Calf, with looped Strap

A 750 mounted on a looped Strap is shown. A closed door is used as the anchor point. This technique can also be done sitting down.

Loop your Strap around your leg and then a suitable anchor point. Avoid stepping into a closed, anchored Strap.
Relax your calf. With your unaffected leg ahead of the other, lean away from the anchor and let your body weight create the required pressure.
For more pressure, push away from the anchor with your unaffected leg. Or, sit to squeeze the loop of the Strap closed with your hand.