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Medical Author:

Richard Weil, MEd, CDE

Richard Weil, MEd, CDE

Richard Weil, MEd, CDE, is an exercise physiologist and Certified Diabetes Educator, and is director of the New York Obesity Research Center Weight Loss Program at St. Luke's Roosevelt Hospital Center in

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Interval Training and Running

Interval training is a method of training where you alternate between high and low intensities during your workout with the objective of increasing your stamina. Research shows that it is an extremely effective method for improving fitness. You set up intervals by using "work to active-recovery" ratios (expressed as work:active-recovery), where work is the faster speed and active-recovery is the slower. The mechanics of it are to simultaneously and progressively over time increase the time at the work interval and decrease the time at the active-recovery. Here's a simple example assuming you can jog or run for 30 minutes at 6 miles per hour (mph).

1. Jog for five minutes at 6 mph to warm up.

2. Increase the speed to 6.3 mph and jog for one minute.

3. Jog for three minutes at 6 mph.

4. Increase the speed to 6.3 mph and jog for one minute.

5. Jog for three minutes at 6 mph.

6. Repeat these intervals for your entire workout.

In this example, the work:active-recovery ratio is 1:3. The idea is to increase the work part to one and a half minutes and decrease the active-recovery to two and a half, and then continue to increase and decrease in 30-second increments (weekly if possible) until you are running at 6.3 mph for the entire workout.

You can also get more specific and use heart rate to set up your intervals. For example, say your heart rate is 70% of your predicted maximum when you run at 6 mph, and it's 85% of your max when you run at 6.5 mph. What you do then is set up your ratio of 1:3 based on your training zone by running at 6.5 mph (85%) for one minute and then 6 mph (70%) for three minutes. As you continue to decrease the active-recovery interval and increase the work interval, your conditioning will improve, and then after a couple of months you should be running your entire workout at 6.5 mph.