So I recently had a sweat test that indicates I lose over 5,000mg of sodium per hour.
I am having trouble finding any info on how to approach this. How much of the 5,000mg should I try to replace per hour, seems like a bucket load of salt??
Is there a % or max amount per hour like carbs that you are generally limited to?
I’m in your boat. Let me try to dig up my report. I’d double check your levels though.
2k sodium/hr as Nuun tablets added to my normal Skratch drink mix. Osmo pre-load night before and morning of.
Generally go by taste. Salt is one of those things that it only tastes too salty when you’ve had too much, so my drink mix tastes sweet when I need salt and salty when I’m good.
E
Edit: 4k
Edit 2: the stomach is like any other muscle or your brain, it can be trained and I definitely “rehearse†for a couple months prior to an A race
https://www.cyclingnews.com/features/exercise-and-effective-salt-replacement/
well you are way above the average of 1,700.
I met Chris Legh at a HIM he was racing and he also had a high sweat rate
https://www.youtube.com/watch?v=_gZDX8uay9M
I have no recommendations, although I’m likely a heavy sweater as I come out of IMs/Ultras/Marys wearing white-face with all the salt encrusting
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So I recently had a sweat test that indicates I lose over 5,000mg of sodium per hour.
I am having trouble finding any info on how to approach this. How much of the 5,000mg should I try to replace per hour, seems like a bucket load of salt??
Is there a % or max amount per hour like carbs that you are generally limited to?
I have never done a sweat test
Do you recommend one? How do you do it please?
I am a fan of Precision Hydration not just for their products, but because of their services. You can do a validated online sweat test without any prep, and I think they have a protocol for a DIY measurement at home. Plus you can chat with them if you have questions.
Agreed. I wasn’t taking near enough. I went and got tested and now use their products.
Although salt supplementation seems to be popular among triathletes (perhaps because everyone wants to sell it to you, along with the associated sweat testing and “custom†hydration solutions), I am wondering if we can have some discussion about the scientific evidence for/against.
These podcasts are a few years old at this point but suggest that some research in ultrarunners at the Western States 100 and in the lab didn’t find as much of a role for large dose sodium supplementation:
https://www.scienceofultra.com/podcasts/2
https://www.scienceofultra.com/podcasts/4
Much of the ultra running research should be somewhat relevant to triathletes doing extended low to moderate efforts as well.
Unfortunately, the websites don’t have easily accessible links to the published studies so I can review in more detail.
Unfortunately, the websites don’t have easily accessible links to the published studies so I can review in more detail.
Get the book Waterlogged, by Tim Noakes. It has several decades of studies on this topic. For those with super high sodium sweat rates, try testing after 2 days of a strict low sodium diet, I guarantee your tested sodium sweat rate will plummet. High sodium sweat rates are a direct and natural response to excessive sodium in the diet 
Unfortunately, the websites don’t have easily accessible links to the published studies so I can review in more detail.
Get the book Waterlogged, by Tim Noakes. It has several decades of studies on this topic. For those with super high sodium sweat rates, try testing after 2 days of a strict low sodium diet, I guarantee your tested sodium sweat rate will plummet. High sodium sweat rates are a direct and natural response to excessive sodium in the diet
Interesting, but perhaps not surprising. I suspect that this topic is not as straightforward as Noakes and Ross Tucker want it to be. I know that I am on the extreme end of salty sweat and also feel dramatically better when doing extended exercise in hot/humid conditions if I sodium supplement (or dramatically worse if I don’t supplement). The below article discusses the issue in what I would describe as a more balanced way …
https://www.gssiweb.org/sports-science-exchange/article/sse-88-hyponatremia-in-athletes
Highly fit athletes who are well acclimated to exercise in warm environments usually excrete sweat with sodium concentrations less than 40 mmol/liter of sodium, because the capacity of the sweat glands for sodium conservation is enhanced with heat acclimation and improved aerobic fitness. This reduction in sodium loss not only helps protect blood volume, but also reduces the risk of hyponatremia. However, relatively unfit and unacclimated individuals, and even some highly trained athletes, may excrete sweat containing sodium concentrations greater than 60 mmol/liter. These “salty sweaters”, particularly those who have high sweat rates, can lose large amounts of sodium. For example, during an Ironman-distance triathlon, an athlete with a normal sweat sodium concentration of 40 mmol/liter, losing a modest 1.0 liter of sweat each hour, would lose 11.0 grams of sodium (contained in 27.6 grams of sodium chloride) in 12 hours of racing. Of course, an athlete with saltier sweat would lose considerably more. The important consideration is that salt loss through sweating can be a contributing factor to the etiology of hyponatremia, with larger salt losses conferring greater risk.
