America is aging.
Within the next decade, more than 19% of the U.S. population is expected to be over the age of 65. Of this demographic, more than 60% are considered physically inactive. Current guidelines suggest older adults should participate in a minimum of 150 minutes of moderate activity per week with an additional two days of resistance training — but it’s likely that up to 90% of adults over the age of 75 do not meet these guidelines.
Prolonged inactivity can exacerbate the systemic — and often deleterious — changes inherent in aging, exposing older adults to myriad health risks. Fortunately, in many cases, increasing physical activity can slow or even reverse these risks.
Healthcare and therapy professionals are ideally placed to prescribe and manage exercise to counteract a sedentary lifestyle and problems associated with aging.
The process of aging
While the process of aging is complex and includes both biomedical and psychosocial factors, there is one commonality: a universal decrease in the body’s ability to maintain homeostasis.
A slowing in the cellular turnover of the dermal and epidermal cells in the skin leads to a thinning of the skin, decreased wound healing, and an increased risk of infection. Elastic tissue throughout the body also decreases with age, resulting in increased stiffness and decreased function in the cardiovascular, respiratory, and musculoskeletal systems.
As a result of physical inactivity, many older adults experience an increased vulnerability to illness and injury, and this may hinder their ability to survive a serious illness, a fall, or any other event — including life-saving surgery — that stresses the body systems.
Cardiovascular system changes
Aging leads to a progressive infiltration of fat into the heart muscle, as well as an increase in the collagen and connective tissue found in the extracellular space around the heart cells. This fatty and connective tissue may also contribute to the increase in thickness in the left ventricle seen with aging.
In addition to the fatty infiltrations’ influence on the heart’s electrical conduction, there’s also a pronounced decrease in the number of pacemaker cells with aging. By the age of 70, fewer than 10% of the pacemaker cells typically seen in younger adults remain.
Respiratory system changes
A lifetime of cellular stress and damage leads to changes in the lung’s tissue, as well as in the thoracic cage and diaphragm, resulting in overall decreased function of the respiratory system.
At a cellular level, there are numerous changes in the lung tissue, or parenchyma, including a decrease in the elastic tissue within the lungs that results in a decrease in the elastic recoil of the lungs, as well as premature closure of small airways during normal breathing.
Musculoskeletal system changes
All parts of the musculoskeletal system are affected by aging, including the connective tissues, muscles, and bones. Ligaments, tendons, and joint capsules become stiffer with age as elastic fibers decrease and cross-links between collagen fibers increase.
Aging results in a decrease in muscle mass, even in healthy older individuals. While muscle mass accounts for 50% of the total body weight in young adults, by the age of 75, it accounts for less than 25% of total body weight.
Though aging is associated with natural decreases in bone mass, inactivity accelerates this decline, and a sedentary lifestyle is a significant risk factor for the development of osteoporosis.
Using exercise as an intervention
Frequent aerobic and resistive exercise can delay the onset of physical frailty and even improve health and function in frail older adults who have already experienced a significant decline in function.
Aerobic exercise can delay the loss of cardio-respiratory fitness, as measured with VO2 max, typically seen with aging. While decreases in VO2 max still occur with aging inactive individuals, the rate of decline is much slower than in sedentary individuals. For example, an active 80-year-old individual who has maintained a high level of physical activity has a VO2 max comparable to that of a sedentary 50-year-old.
Decreased whole body inflammation after an aerobic exercise program is particularly noted in those who start with a high inflammatory level or those who suffer from a pre-existing comorbid condition such as heart disease.
Research has demonstrated that, while it takes 12 weeks of aerobic exercise to see a decrease in inflammatory markers in the blood, it takes only 2 weeks of inactivity to revert to increased levels of inflammation. This indicates that while aerobic intervention may be an effective method for decreasing inflammation in older adults, it is one that needs to be consistent and long-term in order to provide a significant benefit.
Older adults, like all adults, need regular physical activity and should participate in regular aerobic activity to avoid the deleterious consequences of sedentary behavior. A minimum of 30 minutes a day, five days a week of moderate-intensity or 20 minutes a day, three days a week of vigorous-intensity is recommended.
A combination of vigorous- and moderate-intensity exercise can also be used to meet the minimum recommendations. Activity above these guidelines is encouraged because the completion of exercise above the minimum duration can lead to additional health benefits.
However, even older adults who are unable to meet the minimum levels of activity due to comorbid complications, frailty, or simply gross deconditioning should still be encouraged to participate in any duration of aerobic activity they are able to tolerate, with a goal of a minimum of 30 minutes of accumulated daily physical activity at a moderate intensity at least five days a week. Ten minutes of aerobic activity done multiple times a day has been advocated for those who are unable to complete 30 continuous minutes.
Here are some common aerobic activities:
- Elliptical trainer
- Nordic walking
- Water aerobics
- Cross-country skiing
- Golfing without a cart
- Playing with grandchildren
- Aerobics classes
- Heavy housework or gardening
Whatever type of exercise is prescribed, remember: it should be something the patient enjoys, as they’re more likely to continue with the exercise plan if the activity is something they like. Asking older adults what activities they’ve enjoyed in the past may help structure an exercise program.
This article was adapted from the Elite Learning course Exercise Prescription Management of the Older Adult: An Evidence-Based Approach, written by Odessa Addison, DPT, PhD .