Well, I’m a ‘powerlifter’ and I’m 37 and my joints are as strong as ever. I usually belt up on squats when I reach around 80%. On deads the belt usually pisses me off by digging into my ribs if I begin to round my back so for me it sort of serves to keep my chest up. Again it’s usually around 80% but if I’m having a ‘weak’ day I may belt up right after the warm ups. That’s served me well over the years. Doing heavy squats and deads is not the time worry about ‘core work’ save that for later in your work out with accessory movements.
I’ve got some Rehband knee sleeves that I use when it gets cool in the garage. They are awesome and I wish I had gotten them years ago. Knees are super toasty and they don’t give any support. I’ve got some Inzer knee wraps thet I use on rare occasions. I can wrap them so my feet turn purple or I can wrap them to give little to no support. That’s the beauty of wraps. YOU decide what level of support you want.
My thought on the ‘decreased muscle activity’ is do what YOU feel you need to do. Some folks don’t need ‘training aides’ some do. I’d rather be that 60 y/old guy in the gym with ‘decreased muscle activity’ than that 40y/old “who used to be a lifter”. Good luck man…
OH, Buy yourself an INZER forever 10mm or 13mm belt. or something similar, It’ll last you until you grow out of it or you die…lol