**1. Introduction**

Older adults are the fastest-growing age group. Physiological changes associated with primary aging and concurrent chronic diseases have an adverse impact on functional capacity, health outcomes, and quality of life [1]. The normal aging process is characterized by a progression of physiological events that occur throughout the life cycle. Age-related changes take place throughout the body and are most prominent in later years.

Advanced age, even if not associated with the development of a serious chronic disease, is accompanied by a multiplicity of biological modifications that may contribute to reducing skeletal muscle mass, strength, and function, leading to an overall decline in physiological resilience (capacity to withstand and recover from stressors). It is also related to reduced muscle size (muscle atrophy), motor unit loss, and a decrease in contraction speed, which in turn lead to lower muscle strength, power, and resistance [2–4].

As a multifaceted and complex phenomenon, aging manifests itself differently among individuals during their lifetime and is conditional on interactions between genetic, environmental, behavioral, and demographic characteristics [5]. The literature reports that sarcopenia affects motor and muscle performance [3, 6–8]. Losses in muscle function can reduce physical fitness and independence in the activities of daily living. Moreover, significant dependence levels of older people are positively associated with greater fear and risk of falling and lower quality of life [9].

Since most of the risk factors are associated with an increase in chronic diseases with (advanced) age, regular physical activity is essential to attenuate the functional declines associated with aging and improve physical and psychological health-related outcomes among older adults [1, 10].

As such, and considering that much of the senior population is sedentary with low levels of physical fitness, the aims and purposes of this study were to: (i) provide a summary of existing and relevant research, (ii) assess exercise program variables, and (iii) give practical evidence-based recommendations for exercise prescription and resistance training in older adults, according to international guidelines.

#### **2. Process**

Using an evidence-based approach, we combined scientific data, experts' statements, and end-user concerns to improve references for the interests, values, requirements, and choices of the aging population. Thus, the position statement presents an assessment of the main studies obtained after a thorough analysis of the literature.

Since there is a wide-ranging biological dissimilarity among elders of related age, and developmental modifications in voluntary muscle usually start in adulthood, no typical designation of the senior period based on chronological age remained considered adequate. In its place, due to the wide physiological and functional variety, and the beginning of age-related consequences for voluntary muscles, studies involving subjects aged 50 years and older were analyzed.

#### **3. Evidence for summary statements**

Resistance training is the most effective method for maintaining and increasing lean body mass and improving muscle strength and endurance [11]. It is recommended as part of the physical activity guidelines that include working all major muscle groups two or more days a week [10, 12]. Older adults can reap numerous health benefits from resistance training, such as increased muscle strength and mass in addition to maintaining bone density. Furthermore, certain dimensions of health-related quality of life have been shown to improve in older adults as a result of resistance training [13].

Given the adverse physical, social, and emotional consequences of aging, prevention and treatment strategies are essential for the health and well-being of older adults [5, 10, 13]. Among the contributors to the aging process, muscle disuse is an avoidable and changeable factor. Strength exercise is a significant component of a comprehensive workout plan to balance the widely recognized constructive effects of aerobic exercise on well-being and physical abilities [12]. There is vigorous and compelling evidence that strength training can buffer the consequences of aging on the neuromuscular role and functional aptitude [12–17]. Different procedures of

strength training can potentially increase muscle strength, mass, and power output [12]. Moreover, available evidence reveals a dose–response association, where volume and intensity are strongly related to adaptations to resistance exercise [14, 18].

With this in mind, different institutions suggest that adults should engage in moderate- to high-intensity muscle-strengthening activities including working all major muscle groups two or more days a week [10, 12]. For aging adults, the same muscle-strengthening guidelines apply, since resistance training may promote even greater benefits for this population. Several health problems affecting older adults can be mitigated or even prevented through a regular resistance training program [13]. For example, older people have a greater risk of premature death due to falls, which in turn are associated with age-related declines in muscle fitness and balance that may be reduced/improved via different forms of resistance training [19–22].

Seniors can obtain several additional health paybacks from strength preparation, furthermore, greater muscle area and power [13, 23]. Findings have shown that


#### **Table 1.**

*Effects of resistance training on health and fitness variables.*

strength training can improve bone mineral density [24, 25], lipoprotein profiles [26], glycemic control [27], body composition [28], symptoms of frailty [29], metabolic syndrome risk factors [30], and cardiovascular disease markers [31]. This cumulative aggregate of evidence has provided additional support for the findings initially reported in the seminal review by Pollock and Vincent ([32], see **Table 1**), demonstrating that resistance training plays a significant role in improving numerous health factors associated with the prevention of chronic diseases throughout life.

Taken as a whole, evidence indicates that resistance training improves physical health, functional ability, and quality of life in older persons, even in the presence of frailty and chronic illness. Moreover, resistance training levels in line with international guidelines have been associated with increased physical fitness, better cardiovascular risk profile, and decreased overall (all-cause) mortality [33–35].

According to Hunter et al. [36], a substantial portion of the reductions in agerelated strength and muscle function is mediated by decreases in daily physical activity, which in turn induce greater sarcopenia. This results in a positive feedback loop that worsens over time (**Figure 1**). Thus, interrupting this cycle is of paramount importance to maintain the functional capacity and quality of life of aging adults.

