“If muscle isn't stimulated, your body senses that you don't need it," says Dr. Miriam Nelson, a physical activity and nutrition scientist at Tufts University in Boston. "If you're not active, it affects all body systems, literally down to the cellular level, where your ability to transfer oxygen from the bloodstream to cells is diminished and the number of power-producing mitochondria in your cells is less."
Along with the bad news, there is some good news to share: It is never too late to start moving. "Well into your 90s all of these systems can be stimulated," Nelson says. To further stimulate you to get a move on, here are some thoughts to ponder:
DIABETES. There is an increased risk for diabetes and heart disease when people become less sensitive to insulin. "The one thing that seems to deteriorate quickest with inactivity is insulin sensitivity," says Ben Hurley, a professor of kinesiology at the University of Maryland at College Park. "It also responds most consistently when you train. Type 2 diabetes used to be a disease of middle age. But now we're seeing it in young people. It's a sedentary disease."
Two of the most important things you can do to lower the threat of diabetes are to control weight and to exercise 30 minutes daily. Aerobic exercise can increase insulin sensitivity, and along with healthy nutrition, will help to restore normal glucose metabolism, by decreasing body fat. Light to moderate resistance training can also benefit type 2 diabetics by increasing muscle mass and decreasing insulin resistance.
THE HEART. "Exercise affects the function of the heart muscle, but it also affects the blood vessels, from the large aortic artery to the veins and the small capillaries," Nelson says. We have known for some time that exercise has a favorable impact on the HDL, the good cholesterol, and recent research has found that exercise makes the lining of blood vessels more flexible. "If partially blocked arteries are more elastic, they can relax better and send more blood to the heart muscles,'' says I-Min Lee, associate professor of epidemiology at the Harvard School of Public Health in Boston. "It's like pumping blood through a rubber hose instead of a concrete wall."
SARCOPENIA is the loss of muscle tissue as we age. Less muscle means more fat will be deposited in the muscle cells. "Marbling may be desirable for the taste of steak," says researcher Chhanda Dutta, chief of the clinical Gerontology Branch at the National Institute on Aging in Bethesda, Md., "but when it happens to your own muscles, it's associated with insulin resistance." For 80 to 90 percent of adults, if they don't do the right kind of physical activity regularly, they're going to end up with sarcopenia by the time they're in their 60s and 70s, says Timothy Doherty, Canada Research chair in Neuromuscular Function in Health, Aging and Disease at the University of Western Ontario.
To prevent muscle loss, it is very important to strengthen the large muscles around the thighs, arms, shoulders and back. "If you overload it in a gradual way, you can make the muscles bigger and stronger by making each muscle fiber thicker," Hurley says. Performing strength exercises for just two months can increase your strength by 40 percent.
OSTEOPOROSIS. As muscles become stronger, they place positive stress upon bones and bones become stronger when you place more demands upon them. After age 35, our bones stop growing and begin to gradually lose calcium. When the deterioration of old bones and the loss of calcium begin to develop faster than the development of new bone cells, osteoporosis results.
Osteoporosis, which means porous bones, is a disease that causes bones to become weak and brittle, often leading to fractures, commonly seen in the spine, hip and wrist. "The research doesn't consistently show that you can increase bone, but you can prevent loss," Hurley says.
If you are dealing with osteoporosis, be selective when choosing your exercises. It is important to select an activity that is safe and not harmful to your joints. Check with your physician, a physical therapist or a qualified personal trainer before beginning exercises.
To help maintain bone density as a preventive measure, it is recommended to perform at least 30 minutes of a weight-bearing exercise, such as stair-climbing, jogging, walking, dancing, tennis or other racquet sport, three to five days a week and strength-training exercises two to three times a week. If walking is your primary form of exercise, it would be important to add strength-conditioning exercises.
Strength training can preserve bone even more than walking, simply because walking does not offer an increase in weight load, which the bones need. Upper-body strength training will improve bone density in the wrists while lower-body strength exercises will improve bone density in the lower body.
If you are 50 or older and have not been exercising, check with your physician before beginning any exercise program. Write to Sally Anderson, a trainer, in care of LifeTimes, St. Petersburg Times, P.O. Box 1121, St. Petersburg, FL 33731.