Sweat Trial - use a fan or not?

donymo

I did my sweat test in my pain cave, with a fan on me at 72 degrees indoor temp.

Final result was I only lost a half pound, which seems like not much.

I would say I am a light sweater in general, but there is a marked difference when I have that fan blowing on me vs not.

Should I use the fan?

Darren Freeman

Yes to using a fan.. When riding your bike you have a constant breeze and get the cooling effect from that so you need to make sure you simulate that. You could go as far as to make sure the fan is blowing at around the same speed which you will be traveling. Although I think that can be overkill as the cooling area of your body with a fan is less than when you are riding outside under real conditions.

The more important question is.. Does the temp in the room where you performed your sweat test reflect the temperature you will experience when you will be racing? You clearly don't want to do a sweat test in an air conditioned room at 65 degree when you'll be racing in conditions that are 80 degrees.

jaleslie

Sweating cools us by evaporation.  Lower humidity or more air flow/current makes us "feel" less sweaty/wet, but doesn't really change the sweat rate as much as you think (over time, as you benefit less from evaporation, your core temp will rise and you will ultimately sweat at a greater rate).  If it's humid or you're not moving fast (ie....when running vs. cycling) you get soaked because the sweat can't evaporate.  You thus feel hotter (and do eventually experience more core temp rise).  If it's dry (think of the "dry heat" of Arizona!) or you're moving fast, the sweat can actually evaporate and you thus don't get as wet/soaked and also feel cooler.  

So, IMHO, as mentioned below, the most important thing is to try to mimic the conditions you expect on race day when you test.  Or even test outdoors in similar conditions.  It doesn't have to be only one hour either....as long as you do the math correctly (divide by the number of hours you tested in order to get your fluid needs/hr) and don't pee between weighing in, and way nude before and after, it should theoretically be even more accurate.  I think it's prescribed as a one hour indoor test just to minimize "mistakes" and "miscalculations" and keep it simple.  That is fine....but I think it makes more sense to do a longer test (provided it's not so long you have to pee...then it would get really messy!) in conditions close to what you expect.  

So, I don't think the fan makes much difference in the outcome of your test....but you may be less wet when done...but it's not as much because you didn't sweat as much, but rather because some of the sweat was able to evaporate.