In study, aerobics, resistance training lowered risk of insulin resistance, improved motor function
THURSDAY, Jan. 29 (HealthDay News) -- Sedentary seniors can improve their motor function and decrease their risk for insulin resistance by starting an exercise program that includes both aerobics and resistance training, new Canadian research suggests.
"For a long time, the standard recommendation for people of moderate age -- those under 65 -- has been 150 minutes a week of aerobic type activity," noted study co-author Robert Ross, a professor in the school of kinesiology and health studies at Queen's University in Kingston, Ontario. "But for older adults, we haven't had a standard, and there has been little evidence to base guidelines on."
"So now we have found, as a first-time observation, that elderly men and women whose objective is to manage their blood sugar, reduce both diabetic and cardiovascular risk, and simultaneously maintain an ability to live independently, should do both aerobic and resistance training."
On a weekly basis, this optimal training formula would be comprised, said Ross, of 90 minutes of simple aerobics -- such as walking -- alongside 60 minutes of resistance exercise of some kind.
Ross and his colleagues reported on their work -- funded by the Canadian Institutes of Health Research -- in the Jan. 26 issue of the Archives of Internal Medicine.
The authors pointed out that elderly Americans currently comprise about 12 percent of the country's population -- a figure set to rise to about 20 percent by 2030.
They further underscored the fact that the risk for developing insulin resistance -- a pre-diabetic condition in which the body does not properly utilize the hormone insulin to break down food sugars -- has long been associated with growing older.
Ross and his team also noted that American Heart Association and the American College of Sports Medicine advocate routine physical exercise as critical means of achieving healthier aging.
To examine the impact of exercise on insulin resistance and motor function, between 2002 and 2006, the authors focused on 117 sedentary Canadian men and women between the ages of 60 and 80, all of whom were diagnosed as obese in their abdominal region.
None of the participants had a prior history of heart disease, and none had been dieting when the study was launched. Almost all were white.
Over six-month study periods, the participants were put into one of four activity groups: those who did not exercise; those engaged in resistance exercise alone (20 minutes/three times per week); those performing aerobic exercise alone (30 minutes/five times per week); and those who did a combination of both resistance (60 minutes per week) and aerobic exercise (30 minutes/three times per week).
While tracking dietary intake throughout the study period to maintain each participant's initial weight, the researchers assessed skeletal muscle mass and fat composition, as well as insulin resistance, at the beginning and end of the various exercise programs.
The researchers found that among the two groups engaged in aerobic exercise -- either alone or in combination with resistance training -- insulin resistance improved as compared with those who didn't exercise at all. Resistance training alone, however, did not produce any improvements.
The same dynamic held in terms of improvements in cardio-respiratory fitness, in which aerobic or combined aerobic-resistance training produced benefits, while resistance training alone did not.
However, any form of exercise, alone or in combination, appeared to significantly boost motor function among the participants -- although combining aerobic with resistance exercise provided the most benefit.
The authors concluded that older men and women have the most to gain by engaging in a routine exercise program that includes both aerobic and resistance training, while maintaining a healthy diet. And they encouraged health-care providers to advocate this kind of lifestyle to their elderly patients.
"It would certainly be wrong to say that aerobic exercise alone doesn't provide a substantial benefit," noted Ross. "It certainly does. And if an older individual can't get access to resistance training, aerobics alone is much better than doing nothing. It's just that optimal results are obtained from doing both aerobics and resistance."
Dr. Robert H. Unger, a professor of internal medicine and emeritus director of the Touchstone Center for Diabetes Research at the University of Texas Southwestern Medical Center at Dallas, indicated that the findings are strongly in line with what he would expect.
"The reason you have muscle is to move around," he said. "Not to sit still all your life. And you don't have to be a rocket scientist to figure this out. For two and a half million years of evolution, our species always had to use its muscles, until about a hundred years ago. Now we have inactivity 16 hours a day, because we no longer move our muscles to get to work, and no longer move our muscles when we're at work, and when we get home, we watch television."
"So, when we overeat and under-exert, when we don't use our muscles over long periods of time, we obviously will ultimately suffer the consequences and go on to develop all sorts of irregularities, including insulin resistance," added Unger. "So, anything that gets people to move is going to be beneficial."
For more on exercise and aging, visit the U.S. National Institute on Aging.
SOURCES: Robert Ross, Ph.D., division of endocrinology and metabolism, school of kinesiology and health studies, Queen's University, Kingston, Ontario, Canada; Robert H. Unger, M.D., professor, internal medicine, and emeritus director, Touchstone Center for Diabetes Research, University of Texas Southwestern Medical Center at Dallas; Jan. 26, 2009, Archives of Internal Medicine
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