Exercise Advice: Using a hack squat machine, position yourself as you normally would if you were performing a regular hack squat. Place your toes at the bottom of the hack squat platform so that your toes are placed on the bottom edge and your heels are hanging over the edge. Begin by pushing your toes down so that your heels become raised so that you are on your tippy toes. Be sure to really flex your calves at the top of this movement for a one-count. Return to the start position and repeat until failure. The initial upward movement should be quick and explosive.