Thanks, gcoe. I felt a lot better reading your post, and the soreness, as you predicted, has mostly faded. I've never done that to my muscles during any exercise before!

I understand that it'll take quite some time to recover, though I think my PT has unrealistic expectations about my recovery (she seems to think I'll be good to go in a couple of weeks).

I am trying to be patient and not do too much too soon, but I am not used to being so inactive and am looking for ways to exercise while I recover. So I've eliminated the following, either by logical reasoning or trial and error: running, walking more than a mile, swimming (freestyle, at least), stationary bike more than 20 minutes, indoor climbing.

My university gym has a hand bike which I haven't tried yet. I also have access to various swimming pools but not sure what to do that doesn't hurt my ankle. I've gone rowing a couple of times (in a boat, not with the rowing machine, which causes too much ankle motion), which is nicely gratifying but not very aerobic and only an upper body/back exercise.

Any thoughts on what else I can do. I am mainly interested in exercises that: (a) help me keep my hard earned leg muscles (especially the calves, but quads/hamstrings as well) and (b) something sufficient for reasonably aerobic fitness.