General Principles of Exercise Prescription

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Common sense, the ancients, modern research, and practice all point toward the indisputable fact that an important part of a healthy lifestyle is physical activity. Conversely, sedentary behaviors are counterproductive to health. Various forms of physical activity have been shown to increase longevity as well as the quality of that increased lifespan. Countless physical and mental health benefits have been attributed to increased physical activity. Despite all the research and the increased public awareness concerning physical activity and/or exercise, millions of Americans continue to avoid regular physical activity (2). Several recent national standards emphasize the benefits of regular aerobic physical activity and/or exercise and encourage all of us (no matter our age) to engage in at least 20–60 minutes of these behaviors for a minimum of 3 days per week (2,6,9,11,12). In addition, it is important to consider other components of a healthy lifestyle such as resistance, flexibility, and neuromotor training. Most individuals can begin a formal physical activity program without consultation with a health care provider. However, high-risk individuals, specifically those with symptoms of disease, may require medical evaluation and clearance prior to initiation of physical activity.

This chapter addresses specific guidelines for physical activity and/or exercise programming. This chapter also presents the new guidelines from the American College of Sports Medicine (ACSM) as published in the 10th edition of the ACSM’s Guidelines for Exercise Testing and Prescription (GETP10) (2).

Exercise Prescription for All

In 1975, the ACSM defined exercise prescription in the first edition of the GETP as follows (4):

Exercise prescription includes the type, intensity, duration, frequency and progression of physical activity. These five components are applicable to the development of exercise programs for persons regardless of age, functional capacity, and presence or absence of CHD [coronary heart disease] risk factors or CHD.

In the current (10th) edition of the GETP10 (2), these five components of exercise prescription are reported as Frequency, Intensity, Time, and Type (FITT) with the Volume of exercise added along with the Progression component to produce the acronym FITT-VP. In addition, the ACSM has also added the component of the pattern of the activity to be an important consideration in exercise programming (2).

A recent PubMed search performed by the authors of this chapter using the past 40 years as a time frame and searching the term exercise and chronic disease returned over 18,000 research articles that have been published regarding the effects of exercise/physical activity as an intervention in the prevention of, management of, and rehabilitation for many chronic diseases (often known as Special Populations) since the publication of the first edition of the GETP (4). What much of the research in this area over the past 40+ years has elucidated is that physical activity and/or exercise plays a key role in the prevention, management, and rehabilitation of disease processes in conjunction with other healthy lifestyle behaviors. The Domains, as listed in Box 8.1, describe the broad realm of the involvement in achieving overall health of the whole person. Exercise programs clearly have the preponderance of their effectiveness in the Physical Health Domain, but the interactions between the components of all of the domains are undeniable. Exercise has been demonstrated to have a positive impact on many of the aspects of the domains outside of Physical Health (2,7). The exercise professional must be cognizant that an exercise program is just one element contributing to the overall health of a person. Recognition of the other domains in the development of a total program equips the exercise professional with a significant tool in knowing when to refer an individual to other health care providers for healthy lifestyle guidance that lies outside the exercise professional’s scope of practice.

Box 8.1

The Five Domains of Health

1. Emotional Health

2. Social Health

3. Physical Health

4. Mental Health

5. Spiritual Health

The development and administration of an exercise program lies within the Physical Health Domain. As characterized in Table 8.1, the Physical Health Domain consists of Health-Related, Skill-Related, and Medical-Related Components. The degree of impact and overlap of the individual components of a specific domain is greater within that domain as illustrated in Figure 8.1 for the Physical Health Domain. The evidence supporting the importance of regular physical activity and/or exercise in the prevention and treatment of chronic diseases prompted the ACSM and the American Medical Association to co-launch in 2007 the initiative Exercise is Medicine. This initiative has called for exercise/physical activity to be a standard part of disease prevention and medical treatment (7).

Table 8.1

Examples of Individual Elements of Health-Related, Skill-Related, and Medical-Related Components

Health-Related Components

Skill-Related Components

Medical-Related Components

Cardiorespiratory

Muscular strength

Muscular endurance

Body composition

Flexibility

Agility

Balance

Coordination

Power

Speed

Reaction time

Integumentary

Musculoskeletal

Cardiovascular/lymphatic

Respiratory

Neurologic

Endocrine

Digestive/excretory/urinary

Immune

Reproductive

FIGURE 8.1. The interactions of health-related, skill-related, and medical-related components.

