Jared, it really is about what you are trying to attain. You have to think about the time of the run and the effect it is having on your body/energy systems. If you do a 10-15sec sprint at top speed you are using your body’s powerful energy molecule in Creatine and you will be developing your TYPE 2 muscle fibers. These are explosive and larger than TYPE 1 slow twitch fibers. You are even developing muscle with this short of a sprint. I would typically go with a work to rest ratio of 1:3 or 4. So, 15sec sprint/45 sec walking. This is also the best way to burn high amounts of calories. Your body really can not be at full speed in a sprint for more than about 10-15 secs. After that period you are burning carbs and are going for more endurance.
Chris Baietto, CSCS, ACE