Dr Noakes on Hydration and Sodium intake
The podcast below is a good interview with Dr. Noakes (noted exercise physiologist) on proper hydration and sodium intake requirements for exercise and ironman distance races.
His message based on the research done is drink to thirst. If you drink more you will be slower. It is hard to ignore your thirst signals and to drink too little. If you drink to thirst you may lose ~10% of body weight by the end of the race wihch is completely normal for the body in his view.
On sodium – his message is our normal diets have plenty of sodium in it and our body stores a ton of sodium and it has mechanisms to minimize the loss of sodium when needed. So his view is we do not need to take in any sodium in a race.
The Noakes section starts at ~minutes 35 of the podcast.
http://www.bengreenfieldfitness.com...-exercise/
His message is not what the Gatorade / sports drink industry wants to hear.
Comments
Wow Matt, what a find. Thx for sharing. I bet the sports drink industry is having a cow. Interesting he feels 10% weight loss is ok. Always have had drilled into my head >3% is detrimental to performance. Will be studying this closely.
Also the data that the faster marathoner and ironman finishers lose more weight than the slower finishers. I think Coach P was down a bunch at IMLP when he qualified for Kona. The book should be interesting.
The Lore of Running is one of the few books I kept when I purged my sports library a few years back. Dr. Noakes is a brilliant researcher, communicator and scholar. So I listened to the podcast, with an ear towards learning something to improve my race performance. There are two big issues he's talking about: how much fluid/water and how much salt should we ingest during an Ironman? He says: drink to thirst; and don't look to add extra sodium during the race. And he says, it's "OK" to lose 6-12 % of body weight during an Ironman.
I tested those prescriptions against my own experience. I fear that I am bombarded by internal stimuli during the race: my legs hurt, my brain is tired, I'm hungary. During the swim and the first 4 hours or so of the bike, I'm doing what he suggests, drinking by thirst. I seem to gradually increase my intake from 10 >> 24 oz an hour during the first 4 hours of the bike. But towards the end of the bike and during the run, I can't really detect any thirst messages over all the other chaos I'm aware of internally. So I end up drinking to fullness - I take in about 6 ozs a mile (36-40 oz/hour), and back off if I'm starting to feel a little full. I don't take any extra salt (e.g., tablets). I lose maybe 2-4% of my body weight. I can't imagine losing 6-12%. Is he talking about water content? Cause we're about 55% water, and losing 3% total weight would equate to about 6% body water.
So I'm OK with the no salt, and the drinking to thirst for the first half of the race. But I don't know how to do that in the second half, I need a little more direction. And if dropping my weight from 145# to 135 or 130# during an IM is what it's going to take to improve my performance, no thanks. I've lost weight like that, and I can't walk very well at that weight, much less run a 9 minute mile.
my 2¢
The "salt paradox" ("my sweat is salty, so i must need to eat more salt") is also well explained, as I remember. I really think that's a much different issue than cramping. There also may be issues about being able to take water in with some salt in it, and of course, the hyponatremia problem. Of course, Noakes also kind of enjoys being contrarian.
I would be curious to hear what someone has to say who has read this book, or at least the relevant chapters.
During IMFL I tuned in to the body well in first half of bike, but later didn't apply good execution that my brain knew, but my senses did not. I think in the second half of bike, and certainly most of the run there is just too much noise to rely on listening to your body.
On hot days, the amount of fluids necessary to replace your loss will likely lead to hyponatremia if you rely on water alone.
Next IM, I'll start out listening, but hopefully follow my structured plan better as the day progresses. And Noakes or no Noakes, I'll be adding electrolytes.
Just my opinion of course....
To supplement (pun intended ) Paul's comment - I'm currently finishing up Macca's book. He does have a lot of worthwhile stuff slammed into it. Including a story about how he finally stopped getting cramps when racing in Kona. Coke was half the story; the other half involved a French body builder who'd gotten into nutrition for triathletes, specifically the nuts and bolts of what body builders would do to "taper" for their events. Short story: Magnesium, calcium, and sodium loading, done judiciously in the weeks before the event is what McCormack thinks got him over the hump. He also recommends salt during the race, especially during the bike.
