April 2011 Issue
Basics and Benefits of Interval Training
By Joe Cannon, MS, CSCS, NSCA-CPT
Today’s Dietitian
Vol. 13 No. 4 P. 66
When it comes to fitness, few phrases invoke as much interest as interval training. In case any of your clients ask about the specifics of interval training, here’s a rundown of what it is and the apparent benefits.
Interval training essentially means dividing an exercise program into different parts, or intervals. One part, called the work interval, involves exercising at a higher intensity; the other part, the so-called rest interval, involves exercising at a lower intensity. This regimen is very different from steady-state exercise, where an individual maintains the same intensity for the duration of the workout (eg, running for 30 minutes at 6 mph).
People who have worked out within their target heart rate range have engaged in interval training. For example, altering the heart rate between 60% and 80% of age-predicted maximum capacity is, technically speaking, interval training.
Research has demonstrated that a sensible interval-training program can accomplish the following:
• improve aerobic and anaerobic fitness1;
• improve endothelial function and reduce lipogenesis in people with metabolic syndrome2;
• enhance skeletal muscles’ ability to burn fat and carbohydrate3; and
• enhance calorie usage after exercise more than steady-state exercise.4
Among others, these findings—especially the latter one—have grasped the attention of many personal trainers and exercise enthusiasts. The following are several points to consider when discussing interval training with your clients:
• Even though interval training appears to quickly (within two weeks) improve fat burning by mitochondria5, it may not be the best activity for beginners because it can be difficult to perform.
• Because of their low fitness level, beginners are probably best served by steady-state exercise for at least the first one to two months before they attempt interval training. In addition, even though some research has found that interval training may result in greater calorie usage 24 hours postexercise4, the amount is not much greater than with steady-state exercise. Also consider that a 20-minute interval-training program will use fewer calories during activity than steady-state exercise lasting one hour—another reason I recommend steady-state exercise for beginners.
• When designing an interval-training program, exercisers should realize that the rest intervals are just as important as the work intervals. When it comes to interval training, many people fixate on the work periods, but focusing excessively on the work periods can lead to greater injuries, exercise burnout, and subpar enhancements in performance.
When I design an interval training program for someone for the first time, I typically make the rest interval two to three times longer than the work interval, which allows the person greater time to rest and prepare for the next work period.
The following is an example of a simple beginner interval-training program that most healthy people can try:
• After a five- to 10-minute warm-up period on a treadmill, walk at 3.5 mph for one minute. Then walk at 2.5 mph for three minutes. Repeat this cycle five times. Initially, try this routine one day per week and progress to performing it three or four days per week.
Since this simple interval-training program will last only about 20 minutes, clients can add it to their existing steady-state exercise program to increase calorie usage and reduce the boredom that often occurs during lengthy aerobic exercise sessions.
— Joe Cannon, MS, CSCS, NSCA-CPT, is a personal trainer, exercise physiologist, and health educator in the Philadelphia suburbs.
References
1. Tabata I, Nishimura K, Kouzaki M, et al. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Med Sci Sports Exerc. 1996;28(10):1327-1330.
2. Tjønna AE, Lee SJ, Rognmo Ø, et al. Aerobic interval training versus continuous moderate exercise as a treatment for the metabolic syndrome: A pilot study. Circulation. 2008;118(4):346-354.
3. Burgomaster KA, Howarth KR, Phillips SM, et al. Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans. J Physiol. 2008;586(1):151-160.
4. Treuth MS, Hunter GR, Williams M. Effects of exercise intensity on 24-h energy expenditure and substrate oxidation. Med Sci Sports Exerc. 1996;28(9):1138-1143.
5. Talanian JL, Galloway SD, Heigenhauser GJ, Bonen A, Spriet LL. Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women. J Appl Physiol. 2007;102(4):1439-1447.