a global positioning system measuring distance travelled, position and speed. Comparing the total fluid intake of the soldier (12930 mL) to the rest of the participants (mean intake of 9 038 mL) up to 40 km, it is evident that his intake was 3892 mL (approximately 300 mL h(-1)) more than the mean for group. At approximately 17h14 the soldier was found lying by himself at the side of the route, 2.24 km from the finish point. He passed away the next day in a medical care facility. This tragic event provides the valuable opportunity to present data on the pacing, temperature regulation and fluid consumption of an exceptional athlete during the development of a fatal case of combined EAHE and EHS. Pacing, fluid intake, Tc and environmental condition data are presented for 5km intervals throughout the march. We propose a novel hypothesis on the possible contribution of EAHE to the development of EHS.

The soldier drank less than 1.5 times what the others did and he died.
It isn't as if he was drinking twice the amount or 3 times the amount.
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Re: Tim Noakes: we need you back for a moment [shacking] [ In reply to ]
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shacking wrote:
Then what you are saying is that when we find an athlete passed out, we should pump him full of IV fluids for 6 hours until a CT scan shows brain swelling? Since we have identified no reliable way to recognize hypervolemic dilutional hyponatremia in the field, since weight is somehow unreliable. Like any data, it is just data, you take it for what it is worth. It is uncorrect to totally dismiss weight as useful data. I totally disagree with you.

Actually this is what happened to me at IMLP 2003. I walked into the medical tent hypervolemic (likely around 10 lbs), but they had no scales back then. They mistook my symptoms for being dehydration and pumped me with 4 more IV bags making a bad situation near death. At least at North American IM's since then, it seems they generally have been using scales at check in and in the medical tent. While a bit imprecise, the post race weight with skinsuit and running shoes and wet body would still have to be quite a bit higher to surpass the pre race weight from a mid day check in with breakfast and lunch in the body, street clothes on and street shoes (might be the same running shoes, but the street clothes will be heavier. Also pre race race week weight will be higher due to the water being retained with all that glycogen stored on the body.

In general if post race weight is higher than pre race weight, even with discrepency of scales, that weight is going to have "worked really hard" to surpass pre race weight, meaning something is likely wrong enough that the medical staff should not pump you full of IV's.

As a point of reference, since 2003 when I do an IM (and I have done 20 since then some with scales some without), on race week I "tend" to be 2-3 lbs heavier than my weight early in the week. Then on race day I tend to be down 3-4 lbs, which basically ends up meaning I lose around a lb on my early week weight while racing. This is barely 1% of my body mass at 138 lbs race weight.

In Kona 2006, I weighed in at 140 lbs and ended the day at 137 lbs while my early week weight was 138 lbs. That day, I consumed only 4-5 large bottles of Gatorade EF on the bike, zero water and a cup of gatorade at every water station on the run (so something like 26 half cups because those cups are not even close to a quarter full). Estimate is 4L of liquid over 10:20, or around 9 lbs of liquid intake over 10+ hours on a 138 lbs body with no performance degradation. That year in Kona they had Gatorade Endurance Formula with more sodium per bottle and the on course gels were Powergel 3x Sodium, so that was plenty of sodium (even though Trev and Noakes say we don't need any).

If I recall correctly Macca who would routinely blow up in Kona until he nailed his electrolyte intake the previous year ended up running 2:42. 2005 or 2006 may have been the first years they have Gatorade EF + Powergel 3x sodium in unison on the course. Noakes etc will say "not neccessary", but with a decent amount of sodium from these two sources alone, it just took away the need for many to get sodium from additional sources. If I recall the 3x Sodum was around 1250 mg sodium per 100 g of gel so around every 2 gels you got 1000 mg of Sodium. Add to that around 400 mg of Sodium per bottle of Gatorade EF, and someone who takes in 5 bottles and 8 gels ends up taking in around 6000 mg over a long day.

