Place a block or weight plate on the ground underneath the bar in order to elevate your heels and position the bar at a height that allows you to comfortably unrack it.
Position the bar on your rear shoulders and the place balls of your feet on the platform with your feet spaced 1-2 inches outside of shoulder width. Unrack the bar by rotating it backwards.
Start with your calves in a fully stretched position by letting your heels hang down as far as they will go. Look straight ahead and keep your abs tight, back straight and knees very slightly bent.
Press the weight up as high as you can until your calves are fully contracted. Squeeze your calves hard at the top of the movement and then let your body back down by lowering your heels, and repeat.