first sweat test

Chris M.

After falling apart in Louisville last year with leg-locking cramps at mile 6 of the run, one of my goals for this season is to determine my sweat rate and prevent that from happening again.  I lost 6.5 (5 pounds lighter, but drank 24 ounces of water) pounds during todays 1:35 workout in my house where it was in the high 60s.  According to the sweat rate calculator in the Wiki, I need to drink between 65 and 91 ounces every hour.

What is a normal sweat rate, and what is everyone else typically drinking per hour? 

BradBoomer

Wow! I'd re-check. 6.5# in high 60's?! I've never been that high in 85+ and 95% humidity in August.

Chris M.

Yes I agree it seems high so I tested again today, 60 minute ride in the same room, and I lost 3 pounds, taking into account the 24 ounces of water I drank.  I should say that this room is cold when I start, but is probably hotter than that while I'm training.  Still, it seems like a lot of weight to lose in a short amount of time. 

Nemo Brauch

A few things. First, I'd agree, 65-90 oz/hr seems crazy high and I'm not even sure your body would actually absorb it even if you could consume it at that rate. My target for H20/hr usually ranges in the 20-30 ounce area. However, this just goes to show a few things:

1- everyone is different, which is why it is important for you to test
2- you ideally want to test in the conditions you'll be racing. We've had numerous discussions about how and why indoor watts are lower than outdoor. Indoor sweating rate is also going to be different than outdoors. It might be hotter outside, but you'll get more evaporation effect because you are actually moving through the air (humid or not) vs just sitting in a dripping pile of salty gu.
3- there's a certain amount of adaptation that your body will do as the temps rise over the summer which are going to affect your sweat rate.
4- the effort for your 1 hour indoor workout is significantly different than your effort will be per hour on race day.

Which brings me to my main point- I wouldn't use any of your sweat test results done indoors in February at efforts of 95% FTP for a race your are doing outdoors in August at efforts closer to 80% FTP. Good practice yes, good for telling you what to drink for the workouts you are doing now, but no good for guiding you on what your nutrition plan should be in August.

Chris M.

Posted By Nemo Brauch on 12 Feb 2011 10:37 AM

A few things. First, I'd agree, 65-90 oz/hr seems crazy high and I'm not even sure your body would actually absorb it even if you could consume it at that rate. My target for H20/hr usually ranges in the 20-30 ounce area. However, this just goes to show a few things:



1- everyone is different, which is why it is important for you to test

2- you ideally want to test in the conditions you'll be racing. We've had numerous discussions about how and why indoor watts are lower than outdoor. Indoor sweating rate is also going to be different than outdoors. It might be hotter outside, but you'll get more evaporation effect because you are actually moving through the air (humid or not) vs just sitting in a dripping pile of salty gu.

3- there's a certain amount of adaptation that your body will do as the temps rise over the summer which are going to affect your sweat rate.

4- the effort for your 1 hour indoor workout is significantly different than your effort will be per hour on race day.



Which brings me to my main point- I wouldn't use any of your sweat test results done indoors in February at efforts of 95% FTP for a race your are doing outdoors in August at efforts closer to 80% FTP. Good practice yes, good for telling you what to drink for the workouts you are doing now, but no good for guiding you on what your nutrition plan should be in August.

Thanks Nemo.  I will be sure to get an outdoor number when the weather breaks.