Burn More Fat with a Once-a-Week Workout

Thu, 27 Oct. 2011 - 3:39 p.m. MT
Credit: ARA Staff - American Running Association

A study in the Journal of Applied Physiology finds that, in addition to previously observed (and fairly dramatic) improvements in cardiovascular performance, interval training improves the body’s ability to burn fat. The small study, which was first published online in December 2006, asked women to cycle for 10 sets of four minutes of hard riding, followed by two minutes of rest. Over two weeks, they completed seven interval workouts. The findings revealed that these women burned fat during their moderate-intensity workouts by an increase of 36%. Their cardiovascular fitness improved by 13%.

As noted above, other studies have revealed even more dramatic cardiovascular gains in shorter time periods. A 2005 study published in the same journal found that after just two weeks of interval training, six of eight college-age men and women doubled the amount of time they could ride a bicycle at moderate intensity before exhaustion. There was no endurance improvement in the controls, who did not interval train.

Interestingly, borderline sedentary subjects and college athletes alike seem to enjoy similar increases in fitness and fat burning. One advantage to interval training appears to be that it allows the body to spend more time doing high-intensity activity than it could in a single sustained effort. To run hard, the body must use new muscle fibers. Once these fibers are trained, they are available to burn fuel even during low-intensity exercise.

Exercise that recruits new muscle fibers can enhance the body’s ability to metabolize carbohydrates and fat. Interval training also stimulates change in mitochondria, where fuel is converted to energy, causing them to burn fat first, again, even at low- and moderate-intensity levels.

Interval training should never be performed on consecutive days, and is best incorporated into your weekly regimen as a once-a-week workout—twice a week at most for advanced runners. Always start with several minutes of slow jogging to warm the muscles. You may then do eight to 10 strides to ready the legs for the speed and turnaround of tempo or race pace. Interval workouts are easiest to perform, and to quantify, on a track. Once these basic rules are adhered to, there is no end to the variations in distance and repeats with jogging recovery that you can utilize to keep your running fresh, increase top speed, and now burn more fat.

(J. App. Physiol., 2007, Vol. 102, No. 5, pp. 1439-1447; The New York Times, “A Healthy Mix of Rest and Motion,” by Peter Jaret, May 3, 2007)

(RUNNING & FITNEWS^®April / May 2007 • Volume 25, Number 3)