In examining the role of exercise as an intervention with Special Populations, the basic FITT-VP principle continues to apply with the caveat that the exercise professional must know the limitations and contraindications of exercise within each population. The aspects of an exercise program have historically been divided into targeting exercises that address Health-Related and/or Skill-Related Components of the Physical Health Domain. Program designs for the general population typically prioritize targeting the Health-Related Components of Physical Health Domain. The broad spectrum of target components in developing a total program requires the exercise professional to prioritize the specific components of Physical Health that should be the focus of the patient’s exercise program. Although focusing on exercises that address the Health-Related Components have been demonstrated to benefit many of the high-profile chronic diseases, some of the Special Populations may benefit to a greater degree by equally prioritizing some of the Skill-Related Components, such as balance and coordination, with the Health-Related Components in the development of their exercise programs. The following chapters in this book can serve as a guide to the exercise professional in deciding which exercises to incorporate and prioritize for a number of individual Special Populations.

This chapter serves as a guide for general evidenced-based principles in designing exercise prescriptions for all populations. The foundation to developing an effective exercise prescription is the exercise professional’s knowledge of the indications and contraindications of exercise for the intended population and the appropriate use of the “common thread” principles of FITT-VP.

Physical activity is considered to be any bodily movement, whereas exercise is a subset of physical activity that is both regular and structured. Perhaps, the difference between physical activity and exercise is best viewed on an individual-by-individual basis. One individual may find the term physical activity more appealing, whereas another is more interested in increasing exercise. Physical activity can also be thought of as a continuum from light to moderate to vigorous (1).

Current FITT-VP Recommendations from the American College of Sports Medicine

Physical activity and/or exercise recommendations in the United States have been on the national scene since the 1950s. An exercise professional should be aware of and stay current with the evolving nature of these recommendations. It is important to remember that a comprehensive program that supports a healthy lifestyle through physical activity and/or exercise is the overall goal. A summary of the most recent aerobic, resistance, flexibility, and neuromotor training guidelines from the ACSM published in 2018 can be found in Table 8.2 (2,7).

Table 8.2

Summary of the American College of Sports Medicine FITT-VP Components

Aerobic frequency	≥5 d ∙ wk⁻¹ of moderate exercise OR ≥3 d∙ wk⁻¹ of vigorous exercise OR A combination of moderate and vigorous exercise on ≥3–5 d ∙ wk⁻¹	See Intensity for moderate and vigorous definitions
Aerobic intensity	Moderate and/or vigorous exercise Note: light-to-moderate exercise for deconditioned individuals	Moderate = 40%–59% heart rate reserve (HRR) or oxygen uptake reserve (O₂R) Vigorous = 60%–89% HRR or O₂R
Aerobic time or duration	30–60 min ∙ d⁻¹ for moderate 20–60 min ∙ d⁻¹ for vigorous OR A combination of moderate and vigorous Note: <20 min ∙ d⁻¹ for previously sedentary
Aerobic type or mode	Regular, purposeful exercise that involves major muscle groups and is continuous and rhythmic in nature
Aerobic volume	Target of 500–1,000 MET-min ∙ wk⁻¹ Note: a pedometer step count of 7,000 ∙ d⁻¹ Note: Exercising below this may be beneficial for some.	MET-min ∙ wk⁻¹ = METs of activity times the number of minutes per week That is, 3 METs walk performed for 45 min 5 d ∙ wk⁻¹ = 675 MET-min ∙ wk⁻¹
Aerobic pattern	One or multiple (≥10 min) sessions ∙ d⁻¹ Note: Sessions less than 10 min may yield favorable results.
Aerobic progression	A gradual progression of increasing exercise time, frequency, and intensity “Start low and go slow”	Depends on functional capacity, health status, age, preferences, goals, and needs of patient
Resistance training	At least 2–3 d ∙ wk⁻¹ 2–4 sets 60%–70% 1-RM 8–12 repetitions
Flexibility training	At least 2–3 times per wk 10–30 s per stretch — up to a total of 60 s 2–4 repetitions per stretch
Neuromotor training	≥2–3 d ∙ wk⁻¹ ≥20–30 min ∙ d⁻¹

Created from information found in American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 10th ed. Philadelphia (PA): Wolters Kluwer; 2018. 480 p.; and Garber CE, Blissmer B, Deschenes MR, et al. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc. 2011;43(7):1334–59.