If an average human has around 50 g of sodium in the entire body and an average western diet is 3 g intake, then 5-6 g intake over a humid hawaii raced does not seem that excessive that it should cause trouble provided that you don't over drink plain water coupled with it, because I can see how salt and water retention can go hand in hand. The over drinking athlete likely is better off with no sodium intake, because they will likely retain less of the over consumed water (from my understanding), but best plan is to not over drink. No your sweat rates and even if you can't drink to thirst because the thirst quench instinct is all screwed up during racing, you already know now much fluid you lose worst case under racing load and personal heat generation (one might need more liquid dissipating the heat of a 250W effort which generates 1000W of heat than a 150W effort that only generates 600W of heat).
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Re: Tim Noakes: we need you back for a moment [devashish_paul] [ In reply to ]
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I'm not aware Noakes has ever said salt supplementation is harmful but he says it is not 'needed' and does not enhance performance.

As so many do supplement with extra salt and are successful in ironman events it clearly does not harm performance.

The issue is liquid intake. And it seems that now Noakes views on over drinking are now accepted and understood. Sadly many athletes do not understand and still make the same mistake and over drink.

I take issue that the thirst mechanism does not work during training or racing. People assume that because they consume less liquid if they drink to thirst than they do when they follow the usual guidelines that thirst is wrong or delayed or late. This is not the case. Thirst allows some mild dehydration, thirst allows you to end the event or session lighter than you started. This is normal and correct because you should lose weight because you will have burnt off calories and water is lost with every calorie burnt. If thirst is behind the guidelines it is more likely that thirst is correct and the guidelines are wrong.

So first, some loss of weight is normal, this is not dehydration, it is the correct weight because water should be lost with the calories burnt.

Second, some dehydration is acceptable and correct. We evolved to dehydrate and rehydrate. It is not a problem it is normal. As Noakes keeps pointing out, performance is not affected by dehydration, within limits. And it is thirst which keeps you within those limits.

Overhydration is detrimental to performance. If you have drunk 2 pints more than you need you weigh more. And we all know what happens if you continue to over drink.

I do not accept thirst goes wrong, I argue people consume more liquid than is optimal for performance because they drink ahead of thirst.

I also contend that many people live in a perpetual state of over hydration. Fear of dehydration, beleif that drinking lots of water improves skin, following advise to drink 2 cups of water for each coffee, addiction to soft drinks and the completely mental idiotic moronic habit of carrying a bottle of liquid everywhere in case they drop dead of dehydration causes people to consume vast amounts of liquid and waste the planets water because they urinate every 5 minutes.

So if you start a race a kilo overweight because you are retaining liquid which you don't need, then drink a kilo more than you need, you do much of the race weighing 2 kilos more than you need. Add to that time lost urinating. How many minutes does a kilo cost in an ironman?

Add to this extra water the body retains with extra salt.

I'm not saying anyone should dehydrate to weigh less, but I am saying you should not race over hydrated and you should not be afraid to trust in your thirst.

I'm not claiming everyone or most over hydrate. But some do. It might be worth thinking about it. It would be interesting to know if those that die or have problems with consuming too much liquid start the event over hydrated.
Last edited by: Trev: Jul 15, 15 0:27
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Re: Tim Noakes: we need you back for a moment [devashish_paul] [ In reply to ]
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It is entirely possible that there is a point at which over supplementation of sodium becomes detrimental to performance.

Certainly salt intake is associated with water retention. Unnecessary weight in the form of water retention must be detrimental to performance.

There may well be other detrimental effects to performance with too much sodium intake.
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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Trev wrote:
It is entirely possible that there is a point at which over supplementation of sodium becomes detrimental to performance.

Certainly salt intake is associated with water retention. Unnecessary weight in the form of water retention must be detrimental to performance.

There may well be other detrimental effects to performance with too much sodium intake.

