I see you've been working sledges a lot. What are those? Are you striking with a sledge hammer or something?
You are really toughening up all around for a distance runner. Sounds like you're hitting all cylinders.
My work with sledge hammers primarily involves striking a tractor tire for either time or reps. Hand position and planes of motion are varried for infinate possiblilities. I also use it in prehab and mostablility work.
I believe in acquiring total body fitness. Aerobic fitness is weak without strength and strength is weak without aerobic fitness in my opinion.