The traditional, structured approach to exercise prescription described by the ACSM involves specific recommendations regarding mode or type, frequency, intensity and time, or duration of activity often known as the FITT components. The variables of volume of exercise and the progression of the program are also important to the whole exercise prescription process. Addressing the components of muscular fitness, flexibility, and neuromotor training contributes to the whole program.

As a way to involve more individuals who are sedentary, recent physical activity recommendations have adopted a lifestyle approach to increasing physical activity. This newer approach to exercise prescription is sometimes referred to as the public health approach (9). In essence, the concept used with the progression of exercise (“start low and go slow”) can be applied to the overall program when working with a patient who may be deconditioned from years of inactivity and is at an early stage of change that has significant barriers and obstacles to initiating an exercise program.

Overall, the ACSM considers the following five points (2):

1. All individuals should engage in at least 20–60 minutes of aerobic physical activity of at least a moderate intensity on at least 5 days per week.

2. Additional health and fitness benefits can be achieved by adding more time in moderate-intensity activity or by substituting more vigorous activity.

3. Previously inactive men and women and people at risk for heart, metabolic (diabetes), and renal diseases should first consult a health care provider before initiating a program of vigorous physical activity to which they are unaccustomed.

4. Persons with symptomatic heart, diabetes, or renal disease who would like to increase their physical activity should be evaluated by a health care provider and provided an exercise program appropriate for their clinical status.

5. Muscular strength–developing activities (resistance training) should be performed at a minimum of two times per week. Also, flexibility and neuromotor exercises should be included in a prudent overall program.

Note: Points 3 and 4 were previously discussed in Chapter 2.

Aerobic Frequency

Frequency of exercise (i.e., the number of days per week) is an important contributor to health/fitness benefits that result from an aerobic program. Aerobic exercise is recommended on 3–5 days per week for most adults, with the frequency varying with the intensity of exercise. Improvements in cardiorespiratory fitness (CRF) are lessened with exercise frequencies less than 3 days per week and plateau in improvement with exercise performed greater than 5 days per week. Vigorous-intensity exercise performed greater than 5 days per week might increase the incidence of musculoskeletal injury, so this amount of vigorous-intensity exercise is not recommended for adults who are not well conditioned. Nevertheless, if a variety of exercise modes placing different impact stresses on the body (e.g., running, cycling), or using different muscle groups (e.g., swimming, running), are included in the exercise program, daily vigorous-intensity exercise may be recommended for some individuals. Alternatively, a weekly combination of 3–5 days per week of moderate- and vigorous-intensity exercise can be performed, which may be more suitable for some individuals (2,7).

Health/fitness benefits can occur in some individuals who exercise only once or twice per week at moderate-to-vigorous intensity, especially with large volumes of exercise. Exercising one to two times per week is not recommended for most adults because the risk of musculoskeletal injury and adverse cardiovascular events are higher in individuals who are not physically active on a regular basis and those who engage in unaccustomed exercise (2,7,9).

Aerobic Intensity

There is a positive dose response of health/fitness benefits that results from increasing exercise intensity. The overload principle of training states exercise below a minimum intensity, or threshold, will not challenge the body sufficiently to result in changes in physiologic parameters, including increased maximal oxygen consumption (O_2max). However, the minimum threshold of intensity for benefit seems to vary depending on an individual’s current CRF level and other factors such as age, health status, physiologic differences, genetics, habitual physical activity, and social and psychological factors (10). Therefore, precisely defining an exact threshold to improve CRF may be difficult.

