this is a sharpening workout. 3 mins rest is too long to make it a speed endurance session, and 7 reps is too many for a special endurance or lactate buffering session. the point of this workout seems to be to learn how to run fast and controlled repeatedly, without any significant stress. I would aim for a cutdown from mile pace to 800 pace (something like 47-46-45-46-45-44-43)