People use different amounts of power walking up stairs.

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From a physics perspective, two people walking up the same flight of stairs perform an equal amount of work. But if you walk up those stairs faster than another person, you've used more power. For example, imagine two golfers who swing the same club along exactly identical paths. If one golfer swings a bit faster -- in other words, his swing takes less time -- he will generate more power and hit the ball farther. When it comes to walking up a flight of stairs, three factors determine how much power you must use.

## The Stairway's Height

The higher the stairway that you're climbing, the more steps you must take and the more power you have to use. Obviously, walking onto a single step doesn't require as much power as walking up a flight of 10 steps. To make a formal calculation of your power output, you must know how far the top of the stairway is from the bottom. In other words, if you measure the stairway, you must measure it vertically, not horizontally.

## Your Body Weight

It's obvious that carrying a heavy weight up a flight of stairs requires more power than carrying a light weight. But even if you don't carry anything, you still have to push your body weight up against gravity. So the more you weigh, the greater power you must generate to climb the stairs. To perform a precise calculation of your power output, weigh yourself while wearing the same clothes in which you'll walk up the stairs.

## Calculating Your Power

You can quantify the amount of power you generate while walking up a flight of stairs through a simple equation, which expresses your power output in watts. Determine the stairway's height in meters -- multiply the stairway's height in inches by 0.025 to convert it to meters. You must also know your weight in kilograms -- 1 pound equals 0.45 kilogram. Time yourself walking up the stairs and then plug the numbers into the equation, which states that power equals work divided by time. Multiply your weight by 9.81 -- which accounts for the force of gravity -- and then multiply the result by the stairway's height. Divide the answer by your climbing time in seconds to determine how many watts of power you generated.

For example, if the stairway is 5 meters high, you weigh 75 kilograms and you walk up the stairs in six seconds, you would multiply 75 by 9.81,which yields 735.75, and then multiply the result by five, for a total of 3,678.75. Divide that result by six, for a total power output of 613 watts.

## The Time it Takes to Climb the Stairs

You can't change the height of the stairs or, in the short run, your body weight. But it's up to you to decide how fast to walk up the stairs and, therefore, how much of your potential power output to employ. Your potential power is limited by the strength of the muscles you used to climb the stairs. So if you want to generate more power, you need to strengthen those key muscles. The quadriceps muscle group in the front of each thigh is the main workhorse when you climb a stairway. Assisting muscles include the gluteus maximus in your butt, the adductor magnus on the insides of your thighs, plus the soleus and gastrocnemius in your calves. A variety of leg, core and back muscles help stabilize you when you walk up the stairs.