Bounding 3:00 
Now that we have moved house and there is no longer any risk of overstating when we say 'we have a garden', we finally bought a trampoline for the kids. A beast too - 4.5m diameter.
Anyway I did wonder if bouncing on it would be good rehab for the ankle so I tried it and after only a few minutes my right calf muscle was obviously working very hard. Might be too soon for that, will have to ask to physio.
Waking up the next morning it was obvious that it wasn't only my right calf muscle that was working hard! A quick search on the internet and bouncing is considered to be good, all-round exercise. So maybe not just for the kids after all.