Resistance Exercise Increases Functional Capacity and Independence in Older Adults

Introduction

As humans age into older adulthood (age 65 and over), a variety of physiological changes occur that contribute to a process of deteriorating physical and cognitive function (Evans, 1997; Persson et al., 2006). As a result, a general condition of frailty can occur in older adults (Torpy, Lynm, & Glass, 2006). Older adults who become frail are less independent than those who are not, because frail older adults have a greater probability of hospitalization, health problems, and being disabled (Torpy et al., 2006). Frail older adults also have a limited functional capacity, which is defined as the capacity to complete basic human tasks that are essential to everyday living (Evans, 1997; Clark & Manini, 2010; Boström et al., 2014).

Frailty in older adults is of particular concern in the U.S. due to an unprecedented percentage of the population shifting into older adulthood (Knickman & Snell, 2002). In 2030, the elderly population will be doubled in size compared to the year 2000, and it is estimated that one-fifth of the total American population will be 65+ years old (Knickman & Snell, 2002; Anderson, Goodman, Holtzman, Posner, & Northridge, 2012). Due to the future influx of older adults in the U.S., health care costs are projected to increase significantly (Schneider & Guralnik, 1990).

A variety of deteriorative physiological changes occur as humans enter older adulthood, and those changes can lead to frailty (Evans, 1997; Persson et al., 2006; Torpy et al., 2006). Two of those deteriorative changes are sarcopenia, i.e. loss of muscle mass, and dynapenia, i.e. loss of muscle strength (Evans, 1997; Clark & Manini, 2010). A decrease in both muscle mass and muscle strength degrades the body’s ability to move and stabilize effectively, which therefore contributes to frailty. Frailty can then lead to decreased functional capacity and independence in older adults (Torpy et al., 2006; Evans, 1997; Clark & Manini, 2010).

A more subtle deteriorative change caused by aging is the degradation of cognitive function (Persson et al., 2006). Cognitive function is a person’s ability to engage in mental capabilities such as memory, problem solving, and information processing (Daffner, 2010). Cognitive function is an important aspect of functional capacity, as a well-functioning musculoskeletal system is useless if the “operator” cannot effectively control it. When attempting to positively impact functional capacity and independence in older adults, it is shortsighted to not consider cognitive function because degradation of cognitive function is a contributor to frailty (Torpy et al., 2006). Therefore, a focus on both physical and mental improvements is necessary when increasing functional capacity and independence in older adults. See figure 1 for a summary of how aging contributes to frailty.

Considering cognitive function’s relationship to functional capacity and independence in older adults is especially important due to the existence of dementia. Dementia is a mental disorder that often leads to disability in older adults by causing degraded cognitive processes, and it is a highly prevalent disease in the older adult population (Fratiglioni, De Ronchi, & Agüero-Torres, 1999; Agüero-Torres et al., 1998; Gustafson, 1996). A large prevalence of dementia comes with important economic and public health implications, especially considering the inevitable influx of older adults in the U.S. population in coming years (Fratiglioni et al., 1999; Knickman & Snell, 2002).

Resistance exercise is a form of physical activity that involves the generation of musculoskeletal force directed against some form of external resistance (Weil, n.d.). The external resistance is commonly in the form of barbells, dumb bells, resistance machines, elastic bands, or one’s own bodyweight (Weil, n.d.). Resistance exercise involves repetitive movements that are usually performed in periods of exertion called “sets” (Weil, n.d.). The sets are then separated by rest intervals that allow for partial muscle recovery (Weil, n.d.). In the older adult population, resistance exercise has been found to cause many positive effects, including: anabolic hormonal response, increased muscle mass, increased muscle strength, and increased cognitive function (Kraemer & Ratamess, 2005; Peterson, Sen, & Gordon, 2011; Peterson, Rhea, Sen, & Gordon, 2010; Heyn, Abreu, & Ottenbacher, 2004).

Figure 1: How aging contributes to frailty in older adulthood.

1. (Clark & Manini, 2010).
2. (Evans, 1997)
3. (Persson et al., 2006).
4. (Torpy et al., 2006)

Figure 1: Aging is a multifaceted process that has significant consequences on both physical and mental capabilities. The existence of frailty does not necessarily need all three components (muscle weakening, muscle loss, and decreased cognitive function), as long as one or more of the components leads to limited functional capacity and limited independence.

