Turn on the afterburners: make the most of the fat-burn effect after resistance training

resistance-training workouts burn fat in two basic ways. First, long-term training helps you add significant amounts of muscle tissue, causing small increases in your metabolic rate. Second, and probably most effective, you can manipulate the way you work out to burn more calories in the hours that follow your training.

The scientific concept used to understand this latter phenomenon is called excess post-exercise oxygen consumption (EPOC). This means that you use more oxygen after a workout than you normally do at rest. Since the oxygen is used to burn calories, the more oxygen you take in, the more calories you burn. Many different physiological mechanisms have been shown to influence EPOC, including hormonal changes during recovery that stimulate oxygen use, lactic-acid removal that requires oxygen, muscle damage and repair processes, immune processes and glycogen depletion, which favors a more energetic use of fat. No matter what the cause, the outcome is a greater fat-burning effect after training.

How can you use this science to make your gym workouts as effective as possible? Every couple of months, put down those wimpy dumbbells in favor of a week or two of higher-intensity resistance exercise. Workouts that use a large amount of muscle mass, moderately heavy weight (about 80% of your one-rep max, or the amount you can lift for 8-10 reps), shorter rest periods and enough total work induce EPOC that can last for more than 24 hours. Circuit-style weight training that uses very light weight (about 45% 1RM, which is less than half the amount of weight you can lift just once), on the other hand, increases EPOC for only an hour or less.

When it comes to burning fat with resistance exercise, the type of workout you perform is crucial. Keep the following design factors in mind when putting your occasional heavy-resistance workout together; they reflect the different physiological mechanisms that are thought to stimulate a greater EPOC.

1) Stimulate the major muscle groups of the body with primarily multijoint exercises to activate more muscle mass.

2) Use moderately heavy weights that allow you to perform only 8-10 reps per set.

3) Use moderate rest periods of 1.5-2 minutes to create a higher lactic-acid increase and thus increase the need for oxygen to remove it.

4) Use multiple sets (2-4) to accumulate enough total work to stimulate hormonal changes and metabolic demands.

When your workout is optimally designed, you can burn calories at an elevated level for up to 48 hours after your training session--and this is just for your weight training, not cardio. Since this excess post-workout calorie burn appears to use fat as a primary energy source, it should lead to a greater attack on the body's fat stores. And who wouldn't want that?

SELECTED REFERENCES

Schuenke, M.D., Mikat, R.P., McBride, J.M. Effect of an acure period of resistance exercise on excess post-exercise oxygen consumption: implications for body mass management, European Journal of Applied Physiology 86:411-417, 2002.

Thornton, M.K., Potteiger, J.A. Effects of resistance exercise bouts of different intensities but equal work on EPOC. Medicine & Science in Sports & Exercise 34(4):715-722, 2002.

William J. Kraemer, PhD. CSCS, is director of research and professor in the department of kinesiology at the University of Connecticut, Storrs, and editor in chief of the National Strength and Conditioning Association's (NSCA) scientific publication, the Journal of Strength and Conditioning Research.

BY WILLIAM J. KRAEMER. PhD, CSCS, FACSM

COPYRIGHT 2003 Weider Publications
COPYRIGHT 2004 Gale Group