Exercise for adults: Terminology, patient assessment, and medical clearance

INTRODUCTION — Regular exercise has been shown to have wide-ranging health benefits. There is evidence to suggest a sedentary lifestyle may be an even stronger predictor of mortality than such established risk factors as smoking, hypertension, and diabetes [1]. Numerous epidemiologic studies show that unfit individuals are two to three times more likely to experience acute cardiovascular events or die during follow-up compared with their more fit counterparts regardless of their risk profile, including coronary calcium score, body habitus, or the presence of cardiovascular disease. In addition, studies have consistently demonstrated an inverse relationship between physical activity and coronavirus disease 2019 (COVID-19) morbidity and mortality [2,3].

Because physical inactivity is a modifiable risk factor, clinicians should routinely assess and prescribe structured exercise and increased lifestyle activity to all patients.

In this topic, we discuss the fundamental concepts and terminology of exercise, how to assess a patient's level of exercise and physical activity, how to determine whether a non-exerciser is willing to begin exercising, and medical clearance of a patient to begin an exercise program (often, formal medical screening is not necessary). The general benefits and risks of exercise, how to prescribe exercise to patients, and the role of exercise for patients with cardiovascular and other conditions are reviewed separately:

●Aerobic or cardiovascular exercise (see "Exercise prescription and guidance for adults" and "The benefits and risks of aerobic exercise")

●Resistance exercise (strength training) (see "Strength training for health in adults: Terminology, principles, benefits, and risks" and "Practical guidelines for implementing a strength training program for adults")

●Exercise for prevention and management of disease (see "Exercise and fitness in the prevention of atherosclerotic cardiovascular disease" and "Exercise guidance in adults with diabetes mellitus" and "Exercise in the treatment and prevention of hypertension" and "The roles of diet, physical activity, and body weight in cancer survivors" and "COVID-19: Return to sport or strenuous activity following infection")

●Exercise for special populations (see "Exercise during pregnancy and the postpartum period" and "Physical activity and exercise in older adults")

TERMINOLOGY AND COMMON TYPES OF EXERCISE

Exercise terminology

●Physical activity is any sustained body movement that increases energy expenditure, such as walking, jogging, dancing, gardening, swimming, heavy physical labor, etc [4].

●Exercise is a subcategory of physical activity that is planned, purposeful, and repeated on a regular basis in order to improve or maintain health and fitness [4,5]. Exercise may be divided into four major types, although these may overlap for a given activity. They include:

•Aerobic or endurance exercises designed to increase cardiovascular and respiratory fitness, such as walking or running

•Strength (or resistance) exercises designed to increase muscular strength, such as weightlifting or bodyweight resistance exercises (eg, pull-up, push-up, squat)

•Balance exercises designed to improve balance and proprioception and to prevent falls, such as heel-toe walking or tai chi

•Mobility (or flexibility) exercises intended to maintain or improve range of motion around a joint or lengthen a muscle, such as stretching or yoga

●Physical fitness is a set of somatic attributes brought about by engaging in regular activity that allows one to perform vigorous tasks without undue fatigue. The general attributes of fitness can be split into two categories: those related to health and those related to skill (athletic performance) [4].

The health-related components of fitness include:

•Cardiovascular endurance – Relates to the body's ability to supply fuel and eliminate metabolic byproducts during moderate- to high-intensity exercise via the cardiovascular and respiratory systems

•Muscular strength – Relates to the body's ability to exert force against external resistance

•Muscular endurance – Relates to the body's ability to exert force repeatedly within a limited period or continuously

•Mobility – Relates to maintaining a healthy range of motion around key joints, particularly the hips and shoulders

•Body composition – Relates to the relative amounts of body fat, muscle, bone, and other tissues

The skill-related components of fitness include:

•Agility – The ability to change direction with speed and precision

•Balance – The ability to maintain physical equilibrium when stationary and during movement

•Coordination – The ability to integrate sensory input (vision, hearing, touch) in order to perform motor tasks smoothly and accurately

•Power – The ability to perform work rapidly

•Reaction time – The ability to react rapidly to a stimulus

Common types of exercise

●Standard endurance training – Examples include walking, incline treadmill walking, jogging, running, cycling, swimming, and hiking.

●Traditional strength training – Examples include weightlifting (picture 1 and picture 2), Olympic-style weightlifting (picture 3 and picture 4), and training with resistance equipment (eg, leg press machine (picture 5), elastic resistance bands (picture 6)). (See "Practical guidelines for implementing a strength training program for adults".)