I definitely agree that too much water is detrimental to performance and one should lose a few pounds automatically while generating mechanical work and burning through glycogen. Carrying around one or even two kilos less by end of a race is going to be positive to performance which is why I am baffled why cyclists carry around so many bottles often even in short TT's. There were guys in the Tour De France this year carrying round none aero bottles in the Utrecht 13k TT...what is that all about. or I remember in the Torino Olympics in a 44 min 15k XC ski race a coach giving Canadian Medal contender a bottle at the 10k mark...shortly thereafter she fell off the pace, cramped and slid into 4th and the entire time I was thinking, "you would never see a 10,000m track runner going anywhere near liquid at that intensity for those short durations". It seems most coaches are also relatively clued out on the topic as mild dehydration is not a performance limiter...as you said, hauling around less weight alone is not a bad tradeoff. We might diverge a bit on the sodium topic but not dramatically. I can't see mild sodium top up which is slightly more than a normal day when one may only train 1-2 hours and sit around for 8 being bad, given that on an IM day one is going much harder for 8-17 hrs. Maybe it is psychological that after 5 hours of racing by lunch time your body starts asking for a change free sweet foods to salty foods. We generally start lunch and dinner with salty and might end with a sweet desert. During the day of an IM it seems like food is sweet through lunch and dinner time. Perhaps we don't need the sodium physically, and we're just culturally tuned to get an over supply of sodium by lunch time...then you get to race day and you don't and you are mentally messed up and cravingg salt even though according to you and Noakes the person has not lost enough out of the 50 or so grams in the body for the losses to have a real impact. Are the on course salt cravings our bodies asking for more simply because we are in a chronic state of sodium oversupply? Or maybe our bodies are so used to the over supply that we have difficulty on race day not being in that range?
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Re: Tim Noakes: we need you back for a moment [devashish_paul] [ In reply to ]
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I think the problem these days, is so many people are habituated to constantly over consume liquid, sugar and salt. It is as much emotional dependence as physical dependence. People seem to train themselves to think they need or even actually need a constant supply of liquid, sugar and salt.

It is very possible these people can't perform to their best without this constant supply and topping up. There is a reverse placebo affect.

If you spend your life taking in liquid sugar and salt every few minutes you are not going to feel normal going without for 30 minutes let alone an hour or two swimming cycling and running. Look at how the alcoholic can't function without alcohol or the smoker without nicotine. Look at the coffee addictct, he goes through real physical and emotional withdrawal if deprived. Their dependence is both emotional and physical. I'm not trying to compare salt and sugar to alcohol and nicotine but if our system is habituated to a constant supply of something it is going to make things go wappy if you suddenly make it cope without that supply.

Obviously in an ironman you must take on carbohydrate and liquid. But there is only so much you can take in and actually use.

Your comparison of runners to cyclists is a good point. Look how little elite marathon runners eat and drink compared to cyclists. Part of that is cycling does make it far easier to eat and drink on the move, but I'm convinced there is more to it than that. Cyclists seem to be far more worried about hydration and food intake than runners, their mind set seems to be different.

I'm not proposing we go back to the days of consuming too little liquid and using alcohol and amphetamines like Tom Simpson, but it seems to me the mindset has gone to the opposite extreme.
Last edited by: Trev: Jul 15, 15 3:44
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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Trev wrote:


Your comparison of runners to cyclists is a good point. Look how little elite marathon runners eat and drink compared to cyclists. Part of that is cycling does make it far easier to eat and drink on the move, but I'm convinced there is more to it than that. Cyclists seem to be far more worried about hydration and food intake than runners, their mind set seems to be different.

I'm not proposing we go back to the days of consuming too little liquid and using alcohol and amphetamines like Tom Simpson, but it seems to me the mindset has gone to the opposite extreme.


Actually, the difference in intake from elite cyclists vs runners has a lot to do with race and training length. Most elite runners (not ultrarunners) race <26 miles, often <13 miles, so no need for significant nutrition on the run. Elite cyclists will often not only race longer (esp multiday races), but go right back to high-volume bike training the next day (you can't do that with running at the elite level - run that fast so often = injury!) so they need to keep things as topped off as reasonable as well as maintain their ability to intake significant calories while putting out hard efforts.

Ultrarunners who run 50+ miles start looking more like long-course triathletes in terms of closely monitoring weight, salt intake, and calories intake.

In general though, I completely agree with you - AG triathletes, esp at the non-IM distance, hugely overdo the nutrtition aspect of their training/racing. They see pro IM athletes obsessing over their caloriec intake per hour (for good reason!) and then assume they need to emulate that for sprint/oly and even HIM distances, when you dont even need calories for the shorter stuff. Even at the longer distances, training will trump nutrition for overall performance for AGers by far - many AGers just love using nutrition as an excuse to explain why they didn't go as fast as they dreamed they could. Even at IM distance, if you've been doing those long training rides with the 'train like you race' mentality, your nutrition shouldn't been throwing you under the bus on race day, as poor fueling strategies should have been pretty exposed on those training rides.
Last edited by: lightheir: Jul 15, 15 7:26
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Re: Tim Noakes: we need you back for a moment [lightheir] [ In reply to ]
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True, my comments are more aimed at chaps who train one or two hours a day at most. Obviously an elite cyclist out for a 5 or 6 hour training ride will need to take liquid & food.

