Physical Health in Late Life

Research in the field of the aging has been successful in providing evidence of the physiological changes that occur with increasing chronological age. These physiological changes include, among others, changes in cardiovascular structure (DiBello et al., 1993), a slow progressive decline in body mass (Bray, 1979), and a decrease in the strength per unit of muscle mass (Frontera, Hughes, Lutz, & Evans, 1991; Reed, Pearlmutter, Yochum, Meredith, & Mooradian, 1991). The research data suggest that these physiological decrements may contribute to a reduction in the overall quality of life of the older adult population (Buchner, Larson, Wagner, Koepsell, & DeLateur, 1996).

While a number of different metaphors have been attached to the aging process, such as the machine metaphor (i.e., the body as an aging machine that over time begins to break down), it is clear that as we age our physiology changes. One question is whether these age-related changes are absolute or susceptible to the influence of various interventions, including efforts at prevention. For both the older adult and the middle age Baby Boomer, the answer is that many of the age-related physiological changes respond quite well to intervention.

The focus of prevention research has been primarily on methods of developing and maintaining good health, preserving the quality of life of the older adult population, and improving those systems that contribute to the successful completion of the activities of daily living (ADLs). The musculoskeletal and cardiorespiratory systems respond favorably to a variety of interventions.

Seals, Hagberg, Hurley, Ehsani, and Holloszy (1984) demonstrated a 14% increase in maximal oxygen consumption following 6 months of training beginning at only 40% of maximal heart rate. Further, after 12 months the researchers reported an average increase of 30%, with a range from 2% to 49%. Similarly, Saltin (1986) and Spina et al. (1993) found that relative to a sedentary person, the older adult who has maintained an active lifestyle, while presenting with a lower maximal heart rate, has a significantly larger stroke volume. As such, the active older adult has the advantage of a larger maximal cardiac output. The research of Ehsani, Ogawa, Miller, Spina, and Jilka (1991) and Thomas, McCormick, Zimmerman, Vadlamudi, and Gosselin (1992) suggests that endurance training may augment the older adult’s stroke volume and ejection fraction as a result of an increase in myocardial contractility and a decrease in collagen cross-linkage. Both stroke volume and ejection fraction are important if the older adult is to take advantage of the increase in end-diastolic volume (Frank-Starling Mechanism), which serves to compensate for the age-related decrease in maximal heart rate.

Regarding the musculoskeletal system, Pyka, Lindenberger, Charette, and Marcus (1994) recruited men and women between the ages of 61 and 78 to participate in a strength-training program that involved performing a circuit of 12 resistance exercises for 50 weeks. After only 8 weeks the researchers were able to demonstrate significant increases in muscular strength in both men and women. Additionally, the researchers found increases in Type I and Type II fiber areas after 15 weeks and 30 weeks respectively. Fiatarone et al. (1994), utilizing an older group, age 72 to 98 years, demonstrated an increase in local muscle strength of 113% following 10 weeks of resistance training. Additionally, the subjects exhibited increases in gait velocity (11.8%) and increases in stair-climbing power (28.4%). These individuals were all residents of a nursing home, providing good evidence that even frail older adults can benefit from resistance training.

For the baby boomer, however, the approach for a healthy future should be proactive rather than reactive. For example, consider the role of exercise in the prevention of osteoporosis. Simply put, the skeletal system is the framework upon which the body is built. Because of the skeletal system, muscles and tendons have origins and insertions, without which we would not be able to generate movement. While we go from day to day giving little thought to this natural framework, rarely does a day go by that our skeletal system is not undergoing some form of physiological maintenance that relies on the relationship between degradation and deposition. As we age, however, this relationship between degradation and deposition shifts from one that favors deposition to one that is more degradative, with women losing bone mineral more rapidly than men (36 grams/decade vs. 30 grams/decade respectively; as reported by Riggs & Melton, 1992). As a result of this disparity, the older adult is at greater risk for a variety of fractures, with estimates being as high as 1.2 million fractures per year in the female population alone (Smith, Raab, Zook, & Gilligan, 1989). While this age-related change in bone health seems like a dire forecast for the aging adult’s later years, much like the muscular system, the skeletal systems responds quite well to regular physical activity.

At the outset, the young adult whose life includes regular physical activity has a distinct advantage over the sedentary young adult in that regular participation in weight-bearing and load-generating activities develops a higher bone mineral content. And while aging brings bone loss regardless of activity habits, at any given age the active young adult retains a distinct advantage over the sedentary young adult. As such, according to Shephard (1997) it takes many more years for the active young adult to experience bone degradation to such a level as to increase the likelihood of pathological fractures.

Unfortunately, too often regular physical activity is added only after aging has manifested itself in such a way that the individual experiences a decrease in his or her physical capacity. Even so, the addition of physical activity to one’s daily routine, even later in life, can do a great deal towards preventing bone diseases such as osteoporosis. In an early study conducted by Sidney, Shephard, and Harrison (1977), a group of 65-year-old men and woman were followed for one year. The participants carried out a program of aerobic exercise up to four times a week. At the end of the one-year period the group had successfully maintained whole body calcium content. Smith and Gilligan (1989) demonstrated a reduction in bone mineral loss from the radius in a group of women age 35 to 65 years after participation in an activity program that included weight-bearing and arm-strengthening. Similarly, following seven months of high intensity aerobic exercise (110% of heart rate reserve), Hatori et al. (1993) found an increase in the density of the lumbar spine (L2 to L4) in women age 45 to 67 years when compared to control subjects and those subjects who exercised at 80% of their heart rate reserve.

When combined with good dietary habits, which include adequate levels of calcium and Vitamin D, especially during early adulthood, the effect of age on bone health can be minimized and even reduced. Research suggests that both men and women can experience an increase in bone mass and/or a reduction in the risk for developing fractures with increased calcium intake (Cumming & Nevitt,1997; Heaney, 2000). This tends to be especially true in those individuals with initially low calcium levels. Both Anderson and Metz (1993) and Heaney offered that those individuals who consumed low levels of calcium rich foods had, on average, lower bone mass values than those age-matched individuals who regularly consumed recommended or higher levels of calcium.

From these investigations it becomes apparent that if we expect to be successful at staving off the effects of aging and preserving good health, then we must begin a regular exercise routine before age has manifested itself in such a way that it compromises our capacity.

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