My dilemma will be, I can no longer swallow salt pills while riding, so I have to come up with some other solution (pun intended). I don't want a salty drink, so I'm looking into several gels with 200+ mg of sodium/100 calories, planning to take six during the bike, and a couple more on the run.
http://www.epharmacy.com.au/product.asp?id=8190&pname=Ural++Sachets+28+x+4g#description_section
Awhile back we had a thread that referred to 3 year study buy Tanita done at IM Louisville. http://www.tanita.com/en/hydration-data/
The study showed that high pre-race hydration levels correlated with lower finishing times. The elite wining males had % water levels of ~70%.
Lets do some simple math – lets go with a 150 lb male as our elite example. So to lose 10% body weight that would be 15 lbs weight loss. The 70% water hydration level gives 105 lb water total in the body. So if we lose 15 lbs of water, this person would have 90 lbs of water in a 135lb body. This ratio is 67% water levels.
The alternative view is if we view the 15 lb loss of water for a remaining 90 lbs of water against the original 150 lb, we get a 60% hydration level. The study noted that for males who started with hydration levels 55-59%, 88% finished the race. Note the likely had some water loss from their starting hydration level.
So what this seam to say is that if you have the body composition and high hydration levels of an elite racer, you will start the race in the 70% water weight range. Starting there and losing 10% total body weight brings them down to levels that is still better than normal mortals. So this 10% weight lose seems plausible.
Ok a second version. A 150 lb male with only 55% hydration levels at the start of the race. He loses 10% or 15 lbs of water. This takes his water weight from 82.5 lb down to 67.5 lb for a resulting water % on the 150 lb basis of 45%. Now this may be a problem.
So the secret may be finding what the lower level of hydration that your system can still pace. All else being equal, starting with higher hydration levels appear to give you more room to lose water and still function.
But Matt's post has got me thinking about what the possible downside might be if (as I tend to do) we just hydrate with appropriate sodium that works in RRs and training?
My thinking is that if I drink more than I need, the worst that can happen is that I just need to pee?
Or am I missing something? (I do recognise that some peeps don't pee on the bike etc).
For the record, I have body fat of 17% and hydration of 55% (obviously I need to get leaner) so I am in the group that may have problems.
Matt, assuming that's true, that poses a dilemma for me with my own numbers on the Tanita: 5-6% BF, and about 59-60% water. In medical school, we're taught that "average" males are 60% water, women, less so (sorry ladies, it's the higher fat % causing this).
I looked through that paper Matt linked. I note that BF% was not referenced. I don't know if they measured it and correlated, but did not report, or if they just didn't measure it. That raises a question for me as I ponder whether to make a big effort to get "hyper-hydrated" in some way before an IM, especially one like Kona or, in most years, IM Lou.
Since BF% and water content are correlated, what would the graph look like for BF/Finishing time? What about the two combined? Which is more important? If I've maximized my leanness, should I just try to stay well hydrated and not make a big push to get wetter. It would be nice to have a bigger margin for water loss, but not if it unbalances the rest of my metabolism.
In a sense, this may be exactly what Matt is saying.
Can this group possibly come up with something we might be able to test, practice in training? I had the same problem Al described at IMLV losing about 10% body weight and, though I did run the entire marathon, I basically could not walk after I crossed the finish line. The second half of the IM begins to get foggy and, unless I have it written on my arm and tied to an alarm going off, I have a hard time executing the nutrition during those latter hours.......I need to figure out a better process before IM Cozumel this year....
That said, I too was wondering about the ability to sustain pace over the full IM marathon as a function of speed gained by % of water weight lost. It's not a strategy, for sure, but I think the effect is real. Not that I want to lose that much ever again...
If I'm not mistaken, salt is only one piece in the electrolyte puzzle. There are also potassium, calcium, magnesium, chloride, hydrogen phosphate, and hydrogen carbonate. It's the balance of all of these in the body which help determine hydration level and help muscle function. I'd be willing to bet that people don't really need to be taking in as much salt as they do if they were to up the consumption of some of the other components of what we consider electrolytes. Now maybe the other pieces aren't as easily digested which is why they're ignored at this time, I don't know. But it seems to me that there is something more than just the need for salt.
In chemist lingo, "salt" means anything ionic, but in common usage, it means sodium chloride. So when I say "salt loss", I think of all those things in a broad sense. Sorry. For whatever reason "electrolyte" has taken hold in common usage as meaning what chemists mean with just "salt".
Clearly enough, there is a mix of salts/electrolytes...not just NaCl.
Noakes paper Case proven: exercise associated hyponatraemia is due to overdrinking. So why did it take 20 years before the original evidence was accepted?
