Explain the principles behind interval training …

Interval training method:-Interval training method is also called terrace training. It is training of heart, through endurance training .If you run your heart beats at a faster rate. Dr.Woldemar and Gerschler, introduced this training method in 1930.In this method the athlete used to run 400m. race, 10 to 20 times daily, instead of running 10 to 20 miles daily. In fact this training method is based on effort and recovery principle .During interval training recovery period is given to the athlete after each speedy workout. Recovery period can be adjusted according to the efficiency of the athlete. The load can be increased by reducing the recovery period or by increasing the workout. For an athlete of 400 m. following Examples are applicable in his training
1) 400m. race with 80% speed
 2) Walking or jogging until his heart rate comes down to 120 to 140 approximately.