I'm 52 this year and have a lot of the same experiences reported here. Over the last 2 years, some loss in strength and an overall loss in volume capacity. The strength loss was sudden, the capacity loss more gradual. Still able to hit it relatively hard, heavy, and brutal but my forearms and shoulders are now limiting factors with upper body (straps help the forearms but they still ache). I've always had above average legs and back, so they haven't given out yet, but when I hit them hard, they hit back in ways I never noticed before (the effects linger for 3 or 4 days with little motivation to get back to the gym).
As far as standards go, fuk 'em unless you really need them. Train as hard and often as you can and your best performance is your standard.
Substituting some of Thib's Growth Factor routines for my normal work has revitalized my training in an excruciatingly beneficial way, so you might want to check out those articles/post.
Also, Plasma has been a tremendous help. You definitely don't need to use the humongous scoop they provide if you have a normal build. A tub (or bag nowadays) can last well over a month. Dosing Plasma before an important event, stressful situation, or after a late night of moderate drinking is also very helpful. I don't know how I could train without it.