Trust me if you sprint like that 3 times a week you will get a training injury.
Really? 3 sprints, 3 times per week will create an injury? There are plenty of people that have to do that just to catch a bus or a cab. To most that wouldn't even be considered training, but to a couch potato it would help them get fit.
This advice is very good actually. A lot of people walk miles and miles per week, but they never get fit, and they don't know why. A lot of people think mowing the yard, or vacuuming should constitute exercise, but it doesn't. The only things that will help you get fit are things with some intensity to them. They have to get your heart rate elevated, and elicit a chemical response in your muscles. The more consistently you do it, the more efficient the body becomes. 3 sprints, 3 times per week would be a nice, intense, consistent workout that would do a lot of good for blood pressure, metabolism, heart health, and more!