Interesting observations from 70.3 medical tent re: sodium (Page 2)

My take on your findings is that the body is going to try to keep it's sodium levels intact before all else.  Eventually the body will stop sweating (and soon come the chills) to keep things in check, if you are a heavy sweater you know exactly what I'm talking about.

Pretty sure the body has safety mechanisms to keep things like this in balance, at the expense of making you feel like complete cr4p so as to tell you something before you just pass out because you are all out of whack.

I am also curious to the affects more in the long term, several hours or even a day after a strenuous event, what the tests would show.  Sometimes I feel out of whack for a full day after very intense exercise in very hot weather, much like the day after having a bit too much to drink.

Interesting results but not sure what to make of them as I don't have a medical background. I do almost all my training and racing in the heat and am still working on the best mix of electrolyte drink vs. water. It has been my experience that for long workouts and races, total volume of fluids is more important to my perceived well-being and performance than exactly what I drink. Just hydrating on water, however, does not work for me in races/workouts longer than 90-120 minutes in these conditions. I did a long brick a few weeks ago where, for some reason, I took only sports drink. Felt really awful toward the end and afterwards despite not, apparently, being dehydrated. My gut feeling (literally) is that the nutrition I was taking in was increasing my need for fluids, specifically, water. Wondering how nutrition plays into this equation. I also wonder if many of the symptoms that people attribute to dehydration/ electrolyte deficiency are something else--simple heat exhaustion (elevated core temperature), fatigue, poor preparation or overly ambitious pacing.

x2.  And on long runs in the heat.  My face is often crusted with salt after a long run in the heat.  The body is amazingly good at regulating sodium levels despite what we do to it....

Not really. Your body uses sodium to maintain serum osmolarity and blood volume. I can be measured as low but still be normal in some circumstances. In severe dehydration or hyperthermia the body may stop sweating.

Heavy sweaters may produce a dilute sweat so it may not be as bad as you would think. Heavy sweaters who train in cool climates and then travel to warm areas to race may run into problems.

Don't try and over think it. They dumbest kidney is still smarter than the smartest doctor. No one can replace training with electrolyte solutions and expect a good result.

I think triathletes WAYYYY overthink the electrolytes. For short course racing, not needed at all. For HIM/IM, yes you'll need some, but often just enough as supplied in GUs and sports drinks. However, it also won't hurt you at all to get more than you plan on, as long as you have enough water on hand.

THe kidney is an amazing organ when it's working well, which is probably close to 100% of HIM/IM participants. 

It'll basically take care of sodium and water balance for you, as long as you have minimal intake of sodium, and more importantly, sufficient water to drink to thirst. The water is the far, far bigger issue for endurance athletes - cut that off, and the kidney can't respond properly, and you'll feel and perform terribly, and if you keep it up, you'll be in the med tent. 

You can actually take in as much salt as you want - any extra salt you take in will be met with an increased thirst mechanism, so if you go hog wild on salt, you'll likely feel bloated during the race, and you know how it feels to run on a stomach full of sloshing fluid. I'm sure all of you have gorged on super salty foods at buffets or Thanksgiving and have to drink a lot of water afterwards - same effect (you're just not in the middle of a race then!) 

Sports drinks companies have made a huge amount of money by claiming their scientific formulas are essential to good performance, but it simply isn't true. As long as you get a LITTLE bit of salt for long course racing, like a GU per hour or so, you're getting enough electrolytes. Kidneys will do the rest. 

ALmost all the stories of people who were taking GUs or sports drinks and didn't do well, but then swear they improved so much their next race because they upped their salt intake, are placebo effect, and not attributable to the lack of salt. The lab values as stated by the OP fully support this, and most MDs would not be surprised one bit at this finding in athletes during a race. 

The other variables like hemoglobin, Calcium, etc., are much more variable and a lot of it has to do with how far you veer from your baseline. Sodium and potassium however, are so crucial that they're pretty much locked in at 140mm and 5meQ in healthy individuals almost without fail. I could go on for hours about the cellular mechanisms that they're so crucial for (thanks PhD) but all you need to know is that it's so vital that your body has extremely good at managing it - and some newfangled sports supplement is NOT necessary in the slightest.

Interesting and informative thread - thanks folks!

Hey AdventureBear - unapologetic hijack, but I would like to hear more on how you calculated sweat rate?

I remember hearing a "Marathon Talk" podcast with Mark(?) Hetherington (director of acclimatization research at the University of Leeds) and he laid out a what sounded like a pretty good case that only about half of weight loss came from fluid loss, or at least fluid that is used by the body for nutritional processing and cooling. Or at least that is the way I heard it. Does that jibe with your experience? I would  be happy to dig up the podcast and forward in case I have misrepresented his findings in some way.