●High-intensity interval training (HIIT) – HIIT involves short intervals or bouts of intense cardiovascular exercise alternating with brief recovery periods of lower exercise intensity or complete rest. The goal of HIIT is to attain high overall training workloads with low total exercise volume [6]. (See "Exercise prescription and guidance for adults", section on 'High-intensity interval training: Which patients are best suited?'.)

●Dynamic flexibility training – Examples include yoga (picture 7), Pilates, tai chi (movie 1), Zumba, and similar types of activity that focus on improving mobility and muscular endurance. (See "Overview of yoga".)

●Mixed strength and aerobic training – Sometimes called "circuit training," this approach is incorporated into such activities as BodyPump, CrossFit, Orange Theory, "boot camps," and some "aerobics" classes. Many such programs include resistance training of all major muscle groups while using short recovery periods and continual activity to work the aerobic system.

●Functional fitness training – This form of exercise involves training the body for the activities performed in daily life. Functional fitness exercises use varied muscles in the upper and lower body simultaneously, emphasizing core stability.

Some jobs (eg, construction work) often elicit sufficient aerobic and musculoskeletal demands to provide a training effect, which should be factored into any exercise prescription (table 1).

Determining exercise intensity — Intensity is an important factor in developing cardiovascular performance and fitness. Athletes know that to improve performance, some training must be performed at high intensity. While significant health benefits are clearly achieved with moderate-intensity exercise, the results of large observational studies suggest that performing some vigorous exercise is associated with lower all-cause mortality [7]. As an example, a report using data from 11 cohorts in the Health Survey for England and the Scottish Health Survey found that vigorous physical activity was associated with a 16 percent greater reduction in all-cause mortality risk than more moderate-intensity activities [8]. Exercise intensity is commonly described using the parameters outlined below; the physiology of exercise is discussed in greater detail separately [9] (see "Exercise physiology"):

●Training heart rate (THR) is based on the linear relationship between heart rate (HR) and oxygen consumption (VO₂). The THR can be calculated using the HR reserve (HRR) or the Karvonen formula, where the THR equals a given percentage of HRR added to the resting HR (RHR).

●Metabolic equivalent (MET) estimates exercise intensity by comparing the VO₂ during an activity with VO₂ at rest. At rest, VO₂ is approximately 3.5 mL per kg of body weight per minute, which equals 1 MET. An activity rated as 2 METs would require twice the VO₂ that occurs at rest. Tables are available that compare the MET requirements at rest with the estimated aerobic requirements of various recreational and sports activities (table 2).

●Ratings of perceived exertion (RPE) are scales based on an individual's perception of how hard they are exercising. The most commonly used is the Borg Scale, which rates the intensity of activity between 6 and 20 (table 3). Moderate exercise correlates with an RPE of 12 to 13 (somewhat hard), while vigorous exercise correlates with an RPE of 14 to 16 (hard). By adding a zero to the rating on the Borg RPE scale, one can estimate the corresponding HR in healthy young adults when performing activity at that perceived intensity. Thus, moderate exercise would correlate with a HR between 120 and 130 beats per minute. Although this appears simplistic, numerous studies have demonstrated the accuracy of this method [9].

●Non-exercise activity thermogenesis (NEAT) refers to a person's daily physical activity that is not structured exercise [10].

Exercise intensity for aerobic activity may be categorized as follows [9]:

●Light: HRR/VO₂ 30 to 40 percent, 2 to 3 METs, RPE 9 to 11

●Moderate: HRR/VO₂ 40 to 60 percent, 4 to 6 METs, RPE 12 to 13

●Vigorous: HRR/VO₂ 60 to 90 percent, 8 to 12 METs, RPE 14 to 17

●Near maximal: HRR/VO₂ >90 percent, 14 to 20 METs, RPE 18 to 20

For strength training, intensities are typically determined using a percentage of the maximum weight a person can lift for a single repetition of a given exercise. That weight is called the one-repetition maximum (1-RM). As an example, if a person can press 110 pounds (50 kg) overhead just once (1-RM), then 55 pounds (25 kg) would be 50 percent of their 1-RM.

Using this approach, intensities for strength training can be categorized as follows [11]:

●Light: 40 to 50 percent of 1-RM

●Moderate: >50 percent to <70 percent of 1-RM

●Vigorous: ≥70 percent to <80 percent of 1-RM

●Near maximal: ≥80 percent of 1-RM

Before prescribing strength exercise, the clinician or coach should explain how to determine a 1-RM for each exercise. Several online tables and calculators are available to assist the patient in estimating a 1-RM, including the following chart from the United States National Strength and Conditioning Association (NSCA load approximation chart). Actually lifting the maximal weight is typically unnecessary and potentially harmful. Our suggested approach for determining the starting weight for an exercise is reviewed separately. (See "Practical guidelines for implementing a strength training program for adults", section on 'Determining how much weight to use'.)