Application of Resistance Exercise

Resistance exercise is an effective method in increasing functional capacity and independence in older adults. Resistance exercise can positively address sarcopenia and dynapenia by stimulating muscle growth and increasing muscle strength, respectively (Watanabe, Madarame, Ogasawara, Nakazato, & Ishii, 2013; Vincent et al., 2002). As a result of musculoskeletal improvements, older adults will experience decreases in frailty, or in other words, improvements in their functional capacity and independence (Vincent et al., 2002; Roma et al., 2013; Zhuang, Huang, Wu, & Zhang, 2014). Functional capacity is defined as the capacity to complete basic human tasks that are essential to everyday living, such as: locomotion, climbing/descending stairs, lifting/moving objects, balance, and accomplishing basic joint mobility (Boström et al., 2014). Of particular importance, increases in functional capacity can decrease the chance of falling-injuries in older adults (Zhuang et al., 2014). Resistance exercise has also been suggested to be able to improve the cognitive function in older adults (Van de rest et al., 2013). As a result of increased functional capacity and independence via improvements in musculoskeletal and cognitive function, future health care costs of older adults may decrease. It has been asserted that investing in the present day health of the baby boomer population may decrease future health care costs of this population when it reaches older adulthood (Knickman & Snell, 2002). Contribution is summarized in figure 2.

Figure 2: Older adults who engage in resistance exercise and the positive results.

1. (Vincent et al., 2002).
2. (Watanabe et al., 2013).
3. (Van de rest et al., 2013).
4. (Roma et al., 2013)
5. (Zhuang et al., 2014).
6. (Knickman & Snell, 2002).

Figure 2: The potential decrease in health care costs illustrated above would be experienced on both an individual and national level. Due to decreased disability and hospitalization costs in the older adult population, older adults would save on out-of-pocket money, and the state and federal government would save on Medicare and Medicaid costs (Knickman & Snell, 2002).

Limitations

There is general difficulty when the older adult population participates in studies which involve physical exertion due to the population’s age-related deterioration. When studying the relationship between the older adult population and resistance exercise, it is common for study-participants to drop out due to musculoskeletal and/or other health problems (Vincent et al., 2002; Delshad, Ghanbarian, Mehrabi, Sarvghadi, & Ebrahim, 2013; Zhuang et al., 2014). There exists a sort of paradox – if resistance exercise can increase functional capacity and independence in older adults by decreasing frailty, why does it also injure older adults? Resistance exercise is certainty not applicable to all sub-populations of older adults. Even within older adults who can perform resistance exercise, there are still adjustments and limitations to be made on an individual basis for safety during resistance exercise (Nelson et al., 2007).

While resistance exercise can improve frailty in older adults, access to proper exercise facilities may be a challenge for frail older adults (Torpy et al., 2006). There is another paradox – resistance exercise may be an effective lifestyle choice for frail older adults, but the lack of independence and functional capacity may inhibit older adults’ access to training facilities in which they would engage in resistance exercise. Frail older adults who use resistance exercise may require professional supervision and instruction. The problem is more complex than just facilitating access to exercise facilities for frail older adults. It is important to state that there must be a distinction between resistance exercise programs between older adults at risk for frailty, and older adults who are currently frail. Some exercise programs used to prevent frailty in not-yet-frail older adults may actually increase frailty in currently frail older adults (Faber, Bosscher, Chin A Paw, & van Wieringen, 2006).

Resistance Exercise Increases Functional Capacity

Functional capacity is the capacity to complete basic human tasks that are essential to everyday living (Boström et al., 2014). Common examples of functional capacity include ascending & descending stairs, standing up from a seated position, and basic joint mobility actions such as reaching overhead, bending over, and sagittal & transverse movements of the spine. Resistance exercise improves functional capacity by counteracting the muscle wasting and muscle weakening effects of aging by stimulating muscle growth and muscle strength (Watanabe et al., 2013; Vincent et al., 2002). By building a strong physical foundation through increases in muscle size and strength, older adults’ functional capacity can improve (Vincent et al., 2002; Roma et al., 2013). Muscular strength is essential for a healthy functional capacity because muscles allow the human body to move, stabilize and manipulate external objects. Functional capacity depends greatly on proper muscular function because it is largely defined by the ability to move in practical ways with the goal of achieving basic activities essential to daily human life (Boström et al., 2014). Muscular strength is essential to functional capacity, and functional capacity is essential for independence. Therefore, resistance exercise can increase functional capacity and independence in older adults by increasing muscular strength.

