Stopping age-related muscle loss
Put the brakes on the loss with strategic exercise and protein intake
On a January morning, Tufts University exercise physiologists guided two seniors wearing light ankle weights through leg extensions, chair stands, and leg curls and then handed them a post-workout shake. It was part of a six-month study addressing the question: What’s the best way to reverse age-related muscle loss, which makes it hard to do such basic tasks as climb stairs, lift groceries, and walk around the block?
“One of the hallmarks of aging is a loss in muscle mass, and we’re trying to figure out what causes it and what we can do to prevent the loss of function,’’ said senior scientist Roger Fielding of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, who is heading the study, which is funded by the shake manufacturer, Nestlé.
Severe muscle loss, called sarcopenia, is gaining more attention as a disease that could be akin to bone-thinning osteoporosis, leading to immobility, falls, and perhaps earlier death as well as an estimated $20 billion a year in health care costs.
Last May, Fielding led an academic-industry task force that developed recommendations for muscle-mass testing in patients who are bedridden, can’t rise from a chair themselves, or take longer than four seconds to walk a 12-foot span. Those guidelines were in anticipation of drugs, still in development, that aim to build muscle in people who are severely debilitated, with fewer harmful side effects than existing treatments. Testosterone supplements are sometimes used in men to reverse muscle wasting, but a 2011 Boston Medical Center study found that the muscle gain they helped elderly men achieve was drastically outweighed by an increased risk of heart problems.
For now, researchers acknowledge, the optimal treatment is prevention: By the time we hit middle age, we should start lifting weights at least twice a week to retain our muscle. And we need to provide our bodies with a steady intake of fuel throughout the day, in the form of protein, to manufacture the lean tissue.
Beginning at age 30, most of us lose about 1 percent - or a third of a pound - of muscle every year, as the body starts tearing down old muscle at a faster rate than it builds new tissue. (It’s why world weight-lifting records for the 60-year-old age bracket are 30 percent lower in men and 50 percent lower in women compared with records in the 30-year-old bracket.) The loss of muscle, which burns more calories than fat, slows the body’s resting metabolic rate, causing us to pack on fat pounds through the years. While we can’t completely halt this aging process, researchers believe we can do a lot to slow it down, mostly through resistance training, or weight training, that targets specific muscle groups.
“A 70-year-old active individual is probably younger from a biomarker standpoint - muscle strength, balance, body composition, blood pressure, cholesterol levels - than a 40-year-old inactive individual,’’ said Miriam Nelson, a professor of nutrition at Tufts University. Her landmark research conducted 15 years ago demonstrated that previously sedentary postmenopausal women who lifted weights twice a week for a year could increase their muscle strength by about 80 percent. Now Fielding and other researchers are conducting a six-year, multi-center trial in sedentary elderly individuals at risk for sarcopenia to determine whether a resistance training and walking program leads to measurable improvements such as fewer falls, better walking abilities, and less overall frailty compared with a control group. Results are expected in 2015.
While 90 percent of Americans don’t get the recommended amount of exercise, weight-lifting classes for seniors have become trendy at local Y’s, senior centers, and assisted-living facilities for those trying to avoid becoming reliant on walkers or wheelchairs. Margaret Richard, host of the PBS show “Body Electric,’’ last year began offering strength-training classes in the Boston area that draw many women over 50. She said they often express surprise at how quickly they gain strength.
“I’m 65 and totally outlast the 30-year-olds when they first join my class,’’ she said. “I tell them their bodies will adjust to what they’re asking them to do.’’
Florence Reddish, 69, of Jamaica Plain said that after a year of taking Richard’s twice-weekly classes, she now helps her neighbor carry heavy shopping bags and breezes down the T-station stairs, which she used to take slowly to avoid falling. “My clothes fit better,’’ she said. “I have biceps now. It’s amazing what these exercises can do.’’
But those muscle-boosting effects may be limited, in both older and younger folks, without an adequate intake of protein throughout the day, recent research suggests. “The body is constantly synthesizing new muscle but it needs protein to do it,’’ said Douglas Paddon-Jones, a sarcopenia researcher at the University of Texas Medical Branch in Galveston. The 10 grams of protein that most of us get from cereal and milk at breakfast, he added, is not enough to get the body’s muscle-building machinery working at full throttle. For that, we would need to eat about 25 to 30 grams of protein, the amount in a three-egg cheese omelet.
A 2009 study conducted by Paddon-Jones found that this amount of protein, in the form of four ounces of lean beef, boosted the body’s muscle-building rate by 50 percent for three hours in both young and older people when it was eaten immediately after a resistance training workout. He also found that eating 12 ounces of beef didn’t provide any extra benefits.
This argues against consuming a giant porterhouse steak at dinner, while forgetting about protein the rest of the day. “It’s like trying to put 90 gallons into a 30-gallon gas tank,’’ said Paddon-Jones. “We often take in too much protein than the body can convert to muscle at any one time, so that leads to spillover, which gets stored in the body as fat.’’
While the government’s recommended dietary allowance for protein is 46 grams a day for women and 56 grams for men, evidence is mounting that seniors need nearly double that amount to avoid accelerating loss of muscle - especially if they become bedridden from a prolonged illness or injury.
“It’s becoming quite clear that higher levels of protein intake - especially animal protein - will increase muscle and slow the rate of muscle loss,’’ said Robert Wolfe, a muscle metabolism researcher at the University of Arkansas for Medical Sciences in Little Rock.
His studies also indicate that people in their 20s and 30s might get more muscle gain from different compositions of amino acids (the building blocks of protein) than those in their 50s and beyond. The amino acid leucine, found in milk, meat, and fish, appears to be particularly beneficial in helping elderly people build muscle mass. Manufacturers of some supplements, such as Ensure, have been adding extra leucine to products aimed at seniors.
Of course, you can follow the perfect diet and be an avid exerciser, yet still face muscle loss as you age. Wolfe noticed a precipitous decline in his marathon performance a few years ago when he reached his early 60s; his pace was slowing and he felt more winded during training, despite his efforts to maintain his regular fitness regimen and eat adequate protein.
Just like you can’t ultimately avoid wrinkles, gray hair, and reading glasses, growing old with less muscle is inevitable. “You just have to reset your fitness goals,’’ Wolfe said. “You might be a little slower or weaker - maybe you can’t hit that golf ball as far - but you do your best without giving up on it.’’