Thanks for the replies. I'll have a look into the DC programme I've heard of it before but never tried it.
It's a good point about the concentric, I'm going to try speeding it up to 2-3s and just keep the eccentric phase slower.
I've read people say it should be harder on the joints but I get no joint pain at all when I do this very slow and controlled method and it always comes back it I start going faster and more explosive, even with good form.
Reckon I'll stick with the slower tempo to keep my joints feeling good and just focus on everything else nutrition and lifestyle wise to make sure I'm minimizing any negative impact from it.