Instructions

1. Lean at around 45 degrees against a wall. Your feet should be together, glutes contracted.
2. Begin by lifting your right knee quickly, pausing, and then driving it straight down into the ground.
3. Switch legs, raising the opposite knee, and then attacking the ground straight down.
4. Repeat once more with your right leg, and as soon as the right foot strikes the ground hammer them out rapidly, alternating left and right as fast as you can.