I am 8 weeks post op acute bi-lateral ankle fracture and have to wear a boot to walk that one pumps air into. I assume I may pump the air into the boot by pressing the pump.
May I do exercises with a strap and elastic band to stretch the ankle and calf? If I don’t do exercises the foot is very uncomfortable in the boot.
Exercise is for strengthening the ankle.
As long as the pump is not electrical, you can pump the air into the boot. The is an issue with blowing up balloons, but that is only when it is blown up for the first time, because it is fashioning it into a kli. Here that isn’t an issue.
Regarding the exercise, essentially we don’t do exercise on Shabbos, in part because, often it is done in a healing way, therefore included in the prohibition not to take medication for minor ailments on Shabbos. According to a number of poskim it is permitted to do the exercises in your situation. This is because the healing of your fracture is not done via medication, rather thru surgery, and exercise. Regarding using the elastic band, in your situation it would also be permitted. Although doing exercise with equipment is not permitted on Shabbos, ( aside from the actual exercise) because using equipment is considered uvdin dchol (weekday-like, and inappropriate for the ambiance of Shabbos). The poskim say that this prohibition is waived when the action done is in order to avoid pain. Therefore it would be permitted to do the exercise even with the elastic band.
Shevet Halevi 9-78, Orchos Shabbos 8-68. Although a number of poskim prohibit inflating a ball that lost its air, because it is fixing the ball, in your case it seems that it is the norm for the cast to inflated and deflated, therefore it wouldn’t be considered making or fixing a kli.
Regarding exercise see Orchos Shabbos 20-160 ftnt. 222-223, Zera Shmuel ftnt. 460, Chut Shani (Shabbos) 4 pg. 221, Poskim.