But you see people out for an hour armed with 3 bottles and pockets full of gels, salt sticks and an app to remind him to eat and drink every 10 minutes. Then after their one hour ride they down a protein shake and a recovery bar and spend the next 2 hours going over their power data whilst they eat a pizza which contains enough salt to last a week.

These are the sort of people who only ride for longer than an hour when their GPS stops working and they can't find their way home.

Then they do some event, drink so much they need to urinate on the bike, get cramp and blame lack of salt even though they consumed a weeks supply of salt the day before in the bloody pizza.

Bloody Stages users, really wind me up.
Last edited by: Trev: Jul 15, 15 7:58
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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Yeah, I got totally flamed on a cycling forum last year when I responded to a recreational (non-racing) cyclist suggesting that his alleged big underperformance on his 70 minute bike ride was a matter of training, not nutrition. (He said he bonked out on the 70 minute ride, and learned a lesson in that he was going to take at least 350 kcal/hr even for a 60 minute total ride.)

Seriously, like 20 people piled in on that one telling me how wrong I was, and how you had to replace the calories you burn, etc. I responded that marathon runners and other elite endurance athletes barely take in any calories for 2x the duration, and they just pointed at Tour De France riders and said cycling was 'different.' Yeah, right.
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Re: Tim Noakes: we need you back for a moment [shacking] [ In reply to ]
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shacking wrote:
I wonder if Dr. Noakes has ever raced an Ironman in hot, humid conditions?


He has has run more than 70 marathon and ultra-marathon races, including 7 Comrades Marathons (56 miles) and 15 Two Oceans Marathons. I assume he ran mostly in South Africa where it does get hot.
Last edited by: Trev: Jul 15, 15 8:47
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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Trev wrote:
shacking wrote:
I wonder if Dr. Noakes has ever raced an Ironman in hot, humid conditions?


No but he has has run more than 70 marathon and ultra-marathon races, including 7 Comrades Marathons (56 miles) and 15 Two Oceans Marathons.

Was that using the "The Ideal Sports Drink" guidelines from "The Lore of Running"?
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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Noted- thank you. One phrase still haunts me... "drink to thirst". This is a recipe for disaster. It does depend on the athlete, the context. For me, the classic scenario is to dry up like a raisin on the bike, then bonk the run. I am a heavy sweater though. If I "drink to thirst", I will fall apart.
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Re: Tim Noakes: we need you back for a moment [J_R] [ In reply to ]
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J_R wrote:
Trev wrote:
shacking wrote:
I wonder if Dr. Noakes has ever raced an Ironman in hot, humid conditions?


No but he has has run more than 70 marathon and ultra-marathon races, including 7 Comrades Marathons (56 miles) and 15 Two Oceans Marathons.

Was that using the "The Ideal Sports Drink" guidelines from "The Lore of Running"?

As far as I'm aware Noakes is very open about how and when he changed his advice. The fact he is open about when and why he changed his mind is something to applaud.

Typical of those who can't argue to attack the person rather than the argument.

Why don't you read his book Waterlogged?
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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Trev wrote:
The soldier drank less than 1.5 times what the others did and he died.
It isn't as if he was drinking twice the amount or 3 times the amount.

1. We do not know the other soldiers were optimal
2. It may be a "fine line"
3. There could be other confounding factors (To think this is entirely based on fluid consumption is a bit simplistic)

I talk a lot - Give it a listen: http://www.fasttalklabs.com/category/fast-talk
I also give Training Advice via http://www.ForeverEndurance.com

The above poster has eschewed traditional employment and is currently undertaking the ill-conceived task of launching his own hardgoods company. Statements are not made on behalf of nor reflective of anything in any manner... unless they're good, then they count.
http://www.AGNCYINNOVATION.com
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Re: Tim Noakes: we need you back for a moment [xtrpickels] [ In reply to ]
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xtrpickels wrote:
Trev wrote:

The soldier drank less than 1.5 times what the others did and he died.
It isn't as if he was drinking twice the amount or 3 times the amount.


1. We do not know the other soldiers were optimal
2. It may be a "fine line"
3. There could be other confounding factors (To think this is entirely based on fluid consumption is a bit simplistic)


That is my point, we don't know if the other soldiers also drank too much and got away with it, or if they drank optimally.

