allow older frail adults who are limited by poor overall physical fitness the ability to work at higher resistance levels, thereby benefiting from the higher intensity work. Developing an eccentrically biased program may require some creativity because most traditional resistance training exercises are concentrically biased. The key principle with eccentric exercise is to safely overload the muscle for maximal gains. Most research examining the benefits of eccentric exercise has used modified bikes on which the pedals are driven by attached motors – equipment that is not readily available in most clinic or home settings. However, eccentric exercise can still be performed in a traditional clinic or gym setting in the absence of specialized equipment. For example, when working on the leg press, an individual could be taught to straighten both knees, performing a traditional concentric knee and hip extension, then remove the right leg and slowly bend the left leg, resulting in an eccentric contraction of the left hip and knee extensors. This exercise could then be repeated on the other leg. As with all resistance exercise, the individuals should be reminded to move slowly and complete a full range of motion; if proper form cannot be maintained due to fatigue, the exercise should be stopped. Similar exercises could be employed for the upper extremities. All eccentric exercise programs should provide an initial ramping period of 2 to 3 weeks, during which time weight is slowly increased to avoid excessive muscle damage and muscle soreness. While eccentric exercise may provide a good model for older adults with limited physical fitness, some older adults may find that traditional weight training with free weights or weight machines is unappealing or intimidating. Older adults should be encouraged to find and participate in a mode of resistance exercise that is appealing and enjoyable. Downhill walking has recently been explored as a potential method of eccentric lower extremity resistance training (Drexel et al., 2008; Yang, Lee, Cheng, & Wang, 2010; Zeppetzauer et al., 2012). Downhill walking results in an eccentric contraction of many of the large muscle groups of the lower extremities for a prolonged period of time. Recent studies demonstrate that downhill walking results in improved lower extremity strength in those with Parkinson’s disease and decreased cholesterol, insulin resistance, and inflammation in middle-aged adults (Drexel et al., 2008; Zeppetzauer et al., 2012). Zeppetzauer and colleagues (2012) randomly assigned 45 sedentary adults to hike either uphill or downhill 3 to 5 times per week for 8 weeks. The path that was used had a grade of approximately 19% for 2.9 kilometers. Although both the uphill and downhill groups improved cholesterol, inflammation, and insulin resistance, the eccentric (downhill) group made significantly better increases in their glucose tolerance. The authors of this study concluded that eccentric exercise is a promising modality for those who are unable to tolerate more strenuous programs. While strength was not examined as an outcome of this study, Yang and colleagues (2010) also examined the use of downhill walking on lower extremity strength in those with Parkinson’s disease. Thirty- three individuals were randomly assigned to either a PT group that engaged in stretching, balance training, and over-ground walking or to a group engaged in downhill treadmill walking. After only 4 weeks of exercise, those in the downhill treadmill walking group made significant gains in knee extensor strength, while those in the usual PT group did not. Although similar studies have not yet examined the effects of downhill walking on older adults, it is reasonable to assume that similar results may be found, given the previously demonstrated benefits of eccentric exercise in older adults. Tai chi is another mode of resistance training that may appeal to older adults. Traditionally, tai chi has been used more often as a balance or stress reduction program for older adults, but the benefits extend beyond balance. Tai chi is an eccentrically biased program with slow-flowing movements. When performed standing, the intensity of the activity can be varied by the depth of the squat that is performed during the movements. While tai chi may not be vigorous enough as a resistance training program
an exercise to the last repetition of the set. Individuals working at a lower intensity but with higher repetitions will tire later in the set. As with all resistance exercise, individuals should be reminded not to rush, compromise form due to fatigue, or hold their breath. Good posture during all exercises should be emphasized. As fitness and strength improve, older adults should be encouraged to increase the frequency, duration, and weight used for each exercise because greater amounts of activity provide additional health benefits (Nelson et al., 2007). It is generally agreed that once an adult can easily complete 15 repetitions, the weight for that exercise should be increased. When initially starting a resistance exercise program, it may be necessary to progress the patient’s weights every 2 to 4 weeks. Because changes initially may occur quickly, at a minimum, weight should be reassessed every 4 to 6 weeks. As with aerobic exercise, older adults should be encouraged to participate in high-intensity resistance exercise (Nelson et al., 2007). For older adults who have never exercised before or who are not familiar with resistance exercise, resistance exercise should be done under the supervision of an individual familiar with exercise prescription for older adults. While a high-intensity resistance exercise may initially be difficult for a sedentary older individual, studies have demonstrated increased benefits for bone mineral density, strength, and functional outcomes with high-intensity resistance compared to low-intensity resistance exercise (Liu & Latham, 2009; Nikander et al., 2010; Westcott, 2012). If older adults are unable to participate in high-intensity resistance exercise due to poor physical fitness or comorbid conditions, then the implementation of eccentrically biased resistance exercises may be appropriate. Eccentric exercise involves the lengthening of a muscle. Eccentric exercise was once cautioned against because it was viewed as a model of creating muscle damage. However, when used appropriately, it provides results that are similar to, or may even exceed, traditional concentrically biased exercises. Eccentric exercise also has the additional benefit of placing lower metabolic demands on the heart and lungs than traditional concentrically biased strength training (LaStayo, Ewy, Pierotti, Johns, & Lindstedt, 2003a; LaStayo, Marcus, Dibble, Smith, & Beck, 2011; Marcus, Yoshida, Meier, Peters, & Lastayo, 2011). A traditional resistance exercise program involves both a concentric and an eccentric phase of movement. However, traditional resistance exercise is limited by the concentric phase of resistance, making it a concentrically biased program. While concentric exercise works by shortening a muscle to produce work, eccentric exercise results in work being done on the muscle as the muscle is lengthened. Because work is being done on the muscle, as opposed to the muscle doing work, eccentric exercise produces a lower metabolic demand, which results in decreased oxygen consumption and cardiovascular strain when compared with traditional concentric resistance exercise (Gault, Clements, & Willems, 2012; Gremeaux et al., 2010). Eccentric exercise has safely and successfully been applied to a number of older populations, including frail older adults (LaStayo et al., 2003a), older adults following total knee arthroplasty (Marcus et al., 2011), and older cancer survivors (LaStayo et al., 2011). Results from these studies have demonstrated improvements in strength ranging from 60% to 107% (LaStayo et al., 2003b; Marcus et al., 2011). Perhaps even more important than simple strength improvements, eccentric resistance exercise has also resulted in improvements in more functional measures, such as the 6-minute walk test (Marcus et al., 2011); balance (LaStayo et al., 2003a); and stair descent ability (LaStayo et al., 2003a). One study examining the benefits of eccentric resistance exercise in older frail adults found that those who participated in an eccentrically biased resistance exercise program were able to transition from a high fall risk to a low fall risk. Those who participated in a more traditional concentric exercise program were unable to work at the same high levels and, while they made small strength gains, were unable to transition from a high to a low fall risk (LaStayo et al., 2003a). While eccentric exercise is not a magic pill, it may
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