When you are looking for a high-intensity aerobic component to add to your workout or simply want to enjoy the benefits of a sprint without having to go outside then high knees is your go-to exercise.  

What's involved: Quads, front hip flexors, lower abs, calves, arms.

Powered by: Front hip flexors, calves, quads.

Tip: Make it really work for you by landing only on the balls of your feet throughout and by speeding up the motion of your arms.