In a good workout you lose 1-2 pounds of water. We had a scientist in our group who I haven't seen in a while, otherwise I would ask him, who explained it to me once but I forgot the explanation. It had something to do with osmosis (it is not perspiration in the usual sense), and fluid leaving your body in an attempt to achieve equilibrium with the water you are immersed in. It is the same process that makes fingertips prune up.
What I'm wondering is what this loss of fluid does to the sodium/potassium balance and is it related to getting cramps after an hour or so.
Former Member
I wonder it those salt sanitized pools are less likely to make your skin prune up.
Since I only get to train in a saltwater pool, I don't prune up that quick, but it can REALLY dry your skin out if you don't shower and moisturize right after a workout.
The water isn't escaping your body through your skin, though. It's escaping through your kidneys.
I don't know about you, but personally I'm not peeing in the pool. :)
I don't know about you, but personally I'm not peeing in the pool. :)
I think we should stipulate right here to assume that everyone is courteous, sensible, and properly socialized, and thus that everyone gets out for the last step in the dehydration process I described. I certainly never said anything about staying in the pool.
This study looks at how much fluid loss occurs during swimming:
www.swim-city.com/library.php3
It seems to be based on the assumption that weight loss is the sum of urination and sweat loss.
I read that study. Maybe it is just sweat. The next time I see that guy who told me it was osmosis, I'll ask more questions.
Also, I did a little research on rehydrating and what a good level of sodium is, but that can be another subject.
This study looks at how much fluid loss occurs during swimming:
www.swim-city.com/library.php3
It seems to be based on the assumption that weight loss is the sum of urination and sweat loss.
What about metabolic water production? Any idea how much that is? Is it significant compared with sweating? (Sorry, can't do subscripts):
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy (ATP)
While I'm sure some of that water is exhaled, much of it probably exits through the kidneys as well.
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