A few weeks ago I started doing stair sprints. Just wanted to share my experience. I'm lucky enough to work in a building that is 20 stories and has 2 stairwells that are not used much. I had previously been doing HIIT on a stationary bike and elliptical and got bored really fast. So i figured doing HIIT on the stairs would be a nice change and in a month I havent gone back. Here is how I do it: 5 min warmup on treadmill then good stretches 1 min easy jumping jacks at the bottom of the stairs to get heartrate to at least 140. 1 min - sprint up stairs, hitting every stair 1 min - jog down stairs 1 min - sprint up stairs, hitting every other stair 1 min - walk down stairs and I do that cycle 10 times. 10 min jog, down to slow walk on treadmill then stretch. Starting out I could only do about 4 stories in a minute going up, then my heartrate would spike 190 and I always stop when I hit that point. Now, a month later, I can do 10 stories up and then jog 6 down and feel fine. Generally my heartrate hits 185 at the end up my up portion and drops to 150 at the end of the down portion. My average heart rate is usually 170. For my training thats ideal, but others could change that easily by shortening the minute up. This probably isnt something if you have bad knees, and I have to be careful about the turns on each landing. But its been hugely successfull for me, with my diet being solid ive dropped 10 lbs in 3 weeks and my legs have added lean mass, all for just 30 minutes a day, 3 days a week.