All resistance exercise programs should match the individual needs and competencies of older adults. A thorough medical/physical evaluation should be performed to rule out possible comorbidities and contraindications to physical exercise (myocardial infarction, or unstable angina, uncontrolled hypertension, acute heart failure, and complete venous arterial blockage).

Moreover, the established plan/program and its potential side effects (muscle injury, joint injury, and fractures) should also be monitored. In short, exercise prescription should be specific, individualized (health status, chronic disease risk factors, behavioral characteristics, personal goals, and exercise preferences), and progressive to optimize and maximize the magnitude of the strength adaptations in older adults [37–39].

Nonetheless, resistance training may also be prescribed concurrently with aerobic training since both types of physical exercise produce distinct benefits, such as improvements in neuromuscular and cardiovascular functions [16], respectively, and because both muscle strength and aerobic fitness are inversely associated with

#### **Figure 1.**

*Model of age-related functional changes in sarcopenia (adapted from Hunter et al. [36]).*


#### **Table 2.**

*International recommendations of multicomponent physical activity for healthy adults.*

all-cause mortality in older individuals [12, 37–39]. With this in mind, different international institutions have suggested exercise guidelines and recommendations that involve a combination of aerobic and resistance training, agility/balance, and static and dynamic flexibility exercises for adults [40–42] (see **Table 2**).

To promote and maintain health, all healthy adults need to accumulate at least 150 minutes/week of moderate-intensity aerobic exercise (60–70% of maximum heart rate, or 12–13 on a perceived exertion scale range of 6–20 points), on most days of the week or at least 75 minutes of vigorous aerobic activity (70–90% of maximum heart rate, or 14 to 16 on a perceived exertion scale variety of 6 to 20 points). Adults must still execute activities that preserve or rise muscle power, at minimum two non-consecutive days per week. In addition to the minimum levels of aerobic and resistance exercise recommended for adults, older people are advised to perform stretching and balance exercises at least 2 to 3 times/week to prevent falling and maintain and improve their autonomy and quality of life [12, 38–43].

Resistance exercise must be performed 2 to 3 times a week, using 3 sets of 8–12 repetitions, with an initial intensity of 20–30% of 1RM, developing to 70% of 1RM. Strength training can be performed using resistance machines that work major muscle groups (e.g., leg press and knee extension).

Nevertheless, movements that involve monoarticular actions have a minor cardiovascular answer (increased heart rate and blood pressure) but, at the start of the training procedure, are more appropriate to use in persons with cardiovascular disease [38–40]. To enhance the development of functional capability in aging adults, the resistance training program should also include strength exercises that reproduce the activities of quotidian living, such as rising and sitting [44].

Muscle power (high-speed) training may be more beneficial in terms of functional improvement than a muscle endurance training program (low speed) [45].

This type of training, with light loads and explosive movements, should be included in the activities prescribed to older adults because it may be associated with an improved functional capacity [38, 39, 45]. Cardiovascular endurance training should include sets of walking in different directions and speeds, walking on a treadmill, and walking up and downstairs. This activity should last 5–10 minutes in the first weeks, progressing to 15–30 minutes [46].


**Table 3.**

*Guidelines for exercise prescription in older adults (adapted from Casas Herrero et al. [40]).*

Balance training should include exercises in the tandem and semi-tandem position, multidirectional movements under load (2–4 kg), heel-toe walking, climbing stairs with assistance, and body mass transfer (from one leg to the other). Modified tai chi exercises, yoga, stretching, and balance training may also improve physical functioning and benefit patients with hypertension, heart disease, and arthritis (**Table 3**) [16–25].

Multicomponent training programs should include gradual increases in the volume, intensity, and complexity of cardiovascular, strength, and balance exercises. Alternate training days of muscle strength and cardiovascular endurance exercises are an excellent stimulus for improving strength, power, and cardiovascular resistance. When performing training programs that combine strength and cardiovascular endurance, one should preferably perform strength before cardio training [39]. In individuals with low physical fitness levels and/or without regular exercise habits, applying a low training volume may facilitate adherence to the program [12].

#### **4. Evidence for summary statements**

Strength training alone, or combined with aerobic training, is a fundamental part of the primary prevention of many chronic diseases in older adults, in addition to delaying the progression and reducing the symptoms of related chronic conditions. Most of the benefits occur with at least 150 minutes of moderate physical exercise a week. Vigorous aerobic and strength exercises are recommended at least 2 days/week.

Multicomponent exercise programs, especially strength exercises that include muscle power training, are the most effective interventions for buffering the impact of physical disability and other adverse health-related outcomes, even in the oldest

*Strength Training, Quality of Life, and Health in Elderly DOI: http://dx.doi.org/10.5772/intechopen.109026*

old. These programs are also valuable interventions in other frailty domains, such as falls and cognitive decline.

Physical exercise and strength training should be adapted to the characteristics and contraindications of each individual, and prescribed with a progressive individualized plan, to produce continued benefits, like any other medical treatment.

Strength training should also be tailored to match functional needs and preferences, based on a pragmatic strategy that makes exercise both sustainable and safe. Such a strategy incorporates motivational elements and knowledge/monitoring of achievable benefits using an idiographic approach.
