Rice Krispie Syndrome
I ate too many of them as a kid. Now they're lodged in my joints. Elbows, knees, ankles. Gotta warm up good these days.
One thing I've found over the years is that my skeletal carriage doesn't mirror the movement of many of the machines. Dumbells are a little better but have limitations. If you use heavy ones the support muscles bleed off energy that should be directed at the targeted muscle. When I was young I could get away with the heavy stuff. I started going lighter on them to avoid overpowering the joints as I aged.
I eventually got me a welder and a bunch of metal working machines and started modifying things to fit. They fit real good now. Strange as it may seem though I have to go back and adjust them every couple of years.
Sit back and take a real good look the machines on the market today. They're all kind of generic in their fit. Adjustable seat, maybe back pad, etc. Sort of like a 'one shoe fits all'. Just stuff some paper in the toe to make it fit.
Somewhere down the line, someone will probably come up with the idea of making custom machines. Much like going to a tailor and getting fitted for a suit. Probably going to be real expensive though.