I decided not to do it, because I use weights, and would have hated only using one. So I did an hour of Zumba from YouTube.
I didn’t have my sling on, and did the left hand moves, with a lot of caution, and much slower than usual. It felt good.
I now have my flexible cast off for my hour, and only resting it on a doubled up cushion. I don’t want to move it too much.
I will leave it a few days, before washing my hair, without the cast on. Better safe than sorry.