Comments on Joe Friel's Blog: Hydration and Exercise, Part 3

So I am a very heat adapted individual. It is my ...

2008-09-30T20:05:00.000-07:00

So I am a very heat adapted individual. It is my understanding that one of the adaptions that happens is that you tend to sweat earlier, more profusely and less salty.

This summer (in the morning) I went on a 6 mile run. I weighed myself with all of my fluid (24 oz of water) and clothing. When I returned I weighed in again (so now we're talking net water loss since it includes the 24 oz I drank) and I was down 4.5 lbs, or 2.5%. For me this was very normal, and not extreme. (When I run in the heat of the AZ summer it's much more extreme).

In my mind this is an (N=1) indication that the "conventional wisdom" of 2% is horribly wrong. I've never done anything but drink to thirst, and this includes multi-hour runs at temps in excess of 100F.

After 3 hours I think the game could change, and I think the questions are far more interesting.

Thanks for the series. I enjoyed it. I haven't done the calculus to determine at what rate do you need to consume various concentrations of salt to deal with the loss of salt due to sweating at it's concentrations. That would be interesting.

I'll stop blabbing now.

-Jot

Hi sketti- I don't think it needs to be confusing ...

2008-09-30T14:25:00.000-07:00

Hi sketti- I don't think it needs to be confusing at all. Just take a drink when thirsty. That doesn't mean emptying the bottle each time. If you're keeping up with your thirst it won't take all that much. But if you forget to check your thirst regularly, which is certainly possible in a race, and fall behind then you would be forced to take bigger swigs. But, again, remember that you will not replace all of the fluids lost. Don't even want to. "Managed dehydration."

Drink to thirst. That seems easy enough. However, ...

2008-09-30T12:05:00.000-07:00

Drink to thirst. That seems easy enough. However, and i hate to contribute to the "it depends" mantra, i find that when i drink to thirst i will drink 8-16oz or more at one time. Of course this isn't possible or recommended while in a race. So a regimented sip or gulp before i feel the complete onset of thirst seems to make more sense to me. For instance, say i get thirsty on a tempo ride at 90min in, i'm not going to gulp down 16oz of water all at once. I'd rather sip 2oz every 12min to complete my 16oz every 90min. And we are back to the original scheduled drinking habits... my head spins.

Hi Ansis--The onset symptoms of hyponatremia start...

2008-09-29T15:02:00.000-07:00

Hi Ansis--The onset symptoms of hyponatremia start well before reaching 128mmol/l. And there are even those in the medical profession who say hyponatremia is achieved at some number above 128, such as 134mmol/l. The bottom line is that we can avoid overdrinking and its potential symptoms at whatever level of seriousness they may elicit by drinking to thirst rather than to a schedule.

Hi bahzob--I always recommnend that we should all ...

2008-09-29T14:54:00.000-07:00

Hi bahzob--I always recommnend that we should all be skeptical any time someone who is purported to be an authority (including me) tells us anything. But at the same time we must be open minded and be willing to accept new ways. When involved in such discussions I always have a little thought in the back of my mind -- "He may be right." This attitude has led me to accept rather uncommon points of view (for ex, midsole cleats, Paleo nutrition and now drinking to thirst rather than a schedule). So what should you do with conflicting ideas on such a topic as this? My mother used to say that "the proof of the pudding is in the eating." That means try it and see what happens. Training is the place to try such things. Good luck!

Hi Mama S--That's a very interesting story. You di...

2008-09-29T14:46:00.000-07:00

Hi Mama S--That's a very interesting story. You didn't say what your body weight was at the start but 13 pounds is a lot regardless. It's remarkable that you even finished. You must have been highly motivated.

I don't believe that the localized cramping of the propulsion muscles for cycling and running are related to sodium concentration (cramping during hyponatremia is generalized). There is no research to support the theory that sodium is related to cramping I know of. You might see my post on cramping from last May (http://www2.trainingbible.com/joesblog/2008_05_01_archive.html).

How were you able to drink so much and yet remain thirsty? Good question. I don't really have an answer for you as I've never seen any research on such stuff nor have my athletes experienced it. It could be that you were taking in so much sodium that thirst was stimulated. Or perhaps it was the sweetness of the sports drink that kept you drinking while you were fighting off a total bonk. Either way I'd suggest not using sodium supplements the next time and drinking to thirst.

My name is Ansis, I am a doctor in physics, incl. ...

2008-09-27T11:18:00.000-07:00

My name is Ansis, I am a doctor in physics, incl. colloidal chemistry. In your publication I paid attention that with given data it is possible to calculate how liters of pure water (x) one must drink to reach the treshold of hyponatremia (128 mmol/l), assuming the initial concentration to be 140 mmol/l. The equation to solve is:
(5600-40x)/40=128
note that keeping denominator constant means an athlete who compensates all water lost - as suggesting by ACSM, and I take "medium sweat", i.e. 40 mmol/l. This equation returns x=12 liters. I dare to say that nobody loses 12 l of water during exercise... even if we imagine n-times Ironman distance and the athletes do, it seems to be insane to compensate such a huge amount without taking any food.
With solving this simple equation I have to conclude that the threat of hyponatremia due to compensating all water lost with pure water in fact is negligible (?).

Staying properly hydrated during multi-day events ...

2008-09-26T19:45:00.000-07:00

Staying properly hydrated during multi-day events such as a bike tour is extremely important for your health, comfort and performance. The bicyclespokesman blog (http://www.bicyclespokesman.com) has a good post on tips to stay hydrated on multi-day or weekend events.

Help. I would like to believe this and in fact my ...

2008-09-25T02:14:00.000-07:00

Help. I would like to believe this and in fact my experience has been that I have often drunk much less than the recommended amounts on long (6+ hour) rides and not felt bad as a result.

But it is worrying that in the same week subscribers to your blog and that from Training Peaks (which you mentioned in passing) get such contradictory advice.

How can we tell which is right?

Your articles on hydration are highly interesting ...

2008-09-24T18:43:00.000-07:00

Your articles on hydration are highly interesting to me. Thank you for writing them!

I've completed 8 Ironmans, most recently Kona last year, and almost always have issues with cramping toward the end of the bike. I always assumed it was b/c I wasn't taking in enough sodium? Salt tabs usually seemed to work. But last year in Kona I had a major issue that I have not yet figured out. I was drinking gatorade almost exclusively (that and GU for calories). But before the bike turn-around I was feeling twinges of cramps and felt thirsy. So naturally, I drank more gatorade. A lot more.

By the end of the bike I was really cramping and took like 8 minutes in transition before I could start running. Long story short, I managed to run maybe 11 miles but then my body pretty much shut down and I walked the majority of the rest of the day. I felt like I had all the classic signs of dehydration and low sodium (cramping, thirst, but peeing all the time), so I kept drinking as much as I could (again, mostly gatorade b/c I knew water would cause hyponatremia). I also took many more salt tabs over the course of the marathon.

Ends up at the end of the race I was so bloated that my mom didn't recognize me crossing the finish line. I had gained 13 lbs from start to finish as my body was just storing all the liquid rather than letting my body use it as needed. In the med tent, after a blood test, they told me I was low on potassium. I peed off 13 lbs of fluid in the next two days as my body composition returned back to normal.

Lesson? Drink less altogether? Clearly, after reading your articles, that's what it seems... just hard for me to comprehend b/c my issues started relatively early on and I felt so thirsty. What do you think?