One method that may be used to estimate the 1-RM for beginners is as follows:

●Warm up for 10 minutes, then select weight light enough for >10 repetitions

●Perform 12 to 15 repetitions, then rest for two minutes

●Increase weight 5 to 10 percent, perform 10 to 12 repetitions, then rest for three minutes

●Increase weight 5 to 10 percent, perform six to eight repetitions, then rest for three minutes

●Increase weight 5 to 10 percent and perform five repetitions (this should be close to 5-RM)

●Multiply 5-RM weight by 1.15 to get 1-RM

BENEFITS AND RISKS ASSOCIATED WITH EXERCISE — The benefits and risks associated with exercise are reviewed in detail separately. (See "The benefits and risks of aerobic exercise" and "Strength training for health in adults: Terminology, principles, benefits, and risks" and "Exercise prescription and guidance for adults", section on 'High-intensity interval training: Which patients are best suited?'.)

ASSESSMENT OF INDIVIDUAL PATIENT ACTIVITY — Key determinants of health for adults include the number of minutes and the corresponding intensity of physical activity performed each week. Numerous studies and guidelines suggest that regular exercise is perhaps the single most important intervention to prevent and manage chronic disease [4]. The United States Physical Activity Guidelines recommend that adults (18 years and older) perform at least 150 minutes per week of moderate-intensity exercise (like a brisk walk). Guidelines for Canada and the European Union parallel those of the United States. Australian guidelines are similar and offer specific suggestions for activity for different ages. All published guidelines encourage the accumulation of 150 minutes or more of moderate-intensity activity each week [12-17].

Primary care clinicians should ask every patient about their exercise habits at each visit [18]. This can be done using a physical activity vital sign (PAVS; or exercise vital sign). Clinicians should do their utmost to ensure that all patients exercise regularly and should provide an exercise prescription as needed [19]. (See "Exercise prescription and guidance for adults", section on 'Prescribing an exercise program'.)

Physical activity vital sign — PAVS is designed to assess whether a patient is meeting published recommendations for performing at least 150 minutes per week of moderate- or greater-intensity exercise. PAVS can be assessed by a medical assistant as they settle the patient in the examination room and obtain standard vital signs. At several large United States health care organizations, the PAVS assessment is performed by asking the following questions [20]:

●On average, how many days each week do you engage in moderate or greater physical activity (like a brisk walk)?

●On the days you exercise, on average, how many minutes do you engage in this physical activity?

Based on the patient's responses, total exercise time is calculated in minutes per week of moderate or greater (ie, vigorous) physical activity. This number can be displayed in the patient's chart adjacent to the traditional vital signs. The patient's body mass index (BMI), smoking history, and other important information relevant to the patient's capacity for and risks associated with exercise are also recorded.

PAVS allows the clinician to assess a patient's exercise habits quickly and offer either brief advice or a more detailed exercise prescription. At a minimum, providers are asked to offer each patient feedback, saying either:

●"Good job! I see you are meeting the Physical Activity Guidelines of 150 minutes per week of moderate exercise. Keep it up!"

Or, if not meeting guidelines, offer advice, such as:

●"Today I noticed your blood pressure (or blood sugar, cholesterol, etc) is elevated, and you report you are not doing any exercise. Before I put you on medication (or increase your current medication), why don't you try walking briskly for 30 minutes on five or more days each week (along with proper diet modifications) and then follow up to see how that improves your reading? If five times per week is not feasible, try to walk briskly three times per week for 45 minutes each time."

Assessment of fitness with smartphone and wireless technologies — Smart phone technology can be used to assess a patient’s physical activity and fitness. Several studies have described and validated such use [21]. While smartphone applications are increasingly used for both assessment and prescription, evidence to support their ability to improve physical activity is limited [22].

ASSESSMENT OF PATIENT WILLINGNESS TO BEGIN EXERCISING — The transtheoretical model (or "stages of change" model) describes six stages for any major change in behavior:

●Pre-contemplation – Patient is not thinking about making lifestyle changes

●Contemplation – Patient is considering but is not yet ready to change

●Determination – Patient has taken some behavioral steps and intends to take action in the next 30 days

●Action – Patient begins to demonstrate the new behavior consistently for <6 months

●Maintenance – Patient has consistently performed the new behavior for ≥6 months

●Relapse – Patient returns to former (unhealthy) lifestyle habits

A patient's current stage should be determined before a clinician counsels them about a specific behavior change (eg, becoming more physically active) to help ensure their counsel is appropriate. While a pre-contemplator may need help changing their understanding, the contemplator may need help assessing the pros and cons of changing a behavior. Exploring alternative action plans, providing specific instructions (step-by-step guides), offering positive personal feedback, and halting recidivism may be needed for patients in the determination, action, maintenance, and relapse stages, respectively.

