Summary: The repeater knee is a great warm up exercise. Learn how to do the repeater knee on stairs in this free exercise video from a personal fitness trainer.
"This exercise is called repeater knee. Now we are really going to burn out that stabilizing leg. This is a great warm up exercise or even a cardio exercise in and of itself. You can combine this exercise with our other cardio stair exercises that we have reviewed in the series. So for the repeater knee you are going to step up with one leg and you are going to stabilize while this knee repeats and as you are lowering that back foot down to the floor, try not to push your heel to the floor, you just want to tap the ball of the foot down to the floor as you are starting to feel that burn in that stabilizing leg and then come on down and switch. You can perform a repeater on one side for about 30 seconds and then switch to the other side. Again try not to force your heel down to the floor, only the ball of the foot and really pump those arms and get that heart rate up, let that leg burn, that stabilizing leg. So perform about 30 seconds to a minute on each leg and that is your repeater knee."
eHow Article: Stair Exercises: Repeater Knee