Writing the Aerobic Exercise Intensity

It is important to realize that the exact or precise intensity of exercise is an issue with measurement error, especially in the age prediction of maximal heart rate (HR_max) (standard formula for age-predicted maximal heart rate [APMHR] = 220 − age; standard deviation = ± 12 − 15 bpm). There is the potential for significant error in all of the APMHR formulas. The exercise professional should consider these potential errors because the vast majority of exercise prescriptions are done on individuals involving predominately the prediction of HR_max by one’s age rather than knowing precisely the HR_max (as determined from a maximal exercise test).

Exercise Intensity Prescription Calculation Examples from Heart Rate

The following is a bullet summary of some different methods that may be employed in the prescription of exercise intensity by target heart rate (THR). It is common to use a percentage, or range of percentages, to calculate a THR: for example, 50%–85% of O₂ or 60%–90% of HR_max.

Percentage of APMHR

Using the 220 − age = APMHR formula.

For example: If your patient’s age is 45 years old, his or her APMHR is 175 bpm (220 − 45 = 175 bpm).

60% of 175 = 105; 90% of 175 = 156 bpm; THR = 105–156 bpm

Karvonen formula

The popular Karvonen formula was developed by the cardiologist Marti Karvonen in the 1950s and essentially considers heart rate reserve (HRR). The Karvonen formula can be written as [(220 − age) − resting HR] × (% intensity desired / 100) + resting HR. Note you can use any well-supported formula for APMHR such as the one from Gellish et al. (8): APMHR = 206.7 − 0.67 × age. For example: If your patient is 45 years old and has a resting HR of 72 bpm, then the solution to the Karvonen formula would be (using 60% and 89% of HRR)

[(220 − 45) − 72] × (60 / 100) + 72 = 133.8 bpm

[(220 − 45) − 72] × (89 / 100) + 72 = 163.7 bpm

THR = 134−164 bpm (rounded off)

Modified Karvonen formula

Finally, you can use the Karvonen HRR formula but taking into account a known HR_max as measured from a maximal graded exercise test.

[(HR_max − resting HR) × (% intensity desired / 100)] + resting HR

For example: age = 45 years; measured HR_max = 179 bpm; resting HR = 72 bpm

[(179 − 72) × 60 / 100] + 72 = 136.2 bpm

[(179 − 72) × 89 / 100] + 72 = 167.2 bpm

THR = 136−167 bpm (rounded off)

Heart rate is not the only monitoring tool that can be used to determine exercise intensity. Workloads and metabolic equivalents (METs) are two other popular forms of intensity setting parameters for individuals, and there are a few other minor-intensity monitoring parameters such as the rating of perceived exertion (RPE), the talk test, and systolic blood pressure (6). RPEs and other affective scales have been proven through the literature and are a staple in many health and fitness settings (10). Several of these techniques for determining exercise intensity have been summarized in Box 8.2.

Box 8.2	Summary of Methods for Prescribing Exercise Intensity Using Heart Rate (HR), Oxygen Uptake (O₂), and Metabolic Equivalents (METs)
HRR method: Target HR (THR) = [(HR_max/peak^a − HR_rest) × % intensity desired] + HR_rest
O₂R method: Target O₂R^c = [(O_2max/peak^b − O_2rest) × % intensity desired] + O_rest
HR method: Target HR = HR_max/peak^a × % intensity desired
O₂ method: Target O₂^c = O_2max/peak^b − % intensity desired
MET method: Target MET^c = [(O_2max/peak^b) / 3.5 mL ∙ kg⁻¹ ∙ min⁻¹] × % intensity desired

HR_max/peak, maximal or peak heart rate; HRR, heart rate reserve; HR_rest, resting heart rate; O_2max/peak, maximal or peak volume of oxygen consumed per unit of time; O₂R, oxygen uptake reserve; O_2rest, resting volume of oxygen consumed per unit of time.

^aHR_max/peak is the highest value obtained during maximal/peak exercise or it can be estimated by 220 − age or some other prediction equation.

^bO_2max/peak is the highest value obtained during maximal/peak exercise or it can be estimated from a submaximal exercise test.

^cActivities at the target O₂ and MET can be determined using the compendium of physical activities.

Reprinted from American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 10th ed. Philadelphia (PA): Wolters Kluwer; 2018. Box 6.2.

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