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2564296/
Gatorades response: Manufactured arguments: turning consensus into controversy does not advance science
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658914/
I downloaded Noakes' latest book on my kindle this morning. I'm a slow reader, but I'm curious to see what is in it. Now that Al mentioned it, maybe I should also read Lore of Running...
So while yes, I agree with Dr. Noakes, sodium supplementation won't change your serum sodium levels during a race, I also think there is enough anecdotal evidence and alternate scientific rationales to explain why salt supplementation may be beneficial to performance. My $0.02.
He also says that we are very well adapted to regulate sodium in our blood, and we don't need supplements for that purpose. However there was much discussion of salt supplementation on these boards following IM Lake Placid this year, and the anecdotal evidence seemed to suggest that salt can at times settle down a stomach that is going south during a race. Perhaps, as Kevin above states, salt is useful in ways other than electrolyte balance in the blood.
Like I said, I am only halfway through what he has to say so far. Interesting reading for sure.
@ John - l used salt-stick tabs for about two years before switching to S caps on the advice of my EN peeps. They are just as good and a lot cheaper.
His bottom line is to largely drink according to thirst, or if you need a guideline then 400 to 800 ml (14 - 27 oz) per hour is generally good. His main argument concerns drinking too much fluid (and the decades long battle he had to get his message out), but he also states that there is no need to take extra sodium - at least to maintain proper blood sodium levels - especially if you don't over-hydrate. He does not address other roles sodium may play as far as cramping or upset stomach issues, nor does he address the benefits of getting in carbs in a sportsdrink for performance.
The main thrust is that we need to be careful not to over-hydrate - the risk is very real and he cites many studies to back it up. See my highlights for more. Not sure how this jives with what is in the wiki.
I had a HUGE AH HA moment today while reading Noakes' Challenging Beliefs book!!!
I read through his assult on Gatorade and the sports drink industry but found a little gem that applies directly to me. I am 100% sure of it.
Back story: Almost every hard triathlon I have done has caused me to be dizzy and light headed afterwards (regardless of distance). My first Sprint Tri I had to lay on the ground for 10 mins afterwards because I couldn't stand up. 2 out of the 3 OLY races I have done had me laying on the ground afterwards because I couldn't hold my head up It also happened at the Patriot half and IMLou! I just went back to re-read my race report that I posted here in EN for the Patriot Half last June. Here is what I typed about the Post-Race:
Post Race: I guess they took my timing chip off for me. I told them I was fine and my friend said that I wasn't... The paramedics apparently also thought I was lying to them when I said I was fine as they ushered me to the ambulance. When they sat me down, I just couldn't lift my head... My friend brought me the best blueberry muffin I have ever eaten in my entire life. He brought me a banana and a nutrigrain bar and a bottle of Heed. 10 seconds later I had downed all of that but still couldn't lift my head. They kept putting ice water towels on me and squirting me with water. They hooked me up to an EKG and brought me a bottle of water. I kept telling them I was fine, and they still didn't believe me... I tried to stand up and fell back down... They decided to take my blood pressure. "110/70" I asked? The guy looked at me and said "um, it's 70/40" I think we need to get you onto the stretcher but I declined. A woman showed up that looked a whole lot worse than I felt, so I decided to give her my seat... Refusing to get fully into the ambulance, instead I slumped onto the ground in the shade of the Ambulance and laid there for at least 10 minutes or so. I kept being doused with ice water and drinking what I could. My friends and the medic team were awesome! After about 10 minutes I was able to get up... I thanked the paramedics and headed to the buffet to get some real food...
ABSTRACT
Exercise-associated collapse (EAC) commonly occurs after the completion of endurance running events. EAC is a collapse in conscious athletes who are unable to stand or walk unaided as a result of light headedness, faintness and dizziness or syncope causing a collapse that occurs after completion of an exertional event. Although EAC is perhaps the most common aetiology confronted by the medical provider attending to collapsed athletes in a finish-line tent, providers must first maintain vigilance for other potential life-threatening aetiologies that cause collapse, such as cardiac arrest, exertional heat stroke or exercise-associated hyponatraemia. Previously, it has been believed that dehydration and hyperthermia were primary causes of EAC. On review of the evidence, EAC is now believed to be principally the result of transient postural hypotension caused by lower extremity pooling of blood once the athlete stops running and the resultant impairment of cardiac barorefl exes. Once life-threatening aetiologies are ruled out, treatment of EAC is symptomatic and involves oral hydration and a Trendelenburg position – total body cooling, intravenous hydration or advanced therapies is generally not needed.