meters in 15 minutes) by 18% (Pahor et al., 2014). Perhaps even more impressive, the researchers found that individuals who participated in the exercise intervention had a 28% lower risk for ongoing mobility problems compared to the control group that did not exercise (Pahor et al., 2014). This is in agreement with two meta-analyses that demonstrate even low-intensity aerobic exercise benefits frail older adults and results in improved physical function, mobility and gait speed (Chou et al., 2012; Gine-Garriga et al., 2014). Aerobic exercise in frail individuals results in an increased gait speed of .07 m/sec, which matches or exceeds the minimal clinical importance change for gait speed reported in other studies (Chou et al., 2012; Gine-Garriga et al., 2014). Three separate meta-analyses have also concluded that exercise in older frail adults should be “explicitly” encouraged due to the potential benefits to physical function and mobility (Chou et al., 2012; de Vries et al., 2012; Gine-Garriga et al., 2014). The benefits of aerobic exercise both on physiologic as well as on physical function for older adults is clear. However, an exercise prescription for older adults may be more complex and present additional difficulties when compared to prescribing exercise for a young healthy adult. physical activity guidelines (30 minutes per day, 5 days a week) with continuous moderate aerobic activity (i.e., longer than 10 minutes) versus those who met the same guidelines with short bouts of moderate aerobic activity (Loprinzi & Cardinal, 2013). This is encouraging news that therapists may be able to use to encourage even frail older adults to exercise; many older adults are unaware that certain benefits from aerobic exercise can be achieved with multiple short bouts of activity rather than one continuous bout. Therapists may encourage older adults who are unable to participate in 30 continuous minutes to attempt 5 to 10 minutes of moderate activity before each meal. For some older adults, a walk around the block several times a day may be enough to improve aerobic fitness. What is meant by moderate aerobic activity? While exercise intensity is traditionally prescribed as a percentage of heart rate maximum, this is frequently not feasible in older adults because age and comorbid conditions may blunt the heart rate response to exercise. Instead, it is recommended that perceived intensity, relative to an individual’s fitness level, be used to measure exercise intensity in older adults. It is generally recognized that while a short walk may be a “moderate intensity” exercise to a typical healthy adult, it may be of “vigorous intensity” for a frail older individual. The American College of Sports Medicine recommends the use of a 10-point scale to determine the intensity of an activity. On this scale, 0 is resting, and 10 is maximal effort. Any activity that produces a noticeable increase in effort, heart rate, and breathing would be rated at a moderate intensity of 5 or 6. An activity that results in a large increase in effort, heart rate, and breathing would be rated as a vigorous activity, or 7 to 8 on the scale (Nelson et al., 2007). Aerobic activity should be between 5 and 8 to attain a moderate to vigorous level of activity for the most benefit (Nelson et al., 2007). Older adults who have never participated in exercise before may not immediately understand this scale. When prescribing a home exercise program to an individual unfamiliar with exercise, it is recommended that several supervised exercise sessions take place first. During these sessions the participant should be educated about what constitutes moderate versus vigorous physical activity in order to understand the prescribed and desired level of effort. Some older adults may be cautious about exercising at a higher intensity and may require verbal encouragement to understand the desired level of activity. As fitness improves, older adults should also be encouraged to increase both the duration and intensity of their exercise sessions, as it is known that additional activity above the
for much longer (Maarbjerg, Sylow, & Richter, 2011; Zanuso et al., 2017). Though it is currently unknown why insulin sensitivity increases with exercise, it is known that the muscle contractions required to move the body during aerobic exercise can result in an increased glucose uptake that is 20 times that seen at rest (Forbes, Little, & Candow, 2012; Maarbjerg et al., 2011; Zanuso et al., 2017). A recent study that sought to determine the causes of improved insulin sensitivity after a lifestyle intervention program in older adults with coronary artery disease found that the most powerful determinant of insulin sensitivity was the change in daily physical activity (Audelin et al., 2012). This suggests that aerobic exercise and increasing physical activity in older adults can be a powerful intervention to improve insulin sensitivity. Just as important as the effect that aerobic exercise has on physiologic function is the beneficial effect that aerobic exercise may have on physical function and mobility, even in previously frail or sedentary older adults. A large clinical trial of over 1,600 older adults at high risk for disability found that a physical activity intervention aimed at meeting the American College of Sports Medicine guidelines was able to reduce the onset of major disability (defined as an inability to walk 400 Aerobic exercise prescription Prescribing exercise for older adults presents a unique set of challenges. The previously described body systems changes that occur with aging, along with the comorbid conditions that many older adults face, result in a need to alter the typical exercise prescription for both the duration and the intensity of exercise. For example, many older adults are prescribed beta blockers as a treatment for high blood pressure. Beta blockers blunt the rise in heart rate, and thus using heart rate to prescribe the intensity of exercise is not an option for some older adults. Older adults may also be deconditioned from illness or a lifetime of sedentary activity, resulting in the need to modify aerobic exercise prescriptions. Taking into account the physiological changes and comorbid conditions of many older adults, along with the need to encourage increased activity, the American College of Sports Medicine, along with the American College of Cardiology, issued new guidelines in 2007 for prescribing exercise for adults over the age of 65. The guidelines are also suggested for any adults age 50 or older who suffer from a significant chronic condition, such as heart disease or diabetes, that requires regular medical care, or for adults who experience any functional limitations that impair their ability to participate in exercise (Nelson et al., 2007). 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, 5 days a week of moderate intensity or 20 minutes a day, 3 days a week of vigorous intensity is recommended (Nelson et al., 2007). 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 (Nelson et al., 2007). 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 5 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 (Nelson et al., 2007). Recent evidence suggests that numerous health benefits are possible even for those who accumulate their physical activity in bouts that last less than 10 minutes (Loprinzi & Cardinal, 2013). A recent study that examined the effects of activity longer than 10 minutes in duration versus less than 10 minutes in duration concluded that, as measured by blood pressure, blood sugar, or total cholesterol, there was no difference between those who met the minimum
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