In a review of exertional hyponatremia, Montain et al. (2001) provided estimates of the plasma sodium concentration changes that will occur during prolonged exercise when water intake is equal to sweat loss. Their calculations indicate that athletes who excrete sweat containing high levels of sodium are at greater risk of hyponatremia because it takes less water intake to induce dangerously low blood sodium levels. Using their calculations, it can also be estimated that high sweat sodium losses alone can result in hyponatremia during prolonged exercise (e.g., 9 hours or more) even in the absence of overdrinking. In addition, their calculations demonstrate that smaller athletes will be at a greater risk of hyponatremia because they have less ECF to dilute. (Smaller ECF volumes may be one reason why female athletes appear at greater risk of hyponatremia. For example, even if a male and female have the same body mass, the female has less total body water and less ECF, increasing the relative risk of hyponatremia.)
Have you ever had hyponatremia that’s causing this concern?
So I recently had a sweat test that indicates I lose over 5,000mg of sodium per hour.
I think that number would be highly dependent upon sweat rate, influenced by temperature and level of exertion.
I’ve always been a heavy sweater, and was always crusted in white streaks on my gear during long hot raining sessions and races.
I had a PH sweat test done a few months ago, and the results were expressed in mg of sodium loss per liter of sweat.
In my case, the tested value was 1220mg/liter which is a constant, genetically given value (for me). What varies is sweat rate, and for me I’ve found that my sweat rate can vary from as little as 40 ozs (1.2 liters)/hour on a trainer in my garage when it’s 50 degrees Fahrenheit, up to 96 ozs (2.8 liters)/hour when it’s over 95 degrees Fahrenheit and I’m running outside.
I can begin to replicate that sodium concentration in a fluid replacement drink using Liquid IV, with 1.5 times the recommended concentration. I also drink Nuun and Gatorade Endurance with salt supplements. So far so good.
The sweat test was revealing for me as prior to that, I was drinking half Gatorade Endurance and half water on long rides/runs and long races, not knowing I was likely diluting my sodium concentration.
So I recently had a sweat test that indicates I lose over 5,000mg of sodium per hour.
I think that number would be highly dependent upon sweat rate, influenced by temperature and level of exertion.
I’ve always been a heavy sweater, and was always crusted in white streaks on my gear during long hot raining sessions and races.
I had a PH sweat test done a few months ago, and the results were expressed in mg of sodium loss per liter of sweat.
In my case, the tested value was 1220mg/liter which is a constant, genetically given value (for me). What varies is sweat rate, and for me I’ve found that my sweat rate can vary from as little as 40 ozs (1.2 liters)/hour on a trainer in my garage when it’s 50 degrees Fahrenheit, up to 96 ozs (2.8 liters)/hour when it’s over 95 degrees Fahrenheit and I’m running outside.
I can begin to replicate that sodium concentration in a fluid replacement drink using Liquid IV, with 1.5 times the recommended concentration. I also drink Nuun and Gatorade Endurance with salt supplements. So far so good.
The sweat test was revealing for me as prior to that, I was drinking half Gatorade Endurance and half water on long rides/runs and long races, not knowing I was likely diluting my sodium concentration.
You and I are similar.
E
I have been looking into this more due to issues I am having with long, hard zwift sessions (hot and humid room…). I am definitely not getting enough sodium by only mixing gatorade (normal) half strength in two bottles, but going through 4 bottles of fluid… Another forum post was suggesting to consume up to 700mg in fluids/hr, and I might try giving that a go.
Anyway, I noted that it was mentioned that salt concentration was constant, but sweat rate changes. There is a fair amount of research that states that salt concentration increases with sweat rate. That is because normally the salt is reabsorbed by the body in the sweat glands. As your sweat rate increases, there is less time for this absorption to occur. This also appears to be somewhat trainable through heat acclimatization. One study for reference: https://journals.physiology.org/doi/full/10.1152/japplphysiol.00015.2007
So while you might have had one number from testing on that day, your actual salt/sweat ratio will vary based on training and conditions.
I also sweat a lot.
Although some might find it gross, since I usually have a large accumulation of salt on my forehead, I can “supplement” by wetting my finger, wiping the salt, and licking the finger. (Do not ask a support person to do this for you.
This method, however, has the “disadvantage” that you won’t have the excuse that highly-salty sweat ran into your eyes and you had a bad race as a result.
