Exercise key to strength, function in older women

NEWSWISE- On their own, exercise and eating higher protein diets are known to help people lose weight and increase strength. But combining both strategies doesn't necessarily magnify their effects on older women, according to a new University of Georgia study.

The study examined the impact of a high-protein weight-loss diet and exercise on women between the ages of 65 and 80.

The research revealed while exercise during weight loss is critical to preserving muscle strength and function, a higher protein diet when combined with exercise doesn't appear to result in any added benefits to body composition and muscle strength in overweight older women.

"Overweight and obese women and women in general are at a higher risk than men for physical disability with advancing age," says principal investigator Ellen Evans, who serves as associate dean for research and graduate education and professor at UGA.

"If older adults lose weight, especially too quickly or if they focus only on reducing calorie intake, they are going to reduce their risk of obesity," Evans says. At the same time, however, they're going to increase their risk of bone and muscle mass loss, she adds.

The study divided women between the ages of 65 and 80 into three groups: one with a high-protein diet with exercise; one with a high-protein diet without exercise; and one with a conventional protein diet with exercise.

Participants in the high-protein diet groups were instructed to consume at least one serving or 3 ounces of cooked lean beef per day, as well as other lean meats, eggs, protein bars, whole foods, and more.

Those in the exercise groups completed a multicomponent program that included aerobic training, strength training for all major muscle groups, and balance and functional exercises three times a week on nonconsecutive days during each week for six months.

When the results came in, changes in weight and fat mass didn't differ among the groups. But despite losing weight, muscle strength increased in the exercise groups.

Obesity negatively affects lower extremity physical function in older adults. It's also a key determinant - along with cognition - in whether these individuals can function on their own and lead independent lives. In the U.S., 70% of women over 65 years old are considered overweight or obese.

"The larger the body weight, the more muscle strength and endurance is needed to move from point A to point B," says Evans. "We were more worried about lower extremity physical function because when individuals can't move their body weight anymore for basic activities such as walking, climbing stairs, and more, that's when they lose their independence."

While researchers expected participants in the higher protein diet with the exercise group to gain the greatest benefits among the three groups, the higher protein diet didn't alter the beneficial effects of weight loss combined with exercise on body composition change, muscle strength or lower extremity physical function, further highlighting the importance of exercise.

In addition, the nonexercise group - despite eating a higher protein diet - actually experienced reductions in strength and little improvements in lower extremity physical function compared with the exercise groups.

"What's reinforced by this study is if older women are trying to lose weight, they really need to incorporate exercise into their weight-loss program, especially strength training to preserve muscle mass and strength," says Evans. "They will also receive greater benefits from a physical function perspective."

Researchers also found that increasing dietary protein intake, especially up to the levels commonly recommended for older adults who want to lose weight, is behaviorally challenging and usually requires dietaiy prescriptions that mix animal, plant, and supplement forms of protein. Many lean, high-quality protein sources like lean meats, seafood and dairy foods have to be cooked or at least refrigerated, which takes more planning.

"Beef and other high-quality meats that are lean are relatively expensive," says Evans. "And for someone who doesn't regularly eat that much protein daily, to make that happen is difficult. To lose weight, you have to cut calories and at the same time increase protein, which means you have less discretionary calories. It's the combination of the two that can be especially behaviorally challenging."

Management of obesity to prevent physical disability in older adults - especially older women - remains a public health challenge, Evans contends. Researchers believe that an aging society affected by high rates of obesity and low rates of physical activity, especially strength training, may produce an epidemic of physical disability in the future.

"Our weight-loss program was veiy reasonable and aligned with nutrition and exercise guidelines, but it required several behavioral changes," adds Evans. "Many people exercise to maintain their weight or to change their body shape, but for overweight or obese older adults, more people need to understand the importance of weight loss combined with exercise to not only help prevent or manage chronic diseases such as diabetes but also to maintain physical independence. For these individuals, a small amount of weight loss when combined with rigorous exercise, which includes strength training, can greatly prevent physical disability as one gets older."

The study was funded by The Beef Checkoff, the National Institute of Food and Agriculture, and the U.S. Department of Agriculture.