It is clear, however, that activity and exercise slow or even mitigate many age-related changes, resulting in a delayed onset of frailty and mobility limitations in older adults. The benefits of both aerobic and resistive exercise are numerous and will be explored in greater detail in the following sections.
Musculoskeletal Changes • Decreased muscle mass. • Increased tendon stiffness. • Decreased synovial fluid. • Decreased satellite cells. • Decreased alpha motor neurons. • Decreased muscle strength and power.
• Decreased muscle quality. • Increased intramuscular fat. • Decreased bone mass. Note . From Western Schools, 2018.
EXERCISE AS AN INTERVENTION
and even improve health and function in frail older adults who have already experienced a significant decline in function (Chou et al., 2012; de Vries et al., 2012; Gine-Garriga, Roque-Figuls, Coll-Planas, Sitja-Rabert, & Salva, 2014). With this knowledge, the federal government has made increasing physical activity of older adults a major goal. Engaging in both aerobic and resistive exercise as well as flexibility and balance exercises are essential for older adults to combat the numerous changes that occur in the body as a result of aging. activity levels will help improve the health of older adults. Even previously sedentary older adults who have never exercised may benefit from starting an exercise program. Decreases in ectopic fat deposits may be one reason why aerobic exercise is also associated with decreased inflammation in older adults. 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 (Thompson et al., 2010). The majority of studies that have examined aerobic exercise as an intervention to target increased levels of inflammation in older adults have found that aerobic exercise resulted in decreased whole body inflammation, though not all have found this to be the case (Addison et al., 2011). 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 (Thompson et al., 2010). 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. It is interesting that even if aerobic exercise does not result in a reduction in inflammation levels measured in the blood, it may still have beneficial effects on the muscles. While most of the more recent studies have examined the effects of aerobic exercise on circulating levels of whole body inflammation, a few older studies have examined the effects of aerobic exercise on inflammation within the muscle. These studies found that even in frail elderly individuals where no decreases in whole body circulating inflammatory markers could be found, aerobic exercise did result in up to a 50% decrease in inflammation within the muscle (Bruun, Helge, Richelsen, & Stallknecht, 2006; Gielen et al., 2003; Lambert, Wright, Finck, & Villareal, 2008). The combined effect of decreased fat mass and decreased inflammation may also be partially responsible for the decrease in insulin resistance and increase in insulin sensitivity seen with exercise. It has been known since the 1980s that insulin sensitivity is similar in older and younger master athletes (Seals et al., 1984). However, we now know that aerobic exercise can actually improve insulin sensitivity and decrease insulin resistance in older, previously sedentary adults (Audelin et al., 2012). A single session of aerobic exercise results in both an immediate increase in glucose uptake that lasts for several hours after the cessation of exercise and increased insulin sensitivity that lasts
Bed rest was once a common prescription for recovery from illness. Today it is widely acknowledged that bed rest is more harmful than helpful for most illnesses and chronic conditions. It is now understood that physical activity is crucial, even in frail older adults (Chou et al., 2012). Bed rest leads to an increased loss of muscle mass and a rapid decline in physical function, including a loss of muscle strength and power and mobility loss in older adults (Drummond et al., 2012; Kortebein et al., 2007, 2008; Reidy et al., 2017). Frequent aerobic and resistive exercise can delay the onset of physical frailty (Booth & Zwetsloot, 2010) Aerobic exercise benefits Aerobic exercise can delay the loss of cardio-respiratory fitness, as measured with VO 2 max, typically seen with aging (Booth et al., 2011). While decreases in VO 2 max still occur with aging in active individuals, the rate of decline is much slower than in sedentary individuals. An active 80-year-old individual who has maintained a high level of physical activity has a VO 2 max comparable to that of a sedentary 50 year old (Booth et al., 2011). In previously sedentary older individuals, the implementation of an aerobic exercise program can also result in increased cardiorespiratory fitness and VO 2 max (Kokkinos et al., 2010). Increasing fitness in older adults is of critical importance, because a low VO 2 max is correlated with increased mortality in older adults, and either an increase or a decrease in VO 2 max alters mortality risk (Booth et al., 2011; Kokkinos et al., 2010). A study of men aged 70 to 82 found that older men who increased their cardiorespiratory fitness from a low to a high aerobic fitness decreased their mortality risk by almost 50% (Kokkinos et al., 2010). However, the converse was also true. Older males who transitioned from high to low cardiorespiratory fitness actually increased their risk of mortality by 50% (Kokkinos et al., 2010). One reason that aerobic exercise may result in decreased mortality risk is the benefit to the heart and lungs. Aerobic exercise is known to decrease blood pressure as well as to prevent and even reverse arterial stiffness that contributes to increased blood pressure and heart dysfunction (Booth et al., 2011; Ohta et al., 2012). A recent study of 26 older women demonstrated that just 12 weeks of aerobic exercise resulted in decreased arterial stiffness (Ohta et al., 2012). Improvements in mortality with improved physical fitness may also be related to the beneficial changes in body fat that occur with increased physical activity. Aerobic exercise may delay the harmful migration of body fat to ectopic fat deposits such as visceral and intramuscular fat (Wroblewski, Amati, Smiley, Goodpaster, & Wright, 2011). Cross- sectional studies have demonstrated that older master athletes do not differ significantly from younger master athletes in the amount of intramuscular fat found within their thighs (Wroblewski et al., 2011). More recently, it has been found that increased aerobic activity in previously sedentary individuals may actually result in decreases in visceral and intramuscular fat (Addison et al., 2014; Marcus et al., 2008; Murphy et al., 2012). In a formative study on the impact of physical activity on intramuscular fat, Goodpaster and colleagues (2008) found that as little as 30 minutes of walking twice a week was enough to curb the fatty infiltrate into the locomotor muscle of older adults. This is an important finding as it emphasizes that even minor increases in
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