Of mice and muscle men: study finds brawn burns fat

Tuesday, April 7th, 2009

Lifting weights

Jonas Hrebeniuk

YOU DON'T KNOW "SQUAT," BUT THIS DUDE SURE DOES. New studies on mice show that weightlifting can have metabolic benefits similar to endurance exercises like cardio workouts. Will we all turn into Arnold Schwarzenegger? Not bloody likely, but it's still interesting food for thought in our health-mad society.

In a recent study, mice with genetically modified muscles have shown US scientists weight training burns fat just as effectively as aerobics does.

Published in the February issue of Cell Metabolism, the study by researchers at the Boston University School of Medicine, genetically programmed the mice so their muscles resembled those of bodybuilders.

Researchers found the mice lost fat and showed other indicators of metabolic improvement " benefits despite the high fat and sugar diet and unchanged exercise routine of the mice.

The bulky, veiny muscles found on weightlifters fall into type II: “fast-twitch” muscle tissue that contains only small amounts of energy-burning mitochondria.

Type I, or slow twitch muscles, built up through endurance exercise, are rich in intercellular power plants.

Prior to this, it was generally believed that type I muscles had a larger capacity to burn fat.

The study has shown while mitochondria are not in abundance when it comes to type II muscles, there is another fat-burning mechanism in place " the liver, which is one of the body’s most powerful weight controls.

“The liver showed a higher level of oxidation capacity for lipids, and mitochondrial capacity was higher,” Dr. Mark Tarnopolsky, a professor in the department of medicine at McMaster University, said.

“There is some link between muscle and liver that occurred with the greater size of the type II fibers that led to the liver changes.”

Kim Correia, a first-year media information and technoculture student, wants to stay in shape through cardiovascular exercise despite the new study.

Larissa Mills of Pilateez.com stands behind the buildup of type I muscles. “[Like weightlifting, Pilates and Yoga] are great ways to tone and increase muscle strength.”

Aesthetic benefits aside, weight training is good for older adults to prevent and treat muscle loss, which may also provide metabolic benefits.

“Are men not mice?” Dr. Tarnopolsky said. “A very large study is needed to bring out the metabolic effects statistically.”

The mice used in the experiment were obese and were expected to get even larger when researchers activated the Akt1 gene " a gene that promotes type II muscle growth but does not affect type I. Instead, within three weeks of developing the muscle, they experienced weight loss of around 40 per cent.

“Fitness is more important than fatness,” Dr. Tarnopolsky said. “I would not run out and start lifting weights in the hope that it will have a major effect on the metabolic syndrome based on these results.”

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