I did a sweat test today.

[scoolover]

This morning, after reading Nancy Clark's book on sports nutrition, I went to the gym and did a sweat test.

I ran for 1 hour at 10 minute pace on the treadmill at my gym. The gym temp was about 68 degrees.

I weighed myself naked (ladies, minds out of the gutter) before and after. I also dried myself with a towel. Anyway, after doing what I would consider a pertty controled study, I lost 3.5 lbs during the run. That means that at that pace, during a marathon in about the same temperature I would need to drink 14.7 pounds of water (liquld). That is 235 ounces of water during the marathon.

Does this sound right? I am aware of drinking too much without some salt do the death thing doesn't concern me. I have been dehydrated during my last two marathons but can anyone drink that much?

What do you think?

Anyone else done the sweat test?

See ya
Scott

 

[Cindylou]

Hi Scott,

Your math looks right. I did a similar sweat test (although not as nearly as controlled as yours, and I call myself a scientist!!) and turns out I needed to consume 40 oz of water per hour (vs 56 oz for you). I find it hard to believe that I could drink that much during a run and not slosh. I think routinely I drink 1/2 to 3/4 of that. I think there is an upper limit to how much water your gut can absorb per hour. I had found an excellent website a while back, but in searching just now I can't find it. I'll keep looking.

Cindy

 

[Cindylou]

I found another website that says on average a person's stomach can empty 6 to 7 oz per 15 minutes or 28 oz per hour. That's going to leave a whole lot of sloshing liquid in your stomach if you drink 56 oz. It did say that consuming drinks with sodium will lower your sweat rate. You may try the same sweat test while drinking Gatorade then subtract out liquid in to see if you have a similar sweat rate.

Good luck.
Cindy

 

[scoolover]

That's a good idea with experimenting with different things. I also don't know how to factor in the fact that I had gastric bypass surgery and don't know if that changes water obsorbtion. Thanks for the site info.
Scott

 

[mogulskr]

Your math is right, but you will never be able to replace the fluid loss. The general rate for replacement is between 16 - 24 ounces per hour. This amount also takes into fact that your bodies electrolyte level is correct. If it is low you will absorb less fluid. If the fluid contains simple sugers the rate of absorbtion is even lower.

So it is very important to start off hydrated and come up with a plan to replace as much as your body is willing. Also keep you electrolyte level up so you can absorb the fluid.

Hope this helps.