Topics devoted to the transtheoretical stages of change model and its implementation are found separately. The discussion below focuses on its application for exercise. (See "Substance use disorders: Motivational interviewing", section on 'Theoretical foundation' and "Brief intervention for unhealthy alcohol and other drug use: Goals and components".)

●Facilitating behavior change – The likelihood that a patient will change a longstanding unhealthy behavior is governed by a myriad of socioeconomic, attitudinal, and cultural factors, including their expectation of the benefits, costs, and consequences of that behavior [23]. Common barriers to making lasting behavioral changes (eg, following an exercise program) include suboptimal social support, social isolation, financial difficulties, psychological factors (eg, depression, chronic stress), and a lack of free time. Strategizing with the patient to identify realistic options to overcome these barriers, real or perceived, is integral to changing unhealthy behaviors.

The "five As" approach (ask, advise, assess, assist, and arrange) has been reported to produce significant improvements in a variety of health behaviors, including physical activity [24]. Use of the five As for smoking cessation is discussed separately. (See "Overview of smoking cessation management in adults", section on 'The 5A's approach'.)

More clinicians now perform the first two As (that is, ask about the risky behavior and advise behavior change). However, it is the less frequently performed As (assess, assist, arrange) that require more time and specific counseling skills to implement and that have the greatest impact on healthful behavior change [25]. The core of effective counseling is a patient-centered approach, helping the patient to create and implement an "action plan" to reach their self-stated goals [26]. This approach grows out of the patient's answers to carefully worded questions posed by the clinician.

●Motivational interviewing – Motivational interviewing is a form of talk therapy used by the clinician during patient encounters to encourage behavioral change [27]. To achieve healthier lifestyle habits, the clinician must convey understanding, acceptance, and sincere interest in the patient.

The first step is to identify the patient's readiness to change their behavior. Unhealthy lifestyle practices should be discussed in a sympathetic manner, as the clinician helps the patient to understand the factors that contribute to these behaviors.

The next step in getting the patient to understand and accept the need for change is to assist them in identifying and overcoming obstacles. Questions to help them accomplish this task may include:

•What activity would you most like to do if you start exercising?

•Are there any barriers to starting this exercise, and how could they most easily be overcome?

•Could you commit to exercising for a total of 30 minutes per day, three times per week, prior to our next visit?

Next, the clinician should help the patient overcome inertia and become independent and self-motivating, emphasizing that time is an ally to successful lifestyle modification. Patients should be counseled on handling resistance and dealing with recidivism.

Lifestyle modification is analogous to Newton's first law of motion: a body at rest tends to remain at rest; a body in motion tends to remain in motion. We need to get patients to act. The easier we make it for patients to move, using goals suited to their circumstances, the easier it is for them to overcome inertia. Any action they take (eg, repeated 10-minute exercise bouts) may serve as a springboard to permanent lifestyle change.

●Exercise is Medicine (EIM) initiative – EIM was launched by the American College of Sports Medicine (ACSM) and the American Medical Association with the goals of making physical activity assessment and promotion standard in clinical practice and providing clinicians with evidence-based physical activity resources for people everywhere and of all abilities (EIM website). The EIM website has a portal specifically for clinicians that provides a framework for implementing physical activity and other resources to help clinicians and members of their clinical team accomplish the following:

•Assess a patient's physical activity

•Provide concise guidance and an exercise prescription

•Refer patients to resources to help them implement and sustain physical activity

●The Patient-centered Assessment and Counseling for Exercise (PACE) program: A model to emulate? – The PACE program is a comprehensive approach to physical activity counseling [28]. This approach draws heavily on the "stages of change" model, which suggests that individuals change their behavior in stages and uses tailored recommendations for each stage [29].

The PACE program was developed to overcome common barriers to physician counseling for physical activity, using brief counseling sessions (two to five minutes) during a conventional physical examination. The results of controlled trials suggest that the PACE approach can be incorporated effectively into clinical encounters intended to motivate previously sedentary adults to become more physically active [30]. Guidance for how to implement the program can be found in the following reference [31].

