Running is safe. No joint is injured solely by running, despite what you may have heard. Running only damages already damaged joints. You can run forever if you have healthy joints and good running mechanics.
The dreaded “hammy” is the tearing of the muscle or tendon fibers of the powerful hamstring muscles at the back of the leg. It’s dreaded because the pain is sharp, and the recovery can be long. Here is what’s known and what’s new: