Changes in Mobility
Being able to get around on one’s own is an important part of remaining independent. As you will see, we all experience some normative changes that can affect our ability to remain mobile, but most of these changes do not inevitably result in serious limitations.
Muscles and Balance. Although the amount of muscle tissue in our bodies declines with age, this loss is hardly noticeable in terms of strength and endurance; even at age 70 the loss is no more than 20%. After that, however, the rate of change increases. By age 80 the loss in strength is up to 40%, and it appears to be more severe in the legs than in the arms and hands. However, some people retain their strength well into old age (Booth et al., 1994; Skelton et al., 1994). Research evidence suggests that muscle endurance also diminishes with age but at a slower rate. Men and women show no differences in the rate of muscle change (Spirduso & MacRae, 1990).
This loss of muscle strength is especially important in the lower body (El Haber et al., 2008). As lower body strength declines, the likelihood of balance problems and falls increases, as do problems with walking. Exercise may help delay these changes.
Bones. You have probably seen commercials and advertisements aimed mostly at women for products that help maintain bone mass. If you surmise that such products reflect a serious and real health concern, you are correct. Normal aging is accompanied by the loss of bone tissue throughout the body.
Bone loss begins in the late 30s, accelerates in the 50s (particularly in women), and slows by the 70s (National Institute of Arthritis and Musculoskeletal and Skin Diseases, 2005). The gender difference in bone loss is important. Once the process begins, women lose bone mass approximately twice as fast as men. The difference results from two factors. First, women have less bone mass than men in young adulthood, meaning that they start out with less ability to withstand bone loss before it causes problems. Second, the depletion of estrogen after menopause speeds up bone loss.
What happens to aging bones? The process involves a loss of bone mass inside the bone, which makes bones more hollow. In addition, bones tend to become porous. The changes result from body weight, genetics, and lifestyle factors such as smoking, alcohol use, and diet (Aldwin & Gilmer, 2004). All these bone changes cause an age-related increase in the likelihood of fractures, because hollow, porous bones are easier to break. Furthermore, broken bones in older people present more serious problems than in younger adults, because they are more likely to be clean fractures that are difficult to heal. Bones of younger adults fracture in such a way that there are many cracks and splinters to aid in healing. This is analogous
to the difference between breaking a young, green tree branch (which is harder to do) and snapping an old, dry twig.
Women are especially susceptible to severe bone degeneration, a disease called osteoporosis, in which the loss of bone mass and increased porosity create bones that resemble laced honeycombs. You can see the result in Figure 3.1. Eventually, people with osteoporosis tend to develop a distinct curvature in their spines, as shown in Figure 3.2.
Osteoporosis is the leading cause of broken bones in older women (National Institute of Arthritis and Musculoskeletal and Skin Diseases, 2008a). Although it is most common in older adults, osteoporosis can occur in people in their 50s.
Osteoporosis is more common in women than men, largely because women have less bone mass in general, because some girls and women do not consume enough dietary calcium to build strong bones when they are younger (i. e., build bone mass), and because the decrease in estrogen following menopause greatly accelerates bone loss (National Institute of Arthritis and Musculoskeletal and Skin Diseases, 2008a). According to a national study of 48,000 postmenopausal women in the United States, low bone mass occurs in 65% of Asian American, 59% of Native American, 56% of Latina, 51% of European, and 38%
of African American women. Additional evidence form bone scans indicates that 65% of women over age 60 and nearly all women over age 90 are affected; in total, over 20 million American women have osteoporosis and millions more are at risk.
Osteoporosis is caused in part by having low bone mass at skeletal maturity (the point at which your bones reach peak development), deficiencies in calcium and vitamin D, estrogen depletion, and lack of weight-bearing exercise that builds up bone mass. Other risk factors include smoking, high-protein diets, and excessive intake of alcohol, caffeine, and
74 CHAPTER 3
sodium. Women who are being treated for asthma, cancer, rheumatoid arthritis, thyroid problems, or epilepsy are also at increased risk because the medications used can lead to the loss of bone mass.
The National Institutes of Health (Bennett, 2003) recommends getting enough vitamin D and dietary calcium as ways to prevent osteoporosis. There is evidence that calcium supplements after menopause may slow the rate of bone loss and delay the onset of osteoporosis, but benefits appear to be greater when the supplements are provided before menopause (Bennett, 2003; National Institutes of
Health, 2008). People should consume foods (such as milk or broccoli) that are high in calcium and should also take calcium supplements if necessary. Recommended calcium intake for men and women of various ages are shown in Table 3.1. Data clearly show that metabolizing vitamin D directly affects rates of osteoporosis; however, whether supplementary dietary vitamin D retards bone loss is less certain (National Institute of Arthritis and Musculoskeletal and Skin Diseases, 2008b).
