Your bones contain about 99 percent of the calcium in your body. Every day your body also uses calcium to help nerves and muscles function, and to help blood clotting. Your body doesn’t produce calcium—it must come from the foods you eat. When your body doesn’t get enough calcium through food, it takes it from your bones.
Bones are living tissue and are constantly changing. Old bone continuously breaks down and is replaced by new. When you're young and growing, your body makes more bone than it removes. This helps you reach your peak bone mass, the point at which your bones are strongest. This is usually around age 20 to 30.
Once you hit 30 (later, if you're a man), you start to lose bone mass faster than your body replaces it, according to the National Institutes of Health (NIH). This increases your risk for osteoporosis, a disease that causes bones to become less dense. This makes them weak and more vulnerable to breaks. Osteoporosis affects both men and women, but it is more common in women because women generally have smaller, thinner bones than men. For the first four to eight years after menopause, the rate of bone loss in women increases.
For both men and women, bone density is influenced by genetics, food, estrogen (for women) and testosterone (for men), exercise, alcohol, smoking, and the use of certain medications.
Men begin to catch up to women in rate of bone loss as they age. Untreated low levels of testosterone contribute to bone loss in men. By ages 65 to 70, men and women lose bone at the same rate, the NIH says. And the ability to absorb calcium, which is important for bone health, decreases for both men and women as they age. For both men and women, osteoporosis is often caused by steroid medications used to treat asthma and rheumatoid arthritis; alcohol abuse; smoking; gastrointestinal diseases that interfere with the body's ability to absorb nutrients; kidney disease that causes too much calcium to be lost through the urine; or lack of mobility.
Helping your bones
You can help prevent osteoporosis by including enough calcium and vitamin D in your diet and exercising regularly. According to the National Osteoporosis Foundation (NOF), women and men younger than age 50 need 1,000 mg of calcium and 400 to 800 IU of vitamin D daily. For men and women older than age 50, the need rises to 1,200 mg of calcium and 800 to 1000 IU of vitamin D daily.
Like muscles, bones are living tissue, and exercise makes them stronger. In fact, studies have shown that exercise may even help generate new bone in older adults. Two types of exercise can help build bones:
Weight-bearing exercises. When your feet and legs bear the weight of your body—as they do when in walking—your muscles and bones become stronger because they're working against gravity to hold up your weight. According to the NOF, high-impact exercises, such as jogging, climbing stairs, dancing, and hiking, and sports such as tennis, basketball, and soccer, are not for people who have low bone mass or are frail. For these people, low-impact exercises, such as elliptical training, stair-step machines, walking, and other low-impact aerobics, are best. Swimming and bicycling are good ways to exercise your heart and lungs, but they don't strengthen your bones because they're not weight-bearing exercises.
Resistance exercises. Also known as strength-training, these types of activities use your muscles to pull or push against something to build bone and muscle strength. Free-weights, weight machines, and other fitness tools such as elastic bands or weights designed to be used in a pool are often used for strength-training. To avoid possible injury, be sure to learn the proper techniques for the activity you're doing. Many gyms offer classes, or you can work with a trainer.
Balance and posture exercises are a good addition to your workout. They reduce the risk for falls and spinal fractures. They help people move well in daily activities and strengthen leg muscles.
Men and women should also make sure they avoid smoking; use alcohol moderately; and talk with their health care provider to find out if any prescribed medications increase bone loss.
Tips to get started
Talk with your health care provider before beginning any exercise program. This is especially important if you have a chronic condition such as heart disease. If you're a woman older than age 65, your health care provider may recommend a bone mineral density test to screen for osteoporosis. You may need to be tested earlier if you have other risk factors. If you have osteoporosis, your health care provider may advise you to avoid certain activities and suggest medication to help slow bone loss.
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