- Start with rear foot slightly turned out and heel raised as high as possible, pressing down strongly through the ball of the foot.
- Press up onto back of the toes of rear foot, then lower the heel.
- To complete the exercise, lift the rear heel, rising strongly as high as possible, then bend the knee and lower front foot to floor.
- Keep hips level and look forwards.
- Avoid using the foot on the floor to assist.
This exercise is deceptively difficult. Although it principally strengthens the inner knee muscle, the VMO, it also strengthens the foot, the ankle, the calf and the gluteus medius, which is the muscle at the top of the pelvis that keeps the pelvis stable when we walk or run. I went to the Poliquin Strength Institute, Rhode Island, on an exercise technique course, and there it was made quite clear that to just push the rear foot heel down onto the step without rising up high on the foot is poor form and not a true Petersen step up.
The exercise is so tough, that it is a good idea to start doing it working backwards onto a thick book, for example – or even just on the floor. As the legs get stronger, the step height can be increased. And weight can be added by holding dumbbells or a barbell.
If there is pain in either knee, this is not a good exercise to start strengthening it. Click on the linked blog to find the heel elevated Petersen step up, which is an effective preliminary exercise.