So I recently had a sweat test that indicates I lose over 5,000mg of sodium per hour.
I’d be skeptical of this result. Sweat testing frequently overreports total body sodium losses. You probably *are *a salty/heavy sweater, and probably *do *need to think hard about sodium supplementation before and during training.
Thankfully whether you’re hitting 2000mg per hour or 5000mg per hour, it doesn’t matter because as Eric has found, the upper limit for cut comfort is usually around 1800-2000mg/hr unless you’re one of the rare folks that can intake close to 2L of fluid per hour, in which case that number might move closer to 2500mg, but that’s 1 in 10,000 athletes, and only on the bike, if I had to make a guess.
I’m in your boat. Let me try to dig up my report. I’d double check your levels though.
2k sodium/hr as Nuun tablets added to my normal Skratch drink mix. Osmo pre-load night before and morning of.
Generally go by taste. Salt is one of those things that it only tastes too salty when you’ve had too much, so my drink mix tastes sweet when I need salt and salty when I’m good.
Yup. People underestimate the value of monitoring their taste preferences. Most folks reporting that their beverage is too sweet just need to add salt.
E
Edit: 4k
Is this what your hourly report showed, or is this an edit to the hourly amount you consume during or before training?
Unfortunately, the websites don’t have easily accessible links to the published studies so I can review in more detail.
Get the book Waterlogged, by Tim Noakes. It has several decades of studies on this topic. For those with super high sodium sweat rates, try testing after 2 days of a strict low sodium diet, I guarantee your tested sodium sweat rate will plummet. High sodium sweat rates are a direct and natural response to excessive sodium in the diet
I suspect that this topic is not as straightforward as Noakes and Ross Tucker want it to be.
Aint that the truth.
They, and one other prominent MD in the ultra running community who is a loud voice against sodium supplementation have drawn some very misguided conclusions from the literature and data of Western States 100 athletes sodium levels, fluid intakes, and cramping, and blood draws. Laughably bad sport science, and barely-useful medical science.
I have been looking into this more due to issues I am having with long, hard zwift sessions (hot and humid room…). I am definitely not getting enough sodium by only mixing gatorade (normal) half strength in two bottles, but going through 4 bottles of fluid… Another forum post was suggesting to consume up to 700mg in fluids/hr, and I might try giving that a go.
Definitely worth doing. 700mg/hr is a good starting place. Many folks can and should double that.
Anyway, I noted that it was mentioned that salt concentration was constant, but sweat rate changes. There is a fair amount of research that states that salt concentration increases with sweat rate. That is because normally the salt is reabsorbed by the body in the sweat glands. As your sweat rate increases, there is less time for this absorption to occur. This also appears to be somewhat trainable through heat acclimatization.
This is all well-evidenced. Great points.
So while you might have had one number from testing on that day, your actual salt/sweat ratio will vary based on training and conditions.
Precisely. Here’s a piece I wrote a while back looking at the tradeoffs of sweat testing. I think it’s paywalled. 
TLDR (or paywalled) = you’re right. Unless you’re a pro with loads of time and a team of smart people around you testing you regularly, and you love the testing experience… it’s not worth doing.
I’m in your boat. Let me try to dig up my report. I’d double check your levels though.
2k sodium/hr as Nuun tablets added to my normal Skratch drink mix. Osmo pre-load night before and morning of.
Generally go by taste. Salt is one of those things that it only tastes too salty when you’ve had too much, so my drink mix tastes sweet when I need salt and salty when I’m good.
Yup. People underestimate the value of monitoring their taste preferences. Most folks reporting that their beverage is too sweet just need to add salt.
E
Edit: 4k
Is this what your hourly report showed, or is this an edit to the hourly amount you consume during or before training?
This is what my report showed. Don’t think I’ve ever taken in nearly that much sodium or fluids in response.
E
I’m in your boat. Let me try to dig up my report. I’d double check your levels though.
2k sodium/hr as Nuun tablets added to my normal Skratch drink mix. Osmo pre-load night before and morning of.
Generally go by taste. Salt is one of those things that it only tastes too salty when you’ve had too much, so my drink mix tastes sweet when I need salt and salty when I’m good.
Yup. People underestimate the value of monitoring their taste preferences. Most folks reporting that their beverage is too sweet just need to add salt.
E
Edit: 4k
Is this what your hourly report showed, or is this an edit to the hourly amount you consume during or before training?
This is what my report showed. Don’t think I’ve ever taken in nearly that much sodium or fluids in response.
E
Roger. My mind can now rest easy.