Strength Training
— Enhancing Elder Fitness

By NovaLeigh Dodge-Krupa, PT, and Aimee E. Perron, PT, DPT, NCS

Enhancing older adults’ physical strength and endurance increases the potential for individuals to retain physical function and live independently.

Physical therapists can influence elders’ overall health and wellness by providing services that positively impact physical fitness. Such services include interventions that affect cardiovascular/pulmonary endurance; muscle strength, power, endurance, and flexibility; relaxation; and body composition. Older adults’ tendency to become more sedentary creates a challenge. It increases the risk of their losing ability, as well as their functional independence.

One of the primary goals of physical therapy is to support the ability to remain independent in the community. Certain mobility parameters are essential to maintain an independent level of function for community-dwelling older adults. These include the ability to do the following:

1. ambulate at a particular gait speed;
2. walk a minimum distance;
3. complete two to three errands at a time;
4. carry packages while walking;
5. engage in postural transitions;
6. navigate diverse terrain, including stairs, curbs, slopes; and
7. change direction, reach up, look up, and move backward.

Physical therapists are not the only healthcare providers concerned with physical activity. Because studies indicate that so many Americans are highly sedentary, there are many public health recommendations for physical activity and exercise. Healthy People 2010 builds on initiatives pursued over the past two decades by providing a framework for disease prevention. Its baseline data from 1997 showed that only 15% of adults performed the recommended amount of physical activity, and 40% of adults engaged in no leisure-time physical activity.  In older adults aged 65 to 74, 51% reported no physical activity while among those in the age group over 75, 65% reported no physical activity.

Research has demonstrated that regular participation in physical activity plays a significant role in an individual’s ability to maintain functional independence. However, there is still a large segment of the population that remains sedentary. Recent statistics published in Health, United States, 2007revealed that 54% of individuals over the age of 65 are physically inactive and only 21% participate in regular physical activity.

The American College of Sports Medicine  general recommendations for physical activity in adults are represented in the Physical Activity Pyramid, with the base of the pyramid being 30 minutes or more of moderate physical activity on most days of the week. Moderate physical activity includes tasks such as taking the stairs and walking increased distances. Weight-bearing exercises, strength training, and balance training are also recommended as a part of regular physical activity. Many of these activities, such as walking, gardening, and raking leaves, can be easily incorporated into a person’s lifestyle.

Choosing Activities
Aerobic exercise is superior to resistance training for improving stamina and cardiopulmonary fitness, whereas the most dramatic improvements in muscular strength and balance have been found to occur with resistive training. Both have demonstrated benefits for improving longevity and reducing debility. However, overloading a muscle with weight-lifting exercises or resistance training has been shown to largely impede the loss of muscle mass and strength in older individuals.

Aging is a complex process involving many variables, including genetics, lifestyle factors, and chronic diseases, that greatly influence the way we age. Participation in regular physical activity, both aerobic and strength exercises, promotes a number of favorable responses that contribute to healthful aging. Overall, exercise has been shown to improve cardiovascular and respiratory function, reduce coronary artery disease risk factors, decrease morbidity and mortality, and improve well-being, mood, and functional independence.

The American College of Sports Medicine Guidelines for Exercise Testing and Prescription point out that physiological aging does not occur uniformly across the population, making it impossible to define an older adult in terms of a chronological age. With this population, before prescribing any exercise routine, it’s important to consider an individual’s age, physical changes specifically related to age, and any existing comorbidities.

Normal aging changes within the musculoskeletal system can have devastating effects on an older adult’s strength and overall functioning. Sarcopenia, the age-related loss of muscle mass, strength, and function, is found in individuals who are otherwise disease free. This decline is found in 3% to 5% of individuals in their 40s. There is evidence to support that the rate of decline increases with each decade thereafter, with sarcopenia’s prevalence increasing to 50% among elders in their 80s and older.

Aging also affects specific types of muscle fibers. There are three types of muscle fibers found in skeletal muscle. Each skeletal muscle in the body is composed of motor units that include each of the three types of fibers, but wide variations exist among individuals in the number of motor units allocated to each fiber type in similar muscles. The number of muscle fibers affects the magnitude of the response to a stimulus and the type of muscle fibers contained within a motor unit affect the response of the muscle.

Evidence suggests that strength training can directly affect musculoskeletal changes.  Resistive exercises, combined with adequate nutrition, have been identified as factors that limit the effects and severity of sarcopenia and specific exercise selection can change muscle fibers from one type to another. Therapists must consider this evidence as they develop strength-training programs for their clients. Training programs must be specific to the clinical needs of the individual. Therapists with a comprehensive knowledge of the normal age-related changes who apply reasonable clinical judgment find it entirely possible to safely increase older adults’ strength without injury or exacerbation of medical conditions.

Developing Recommendations
Proper assessment in identifying muscle strength deficits is necessary prior to implementing a strength-training program. Physical therapists use various tools and methods to measure both specific muscle strength and functional strength. The most common methods to measure specific muscle strength are manual muscle testing, a method that has a standard and precise testing protocol with specific muscles graded on a 0 to 5 ordinal scale, and dynamometry, which entails the use of a dynamometer that provides an objective measure of the muscle’s strength.

A strength-training program should be established based on some basic principles, such as frequency, set repetitions, intensity, progression, and exercise selection. For many years, debate has surrounded proper frequency, but extensive research since the 1980s consistently demonstrates that twice per week per muscle group is as effective as three times or more per week, especially for the older adult population. A consistent schedule should be established, and the same muscle or muscle group should not be exercised on two consecutive days because a muscle requires 48 hours to undergo a repair and rebuilding process. 

Repetitions and sets are considered with intensity as physical therapists not only assess strength but also establish the strength-training program. The intensity of the exercise can be adjusted by changing the resistance level to allow for more or fewer repetitions.  By adjusting intensity, the therapist can respond to an older adult’s medical condition or disease process yet remain confident that proper strength gains can be achieved.

Therapists can also adjust the number of sets to respond to clients’ needs. One to three sets have been shown to be equally effective for enhancing strength and/or endurance.  When establishing the number of sets, it is important to consider an individual’s endurance and tolerance of high-intensity exercise. Beginning with one set may be beneficial in terms of ensuring compliance with the exercise program. 

Progression and exercise selection should be considered together. Exercise should be selected based on an individual’s needs. The therapist may select a limited number of exercises at the start of a program and gradually increase that number as the elder progresses, and later gradually increase the intensity of the exercises. Intensity should be increased as the individual is able to perform more repetitions. When an individual is able to complete five or more repetitions at a particular level for two consecutive sessions, the resistance should be increased so the individual is working at the appropriate intensity level. Progression may be achieved by adjusting both resistance and number of exercises. 

Strength training should be an integral part of older adults’ routines for physical activity to promote healthful lifestyles. Programs must be tailored to elders’ needs, adjusting for lifestyles, considerations for comorbidities, and adaptability for medical conditions and/or disease processes. It’s essential to apply the basic principles of strength training and prescribe the proper dose, frequency, and intensity to promote a positive outcome.  Physical therapists can adapt the intensity of strength-training programs to address individuals’ needs and/or to respond to medical conditions without compromising the effectiveness of the strengthening program. Strength-training programs for healthy older adults and for those who are frail and weakened by disease processes can be safe and effective when they are prescribed by exercise experts.

— NovaLeigh Dodge-Krupa, PT, is the director of clinical operations for Genesis Rehab Services in the New England States.

—Aimee E. Perron PT, DPT, NCS, is a clinical specialist for Genesis Rehab Services in Massachusetts.