MEDICAL ASSESSMENT AND CLEARANCE FOR EXERCISE

General approach to medical assessment — Our suggested approach to determining which patients need a medical assessment prior to beginning an exercise program is summarized in the following algorithm (algorithm 1).

In the past, medical organizations, including the American Heart Association (AHA) and American College of Cardiology, emphasized preparticipation screening examinations to identify "at risk" individuals who should seek more detailed medical evaluation prior to beginning exercise. Such medical evaluations might include a history and physical examination, exercise stress testing, or more extensive diagnostic testing. To increase participation in exercise programs, screening has been deemphasized.

Little evidence supports the role of routine screening examinations or diagnostic testing in reducing the risk of exercise-related cardiovascular events [32-35]. The United States Preventive Services Task Force 2018 recommendations advise against routine screening with exercise testing to prevent cardiovascular events [36], including higher-risk populations with diabetes mellitus [37].

In addition, there is a lack of consensus among organizations about the extent of the medical evaluation needed for screening [4]. In part, this stems from the many variables to be considered, such as patient age, intensity of the exercise to be performed, prior training history, and whether the patient has known cardiovascular, metabolic, or renal disease [38]. Regardless of organization guidelines, many patients will seek advice from their medical providers before engaging in an exercise program. The clinician needs to be aware of current guidelines for identifying high-risk individuals who may require a more thorough evaluation before beginning an exercise program, as well as what advice to give low-risk individuals.

Asymptomatic patients who might benefit from peak or symptom-limited exercise testing before beginning a physical conditioning program, especially if vigorous exercise is contemplated, include those who meet any of the following criteria:

●Previously sedentary with multiple cardiovascular risk factors (algorithm 2) (see "Atherosclerotic cardiovascular disease risk assessment for primary prevention in adults: Our approach" and "Cardiovascular disease risk assessment for primary prevention: Risk calculators")

●Elevated coronary artery calcium score (see "Coronary artery calcium scoring (CAC): Overview and clinical utilization")

●Family history of premature coronary heart disease

●Clinician judgement that the patient may be at higher risk (eg, patient unlikely to share symptoms or provide an accurate history)

Patients who do not need preparticipation screening — The 2018 Physical Activity Guidelines for Americans promulgated by the United States Department of Health and Human Services state: "People without diagnosed chronic conditions (such as diabetes mellitus, heart disease, or osteoarthritis) and who do not have symptoms (such as chest pain or pressure, dizziness, or joint pain) do not need to consult a health care provider about physical activity" [16,17]. While we concur with this approach, many patients seek advice from clinicians, and this provides an important opportunity to educate patients and promote regular exercise. (See "Exercise prescription and guidance for adults".)

American College of Sports Medicine recommendations for pre-exercise medical assessment — The American College of Sports Medicine (ACSM) has published recommendations describing which patients warrant a screening evaluation before starting an exercise program. Our suggested approach to determining which patients need such a medical assessment is consistent with that advocated by the ACSM and is summarized in the following algorithm (algorithm 1). (See 'General approach to medical assessment' above.)

The ACSM approach uses four major categories for assessment [33]:

●Current level of physical activity

●Presence of known cardiovascular (eg, coronary artery disease, peripheral vascular disease, cerebrovascular disease), metabolic (eg, type 1 or 2 diabetes), or renal disease (chronic kidney disease); or symptoms or signs suggestive of such disease

●Desired or anticipated exercise intensity

●Potential hazards of unaccustomed, high-intensity physical activity

The ACSM recommendations can be summarized as follows:

●Asymptomatic and already physically active – For a patient who is asymptomatic and already physically active, with or without known cardiovascular, metabolic, or kidney disease (CMKD), medical clearance is not necessary for moderate-intensity exercise. Individuals without known disease or symptoms may progress to vigorous exercise using an appropriate approach (as outlined in separate ACSM guidelines [4]), whereas asymptomatic individuals with CMKD may progress to vigorous activity after medical clearance.

●Symptomatic during exercise – Any patient who was previously physically active and asymptomatic but who becomes symptomatic during exercise should immediately discontinue such activity and seek medical evaluation before resuming physical activity.

●Inactive, asymptomatic, without CMKD – For a patient who is inactive, asymptomatic, and without known CMKD, medical clearance for light- to moderate-intensity exercise is not necessary. Such individuals may progress, over time, to vigorous exercise (as outlined in separate ACSM guidelines [4]), provided they remain asymptomatic.

●Inactive, asymptomatic, with CMKD – For inactive, asymptomatic patients with known CMKD, medical clearance is recommended for light- to moderate-intensity exercise. For inactive patients with any symptoms or signs that suggest CMKD, medical clearance is recommended before participating in light- to moderate-intensity exercise with progression.

