Hands on the wall, fire three fast knee drives.
Keep your body in a straight line from heel to head, don't let your hips sag.
Firing three rapid knee drives on the same leg before switching turns the wall drill into a rhythm and repeatability test. Your quads have to punch the knee to hip height three times without the position degrading, while the glutes on the stance side keep your hips tall and your body line locked against the wall. It builds the ability to repeat fast, clean strides, which is the difference between one good step and actual acceleration.
Repeating drives on the same side tests whether your position survives speed. Anyone can hold the line for one drive. Three in a row exposes hips that sag and cores that switch off.
As fast as you can go while your body stays in one straight line from heel to head. If the third drive is sloppier than the first, slow down until all three match.
Anything solid at the right height works, a wall, a rack upright or a sturdy railing. What matters is the forward lean angle and straight arms, not the surface.
