HOW: Grab two kettlebells or weights that are heavy enough that they are difficult to move. Set up in a half kneeling position with the kettlebells to the inside and outside of the front leg.
Slide the shin of the front leg forward over the toes. With both arms, grab onto the kettlebells and get the spine tall. Begin to push the ground away from you, as if you want to stand straight up. Hold this tension not letting your body move.
FEEL: You should feel this in the quadriceps of the front leg.
COMPENSATION: Avoid letting the heel rise off the ground. Avoid letting the torso fall forward.