I am infinitely entertained that Andy's home page is my Sprint 8 page. I rank 6th at Google for the term 'sprint 8' if you remove duplicates, 8 if you don't. Not bad, considering the entry is just a blog post about my first time running a sprint 8 workout.
So that you know...
Sprint 8 is a workout of 8 30 second sprints, with a minute and a half recovery time between sprints. The whole workout is done, if you include warmups, in less than half an hour. The workout should be done three times a week.
The hypothesis (not fact, not theory) behind this workout is that the intense effort of the workout increases the natural levels of "stay-young" hormones in your body, with a minimum of effort. Personally, my "minimum" effort in a sprint 8 is still a lot of effort.