The ACSM guidelines have eliminated age cutoffs, risk factor profiles, and the use of low-, moderate-, and high-risk classifications. The term "medical clearance" is used, rather than specific recommendations for performing a formal medical examination or exercise testing, as the authors felt that such evaluations should be left to the clinician's discretion. In addition, patients with pulmonary disease are no longer automatically referred for medical clearance because pulmonary disease does not necessarily confer greater risk of nonfatal and fatal cardiovascular complications during exercise [33].

Patients who need medical evaluation before starting an exercise program — The screening of recreational and competitive adult and adolescent athletes to identify those at increased risk of sudden cardiac death is reviewed in detail separately. Initial assessment of patients who warrant medical evaluation before beginning an exercise program is discussed below. An algorithm outlining our approach to determining which patients need such a medical evaluation is provided (algorithm 1). (See "Screening to prevent sudden cardiac death in competitive athletes".)

Recreational athletes and those beginning an exercise program with heretofore unknown structural cardiovascular abnormalities or atherosclerotic cardiovascular disease (placing them at risk of sudden cardiac death during strenuous exercise) may be identified through several means. These include:

●Comprehensive evaluation by a primary care clinician or specialist (eg, clinical cardiologist)

●Systematic screening of those whose families have a genetic predisposition to premature cardiovascular disease

●Incidental findings on clinical examination or an imaging study detected during evaluation for another medical problem

●Systematic population screening, with or without concomitant diagnostic testing

●Symptomatology (eg, chest pain or pressure, unusual shortness of breath, palpitations or abrupt tachycardia, syncope) at rest or during moderate-to-strenuous activity

While most patients do not need clearance prior to starting a regular light- to moderate-intensity exercise program, those with concerning symptoms, findings identified through one of the methods listed above, or other concerns should be evaluated, starting with an appropriate history and physical examination. (See 'American College of Sports Medicine recommendations for pre-exercise medical assessment' above.)

If the patient responds in the positive to any of the following questions, a more thorough evaluation for possible cardiac disease is needed:

●Any history of chest pain, particularly during exertion?

●Any history of feeling dizzy or faint or passing out during exertion?

●Any history of palpitations or excessive shortness of breath during exertion?

●Any history of paroxysmal nocturnal dyspnea or orthopnea?

●Any prior medical condition that has caused symptoms with exertion?

A more thorough evaluation for possible cardiac disease is needed if any of the following findings are noted on examination:

●Significant elevation in blood pressure or pulse (see "Hypertension in athletes" and "Exercise in the treatment and prevention of hypertension")

●New cardiac murmur (systolic above grade 2/6 or any diastolic) or arrhythmia

●Significant ankle or lower extremity edema (2+ or greater)

●Other concerning findings consistent with cardiac disease (eg, bilateral crackles)

Based on the results of the history and physical examination, the clinician may decide to pursue further testing, possibly including a stress electrocardiogram, resting or stress echocardiogram, exercise testing with myocardial perfusion imaging, or other studies. (See "Selecting the optimal cardiac stress test", section on 'Indications for stress testing'.)

Musculoskeletal dysfunction from injury or chronic disease can present significant obstacles to exercise. Patients with new musculoskeletal complaints or known chronic conditions should be evaluated and managed as necessary. Appropriate modifications to a standard exercise program may be needed for such patients. Multiple UpToDate topics address the workup of patients with musculoskeletal complaints and issues around exercise in patients with chronic conditions. A sample of such topics include the following: (see "Approach to the adult with unspecified knee pain" and "Approach to the adult with knee pain likely of musculoskeletal origin" and "Approach to the adult with unspecified hip pain" and "Approach to hip and groin pain in the athlete and active adult" and "Management of knee osteoarthritis", section on 'Exercise' and "Evaluation of the adult with shoulder complaints").

Determining functional capacity using the history — In many cases, a patient's functional capacity can be estimated based on their clinical history. A patient who uses a walker or seldom leaves their single-level home because of symptoms has poor functional capacity, while a patient who walks approximately 3.5 miles (5.5 km) in one hour several times per week or regularly plays singles tennis has an above average to high functional capacity.

In select patients, simple surveys (such as the Duke Activity Status Index) can be used to obtain a valid and reliable estimate of the patient's functional capacity (expressed in metabolic equivalents [METs]) [39]. (See 'Terminology and common types of exercise' above.)

Others have shown that cardiorespiratory fitness can be estimated accurately from readily available demographic and clinical data, including sex, age, body mass index (BMI), resting heart rate (RHR), and self-reported physical activity [40].

