On the rare times when Chris Guevin takes the elevator at work, he sometimes forgets he has to push a button to get to the right floor. And though he has a perfectly good bathroom on the upper level of his St. Paul townhouse, he often walks down to the bathroom in the lower level.

Guevin really likes taking the stairs.

He’s one of a small but growing number of people who race past you on the steps while you’re riding the escalator at the airport, intentionally park on the upper decks of parking ramps, ask for rooms in higher floors in hotels or hit the stairwell during workweek lunch breaks just to squeeze some extra steps into the day.

For them, taking the stairs — often hundreds a day — is a cheap, convenient, low-impact way to stay healthy that doesn’t require special skill, coordination, equipment, gym clothes or even athletic shoes. The more competitive among the stair masters are turning it into an extreme sport.

“For certain, 10 stories or less, I will take the stairs,” said Guevin, 60. “I can go five sets of flights with someone half my age and not be winded at all. I have seen the benefits physically and mentally.”

Stair climbing has been described as more taxing than brisk walking, rowing or jogging. It can lead to improvements in blood pressure, weight, cholesterol numbers and waist circumference, according to one study.

Men who average at least eight flights a day have a 33 percent lower mortality rate than men who are sedentary, according to Harvard Medical School.

Even brief “snack-sized” bouts of exercise on the stairs — a quick three flights, three times a day, three days a week — can lead to increased fitness among sedentary young adults, according to another recent study.

The most dedicated stair climbers do a lot more than that.

Maureen Wegner, a 57-year-old administrative assistant at the Mayo Clinic in Rochester, said that a few times a week, she tries to climb 50 flights of stairs during her breaks at work.

“I time myself. I know I can climb to the 17th floor in under 4 ½ minutes,” she said.

David Hanley, a 46-year-old software engineer from Chicago, started walking up the stairs because he was overweight and found it embarrassing to do other forms of exercise.

“I could run like a block, and I had to stop,” he said. “I needed to do some sort of exercise where nobody could tell I was bad at it. No one is on the stairs, typically, at my job. Nobody’s going to know if I’m doing it slow or bad or wrong.”

Hanley lost 40 pounds by taking the stairs. Now he considers waiting for the elevator “a giant waste of time.”

He’s also become an avid tower running competitor. That’s the extreme but increasingly popular sport where people compete to be the fastest up to the top floor of skyscrapers around the world — from the Empire State Building in New York City to the IDS Center in Minneapolis.

“I’ve been in stairways in lots and lots of buildings,” said Jason Larson, a 36-year-old engineer from Golden Valley who is one of the top ranked stair climbers the country.

Among competitors, it’s a weird and punishing ordeal that involves an unrelenting fight against gravity, repeatedly lunging upward two steps at a time while hauling with both hands on the handrails.

Some events, like the Dallas Vert Mile in Texas or the Break the Bank at TCF Bank Stadium in Minneapolis, are endurance challenges lasting for hours and involving multiple laps on a building’s staircases. Others are just a lung-busting sprint from the ground floor to the top, fending off elbows from fellow competitors jostling for position.

Dry air, no cheers

In a narrow stairwell, there’s no room for spectators to cheer you on. And, depending on the race, the reward for finishing may be nothing more than a great view. Competitors say they also finish races with “track hack,” an irritated throat from gasping dry air in the staircase.

There’s also “the heat and the smell,” said Melissa Gacek, an elite White Bear Lake runner who has won the IDS Center tower run multiple times.

“It was the hardest thing I’ve done, next to giving birth to my daughter,” said Jane Trahanovsky, a 62-year-old from Orange County, Calif., of her first stair climbing race.

But for Trahanovsky it’s worth it.

“It ended up being a life-changing experience for me,” she said. She lost 80 pounds through stair climbing, then wrote a book, “See Jane Climb,” about competitive tower racing.

Taking the stairs isn’t just about recreation and waistlines. Many stair climbers feel they are maintaining a critical life skill: the ability to move up and down between floors without relying on the elevator.

“What if you need to do something like that in an emergency?” Trahanovsky said.

That question is particularly relevant to Daniel Casper. The 52-year-old captain in the Minneapolis Fire Department is a world champion competitive cyclist. He’s also an avid stair climber, competing in races up the IDS Center and the Empire State Building.

He and fellow Minneapolis firefighters plan to race up the 31 floors of the U.S. Bank Plaza building in Minneapolis on Saturday, wearing 45 to 50 pounds of firefighting gear in a competition with teams of firefighters from other departments around the state.

It’s good practice for something a firefighter might have to do in real life.

“Climbing stairs is really important to us. It’s integral for our jobs,” said Linda Sone, another Minneapolis firefighter and stair climbing competitor.

The firefighters trained for the tower climb competition by climbing from the third to the 24th floor of Hennepin County Government Center, taking the elevator down, and then going up again and again. Casper said he’s done that climb as many as 20 times in a single workout.

Casper usually times his sessions at the Government Center at the end of the day when there are fewer workers in the building.

“The last thing I want people to do is say, ‘You know these guys are really stinking up the place,’ ” he said.

Instead of kicking the firefighters out, security guard Kayla Goley joined them for a lap during a recent workout. She, too, wants to be ready if she has to use the stairs.

“This is my building, and I know I can get up and down the building if I need to,” Goley said.

To promote fitness, places like the Mayo Clinic post signs at employee elevators, encouraging staffers to take the stairs. There’s even one building in the Mayo complex that has music playing in the stairwell.

Dedicated stair climbers, however, don’t mind if a stairwell is dreary or deserted.

“If I see a really tall building, I wonder how many floors is in that building,” said Nam Truong, a stair climbing competitor from Eden Prairie. “I wonder how can I get inside.”