Interestingly, it has been found that increases in muscle strength can occur without gains in muscle size via neurological adaptations (Watanabe et al., 2013; Vincent et al., 2002; Romero-Arenas, Martínez-Pascual, & Alcaraz, 2013) However, gains in muscle size are important because they have been found to help prevent disease and improve immune function, both of which are important aspects of frailty prevention (Clark & Manini, 2010). Several studies have found that older adults who engage in low-intensity resistance exercise can achieve the same strength gains seen in high-intensity resistance exercise participants (Watanabe et al., 2013; Vincent et al., 2002; Van Roie, Delecluse, Coudyzer, Boonen, & Bautmans, 2013). This is an important finding, because less effort for the same result is a clear example of cost/benefit efficiency in resistance exercise training.              

Balance & Risk of Falling

One of the primary components of functional capacity is balance. Poor muscle strength can lead to poor balance, and poor balance leads to an increased risk of falling (Zhuang et al., 2014). Falling may lead to hospitalization as well as a potential disability due to injury, and this series of events would lead an older adult to an increased probability of developing frailty. Many studies suggest that older adults who engage in resistance exercise programs, as well as exercise programs that incorporate resistance exercise, may experience a decreased risk of falling due to improved stability and neuromuscular control (Lord, Ward, Williams, & Strudwick, 1995; Kannus, Sievänen, Palvanen, Järvinen, & Parkkari, 2005)

Preventing falls in older adults is critical in maintaining independence, and falling often signals a deficit in functional capacity due to ineffective stability and strength. Falling in older adults can lead to hospitalization, functional impairment, fractures, and head injuries, all of which encourage frailty (Kannus et al., 2005). In extreme cases, falling can lead to death (Kannus et al., 2005). Resistance exercise gives older adults an opportunity to maintain their independence by decreasing the risk of falling.

Movement & Mobility

Resistance exercise can increase older adults’ ability to complete functional tasks such as ascending and descending stairs (Vincent et al., 2002; Rooks, Kiel, Parsons, & Hayes, 1997). Utilizing stairs is just one of many movement tasks that older people need to accomplish if they are to maintain independence. Resistance exercise can improve other essential movements such as walking and picking up objects from the floor by increasing neuromotor function and joint mobility (Rooks et al., 1997; Roma et al., 2013). 

Resistance Exercise Increases Cognitive Function

Dementia is a highly prevalent problem affecting the older adult population, and it can severely reduce independence within this population (Fratiglioni et al., 1999; Agüero-Torres et al., 1998; Gustafson, 1996). Physical activity, including resistance exercise, may be able to decrease the effects of dementia as well as prevent the occurrence of dementia and cognitive degradation (Van de rest et al., 2013). Beyond preventing dementia and cognitive decline, resistance exercise can also improve normal older adult cognitive functioning (Van de rest et al., 2013; Cassilhas et al., 2007)

Future Direction

There is ample research that has suggested the effectiveness of resistance exercise in increasing the functional capacity and independence of older adults. However, there are obstacles that hinder older adults from actually engaging in the practice of resistance exercise, and those obstacles need to be studied further. One of the obstacles is access to a training environment. Older adults not only need accessibility to training facilities, but they also need proper training instruction in order to avoid injuries that could contribute to frailty. After all, the goal of resistance exercise training is to decrease frailty. It has been found that exercise intended for preventing frailty in pre-frail older adults can actually increase frailty in already-frail older adults (Faber, Bosscher, Chin A Paw, & van Wieringen, 2006). Such cases of harmful resistance exercise programs need to be given due attention with further research. Comparative analyses of the effects of resistance exercise on pre-frail vs. frail older adults needs to be done in order to better understand how to prevent harmful resistance exercise programs. To avoid prescribing harmful exercise, non-medical health & exercise professionals who work with older adults should be well educated on the differences between pre-frail and frail older adults. Also, having an effective knowledge of the specific sub-populations of older adults would improve non-medical health & exercise professionals’ ability to refer out their older adult clients to the proper medical professional, if necessary. Similarly, medical professionals need to be well-versed in communicating the needs of older adult patients to the non-medical health & exercise professionals who work with the older adults. In the care of frail older adults, educational programs that bridge the gap between doctor and trainer need to exist for the optimal application of resistance exercise.


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