Ask HN: Undo muscle loss due to chronic overuse

I have a problem that I have a heavy physical regiment because I have an autistic child with ADHD who needs constant safeguarding and physical interaction, picking up throwing around, take to playgrounds 6-9 hours a day on weekend, constant watching etc.

I'm in Denmark so I get some help with this, but my muscles are basically worn out from overuse and I used to be quite muscular. My legs especially, I find it difficult to go up ladders, and other things requiring leg strength because I never get an adequate chance to rest my legs up (if my child goes away for a couple of days I need to spend those days fixing everything around the house, so constant movement)

Part of this is age obviously but from my experience guys who are in their late 50s generally don't have these problems if they have kept in shape, to me it seems a result completely of over stress and the problems of age regarding rebuilding muscles once they are torn down.

So what I'm asking is what medications etc. would one recommend to reverse chronic overuse muscle loss in a man near retirement age who also needs to keep using his muscles all day long?

I need a plan I can basically talk to my doctor and argue for, because the way the Danish medical system works is you don't get anything unless you fight for it. I've already been told there is nothing that can be done. But I find stuff about handling muscle loss in older people when I google so I think there is probably something that could be done to help.