Christian,
I feel you 😉 I’m 53 and facing a similar question. I’ll let others chime in, but here are a some ideas to play around with based on my experience.

– shift to a 3-week cycle: 2 build weeks, 1 recovery week.

– add an extra recovery day each week — i.e. 2 in build weeks and 3 in recovery weeks — I am about to start doing this as of next week, and I’m excited about the possibility that I’ll be able to push harder in the workouts and thus get more out of each individual workout because the body will have more time to recover — you’d need to decide what to jetison, and that might change depending on where you are in the training cycle.

– if you’re not already, be assiduous about mobility and stretching:

a) for years I’ve done a 5-8 minute standing yoga routine EVERY morning that has been invaluable in preventing issues like lower back twinges. I also put standing balances in it (e.g. twisting half-moon, dancer pose) that give the body daily practice at alignment and balance on one leg while twisting into strange shapes 😉 I do not feel like doing this every morning, but the rule (it is a *rule*) is that I’m not allowed to get dressed until I’ve done the yoga routine. It’s worth it, every day.

b) about a year ago I also introduced a nightly stretching routine following the principles outlined in this Huberman Lab episode (https://www.hubermanlab.com/episode/improve-flexibility-with-research-supported-stretching-protocols; written notes: https://www.hubermanlab.com/newsletter/stretching-protocols-to-increase-flexibility-and-support-general-health) This has had a significantly and noticeably beneficial effect on baseline mobility. In this case, I do the routine after I shower while the muscles etc. are still warm; and the rule here is that I’m not allowed to eat chocolate until I’ve done the stretching routine ;))

I’m assuming that you’re also discussing this with your physio / physician.

Hope that helps.
Jane