Question: I want to do step-ups this winter for added leg strength, but don’t know how tall the box should be. I am 5-foot-3 and ride a 50-cm frame. — Patty G.
Coach Fred Matheny Replies: The box should be high enough so that when you face it and put one foot on top, the knee of that leg is bent about as much as it is at the top of the pedal stroke.
If the box is much higher, you run the risk of injury. Your knee will be bent too much as you begin the stepping motion. This can produce quite a bit of shearing stress on the back of the kneecap.
Also, an overly high box means that you’ll tend to push up from the leg on the floor rather than lift your body using the leg on the box. That may improve your vertical jump, but it doesn’t work the quad muscles much, and that’s the goal of this exercise.
I’m 5-foot-10 and use a box that’s 14.5 inches high. It seems to work fine for me. So I’d estimate that around 12 inches might be a good size for you to try. You’ll have to experiment to see what height works the quads without causing knee strain.
Tip! To match your step-up knee bend with your pedaling knee bend, make a goniometer. Cut two long strips of cardboard about an inch wide. While sitting on your bike with the pedal at the top of the stroke, have a friend center one strip on the side of your upper leg, and the other strip on your lower leg, with the junction at the outside center of your knee. Hold that angle, move to the box, put your foot on it, and see how the strips align with your leg. Adjust the box height accordingly.
Step-ups are a great winter training exercise. My eBook, Off-Season Training for Roadies, has instructions on how to do step-ups and incorporate them into a program that builds strength and converts it to cycling-specific power.