The authors prefer to use two simple questions to estimate a patient's functional capacity [41]:

●Can you walk approximately 10 minutes at a pace of 2.5 to 3 miles per hour (4 to 5 km per hour; approximately 3 to 3.5 METs) without experiencing limiting symptoms (eg, shortness of breath)?

●Can you climb two standard flights of stairs without stopping because of limiting symptoms?

An affirmative answer to either question suggests the patient's functional capacity is adequate (ie, ≥5 METs) and above the least fit 20 percent of patients, which typically places them in a lower-risk cohort. Conversely, clear negative responses to both questions generally confirm that a patient has reduced exercise tolerance or poor functional capacity.

Functional screening of mobility and strength — A variety of screening tests have been proposed to identify individuals who are predisposed to injury, whether from sports, occupational labor, or exercise. The Functional Movement Screen (FMS) is one of the most widely used and consists of seven individual tests used to assess mobility and injury risk. Despite widespread use, the strength of association between FMS composite scores and subsequent injury does not support its use as an injury prediction tool [42,43].

Screening exercise testing — Screening for cardiac disease and the appropriate use and performance of exercise testing is reviewed in detail separately. The role of such testing in patients beginning an exercise program is discussed briefly below. (See "Screening for coronary heart disease" and "Exercise ECG testing: Performing the test and interpreting the ECG results" and "Selecting the optimal cardiac stress test".)

The United States Preventive Services Task Force advises against screening exercise testing in low-risk asymptomatic adults and found insufficient evidence for or against exercise testing in the preparticipation assessment for structured exercise in subjects at higher risk [36]. The AHA echoes these conclusions, emphasizing the absence of data from randomized controlled trials about the value of exercise testing to screen individuals at potential risk during exercise [34,38]. The authors of a systematic review of the benefits and risks of structured exercise in persons over 75 years of age have argued that mandatory preparticipation exercise testing, in addition to being expensive and of unproven benefit, could deter many older persons from exercising and cause more harm than good [44].

Limitations of exercise testing — While not needed for most adults beginning an exercise program, exercise testing can be helpful for assessing a range of potential cardiovascular disorders in patients at risk. Suitable candidates for exercise testing prior to beginning a vigorous exercise program (ie, activities involving ≥60 percent oxygen consumption [VO₂] reserve or >6 METs) include individuals with known or suspected coronary heart disease (eg, symptomatic, history of diabetes) [4,45]. However, as most acute coronary syndromes that occur in previously asymptomatic subjects are due to vulnerable plaque disruption, it is impractical to use exercise testing to prevent acute cardiovascular events at rest or during exercise in asymptomatic subjects [32]. Other patients who may benefit from such testing prior to beginning an exercise program include those whom the clinician suspects may be ignoring symptoms or not giving an accurate history, patients with atypical chest pain at rest or during exertion, and those who complain of palpitations [46].

SURVEILLANCE OF THE ADULT EXERCISER

Beginning exerciser — The primary care clinician plays an important role in monitoring the new exerciser moving from a sedentary to a more active lifestyle, as well as the more advanced exerciser. Evidence to guide such surveillance is scant; what follows are the authors' suggestions. Our approach to primary care surveillance of exercisers is summarized in the following table (table 4).

Attrition rates among sedentary individuals embarking on a new exercise program are high, with one source citing adherence rates of 50 percent or lower [47]. According to a small observational study, poor exercise adherence was associated with overly optimistic expectations among inexperienced exercisers, which led to disappointment [48]. Interventions to help ensure realistic expectations among participants may increase success with exercise programs. One strategy is to remind patients of the considerable health benefits gained from even small increases in physical activity.

Most beginning exercisers are thought to face their greatest challenges in maintaining their exercise regimen during the initial conditioning stage (first 5 to 10 weeks), and so it makes sense for primary care clinicians to intervene during this time. Interventions can include phone calls from office staff or the clinician to encourage adherence. In addition, as dropout rates are highest during this early period, we suggest making a scheduled office visit to reinforce the new behavior and to help overcome any obstacles to exercising.

Although evidence is limited, a range of technologies may help patients maintain their exercise regimen and achieve activity goals. Digital tools on smartphones and tablets, apps that promote physical activity, and activity trackers may all reduce barriers to regular physical activity and provide daily goal reminders [49]. Self-monitoring techniques or devices (eg, pedometers, accelerometers, heart rate [HR] monitors) can be helpful. Active-play video gaming with aerobic requirements (approximately 2 to 6 metabolic equivalents [METs]) can help patients meet goals and serve as a gateway to structured exercise programs [50,51]. Collectively, data suggest that using technology, a contributor to the physical inactivity epidemic, may also be part of the solution.

