For most sauna enthusiasts, sitting in a steaming hot room is a relaxing, social or even spiritual experience. But for the 100-plus people who sweated it out in this year's World Sauna Championships in Finland, sauna is a sport -- one that has raised eyebrows since its inception more than a decade ago.

When a man died in the competition last weekend, extreme sauna-sitting drew a new round of attention. The death also sparked questions about what even moderate sauna use might do to our bodies. With claims that saunas and sweat lodges can prolong life and cure illnesses, experts say, it might be time for a hot-air reality check.

"A sauna is like a glass of wine: It's probably safe if used in moderation and in an intelligent fashion," said Thomas Allison, an exercise physiologist at the Mayo Clinic in Rochester, Minn. "It's enjoyable, but there's no hard data to suggest that the use of saunas or hot tubs has any bearing on your overall health."
The concept of creating a hot space in which to sweat dates back hundreds, possibly thousands of years to multiple cultures. Native American sweat lodges, Turkish hamams, Russian banyas, ancient Greek hot-air baths and traditional Finnish saunas have invoked different rituals and a variety of methods for producing heat.
What they all share in common is the idea that sweating feels good and is in some way good for you.
In Finland, the practice is a way of life that begins at birth, said Kalevi Ruuska, a native Finn who is president of the North American Sauna Society in Fishkill, N.Y.
"The sauna is almost like a holy thing in Finland," Ruuska said. "You don't mess with that."
But not all Finns share Ruuska's sense of purity. In the 1990s, driven perhaps by some innate human desire to take all activities to the extreme, a group of men in southern Finland grew increasingly competitive with each other in the public sauna of a town called Heinola.
In 1999, according to Heinola's website, the event became official, drawing people from around the country as well as from Holland and Germany. Each year since then, the World Sauna Championships have drawn more competitors from more countries along with more media attention.
The rules are simple. In a sauna that starts at 110°C (230°F), competitors try to sit as long as possible. Every 30 seconds, half a liter of water is thrown onto the heater. Finns, who regularly grow up sitting in saunas, usually win. The record, set by Finn Timo Kaukonen in 2003, exceeds 16 minutes.
After about six minutes in this year's finals, however, Kaukonen and Russian Vladimir Ladyzhensky fainted. Both had severe burns on their bodies. Ladyzhensky died. While police continue to investigate, the tragic event was probably a result of extreme heat combined with moisture in the air of the sauna, said Chris Minson, an exercise and environmental physiologist from the University of Oregon in Eugene.
The human body normally responds to heat by expanding the blood vessels, which can then deliver more blood to the skin, where extra heat escapes. In turn, cooling comes from the evaporation of sweat, which begins when the core blood temperature rises by about a degree. At the same time, Minson said, blood pressure drops, heart rate goes up and the heart pumps as much as three times more blood.
The system generally works well -- until it doesn't anymore.
After too much time in an overly hot sauna, the body might lose too many fluids, which would hinder the skin's ability to sweat and the heart's ability to keep up with demand. As the air in the Heinola sauna grew more humid, the men's sweat would have also stopped evaporating, eliminating its ability to cool. Water in the air would have conducted heat, as well, making the air feel even hotter.
Combined with the drop in blood pressure, dehydration and severe heat exhaustion usually cause fainting, which in a sauna can lead to serious burns when the skin comes in contact with searing surfaces. Heart attacks can ensue. And proteins can become denatured, causing a complete shutting down of the kidneys or other organ systems. Any of those events may have struck Ladyzhensky.
"The brain is very sensitive to high temperatures," Minson added. "When we raise the temperatures of our bodies, high-clarity thinking starts to leave. I would guess he cooked his brain, for lack of a better term."
People can acclimate to heat and get better at dealing with it, said Minson, who trains athletes to perform in hot conditions. But while athletes can stop running and cool off when their bodies get too stressed, sauna competitors are trapped in oppressive heat.
This may be the first death in a sauna competition, but other people have died in similar conditions. The tragedy evokes the cult sweat lodge that killed three people in Arizona last year.
People also occasionally die in commercial saunas, especially when alcohol is involved, people are basking alone, or saunas are poorly made and unventilated, said Richard Livingston, a psychiatrist at the University of Arkansas for Medical Sciences, who has studied the health effects of sweat lodges.
To be safe, Ruuska recommends, use certified saunas that can't get hotter than 194°F. Take breaks. Drink water. And get out of there when you start feeling unwell. Avoid saunas if you are very old or young, pregnant, have a history of heat intolerance, or have any kind of condition that might affect your heart, including diabetes.
In moderation, the habit may even do you some good. Like any other activity that causes sweating and a bit of heat stress, some studies suggest that saunas may help reduce blood pressure, boost the immune system, prevent skin infections, or at the very least, relax a little. A little bit probably goes a long way.
But Livingston added, "Doing it to point where you can't do it anymore as an endurance test, just doesn't seem like all that great an idea to me."