MELBOURNE, Australia -- Sprinting, not jogging, helps men lose harmful belly fat faster, scientists in Sydney found.
Eight-second bursts of sprinting repeated intermittently for 20 minutes helped overweight men lose 4 pounds of body fat over 12 weeks, researchers at the University of New South Wales said Thursday. Importantly, there was a 17 percent reduction in the amount of fat stored around their liver, kidneys and other internal organs that is associated with an increased risk for cardiovascular disease.
The findings, published in the Journal of Obesity, add to evidence that high-intensity exertion may result in greater fat loss than less vigorous forms of exercise such as jogging. The research also indicates bouts of sprinting over 20 minutes three times a week may be enough to spur a significant reduction in fat, including around the trunk, in overweight young males.
"Sprinting is a very efficient form of exercise and it's fun," said Steve Boutcher, an associate professor in the university's school of medical sciences, who led the study. "Other studies using aerobic exercise, such as continuous jogging, have found that the amount of exercise needed to produce a similar decrease in visceral fat was about seven hours per week for 14 weeks."
Two-thirds of U.S. adults are overweight and one-third are obese, according to the Atlanta-based Centers for Disease Control and Prevention. The obesity rate may rise to 42 percent of the U.S. population by 2030, the CDC said in May.
The Sydney researchers randomly allocated 46 inactive men in their 20s into either an exercise or control group. Those selected to exercise were required to sprint for 8 seconds on a stationary bike followed by a 12-second recovery phase in a training cycle lasting 20 minutes and repeated three times a week over 12 weeks.
Weight and waist circumference increased in the control group. While those in the exercise group lost weight, they put on 2 pounds, 10 ounces of muscle in their legs and trunk, according to the study, which was supported by Diabetes Australia.
"Participation in regular aerobic exercise typically results in little or no gain in muscle mass, whereas moderately hard resistance exercise over months may increase muscle mass," Boutcher said.