It probably is a fine line which is actually worrying.

Agreed there may well be other factors.

It is also possible the soldier started over hydrated. Perhaps he was low on sodium at the start, might have been ill recently?

As I said, it isn't as if he drank that much more than the others.

Anyway, I'm getting thirsty defending Noakes so I'm off to the pub.
Last edited by: Trev: Jul 15, 15 9:09
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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I have read it.
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Re: Tim Noakes: we need you back for a moment [J_R] [ In reply to ]
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J_R wrote:
I have read it.


You will have read this then.


"Dehydration" is a physiological term indicating a reduction in the total-body water content. Once the reduction in body water causes the solute concentration, especially the sodium concentration (actually the osmolality), of the blood to rise, the brain detects the change and develops the symptom of thirst. This is a normal biological response that has evolved in all creatures to ensure that they maintain a constant body water content at least once each day, usually after the evening.
When fluid is lost from the body, either in sweat as a result of exercise or from the gastrointestinal tract in diseases like cholera or typhoid, the concentration of solutes, especially sodium in the blood, rises, causing the blood osmolality to increase. This rise stimulates receptors in a special part of the brain, the hypothalamus, which in turn interact with three other nuclei, which increase secretion of the hormone AVP/ADH (arginine vasopressin, also known as antidiuretic hormone), whose function is to increase water reabsorption by the kidney. In response to the action of AVP/ADH, the kidney reduces the amount of fluid secreted. As a result, urine flow into the bladder is reduced. Nucleus 5 also stimulates the cells in another part of the brain, the cingulate gyrus, which increases thirst. As a result, the desire to drink is increased and water (and sodium through the action of aldosterone) is reabsorbed by the kidneys. The result is that the blood osmolality returns to its homeostatically regulated value, switching off the desire to drink.

Thus the only symptom of dehydration is thirst. If, however, the thirst cannot be quenched because fluid is unavailable, as occurs in those stranded in the desert, then the body activates a series of emergency adaptations that prolong life for a period but ultimately cause death when all the major bodily organs fail, leading probably to cardiovascular collapse.

The remarkable achievement of the sports drink industry was that it convinced recent generations that these control mechanisms do not exist. Instead, we've been told, all athletes must drink to ensure that they do not lose any body weight during exercise. But there are no known receptors that regulate thirst by monitoring the extent of the body weight lost or gained. In addition, this myth also convinced exercisers that they could become dangerously dehydrated not just when lost in the desert for more than 48 hours but when running for a few minutes in, for example, a big-city marathon, during which they have unrestricted access to as much fluid as they might wish. I am unaware of any other human activity in which so much fluid is freely available as in a modern big-city marathon. How is it possible under these circumstances to become dehydrated except according to a definition that has no proper biological basis?

In response to the body's pure fluid loss, the usual human living in a Western society with easy access to fluid will develop the sensation of thirst and will usually drink fluid as a result. Receptors in the back of the mouth and the esophagus, but particularly in the stomach, then detect how much fluid has been ingested. Once the stomach is filled, the desire to drink is temporarily curtailed but resumes as the stomach empties, especially if food is eaten at the same time. Eventually enough fluid (and sodium) has been ingested to return the solute concentration of the extracellular fluid (ECF) back to the normal range. Since the ECF (and hence whole body) osmolality is then within the homeostatically regulated range, the symptom of thirst is switched off; as a result, most people will stop drinking.

SYMPTOMS OF INADEQUATE FLUID INGESTION
When athletes sweat during exercise, they lose both water and electrolytes, especially sodium, in varying amounts. Because sodium is the dominant solute lost in sweat, and since the sweat sodium concentration is always less than its concentration in the ECF, sweating will always cause a greater loss of water than solute from the ECF. As a result, in the absence of any fluid ingestion, sweating must cause the ECF solute concentration to rise. Ultimately this will change enough to stimulate thirst in everyone.

However, this response is highly individualized—some athletes will become thirsty at quite low levels of weight loss, whereas the thirst of others allows them to lose up to 12 percent of body weight during ultra-endurance exercise, as in the Ironman Triathlon, without developing any more severe symptoms of homeostatic failure. To understand the real symptoms that develop when people drink less than their thirst dictates, we need to look at those studies in which participants are forced to exercise for prolonged periods while they have access to less fluid than their thirst dictates. These people develop both an unquenched thirst and additional symptoms caused by a progressive biological failure due to a falling total-body water content. One of the original studies to define these symptoms was performed in the Nevada Desert during the early years of World War II.

