Absolutely 100% beneficial to me...
I recently wrote a diary entry about the incredible saunas here in China. One thing I did not mention was how going 1-2 times a week has completely motivated me to keep going and work harder. I have never heard any concerns about dehydration or other problems related to sauna's, especially for only 10-15 minutes. Seems a little far fetched to me. As you said, bringing a bottle of water would solve that problem. For me however, that heat and the water jets 100% make the difference after a long week of working out and exercising as not only do my muscles relax and release their tension, but I also relax and let the stress and worries of the week slip blissfully away as I soak, stretch and resoak for 1-2 hours at a time. Never once in my life have I heard or read any medical concerns regarding therapeudic soaking/steaming/sauna. It makes going to that gym (in the sauna I go to) one of my favorite activities of the week. I would rather go to workout in a place with steam and sauna any day before somewhere that just offered showers.
All through history many different races and cultures have used steam and sauna as a very successful therapy for treating too many different maladies and conditions to list. Sauna's are famous around the world. Sadly in Canada and the US they are few and far between which is unfortunate, as I believe everyone could benefit greatly from them. But for the native american, russian, chinese, japanese and many other cultures, saunas and steam are a cultural norm and have been in operation for 1000's of years. I thank god I am in China now where not only can I go have a steam anytime I want, but I am treated like absolute royalty when I do so. I don't even need to bring water, as the waiters will happily bring me water, fresh fruit, iced tea, or anything else I want. And here, because it is a cultural norm, it is not only fantiastic as far as service, but it is cheap CHEAP too!
If dehydration is a concern (which like I said I have never heard of) then drinking extra water would fix that. But the relaxation and muscle reliveing aspects of the sauna, in my mind, would completely out-weigh any dehydration threat. I wouldnt go every single day and steam for hours on end, but those 2 times a week I do go now are the high point of my week and give me nothing but strength and motivation to move on and go hard!
With all this sauna talk I may just have to go tonight.....
sirant