While it does not sound like what the OP experienced in the med tent in Texas, I think I remember Hetherington also stating that his research showed that electrolyte intake may be less important for FOP athletes than it is for MOP/BOP racers, simply because MOP/BOP athletes are on the course for so long and have way too much time to take in way too many fluids in the first place.

This last theory is most likely why Bryan is always recommending that everyone would be simply better off surviving off of berries and dandelion dew found along the racecourse - he just does not understand the complex needs of us BOPrs....

I kid, Bryan, I kid...

Hey, don't under-estimate dandelion dew.  Bryan and I are starting a sports drink company based on this concept... 

Obviously I can't answer for Suzanne, but in general sweat rate is calculated by weighing yourself (in your birthday suit) before and after a training session.  The rate will be different for different sorts of training session under different conditions (heat, humidity, and intensity being important factors).   But if you measure carefully, you can get some sort of picture of how much weight you lose per hour.  There are several complicating factors.  The test doesn't necessarily extrapolate to other conditions.   It doesn't tell you what the composition of your sweat is (ratio of electrolytes to water, for example).  And your sweat rate will change over time in response to training.  Nor, of course, does it tell you how much was lost to sweat versus simple burning of calories.

There is another crucial component of the picture (often overlooked, but Suzanne's reply makes it clear that she doesn't overlook it) -- the rate at which your body can absorb water (and nutrients).  What if you learn that you sweat away 32oz of water per hour under certain conditions?  It is entirely possible that you are capable of absorbing only 24 oz/hour.  So if you try to ingest 32oz in an hour, you'll just end up with an extra 8oz sitting in your gut, and that's no fun.

The situation is in fact more complicated than I've indicate.  So much so that I'd respectfully suggest that you enter into your training with a very simple and conservative plan and adjust from there based on experience, rather than trying to calculate an 'ideal' plan.

AB's raises a great point about individual cases.  There's good data that sweat rates can vary up to 400% between athletes under similar conditions.  And sweat sodium concentrations vary too, even in same athlete (e.g. sweat sodium concentration generally drops when heat acclimatized).  Agree that vast majority of athletes overthink hydration/e'lytes/fueling, but there are some who require more attention to detail.  In shorter races it's non-issue, but over HIM/IM (or longer) small details can become big issues for certain individuals.

Agree that Luke's observations are not surprising.  Vast majority of problems are generally due to typical dehydration & fatigue.

Strongly agree with this. We can work well with much less than most people seem to think nowadays.

Even if you have a high sweat rate, your thirst mechanism will be all you need to guide you.

It's so powerful that it will kick in before dehydration will affect your electrolytes. No need to overthink this one too. Drink when thirsty or anticipate thirstiness, and don't overdo it. Kidneys will do the rest.

I will point out one thing here in regards to the hydration belts. I wear mine for all of my races (shortest running race I do is 12k) not because I need it necessarily but because I like to race the same way for all races - including my belt. though from the sounds of it many of those people were using them to use them...

My simple 2 step advice for nutrition in longer course racing.

1.  Practice your nutrition race plan in training, and in race conditions (as much as possible).  Experiment and see what works for you.

2.  Keep your nutrition plan flexible, and make sure you can adjust your hydration and nutrition independantly. 

bryancd - 2012-04-02 7:31 PM I'm still laughing wondering what dandilion dew may actually taste like.

"It is said that the Dragon Warrior can go for months without eating, surviving on the dew of a single ginko leaf and the energy of the universe" - Tigress, Kung Fu Panda

"Then I guess my body doesn't know I'm the Dragon Warrior yet. It's gonna take a lot more than dew, and, uh, universe juice" - Po, and apparently many AG'ers…

Sorry I was talking about the other stuff. I'm not interested in the sodium stuff. To me that's mostly internet fodder. The lead docs in Kona stress sodium, the top 10 in kona for the last decade (or more) use sodium supplements. People have been taking salt pills (or similar) since sailors in the 1500's, farmers from WAY back,  and soldiers in all the various wars. It's not new, it's just fun to debate. Whether you get it in food, drink or pill, it's nothing new that you need it. If it had no value, they wouldn't offer chicken broth at races and IV wouldn't be saline. The argument is how much. Those in the south will say more, those in the north will say less. Humid places more, dry places less. Trouble if you take too little, minimal downside to taking too much (outside of stomach distress). I'll let you guys argue that. I've looked an ER doc in the eye who got me out of a very bad place and told me I should have taken more, so I'm biased.

What interests me is the other stuff. How much breakdown of this, why's that's elevated, what's surprisingly level throughout. That's one reason why I haunt joints like this. I want to find a little nugget and learn something possibly big, then test it during training and search for research that has studied it.

The reason for my comment is that the overriding game changer in an Ironman is temperature. Nothing affects the day more than hot/cold temps. So my question is what else would a blood test tell us about the affects that a long day has versus a long day that is hot.