How much do you sweat when you swim?

I was in a heated pool this afternoon trying to incorporate some treading water into my weekly cardio routine for the first time. Water was just warm enough to be comfortable upon immersion. I treaded water for about 20 min. and was wondering how much fluid (sweat) I lost during the workout. I can usually tell from a jog or a bike ride, but I really could not tell how much fluid to replace as I went for a drink. Not a huge deal, as several hours later (now) I am beginning to “feel” like I did indeed lose close to the equivalent of a jog or bike ride indoors but I was just curious if there was some knowledge about this out there.

Not sure if you could do a study on this or if people just know from experience or theory… wow, the low-impact nature of the water sure does feel GREAT compared to terrestrial activities!

I want to make clear I am not asking for a numerical answer, more just in terms of kW/hours compared to above water atmosphere activities.

FWIW, the label of the bottle of Gatorade I’m drinking right now sez that swimmers lose 2-3 cups of sweat per hour they train.

All I can offer is the fact that, as a serious lap swimmer, as soon as I get out of the pool I start sweating profusely and feel as heated up as though I’d just done a gym workout.
It’s strenuous cardio exercise, but it’s taking place in an environment which lowers your body temperature (the pool). What this means in terms of perspiration fluid loss I have no idea.

Let’s put it this way-- they never have to add more water to the pool.


Weigh yourself before and after.