Take more ibuprofen! I'm joking. But that's what many do when older, and even a doc might recommend that. There were a few studies that appeared to show that ibuprofen was anabolic in old people but what was likely happening was that the drug was allowing them to lift so their muscle and strength increased as a result. So on balance the drug might have been beneficial (if organs aren't crying).
When older work capacity is reduced and you just can't tolerate as much volume and frequency. I like what others have said about higher reps and lower loads not necessarily helping, the added volume might increase inflammation. I would suggest for example is to keep a "heavy" squat type movement in the routine and do say just 2 heavy sets of 5 once a week. I might be enough to keep and sometimes even increase your strength. Choose a squat type movement that causes the least pain. It's surprising how little volume you need for strength. If lower back is causing issues don't do a ton of bent over rows but choose a chest supported row instead, so as not to add irritating volume to your routine.
I was at my strongest after 40 (in my profile pic, I was lifting just once a week). Then covid came. Now at 48 I'm as strong as ever on some movements but not at peak in whole body moves, but not giving up.
I bought naproxen yesterday for my lower back, already feeling better
