Inactivity leads to quick muscle loss

March 3rd, 2009 - 1:38 pm ICT by IANS  

Toronto, March 3 (IANS) Lack of use of muscles leads to their quick loss, says new Canadian research.
Researchers at Toronto’s York University say muscles shrink quickly when they are not used.

According to Michael O’Leary, a doctoral student in York’s School of Kinesiology and Health Science, a week of total muscular inactivity can cause 24 percent muscle loss.

“It really is a case of ‘use it or lose it’,” he said in a university statement here.

“We are seeing more and more evidence of how easy it is to lose muscle, compared to how difficult it is to regain it,” said O’Leary.

During chronic muscle inactivity, he said, a process called autophagy - or type 2 cell death - joins with apoptosis - or type 1 cell death - in attacking cells and causing muscles to shrink. Muscle inactivity leads to big increases in the proteins LC3 and Beclin 1 in the body, O’Leary said.

He said these proteins are activated by a decrease in oxygen consumption (by the mitochondria, which supply power to our cells) during muscle inactivity.

This leads to an increase in tiny molecules called reactive muscle oxygen species which are blamed for causing conditions ranging from cancer to wrinkles.

In high doses, these molecules wreak havoc on body cells by activating the production of these proteins, O’Leary said.

In his research, he said, he also observed heightened levels of LC3 in mitochondrial membranes, degrading the mitochondria (which supply power to human cells).

The Canadian said researchers are looking at how to lessen or even prevent this damage to muscle because of inactivity. He said their research assumes significance as more and more people today lead a sedentary life bereft of any physical activity.

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