This is a great VO2 activity because it’s easy to understand, you probably already know how to sprint, and as long as there is a flat stretch of street or track nearby (you don’t want an incline for this one). As a general rule, you want to sprint as if you were trying to win a 1-mile race. You should be totally out of breath by the time you finish, but not ready to pass out.
If you’re fit and you’re feeling really good about your sprints, you can start bumping your times up toward four minutes instead. Just remember to get your cooldown period in, too!
There is no set amount of times you have to do this when you are first beginning, but it needs to be more than one. Aim for three to four if you don’t have any experience with this type of activity. Work up to half a dozen reps, and make it a goal to eventually reach 10. By that time, you’ll have a good idea of what your body can handle.