A month ago, 666 people (seriously) put themselves through their own form of hell by taking the long way to the top of one the tallest buildings in the world when they scaled the Empire State Building from its stairwell. That's 1,576 steps and 86 flights of hamstring- and gluteal-writhing agony all the way to the building’s glowing observation deck.

Runners ranged from guys like Thomas Dold -- a German who won in a time of 10:38 for his seventh consecutive year -- to firefighters (in full gear) walking up for charity.

Obviously we aren't about to recommend trying something like this unless you have a bizarre running bucket list, but the good news is you don't have to slog up 86 flights to reap benefits from working out on stairs.

In a British Journal of Sports Medicine study, sedentary people who walked a 199-step staircase for 8 weeks at least twice a day 5 days a week -- a daily total of about 10 minutes of climbing -- increased their VO2max (a measure of aerobic fitness) by 17 percent compared to a control group.

The reason for the benefits from an otherwise short workout spread through the workday? A short, high-intensity exercise is just as effective at improving your aerobic fitness as doing cardio at a long, low-intensity, says Colin Boreham, Ph.D., who worked on the studies and is director at University College Dublin Institute for Sport and Health. (Another great way to work in quick, high-intensity exercise: Kettlebells. Learn what recent research says on How Kettlebells Compare To Free Weights.)

And that's just with walking stairs. Imagine what running steps might be able to do for your fitness. "Stairs are like running uphill but harder," says Men's Health adviser Rachel Cosgrove, creator of the Men's Health Spartacus Workout Series. And since interval training is great for getting the best fitness and body benefits for your time, adding a set of intervals up stairs doesn't get much more intense.

Another benefit of running stairs is that experts believe it could help your overall speed because the workout engages more leg muscle mass -- including hamstrings and gluteals -- as they have to lift the body repeatedly. "Stronger muscles are more powerful muscles, and running speed is all about power," says Boreham.

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Try this interval workout from Cosgrove, who trains on stairs herself:

Find a set of steps -- whether at the local high school football stadium or at a nearby park -- and run up as fast as you can to get your heart pumping. However long it takes you to get up, take 1 to 2 times that to recover as you come back down before going again. Shoot for 20 to 30 minutes of stair climbing, which should be about 5 to 10 rounds.

For more fat-burning, heart-pumping workouts, pick up the Men's Health Big Book of 15-Minute Workouts and Women's Health Big Book of 15-Minute Workouts.

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