Interval Training: An Investment That Pays Off
Friday, May 27, 2011
LifeTime WeightLoss

Written by: Tom Nikkola – Director of Nutrition & Weight Management

When we spend our money, we like to talk about value — getting a lot of benefit from something without investing a lot of money. You dedicate a certain amount of your time every week to exercising and you may be able to get more value for the time you invest. Interval training may be the way you achieve the same benefit you’re getting today with less time invested — or gain even more benefit in the same amount of time.

What is interval training?

Interval training is a method of exercising by varying your level of intensity, using short bursts of exercise at high intensities, interspersed with brief periods of recovery. This type of training protocol allows an individual to perform a significant amount of intense work and gain cardiovascular benefits in a fraction of the time it takes to gain benefits from steady-state, lower intensity exercise.

A recent study on youth compared seven weeks of sprint intervals three times a week against another group who performed 20 minutes of steady-state exercise three times per week for seven weeks. Both groups saw improvements in fitness levels and cardiovascular disease risk factors. The primary difference between the two groups: The steady-state group exercised a total of 420 minutes over seven weeks while the sprint group exercised a total of 63 minutes during the same time!

Another way interval training has been studied is by comparing a group who performs low-intensity, steady-state workouts against another group performing high-intensity training, and ensuring the two groups achieve the same calorie expenditure. The steady-state group exercises longer to achieve the same calorie expenditure. If our bodies managed calories by the often-quoted calorie balance equation, the effect from exercise on body composition would be the same. That’s not the case. When keeping calorie expenditure the same, those performing interval training lose more body weight, body fat and belly fat. In addition, insulin sensitivity is often more improved.[i],[ii] The hormonal effect of interval training likely supports these physical changes. 

Even if you have a chosen sport which relies on great endurance, or are training for an endurance event, interval training can easily be included in a training program and can be a great way to avoid letting your training program become stale. Aside from the physical benefits, high-intensity interval training also appears to be more enjoyable for participants.[iii] For those who are not avid endurance participants, it makes sense that shorter, more focused workouts could be more appealing.

Drawbacks of interval training

As good as the benefits of interval training sound, there are some drawbacks. First, interval training requires a different level of commitment to the workout routine. Though sessions are typically shorter than steady-state exercise sessions, they require more focus and motivation to achieve appropriate intensity levels.

In addition, high-intensity exercise increases the secretion of cortisol, the body’s main stress hormone.[iv] Many people are faced with significant levels of stress already. It may not be appropriate to take on this type of exercise routine if your cortisol levels are already out of range. You can have your cortisol levels checked with a simple saliva test. Just talk with a fitness professional at your local Life Time. If you do have high levels of stress, low-intensity, exercise can be very beneficial. Steady-state workouts have been shown to actually help lower cortisol levels. To avoid excessive stress, intense interval training should not be performed more than a couple times per week (for most people).

Incorporating interval training

Interval training can be incorporated into a walking program by varying the grade, such as changing the incline on a treadmill or walking on rolling hills. It can be done on a bike outside or indoors, just by changing gears. Many group fitness classes are designed around the concept of intervals. A fitness professional can help design an appropriate plan based on your goals, current level of conditioning, your workout schedule and your lifestyle.

Once you’re ready to try intervals, there are several different ways to incorporate them into your program. The following are just a couple ideas to get you started.

Interval training is not for everyone but if you’re interested and committed, it can be beneficial, time-saving and possibly more enjoyable. As you get into better shape, you’ll be able to push yourself further with “all-out” intensity.  However, if you’re just getting started, take it a step at a time. Add a short jog every few minutes into your walk. Eventually, you’ll be running and then sprinting. Be smart about your training. You’ll get no benefit from sitting on the couch, nursing an injury because you did too much, too fast. In a future article, we’ll look at how you can optimize your interval program through heart rate training and the use of a heart rate monitor. Happy training.

This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.

Share thoughts and post questions below.


[i] Irving BA, Davis CK, Brock DW, et al. Effect of exercise training intensity on abdominal visceral fat and body composition. Med Sci Sports Exerc. 2008;40(11):1863-1872

[ii] Tjonna AE, Lee SJ, Rognmo O, et al. Aerobic Interval Training Versus Continuous Moderate Exercise as a Treatment for the Metabolic Syndrome. Circulation. 2008;118:346-354

[iii] Bartlett JD, Close GL, MacLaren DP, Gregson W, Drust B, Morton JP. High-intensity interval running is perceived to be more enjoyable than moderate-intensity continuous exercise: implications for exercise adherence. J Sports Sci. 2011;29(6):547-553

[iv] Hill EE, Zack E. Battaglini C, Viru M, Viru A, Hackney AC. Exercise and circulating cortisol levels: The intensity threshold effect. J Endocrinol Invest. 2008;31:587-591

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