Interval Training

  • Author:
    Richard Weil, MEd, CDE

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Quick GuidePictures of the 7 Most Effective Exercises to Do at the Gym or Home (and Tips to Improve Form)

Pictures of the 7 Most Effective Exercises to Do at the Gym or Home (and Tips to Improve Form)

How often should I increase the intensity of the intervals?

Interval training will improve your conditioning and performance quickly, usually in just a few weeks. As your conditioning improves, your heart rate will be lower at both the work and active-recovery interval even though you are training at the same speed you started the intervals with. When that happens, you increase the work ratio by one-half minute or even a full minute and decrease the active-recovery interval. For example, you change the 3:1 ratio to 2.5:1.5 or 2.0:2.0. You keep changing the ratio over the weeks until you are doing all the work intervals for four minutes and then you start over with a new 3:1 ratio.

Here's an example of a six-week program using one-minute interval increases.

Week one. 6 mph:7.5 mph (three minutes at 6 and one minute at 7.5)

Week two. 6 mph:7.5 mph (2.0:2.0)

Week three. 6 mph:7.5 mph (1:3)

Week four. 6 mph:7.5 mph (all at 7.5 mph for four minutes) Now a new interval at higher speeds

Week five. 6.5 mph:8 mph (3:1 minute)

Week six. 6.5 mph:8 mph (2:2)

Important: Intervals are tough, and so you might want to increase each week in half-minute intervals. You should be out of breath and sweaty during the work interval to make it work but not so hard that you put yourself at risk for injury. For instance, if you can't run at 7.5 mph because your legs simply won't go that fast, then don't do it. Instead, you can increase the incline of the treadmill, and outdoors you can perform the work interval on a hill. Listen to your body and experiment until you find what works best. It's much safer and more effective if you slowly and efficiently work up to a long-term goal rather than try to achieve it as quickly as possible.

How do I know how high my heart rate is?

The intensity of your intervals will make it tough to remain still enough to monitor your heart rate with your hands or even with the monitor on your treadmill or bike. This is where a heart-rate monitor comes in. They are excellent tools for measuring intensity during intervals. Check out Polar heart-rate monitors online at You can buy an inexpensive one for around $50-$60.

Subscribe to MedicineNet's Weight Loss/Healthy Living Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Health Solutions From Our Sponsors