Topic: Do swimmers sweat ?

[khendar]

Apparently they do:

http://www.swim-city.com/library.php3?id=34

This is clearly not a scientific study, but the results were interesting nonetheless.

The results showed, that swimmers lost about 600ml of sweat during their typical training session (mean distance = 4km, mean time = approximately 1 hour of training). We found that male swimmers sweated more and drank more than female swimmers. And we saw that the "sweatiest" sessions were ones based on anaerobic threshold training. Not only did these sessions increase the rate of sweat loss, but the swimmers seemed less successful in drinking enough fluid to replace their losses.

[Cognoscento]

I can't argue with that. I sweat a good deal when I'm doing sets of 50m sprints. Especially if the pool temp at the gym is even a little warm (sometimes they turn it up because the old foagies complain about the cold).  I can feel the sweat pouring out of my face. I usually bring a bottle of Gatorade or something when my swim is longer than an hour.

[DoctorOHM]

How can you tell, so does it matter?

[Cognoscento]

How can I tell? Well, I can feel it, I guess. My face (and my shoulders, especially) have a kind of pulsating feeling. It's hard to describe the feeling.  It also tastes salty compared to the chlorinated water.  I know it's definitely not imagined because I've weighed myself before and after the workout. 

[quokka]

This page probably looked at the same studies as the web page above. http://www.swimmingscience.net/2010/05/sweat-loss-in-swimmers.html

One study found untrained swimming (0.5L/hr) causes half the volume of sweat per hour compared to running (1.1 L/hr) and a third the loss of cycling (1.5 L/hr)

Most studies look at pre and post exercise weight.  This method does not determine the exact content loss and the weight after the swim is inaccurate secondary to improper drying techniques and water absorption through the skin during submersion. Luckily, the skin is a great repellent of water or we would swell up like balloons during Tennessee rainfalls, but immersion during swimming still results in approximately 0.4 L/hr absorption.

In fact one study found after training the researchers found the male swimmers lost 0.21 pounds, but women gained 0.02 pounds. These researchers believed excessive fluid consumption lead to increased weight gains, but passive water absorption is more likely.
 
A few other studies have looked at fluid loss following swim workouts and data suggest water temperature and swim intensity the most influential factor.  Swimming in temperatures above 30 degree Celsius at an average speed over 1 m/s resulted in a fluid loss of 1 L/hr.

[lonely moa]

Why wouldn't they sweat?

[khendar]

I don't know. I figured sweating is primarily a mechanism for thermo-regulation, and that the water in which they were swimming would eliminate the need for it. However it seems that the evaporation of water from the skin only reduces skin temperature, whereas sweating itself decreases the core temperature. So if your core temperature is high enough, you will still sweat, regardless of your skin temperature.

[David "Stubb" Oswald]

I remeber talking with a doctor about my work out durring a physical and at the time I was swimming a lot. He stressed the need to stay hydrated because "people usually don't realize how much they sweat while swimming". I usually swim a mile in about 35 minutes twice a week and I feel dehydrated from it, and I loose weight.