A790 how do you feel about this running?
It's not the best for back injuries that's for sure.
For cardio if you find sprinting to tough, try Barbell complexes. I think I read you added them but Some more bigger ones are ideal for cardio. Can help increase core strength and dial you in per se for form.
"The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents... some day the piecing together of dissociated knowledge will open up such terrifying vistas of reality, and of our frightful position therein, that we shall either go mad from the revelation or flee from the light into the peace and safety of a new Dark Age."
-H.P. Lovecraft