I like to run on the treadmill at like a 7 minute mile pace for a minute and then sprint for a minute, alternating back and forth for like 20 minutes. I'm someone that runs a mile in under 6 mins. Trust me it will smoke you in those 20 mins if you put out
^^^ this is what I like to do, but in reality at first 20 max and you are toast! Legs will be noodles!!! Make sure to stretch hamstrings and calves, don't want to pull those!
I am still trying to run fast on treadmill, as of now my digital reading has reached 8.7, which probably means 8.7 km/hour. But this is really tough! I may run at 8.7 km/hour for 12 minutes for couple of weeks but after a while it slides down to running at that speed in 5 minutes. It is so tough, weight training appears to be lot more easier.