Aging and Muscle Loss
As adults become more sedentary, they lose strength and endurance, become tired more easily and may be less likely to exercise. Exercise helps maintain or build muscle. So without regular, strength-building activity, muscle mass continues to decline. According to the American Council on Exercise, after 25, most adults lose about one-half pound of muscle a year.
The natural, progressive loss of muscle associated with aging is known as sarcopenia. Muscles burn more calories than fat. So as muscle mass declines, the body burns fewer calories. If energy intake isn’t adjusted, people gain weight. When weight gain is coupled with a lack of physical activity, people are at increased risk for insulin resistance and type 2 diabetes.
Loss of muscle mass can affect quality of life, the ability to carry out daily activities and, for some, the ability to live independently. Muscle strength is needed to maintain balance, get out of a chair, walk up stairs and carry groceries into the home. Experts say strong leg and hip muscles reduce the risk for falls and potentially debilitating hip fractures.
Strength Training for Seniors
Health experts say all adults should get at least 2½ hours of exercise a week. But many Americans become less active as they grow older. The Centers for Disease Control and Prevention reports, by 75, roughly 33 percent of men and 50 percent of women don’t get any exercise.
Marcas Bamman, Ph.D., Physiologist with the University of Alabama at Birmingham School of Medicine, says as the body ages, the size of muscles decrease, and so does the amount of force that can be exerted by the remaining muscle fibers. By 55, the rate of muscle loss accelerates rapidly. Thus, strength training exercises are especially important to maintain or build muscle mass.
However, in a earlier study, Bamman and his colleagues found that older adults adapt differently to strength training than younger people. The researchers also found that older people needed a little more time to recover after exercise so the body is able to recruit muscle stem cells and build new muscle.
Investigators now want to find the best type of exercise program for older adults who want to improve their overall health, fitness and performance. The new study is following healthy adults, 60 to 75, who have not had done any strength training in the previous three years.
Participants undergo an exercise and fitness screening, then perform general strength training exercises three days a week for 4 weeks. After this initial pre-training phase, the subjects are randomly assigned to one of four intervention groups. The total length of the program is about 38 weeks.
Throughout the study, researchers will measure the effects of the exercises on the body, using treadmill tests, body composition analysis, thigh composition, skin fold and body circumference measurements and other performance tasks. In addition, researchers will take blood samples and muscle biopsies.
Bamman is hopeful the study will provide answers about the best exercise recommendations for older patients. Ideally, experts will be able to use that information to develop strength training programs that can be done at home with minimal cost for the patient.
Alliance for Aging Research, http://agingresearch.org
American Council on Exercise, http://www.acefitness.org
American Senior Fitness Association, http://www.seniorfitness.org
Centers for Disease Control and Prevention, http://www.cdc.gov/physicalactivity/everyone/guidelines/olderadults.html
National Institute on Aging, http://www.nia.nih.gov
National Strength and Conditioning Association (NSCA™), http://www.nsca-lift.org
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Hanson, E., et al., “Effects of Strength Training on Physical Function,” Journal of Strength and Conditioning Research, December 2009, Vol. 23, No. 9, pp. 2627-2637.
Keogh, J., et al., “Strength and Coordination Training are Both Effective in Reducing the Postural Tremor Amplitude of Older Adults,” Journal of Aging and Physical Activity, January 2010, Vol. 18, No. 1, pp. 43-60.
Rexach, Jose, et al., “Health Enhancing Strength Training in Nonagenarians (STRONG) Rationale, Design and Methods,” BMC Public Health, May 26, 2009, Vol. 9, No. 152