Hey Mikey,
I have read articles that sprinting is more taxing on the CNS than heavy squats. Your best bet is to use both types of cardio to your advantage... Interval cardio can raise your metabolism anywhere from 24 to up to 72 hrs in some instances. I would rotate days, and use HIIT max 4 days a week. I also use body complex's as a form of cardio as well. It breaks the monotony and burns fat as well.