I am trying to do interval training 1-2 times a week out of my 3-4 weekly runs. I have set up 5 x 40 second sprints with 3 mins in between at a steady pace on my Runkeeper ap. But to get my HR back down to 155 - the steady pace I have calculated, means I have to go very very slowly. It is great to sprint, but annoying when everyone starts overtaking during the steady runs. Anyone else have this problem or experience of interval training?