I've only recently started plyo. I've been planking for months - front, side, etc. I can hold a front plank for 5 minutes if I want. I do lunges weighted, unweighted, I do 100 body weight squats no problem. I can do 100 leg raises, no problem. I can actually do a few l-sits hanging from a pull up bar. I started working on strength a while back and I've only recently incorporated box jumps, burpees, etc.
Basically below navel I'm decently strong. Above navel, tiny arm shoulder syndrome ;P
I guess I'm getting 'old'.
The things you were mentioning as possible problems? Ice, ibuprofen, foam roller, and rest? Is that pretty much the regime?