individuals compared to the strongest individuals (Cooper, Kuh, & Hardy, 2010). While this statistic may sound alarming, it is promising that even frail older adults can make improvements in strength with resistance training (Villareal, Smith, Sinacore, Shah, & Mittendorfer, 2011; Weening-Dijksterhuis, de Greef, Scherder, Slaets, & van der Schans, 2011). One study of frail institutionalized older adults found that resistance exercise performed twice a week for 14 weeks resulted in a 60% increase in strength (Westcott, 2009). This encouraging finding suggests even the frailest older adults can benefit from the implementation of a resistance training program. Resistance exercise also has significant positive effects on bone mineral density for older adults (Chodzko-Zajko et al., 2009). While endurance or aerobic exercise training may have little to no effect on bone mineral density (Nikander et al., 2010), resistance exercise may prevent or reverse a 1% bone loss per year in older adults (Westcott, 2012). Resistance exercise may also improve bone mineral density in previously sedentary individuals (Chodzko-Zajko et al., 2009), though many of these gains are reversed once the exercise is stopped, suggesting that resistance exercise should be a lifelong pursuit instead of a one- time goal (Westcott, 2012). Just as important as the physiological benefits, resistance exercise also leads to functional improvements in older adults. A recent Cochrane meta-analysis concluded that resistance exercise in older adults leads to improvements in strength, gait speed, timed up and go, and the time it takes to complete sit-to-stand (Liu & Latham, 2009). Furthermore, this review also concluded that participation in a resistance exercise program results in decreases in disability in older adults. The clear benefits of resistance exercise suggest that all older adults should be educated and encouraged to begin an exercise program. However, just as with aerobic exercise, developing a resistive exercise program for older adults may be more complex and present additional difficulties when compared to prescribing exercise for a young, healthy adult. Additionally, many older adults may never have participated in resistive exercise, which may make implementing a home resistance exercise program more difficult. rest breaks between exercises may initially be required. For resistance exercise, a moderate to high level of intensity refers not to the overall work of the exercise but to the work of the specific muscle group that is being used. If 0 is no movement and 10 is a maximal effort to move a muscle group, then a moderate intensity is a 5 to 6, and a high intensity is a 7 to 8. This means that intensity will be exercise-specific and should be evaluated with each exercise and each muscle group. Adults who are new to resistance exercise may require education and demonstration to understand this concept. Initially, working larger groups of muscles, such as the knee flexors and extensors, may lead to large changes in breathing and heart rate due to the large amount of muscle mass activated. With resistance recovery and to move safely to the next exercise. However, for frail patients or those with high levels of deconditioning, longer exercise, older adults should be taught to focus not on the total body effort for heart rate and breathing but instead on the specific muscle group being worked. Using resistance training to work large muscle groups, such as knee extensors, will increase the heart rate and breathing. This increase in heart rate and breathing may not be as evident when exercising smaller muscle groups such as elbow flexors. Although performing bicep curls may not increase heart rate or breathing in the same way as leg extensions, older adults should nonetheless work at a moderate to high level of intensity for the biceps. They should feel fatigue in their muscle at the completion of the exercise. In fact, if working at a high intensity for 10 to 15 repetitions, they should feel fatigue from approximately the eighth repetition of
body fat, visceral adipose tissue, and intramuscular adipose tissue, resistance training has the additional benefit of producing significant changes in muscle mass, strength, and bone mineral density (Chodzko-Zajko et al., 2009; Liu & Latham, 2009; Westcott, 2012). Resistance exercise is also a powerful stimulus to promote muscle hypertrophy. The loss of muscle mass in aging has been postulated to increase functional limitations, falls, and disability in older adults (Goodpaster et al., 2006). Increasing muscle mass may result in improved strength and mobility in older adults. A single bout of resistance exercise can increase muscle protein synthesis for up to 48 hours in previously sedentary individuals (Koopman & van Loon, 2009). The consistent performance of resistance exercise results in frequent increases in muscle protein synthesis and eventual muscle hypertrophy (Koopman & van Loon, 2009). In older adults, increases in muscle mass generally result from a preferential increase in type II (fast-twitch) muscle fiber size (Leenders et al., 2012). While some research reports that older adults, particularly frail older adults with comorbid conditions, may have a blunted ability to improve muscle mass, it does appears that even frail older adults can make improvements in muscle mass, especially with the use of high-intensity training (Chodzko-Zajko et al., 2009). Studies typically demonstrate a muscle hypertrophy of between 10% and 62% in older adults after the implementation of a resistance exercise program (Chodzko-Zajko et al., 2009). While these gains are smaller than those found in younger adults, it is important to remember that any gain in muscle mass is a positive reversal from the progressive loss of muscle mass found with aging. Even if there is an absence of the expected change in muscle mass, there may still be an improvement in strength. Studies involving older adults have reported increases in strength ranging from 25% to 100% after a program of resistance exercise (Chodzko-Zajko et al., 2009; Leenders et al., 2012; Liu & Latham, 2009). Improvements in strength are critical, as strength is inversely and independently associated with mortality in older adults. This means that even after statistically accounting for a number of other important variables, such as sex, age, and body size, strength was still an important predictor of mortality in older adults. A meta-analysis of more than 53,000 individuals determined that mortality risk increased by 67% in the weakest Resistance exercise prescription Older adults who have never engaged in resistance exercise may feel confused or intimidated at the prospect of starting a resistance training program. Misinformation about the expected outcomes or a negative association with resistance exercise may initially make implementation of a resistance program difficult (Winett et al., 2009). Older adults may have incorrectly learned that resistance exercise is not appropriate for those with high blood pressure, that resistance training leads to the addition of bulky muscle mass, or that resistance exercise is bad for the joints and will lead to increased injuries. For those unfamiliar with resistance exercise, it may be beneficial to initially undertake a period of supervised exercise until the individual feels comfortable performing the exercises independently. As with aerobic exercise, the American College of Sports Medicine and the American Heart Association have issued recommendations for resistance exercise for older adults, those with chronic conditions, or individuals with significant mobility limitations. To maximize the benefits from resistive exercise, older adults should perform resistance exercise a minimum of 2 days a week at a moderate to high intensity. It is recommended that 8 to 10 exercises be performed during each exercise session targeting most major muscle groups, with 10 to 15 repetitions for each exercise performed at a moderate to high level of intensity (Nelson et al., 2007). It is generally expected that once individuals are familiar with resistance exercise, performing 10 to 15 reps of 8 to 10 exercises will take 20 to 30 minutes to complete. Adequate rest should be given between exercises to ensure patient safety and comfort. In general, 1 to 2 minutes of rest between sets of exercises should be sufficient to allow
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