cardio endurance not much better?

Hozman121

So about 6 weeks ago I started doing couch-2-5k on the elliptical. I have horrible shin splints and the treadmill for running is not my friend. Anyway I don't feel like my cardio endurance is getting that much better or is as far as it maybe should be using the elliptical. I know it is better than week 1 day 1 cause that about killed me and now I can do weeks 1-5 without issue, but to jog outside for the first time kicked my butt. Only run a couple blocks then walk cause of shins.

Anyway isn't elliptical good for cardio endurance? How does it compare to jogging. I also do a lot of balls to the walls for 5-15 minutes and need my endurance up for that. So what should I be doing for that? HIIT sprints, circuit training?