I'm 50 and had both hips replaced last year... I have been slowly getting back to a high standard of fitness as I was very fit before my hips gave out..
I have just ran 5 kms in 25.20 is this an ok time for my age ?
In old money, that works out at around 8 minute miles (over three miles distance) – I bet that there are a lot of 50 year olds who have not had hip replacements who could not match that for one mile.
But given the stresses running places on the body – I would consider swimming as an alternative exercise. Replacement hips don’t last forever (but I suppose they can be replaced again).