The Nevada Desert study reported the sequence in which symptoms of unreplaced water losses, since conveniently termed "dehydration," developed. Of course, one can equally argue that some of these symptoms are due to an absence of drinking and the knowledge that drinking will be allowed only when the activity is completed. We now appreciate that the brain responds not just to biological stimuli but also to what it anticipates will happen in the future. Knowing that a demanding activity must be performed without fluid replacement will cause all symptoms to be experienced more intensively.

The head of the Nevada Desert study wrote, "The order of appearance of the signs and symptoms is particularly characteristic. Thirst is noticeable very early, but does not increase much in intensity as the water deficit continues to increase. Vague discomfort, not experienced by controls who drank water, gradually becomes defined in the flushing of the skin, heat oppression, weariness, sleepiness, impatience, anorexia and dizziness. At about the time that the walking pace can no longer be maintained, dyspnea, tingling and cyanosis, as well as a suggestion of tetany, appear. Still later, a man cannot stand alone, either because of impaired coordination or fainting." The Nevada researchers also recognized that the inability to stand was due to the development of a low blood pressure, postural hypotension: "The inability to continue muscular work (exhaustion) seems to be a consequence of circulatory inadequacy. Temporarily, the movements themselves help in some degree to improve the return of blood to the heart. When the movements stop, failure is suddenly imminent; some persons faint at this point. Lying down promptly relieves the circulation and the symptoms."

Another Nevada Desert researcher described his experiences: "Aside from thirst, the symptoms of dehydration were in large part indications of impending collapse. A vague, generalized discomfort and a feeling of restlessness followed closely the stage of 'mouth thirst.' There was a great desire to sit or lie down. Drowsiness was often noted. A feeling of heat oppression was a frequent complaint; it was often more serious than thirst. Muscular tiredness grew more acute progressively, although manual coordination was not measurably altered. Among the signs of approaching collapse, the most reliable were a rising pulse rate and a rising rectal temperature. Sometimes there was a noticeable dyspnea. Frequently, the subject was cyanotic and his face became flushed. In the exhausted state, tingling in hands, arms and feet occurred in some cases."

So described are the real symptoms that develop when people exercise in extremely hot conditions without any chance to replace their fluid losses appropriately. Of course this is not what happens in modern marathon races in which athletes exercise usually for relatively short periods of a few hours in much cooler conditions while they have access to unlimited amounts of fluid.

The extensive research of the Nevada Desert research group established a range of findings that subsequent research has not contradicted. Not all these findings have received equal exposure over the years. Those findings that dehydration may not be quite as dangerous as the dehydration myth proposes have not been as widely propagated as those supporting the value of fluid ingestion during exercise. The principal findings were as follows:

1. Even when given free access to adequate fluids, people drank less than they lost in sweat or urine. Hence they developed "voluntary dehydration," which was corrected only after exercise and when food was eaten, especially at the evening meal.

2. In the experiments in which groups of soldiers either drank freely or not at all during day-long marches in desert heat, a much greater percentage of those who did not drink during exercise were likely to terminate the exercise bout prematurely.

3. Subjects in the groups who did not drink during these marches usually stopped when they had lost 7 to 10 percent of their starting body weights. In this state they experienced postural hypotension (EAPH), but after they experienced the symptoms of fainting caused by EAPH, they recovered rapidly within minutes of lying down and ingesting fluid.

4. Dehydration reduced neither the sweat rate, nor the rate of urine production during exercise. However, the rectal temperature and heart rate rose as linear functions of the level of dehydration. The body temperature rose about 0.2 to 0.3 degrees C for each 1 percent level of dehydration.

5. There were no immediate health risks associated with the level of dehydration of 7 to 10 percent present at the termination of exercise in those who did not ingest any fluids during exercise. The authors considered that only at very high levels of dehydration (15 to 20 percent) was there a serious risk of organ failure.These studies, which clearly established the value of fluid ingestion during exercise, had little impact on the athletic community. Instead, for at least the first two decades after the publication in 1947 of the book describing these studies, athletes continued to be advised not to drink at all during exercise. Only after the development of Gatorade and the publication of relevant studies was proper attention finally paid to the use of fluid ingestion during exercise.

