Then if you want to calculate your horsepower output in stair climbing, estimate as closely as possible the height of the stairs (rise/step x #of steps) and measure the time it takes to go up the steps and using the datum that 1 horsepower is 33,000 ft-lbs/min you can calculate your HP for that climb. For example, I and a pack weighed about #170 and I fast walked up 10flights of 10 steps 7" tall (58' +/-) in 33sec. 58x170=9860 ft-lbs x60 div by 33 or 17927 ft-lbs/min. Divide by 33,000 to get 0.54 HP. So my unsustainable power output for a short time is close to 375watts. This blows me sky high of course. Nice fun and games to time yourself now and then and see where you are.