Australian Natural Bodz - - Train Smart -

As the world strug­gles with ev­er­ex­pand­ing waist­lines, the rem­edy sug­gested by friends and health gu­rus is usu­ally a health­ier diet and more aer­o­bic ex­er­cise. But wait, be­fore you step out for your next power walk have a read of the re­search by a team of Bos­ton Univer­sity sci­en­tists sug­gests that lift­ing weights may be just as im­por­tant as the Stair­mas­ter when it come to los­ing weight and im­prov­ing health.

In ex­per­i­ments with ge­net­i­cally en­gi­neered mice, Ken­neth Walsh, a School of Medicine pro­fes­sor of medicine, and fel­low re­searchers have demon­strated that so-called type II mus­cle, the tis­sue cre­ated by re­sis­tance train­ing, im­proves the body’s over­all me­tab­o­lism through chem­i­cal sig­nals that pro­mote fat­burn­ing by other tis­sues, such as the liver. Their find­ings ap­pear in this month’s is­sue of the jour­nal Cell Me­tab­o­lism.

“Th­ese mus­cle fibers have been un­der­stud­ied and their meta­bolic ef­fects have been un­der­ap­pre­ci­ated,” says Walsh, whose lab at MED’s Whi­taker Car­dio­vas­cu­lar In­sti­tute fo­cuses on how meta­bolic dis­eases such as obe­sity and di­a­betes neg­a­tively im­pact heart health. “Peo­ple thought th­ese tis­sues were im­por­tant for pick­ing up heavy things and not much else.”

Walsh and his team ge­net­i­cally al­tered mice so that the Akt1 gene, which reg­u­lates the growth of type II mus­cle fibers, was turned off. For sev­eral weeks, the re­searchers fed the mice a high-fat, high-sugar diet, the ro­dent equiv­a­lent of fast food. The re­sult, says Nathan LeBrasseur, a MED as­sis­tant pro­fes­sor of en­docrinol­ogy: “Every­body got fat.” Re­ally fat. The mice be­came obese and in­sulin­re­sis­tant. Fatty acid de­posits formed around their liv­ers, a con­di­tion known as he­patic steato­sis, or fatty liver dis­ease.

But then the re­searchers turned on the Akt1 gene in one group of mice they dubbed My­oMice. The re­sults “were quite strik­ing,” says LeBrasseur. Over the course of two weeks, body fat of the mice whose type II mus­cle fibers were al­lowed to grow melted away. Fat also dis­ap­peared from their liv­ers. The My­oMice grew phys­i­cally stronger and blood tests re­vealed that they had again be­come metabol­i­cally nor­mal. Plus, all this hap­pened with­out any in­crease in phys­i­cal ac­tiv­ity.

Walsh spec­u­lates that the ease with which re­searchers can prompt ro­dents to do aer­o­bic ex­er­cise may have con­trib­uted to the re­search ne­glect of type II mus­cle fibers. “The thing is, if you put a lit­tle wheel in a cage, the mouse will run sev­eral kilo­me­ters ev­ery night,” he says. “But I chal­lenge you to get a mouse to lift weights.” For­tu­nately, hu­mans may be eas­ier to con­vince. Walsh and his team say their find­ings in­di­cate that peo­ple should con­sider adding re­sis­tance train­ing to their ex­er­cise pro­grams.

They’re hop­ing their next study will help iden­tify the novel pro­teins, known as myokines, that the type II mus­cle fibers are us­ing to com­mu­ni­cate with other tis­sues in­volved in me­tab­o­lism.

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