Another set of U.S. Army studies occurred soon after American troops began to fight in jungle heat in Burma during World War II. It soon became apparent that on first exposure to conditions of high temperatures and suffocating humidity (caused by the transpiration of water from the leaves of the jungle vegetation), soldiers were essentially incapacitated but began to adapt within a few days. To study the special physiological challenges posed by jungle heat, a special research group was established at Fort Knox, Ky., where a "hot room" was built in which the environmental conditions present in either the desert or the jungle could be reproduced.

These studies showed that the major cause for incapacitation on first exposure to both desert and jungle heat was the development of EAPH, beginning the moment the exercise bout terminated. This disappeared within a few days of repeated heat exposures. An important contribution of these studies was to establish the condition of EAPH as a cause of post-exercise collapse and to show that this condition was not simply due to dehydration, as would become the industry-driven mantra after the 1980s.

These researchers were also interested in the psychological effects of exercising in the heat without fluid replacement. Thus they wrote the following: "An important change which the chart does not show was the actual condition of the men, their low morale and lack of vigor, their glassy eyes, their apathetic, torpid appearance, their 'don't-give-a-damn-for-anything' attitude, their uncoordinated stumbling, shuffling gait. Some were incapable of sustained purposeful action and were not fit for work. All they wanted to do was rest and drink." This shows that the symptoms of dehydration are largely of a psychological nature, the goal of which is to stop the athletes from continuing to exercise. It's a built-in mechanism to prevent bodily damage.

Scientists at the United States Army Research Institute of Environmental Medicine have conducted a study to evaluate the influence of unreplaced fluid losses on the development of various symptoms. The study used fluid restriction and exercise to produce four levels of loss of body weight (0 percent, 3 percent, 5 percent, and 7 percent) and showed that the intensity of sensations of thirst, tiredness, weakness, lightheadedness, weariness and dizziness increased linearly with increasing levels of weight loss. But thirst was the symptom that was felt with the greatest intensity.

The study is important for two reasons. First, it shows that thirst is the symptom that best indicates the presence of a fluid deficit caused by exercise and fluid restriction. This conflicts with the myth developed in the 1990s that thirst is an inadequate guide to the fluid needs of the body. Rather, in this study, a weight loss of 7 percent produced near-maximal thirst sensations.

Second, during competition, some athletes develop levels of weight loss in excess of 7 percent without developing the same intensity of symptoms experienced by the participants in this study. This shows the individuality of the thirst response. Athletes who lose substantial amounts of weight during exercise without becoming as thirsty either prevent a large increase in the solute content of their ECF (as a result of internal relocation of body sodium stores) or because their brains are less sensitive to any large changes in ECF solute concentrations.

These individuals are, in fact, dehydrated because they have lost total-body water; however, this water loss is easily replaced by drinking normally, often with a meal, after the race. It does not lead to myriad ill effects, as the sports drink industry would like us to believe. In fact, the best endurance athletes in the world are typically those who lose the most weight during exercise, who have the least thirst and who run the fastest when they are quite markedly dehydrated, perhaps because the weight loss is beneficial to performance, just as the avoidance of thirst must have been an advantage to early hominid persistence hunters.

More recent studies further confirm that the sensations of thirst are always sufficient to ensure proper hydration both before and during exercise. Participants who began exercise in a dehydrated state (-3.4 percent BW) drank 5.3 times as much fluid during 90 minutes of exercise than when they started exercise normally hydrated such that, provided they were able to drink during exercise, it made no difference whether subjects began exercise dehydrated or normally hydrated; by the end of exercise their core body temperatures, heart rates, blood osmolalities and thirst ratings were the same.

FLUID LOSS AND PERFORMANCE
If fluid loss leads to thirst, why do some of the best competitors finish endurance races in quite advanced states of fluid loss? Time and again, studies, even those by researchers expecting different outcomes, have shown that the runners who are the most dehydrated, as measured by percentage of body weight loss, run the fastest. Two examples that valdiate this conclusion are the results of the 2000 and 2001 South African Ironman triathlons and the 2004 New Zealand Ironman Triathlon.

