While I can't comment on what it feels like at the age your at, I CAN completely agree with the duration it takes to recover. But were a little wiser and aren't trying to max out and blow a shoulder or triceps out. Now it's as you said to stay the effects of aging and not lose muscle mass. Lighter weights & more repetitions. Also I'd point you to looking at an seated elliptical machines as they mimic riding and provide you with an upper arm workout. They're good for back injuries as they don't require as much strain on the back as running.