This can be done outside or on a treadmill!
Beginner/Injuries: If you cannot run, but you are cleared for other exercise (i.e. bike, elliptical, swimming, etc) use the same format for your exercise of choice.
Advanced: Instead of brisk walk do a light jog and in lieu of leisurely walk do a brisk walk.
Sprints are great for improving running time, burning fat, and revealing the coveted abs/muscles you have worked so hard to build. Sprinting is great for your core, and helps tighten up your whole body. It is also great for improving athletic performance. According to a study in The Journal of Physiology, exercise performance and muscle oxidative capacity both increase through sprinting intervals, while only committing about 10% of the amount of time as endurance activities.
Sprints For Everyone
Whether you are new to fitness or have been working out for years, sprints will help increase your vascular fitness. If you are a runner, adding sprints can increase your speed through increased efficiency. If you cannot run, add sprint intervals to a lower impact activity such as swimming or biking. Running sprints will yield the best results, but sprints of any kind will do wonders for your body and self-esteem.