The largest body weight loss in these studies was 12 percent in an athlete who finished the race in ~720 minutes. The five fastest finishers in the South African Ironman all finished in less than 9 hours and all lost 6 to 8 percent of their body weights during the race. Three years later, this relationship was confirmed in finishers in the 2004 New Zealand Ironman Triathlon.

Why would the fastest endurance performers exhibit the highest percentages of body weight loss during their winning performances? Perhaps clues exist in the phenomenon that has been termed voluntary dehydration. Exercising humans do not drink to maintain a constant body weight every moment of the day. Rather, we develop a water deficit termed voluntary dehydration by drinking less than the amount of weight (assumed to be due entirely to water loss) that we lose as sweat during exercise. Only at mealtimes do humans increase water intakes and so correct exactly the fluid loss developed in the hours between meals.

There are a number of probable explanations for this phenomenon. First, not all the weight lost during exercise is fluid that needs to be replaced immediately. For example, there is an inevitable loss of weight caused by the fuel, either fat or carbohydrate, that must be burned in order to provide the energy needed for the exercise. The analogy would be the fuel in a motor car that is burned as the car travels—the result is that, until it is again filled with fuel, the car loses weight in direct proportion to how far it travels.

An additional factor is not covered by this car analogy. It is that the carbohydrate that is burned during exercise may be stored in the muscle and liver in a complex that includes a substantial mass of bound water. It has been argued for some years that each gram of carbohydrate used during exercise releases up to 3 grams of water. This water acts as a fluid reserve that is restored only when the body's carbohydrate stores are again filled 12 to 36 hours after exercise. Because the body can store 500 grams of carbohydrate (with an associated 1,500 grams of water), this would explain why humans might lose at least 2,000 grams of weight during exercise without any real water loss. Indeed, studies of this problem have shown that exercising humans can lose at least 1,000 grams without a measureable change in their total-body water content.

Thus the term "voluntary dehydration" may not accurately describe what happens in athletes who lose less than 1 kg during exercise because they may not have lost any body water and hence are not dehydrated. But athletes who lose more than 3 kg during prolonged exercise probably do show a reduction in total-body water content and hence are likely to be voluntarily dehydrated to varying degrees. The explanation for this phenomenon is that already given—either they prevent a large change in ECF solute concentration in response to quite large changes in body water content or their brains are less sensitive to a normal increase in ECF osmolality (solute concentration). But either way, the fact that athletes with the greatest levels of weight loss are usually the fastest finishers in endurance events shows that the response of their brains to body water loss has been entirely appropriate, perhaps optimal.

There is no direct evidence that exercise performance is impaired in those who lose weight during exercise, provided they drink to the dictates of thirst and do not become thirsty. In fact, evidence that the best marathon runners have a remarkable capacity to resist high levels of fluid loss has been provided in countless races around the world.
Last edited by: Trev: Jul 15, 15 10:10
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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I must admit I don't recall ever reading anything in that book regarding tips on losing love handles
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Re: Tim Noakes: we need you back for a moment [Trev] [ In reply to ]
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That is my point, we don't know if the other soldiers also drank too much and got away with it, or if they drank optimally.

It probably is a fine line which is actually worrying.

Agreed there may well be other factors.

It is also possible the soldier started over hydrated. Perhaps he was low on sodium at the start, might have been ill recently?

As I said, it isn't as if he drank that much more than the others. \\



As you continue to defend Noakes and his theories, I will just chime in here and add one thing that it appears that no one mentioned. Perhaps different bodies work differently in the heat? Maybe some lose more sodium and magnesium than others? Perhaps there is not a one size fits all formula here? Maybe the soldier did exactly what everyone else did, but his body reacts differently to heat stress?


My answer to all of these questions is yes of course, seems quite logical that since our bodies vary in so many different ways, why not in how we handle heat stress. And if that is the case, then not knowing how the individual you are talking about reacts, well seems like circle jerking around and around, getting no where really. You cannot tell anything at all, except to what eventually happened to him. He might have drank too much water, or he might have drank too little with electrolytes. Either could have caused his death, along with a few other possibilities.


I'm not saying that Noakes is wrong, just wrong for a lot of people. Just like diet people that like to claim that this or that program is optimal for athletes, or you can just minus your age from 220 to get your max heart rate. I have found that more people fit outside the norm than inside on a lot of issues, especially nutrition.
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