30 was when I first noticed it, that I had to work harder for the same results. 40, it didn't matter, Work hard, diet down, body still wasn't responding very well. Then the injuries kicked in. Years of lifting heavy had just destroyed my joints and tendons. Looking back, I would have approached it differently. I would have stuck with lighter weights. But I bought into Dorian's heavy weight/intensity thing. Didn't end well.
I've done that a few times, when I had training buddies. But I think volume works best for me. When I show up in the gym and train for 60 minutes... not 59, but at least 60... I can get in 30+ sets with moderate intensity. I'm not maxing out on bench or squats like I was ten years ago. But I'm going heavy for 8 sets, moderate for 8 sets, then light to wrap things and focus on stamina. I've focused a lot on core... an opportunity as a corporate dance partner arrived and i gotta be able to bend & twist in all sorts of new ways, pick my partner up, go down pretty close to a split... i'm feeling my age haha. I should go read up on core and stamina training, but the WYHI threads are way more interesting