Sprints are still one of the best ways to perform your interval workouts. Here’s a great sprint and bodyweight workout by Craig Ballantyne:
Traditional interval training consists of intense running followed by a period of active rest (ex. jogging or walking). Common distances include 200, 400, 600 and 800 meters. The active rest period typically ranges from 30 to 90 seconds depending on interval distance and the athlete’s condition.
The Interval Challenge (below) differs from the traditional interval training protocol. The workout integrates interval running with a variety of bodyweight calisthenics. There are no defined rest periods between intervals. The athlete attempts to complete the circuit as fast as possible. Rest comes on an as needed basis.
When performing The Interval Challenge, the athlete must complete four continuous circuits. This brief conditioning routine is extremely demanding (physically and mentally). Read more

