Well, if it is the case the lifting heavy bothers your joints, rather than something to do with technique, exercise selection, programming, diet, other activities, etc. then no, you're not going to be able to maintain strength or power.
Strength and power comes from training to produce large amounts of force. Which means more load is transmitted through the joints. Normally, with good technique, balanced musculature, and appropriate programming, this isn't a problem, and is actually good for long term joint health. For individuals with degenerative conditions, or perhaps particularly bad past injuries, this is not the case.
I'd be interested in knowing how you came to the conclusion that load was the issue, rather than any other potential issue. I'd also be interested in knowing what sort of programs you've followed in the past, and currently. Assuming you're right, and you're technique is fine, I'd assume any joint issues are most likely due to programming.