Why do my sweat levels vary so much?
I know this may sound like an odd question but I have been curious about it. When I work out, I can be doing pretty much the same calories and one time I will be barely sweating and the other time I will be literally dripping with sweat.
An example -
On Monday I did 40 minutes on my exercise bike and according to my heart monitor I burned just under 300 calories. I was just barely sweating when I was done.
Yesterday, I did 40 minutes again and again my heart monitor said I burned about 300 calories but this time I was soaking wet with sweat. I literally was having to wipe it away from my eyes.
The only difference was that the first day I did a hill climb program and on the second day I just did flat pedalling. However, with having apparently burned the same number of calories, why is the sweat level so different and which is best?
Both days I ate about 1500 calories
not an expert, but your body sweats to keep itself cool. The air conditioner could have been lower. The fan not on? Your hydration level may have been higher/lower. You could have been working harder because you were sore from Monday. I wouldn't worry about it too much. Just make sure you are staying hydrated.
I think it also depends on how much water is in your body. You won't sweat much if you haven't been drinking much, and vice versa. There's probably a lot of factors involved, including how hot you are. It could be the hill program had a lot more resistance and therefore you weren't moving as fast (and generating heat) as you were while doing the regular program. Or maybe you just drank a lot more that day.
I often wonder the same thing. For instance, if I drink a lot of water one day and I have too much in my body, does that mean I'll sweat more?
hmmm..could be. I can't recall for sure but I may have been drinking a lot of water the day before.
It could also be the humidity - higher humidity means that sweat takes longer to evaporate, which means that more accumulates on you, which means that you aren't getting cooled off as effectively.
So we all get the "drink lots of water" advice, but I've been seeing things now that recommend "drink for thirst," rather than drinking a lot during exercise. I've also seen advice that says if you wait until you're thirsty, you're already slightly dehydrated, but that was aimed at hikers in AZ, so I'm not sure it translates. At any rate, I'm not sure what to take away from this. I know hyponatremia is very serious, but I thought it was pretty difficult to achieve unless you were really sweating like crazy and replacing it only with water. However, a couple of articles in running magazines are advocating the "drink for thirst" mantra as well as actually eating salt during races...hmmm. Back to the point, The Penguin over at Runner's World gave some advice to a profuse sweater in a recent column. He's a runner, not a doctor, but hopefully someone at the magazine vets their columns: http://thepenguin.runnersworld.com/2009/09/sw eating-buckets.html
I am actually digging into nutrition for athletes as we speak, and its recommended that I drink 8 oz of water per hour all day 120-136 oz a day, and thats with no exercising.
I can tell you that drinking when you are thirsty (during exercise) is a bad idea. By the time you realize you are thirsty, your body is dehydrated and your heart has to work harder to pump less blood through the body. Then you are playing catch up and that too is fraught with peril.
My coach recommends taking two salt tablets per hour during training and races. Salt helps you retain water and (may) ward off cramping. I learned this the hard way at Augusta 70.3 a few weeks ago. When I got off the bike, I had only drank 3 26 oz bottles of Gatorade and water. I cramped up badly on the run and was dehydrated the whole time.
This doesn't mean much for folks that are exercising for weight loss, but I theorize that replacing what you lose while sweating is NEVER a bad thing. You can figure this out by trial and error and/or weighing yourself before and after your workout (naked) (add whatever you drank during exercise - potty breaks).
I think its pretty hard for people that exercise less than 2-3 hours to get hyponatremia.
I've read that your heart rate can be up to 10 beats higher per minute when you are dehydrated. This would explain a little of the cardiac drift (besides getting tired) when exercising. You HR is higher at the same pace.
Stay hydrated! Experiement. Find what works best for you.
Original Post by delaney86:
I often wonder the same thing. For instance, if I drink a lot of water one day and I have too much in my body, does that mean I'll sweat more?
No. Your body closely regulates the amount of water in your body. If you have an excess, it ain't coming out via sweat.
The amount you perspire has nothing to do with how much water you have been drinking. If you ever reached a point of heat exhaustion where you stopped perspiring, you would be experiencing an acute medical emergency, not a daily fluctuation in hydration level.
Original Post by azdak:
Original Post by delaney86:
I often wonder the same thing. For instance, if I drink a lot of water one day and I have too much in my body, does that mean I'll sweat more?
No. Your body closely regulates the amount of water in your body. If you have an excess, it ain't coming out via sweat.
The amount you perspire has nothing to do with how much water you have been drinking. If you ever reached a point of heat exhaustion where you stopped perspiring, you would be experiencing an acute medical emergency, not a daily fluctuation in hydration level.
Good to know. I'm glad I brought it up. Thank you!
Original Post by wesmckean:
I can tell you that drinking when you are thirsty (during exercise) is a bad idea. By the time you realize you are thirsty, your body is dehydrated and your heart has to work harder to pump less blood through the body. Then you are playing catch up and that too is fraught with peril.
See, and this is always what I'd heard, too, but check this out: http://aimsworldrunning.org/guidelines_fluid_ replacement.htm
They don't cite sources, but the NYC marathon page also says the same thing, according to the International Marathon Medical Directors Association (again no journal citations). I'd like to believe they've done their homework. Still - it's absolutely against what I'd always heard. I suppose that once running for 2+ hours becomes possible for me again, I'll have to give it more thought.
I think you're right in that it's difficult to suffer hyponatremia if you're not exercising for longer than 2-3 hours.
ETA: Here's a review article posted in a British medical journal - it cites specific studies. http://www.pubmedcentral.nih.gov/articlerende r.fcgi?artid=1872071
