I've been thinking of try something like this. The way I thought about it was to only run a five minute mile. My plan is to go to the track and sprint for as lo

I've been thinking of try something like this. The way I thought about it was to only run a five minute mile. My plan is to go to the track and sprint for as long as I can at a five minute mile pace. When I drop below that pace, I walk until I return to walking heart rate. Then I run at a five minute mile pace. The workout ends when I have run a cumulative mile at a five minute mile pace. I figure the workout will take about 20 minutes.