Any lifter is going to hit a Bell curve in later years. When you will be getting diminishing returns for your efforts in the gym. That's just the reality of growing older. Which, doesn't always mean you will be a shrunken hulk of your younger years. The peak years may be past, but still holding on to a good amount of strength and muscle mass is possible. Can be in your 70's and be somewhat impressive in strength and size....though not in the personal record breaking sense. If in your late 50's. early 60's and your best PR for the bench was 320 for 5 reps in your prime, you may be doing anywhere from 250 to 275 for those 5 reps..still impressive for anyone.
May require a different approach to training and diet. One of the more important factors is the ability to recover from workout to following workout. Having briefer training sessions, with fewer exercises, including sets, assure better odds of physical recovery. Taking long workout, too many times in a week, will surly affect the CNS and immune system, which becomes that much more important as we age. You can be intense in workouts, but for shorter periods of time. Taking 1 1/2 to 2 hours workouts in the past, may be better served by cutting the time down to 30 to 40 minutes max. May find that losing muscle mass & strength will be the result of doing longer workout as before.
I've worked with older gentlemen, the older ones in their middle 70's. Find that full stretching and holds become very important before and after working out. Actually doing flex movements (stretch/holds) become just as important on off workout days. Joints/ligaments/tendons concerns become of major important as we age.
Just to note: One elderly GB'er, in his late 60's had been doing 24-26 sets for delts alone. While using Nautilus machines for some of his delt work. Trying not to be critical, but that is a worse of what not to do , even for much younger men. Taking that delt work down to 4 or 5 sets max, may prove much better results. But I do wish this gentlemen well in hs future training. Good Luck