In terms of medication interventions, biophos – phonates are the most commonly used and are highly effective (Kennel, 2007). Fosamax, Actonel, and Boniva are three common examples of this family of medications. Biophosphonates slow the bone breakdown process by helping to maintain bone density during menopause. Research indicates that using biophosphonates for up to five years appears relatively safe if followed by stopping the medication (called a “drug holiday”); there is evidence for protective effects lasting up to five years more.
Recommended Calcium Intakes
Birth-6 months 6 months-1 year Children/Young Adults
1-3 years 4-8 years 9-18 years
Adult Women & Men
19-50 years 50 +
Pregnant or Lactating
18 years or younger 19-50 years
Sources: National Academy of Sciences, 1997; http://www. niams. nih. gov/ Health_Info/Bone/Bone_Health/Nutrition/default. asp (revised November 2005).
Lowering the risk of osteoporosis involves dietary, medication, and activity approaches (National Institutes of Health, 2008). Some evidence also supports the view that taking supplemental magnesium, zinc, vitamin K, and special forms of fluoride may be effective. Estrogen replacement is effective in preventing women’s bone loss after menopause but is controversial because of potential side effects (as discussed later). There is also evidence that regular weight-bearing exercise (e. g., weight lifting, jogging, or other exercise that forces you to work against gravity) is beneficial.
Joints. Many middle-aged and older adults complain of aching joints. They have good reason. Beginning in the 20s, the protective cartilage in joints shows signs of deterioration, such as thinning and becoming cracked and frayed. Two types of arthritis can result: osteoarthritis and rheumatoid arthritis. These diseases are illustrated in Figure 3.3.
Over time the bones underneath the cartilage become damaged, which can result in osteoarthritis, a disease marked by gradual onset and progression of pain and disability, with minor signs of inflammation (National Institute of Arthritis and Musculoskeletal and Skin Diseases, 2006). The disease usually becomes noticeable in late middle age or early old age, and it is especially common in people whose joints are subjected to routine overuse and abuse, such as athletes and manual laborers. Thus osteoarthritis is a wear-and-tear disease. Pain typically is worse when the joint is used, but skin redness, heat, and swelling are minimal or absent. Osteoarthritis usually affects the hands, spine, hips, and knees, sparing the wrists, elbows, shoulders, and ankles. Effective management approaches consist mainly of certain steroids and anti-inflammatory drugs, rest, nonstressful exercises that focus on range of motion, diet, and a variety of homeopathic remedies.
A second form of arthritis is rheumatoid arthritis, a more destructive disease of the joints that also develops slowly and typically affects different joints and causes other types of pain than osteoarthritis (Mayo Clinic, 2008a). Most often, a pattern of morning stiffness and aching develops in the fingers, wrists, and ankles on both sides of
Physical Changes 75
the body. Joints appear swollen. The typical therapy for rheumatoid arthritis consists of aspirin or other nonsteroidal anti-inflammatory drugs, such as Advil or Aleve. Newer treatments include diseasemodifying anti-rheumatic drugs (DMARDs) (such as hydroxycholorquine and methotrexate) that limit the damage occurring in the joints, and TNF-alpha inhibitors that act as an anti-inflammatory agent and have been shown to stop the disease’s progression in some patients. Rest and passive range – of-motion exercises are also helpful. Contrary to popular belief, rheumatoid arthritis is not contagious, hereditary, or self-induced by any known diet, habit, job, or exposure. Interestingly, the symptoms often come and go in repeating patterns (National Institute of Arthritis and Musculoskeletal and Skin Diseases, 2004). Although apparently not directly inherited, family history of rheumatoid arthritis plays a role because researchers think that you can inherit a predisposition for the disease (Mayo Clinic, 2008a).
Surgical interventions for arthritis have advanced significantly (Mayo Clinic, 2008a). For example, arthroplasty, or the total replacement of joints damaged by arthritis, continues to improve as new materials help artificial joints last longer. When joints
become inflamed, surgeons may be able to remove the affected tissue. Or in some cases cartilage may be transplanted into a damaged joint. These latter two approaches help patients avoid full joint replacement, generally viewed as the method of last resort.
Comparisons among osteoporosis, osteoarthritis, and rheumatoid arthritis can be seen in Table 3.2.