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Sweat Test Question
I plan to do my first EN sweat test tomorrow on the tail end of my long bike. I'll be doing this on the trainer in my basement. Is it ok to conduct the sweat test with a fan on...or will this affect my sweat rate by increased evaporation and cooling?
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Brad....it doesn't matter, for several reasons:
1) Fan replicates air flow you'll be generating on the road on race. I think the only reason it's suggested to do the sweat test on trainer is just to simplify things and make sure you're doing a consistent effort (no stops for lights, traffic, etc) at a consistent temperature (that is not cold nor ridiculously hot). What you REALLY want to know is, what is my sweat rate going to be on race day in race conditions.
2) Sweat rate is influenced mostly by ambient temp and effort (and your hydration status too). I.e....if your're dehydrated, you won't be sweating as much as you could/should. The temp and your effort are the key. So if you're gonna race at Z2, then ride Z2 power for your test. The temp is the major factor though. We all think about humidity affecting sweat rate, but it really doesn't affect the rate you sweat....just how soaked you get. Sweating "works" to cool us by evaporation (think of how ethyl alcohol on the skin feels cool....that's because it evaporates very quickly). When it's humid, it doesn't evaporate quickly (or at all sometimes) so you end up soaked (and hot). When it's dry (Arizona, high mountains, etc.) you "feel" cooler and don't end up as soaked at the same temperature, because evaporation is occurring and keeping your skin cooler. A fan helps with evaporation some, but it shouldn't change your rate of sweat production (but you'll feel cooler).
I did the same test you're about to do a few months ago during the IMTX build. I got a completely different number from a prior test I had done as a "stand alone" on the trainer. The stand-alone was a warm up then 1hr at Z3 (HIM prep). Got a rate of 43-58oz/hr! Used 48oz/hr at Austin 70.3 (low 70's) and was perfect...had to pee really badly at mile 50...solid HIM run for a slowpoke like me. When I did the 4hr ride a few months ago, with the 4th on the trainer (weighing before and after, etc.), at Z2, I got a much lower rate. However, I suspect I was behind on fluids already and The Woodlands will be much warmer than inside my house! I have thus chosen a rate 48oz/hr for IMTX (but will push it to the point of burping). My point is just that while I think this is a valuable exercise, it's not perfect, is affected by temp and effort mostly, and if you start it dehydrated, you may get a lower number than you need (that's my interpretation of my recent result).
Hope that helps.
Brad, thanks for alerting me to the Sweat Trial in the wiki. I had not seen that before. I understand the precision involved now. So, regarding my comments … Never Mind!
I suppose, just for fun, I could give this a try on Monday, when I'm planning on a five hour ride (the Saturday long ride). Regarding your Original Question - I would/will do it with a fan. My trainer is outside in the shade. Even so, it is *stationary*. When riding on the road, we get the advantage of about a 20 mph wind chill effect (assuming the average wind speed is 0 mph). Without the fan, its like riding in 90-100F heat, I would suspect.
My additional $0.02 is that the longer the "trial" and the closer to race conditions the better. The main "challenge" is making sure that you don't pee unaccounted for! If you can ride three or four hours outside, keep track of how much you drink and weigh naked immediately before and after, without urinating, I think you'll get the best estimate. We discussed this a bit in the IMTX forum a couple of months ago when this came up in our plans too! Obviously, you have to divide by the number of hours for your "test".
One note, yesterday turned out to be the first day with some humidity here in the Northeast, with some some followed by a few day as of rain. I rode in these conditions and not surprisingly found the need to drink more on the bike. In fact, I pulled over at a store and bought more Gatorade to get through the ride w/o running out. There are definitely many factors involved here (temperature, humidity, etc), so I'm sure that we cannot go by a sweat test alone to come up with a magic number for race day.
https://docs.google.com/spreadsheet/ccc?key=0AnROJZ4wXMC8dFJtM01QR21fLWFnNVVKUzRUVWdid1E&usp=sharing
On my own document, I keep track of heat & humidity at the mid-point of the ride/run, along with the sweat rate, to help me figure out what my target for the race should be. Depending on the environmentals, my sweat rate on the bike is usually north of 55 oz/hr and on the run I am right about 60 oz/hr.
I know this is an older thread, but I am up for a Long Ride + Indoor Sweat Test this Saturday. My Q is if I can do the whole test inside rather than trying to time it just so to get off the bike, get it on the trainer and start the test.
Thanks so much,
Beth
Absolutely Beth. You can execute the entire ride indoors on a trainer.
It is a suggestion to perform the last hour of the ride indoors on a trainer for several reasons, most importantly:
Also, EFM preaches long rides outside if at all possible. The sweat test protocol recommends performing the test @ the end of a long ride. I believe this is why the protocol mentions ending the long ride on the trainer. To help clarify IF you are doing a long ride outside.
Hi Dave,
Thank you so very much! I did the whole ride inside and am not sure I did the test correctly because post test weigh in, I gained weight??!!
I weighed 135# before the test, and 136.5# after. I ate 2 Scratch orange gels and consumed 1 bottle of water.
If my calculations are correct, I lost 1.5#.
For the math,
16x135=2160 or 22
16 x 136.5= 2184 or 22
24x136.5=3276 or 33
24x135=3240 or 32
To make sure I am correct, on this, I add the results from each calculation (16) and (24), therefore giving me 44oz total ounces per hour for cool days and 65oz total ounces per hour for warmer days.
This is the first time I've done something like this, and if this is correct, then my liquid intake has been way off for each race I've ever done - frightening!
Thank you in advance for your help.
Beth
I had a similar issue, I drank 28 ounces in the hour (I guess I was thirsty) and gained 0.6 pounds so that leaves my amount per hour at 18-27 ounces. I'm going to repeat that in the next couple days, with a fan on this time just to see what effect that has, and will post the results in case it's helpful.
@Carole,
Thank you so much for jumping into the conversation. I agree that my math was way off. I've always tried for one bottle (20-24oz depending on size of bottle).
Please loop back with your results. I am always learning.
Cheers,
Beth