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Muscle mass building in elderly
Now, though, University of Texas Medical Branch at Galveston scientists have determined that moderately and temporarily restricting the flow of blood through muscles a practice adopted by bodybuilders who noticed that it made light weights feel heavier can be combined with low-level resistance exercise training to produce muscle-mass increases in older men.
"We believe that this appears to be a novel therapy for older people who need to bring their muscle mass back up," said UTMB physical treatment professor Blake Rasmussen, senior author of a paper on the investigation ("Blood flow restriction exercise stimulates mTORC1 signaling and muscle protein synthesis in older men") appearing in the recent issue of the Journal of Applied Physiology "It could also be used for patients who have had surgery and aren't capable of lifting enough weight to keep their muscles in shape, or for people who have arthritis or other conditions that make lifting heavy weights a problem."
The UTMB researchers studied changes in the thigh muscles of seven older men (average age 70) when they performed four minutes of low-resistance leg extension exercises both with and without inflatable cuffs that reduced blood flow out of the muscles. Muscle protein synthesis was measured in each of the men by monitoring changes in a chemical tracer infused into the bloodstream. In addition, a series of biopsies yielded muscle samples that were analyzed to track alterations in biochemical pathways critical to muscle growth.
"We saw that when we put the cuffs on, they responded similarly to young people doing traditional high-intensity resistance exercise," said UTMB graduate student Christopher Fry, the main author of the paper. "The low-intensity exercise produced increases in protein synthesis, and activated two cellular pathways that stimulate protein synthesis and muscle growth in the post-exercise period".
Exactly how restricting blood flow in the muscles generated these effects remains unknown, eventhough Rasmussen and Fry speculated that either an improved ability to activate Type II muscle fibers or a response to the sudden surge of blood into the muscles when the cuffs were released could be responsible. Whatever the mechanism, Rasmussen said, "we think it's an exciting potential new rehabilitation tool".
"You could use this following ACL knee surgery or hip fracture surgery, for example," Rasmussen said. "In the first few weeks after ACL surgery, the joint just won't allow you to lift heavy weight. So instead, you could use a really light weight with a restriction cuff, which may prevent the muscle loss that you normally see following knee surgery".
Posted by: Evelyn Source