Place the balls of your feet on the platform and secure your knees under the pads. Remove the stopper and fully extend your calves by letting your heels come down as far as you can. Using only your calves, drive the weight by coming up on your toes until you calves are fully flexed. Pause briefly at the top and then lower your heels back down. Continue until you reach muscular failure and then put the stopper back in place.
Tip: Make sure to use only your calves during this exercise. Avoid rocking your body and using momentum to lift the weight. It may also be helpful to use a spotter during this exercise in order to help you place the weight stopper back in place as soon as you reach failure.