Extreme endurance exerciser — Extreme exercisers pose a different set of challenges for the clinician. While improvements in cardiac function are seen in individuals who perform three or more hours of vigorous exercise weekly, extreme exercise is more commonly used to describe endurance athletes who perform 15 to 40 hours of training per week [52].

Individuals involved in high-volume, high-intensity training regimens or competitions are not immune to structural cardiovascular abnormalities or atherosclerotic cardiovascular disease, and extreme exercise is more likely to trigger acute cardiac events in such participants. Therefore, preparticipation and serial screening aimed at identifying athletes at risk of exertion-related sudden cardiac arrest or progression of cardiovascular disease appears warranted. Clinicians should be aware of the potential risks associated with extreme endurance exercise or high-intensity interval training (HIIT) and provide appropriate counsel to patients contemplating such activity [38]. The issues surrounding the screening of such athletes are reviewed in detail separately. (See "Screening to prevent sudden cardiac death in competitive athletes".)

We believe that the management of extreme endurance exercisers should be individualized. At minimum, an annual cardiovascular assessment, including an electrocardiogram, seems to us a reasonable approach. Most individuals who experience an exercise-related cardiac arrest have risk factors or a history of cardiovascular disease, have structural heart disease (eg, hypertrophic cardiomyopathy), or experience symptoms at some time prior to the arrest. Therefore, it is important for clinicians to counsel their patients about warning signs and symptoms of cardiac disease [38,53].

While moderate-to-vigorous exercise is clearly beneficial to health outcomes, the dose-response relationship between extreme exercise and health remains incompletely understood [52]. Little evidence is available to inform how to approach surveillance of the extreme endurance exerciser. In a review of this subject, one team of researchers suggested that extreme exercise not be discouraged but recommended annual surveillance [54].

The results of several large observational studies suggest that excessive endurance exercise may be harmful for some individuals:

●The Copenhagen City Heart Study reported a U-shaped relationship between mortality and duration of exercise among joggers [55]. Runners who exercised over four hours per week had slightly higher hazard ratios (0.86) compared with those who exercised between two and a half and four hours per week (0.79).

●In a longitudinal study (average follow-up nine years) of 1.1 million women in the United Kingdom, female participants reporting daily, strenuous physical activity had significantly higher risk of coronary heart disease, cerebrovascular disease, and venous thromboembolic events than those performing such activity two to three times each week [56].

●A meta-analysis of case-control studies found that 147 of the 655 subjects (23 percent) who engaged in high-volume endurance exercise developed atrial fibrillation compared with 116 of 895 controls (12.5 percent) who did not [57].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Exercise in adults".)

SUMMARY AND RECOMMENDATIONS

●Terminology – Exercise is physical activity that is planned, purposeful, and performed regularly to improve or maintain health and fitness. Exercise has wide-ranging health benefits. Exercise types include endurance exercise to improve cardiovascular and respiratory fitness, resistance exercise to improve strength and power, exercises to improve balance and proprioception, mobility exercises, and combinations of these. The different types and facets of exercise and physical activity are reviewed in the text. (See 'Terminology and common types of exercise' above.)

●Patient assessment and time spent exercising – One key determinant of cardiovascular health is the time spent being physically active. The 2020 World Health Organization guidelines encourage the accumulation of 150 minutes or more of moderate-intensity activity or 75 minutes or more of vigorous-intensity activity, or equivalent combinations, each week. Assessment of a patient's physical activity and of a sedentary patient's willingness to embark upon an exercise program are reviewed above. (See 'Assessment of individual patient activity' above and 'Assessment of patient willingness to begin exercising' above.)

●Who needs a medical assessment before starting to exercise? – Patients without diagnosed chronic disease (eg, heart disease, diabetes, kidney disease) or concerning symptoms (eg, chest discomfort, dyspnea at rest, dizziness) generally do not require a health screen prior to beginning a moderate-intensity exercise program. Patients with significant cardiovascular, metabolic, or kidney disease (CMKD), those who develop concerning symptoms at rest or during activity, and some others should be evaluated by their primary care clinician prior to embarking on an exercise program. Our suggested approach to determining which patients need a medical assessment before starting an exercise program is summarized in the following flow chart (algorithm 1). (see 'Medical assessment and clearance for exercise' above).

●Surveillance of exercising patients – Evidence to guide primary care surveillance of the adult exerciser is scant. A table summarizing our approach is provided (table 4). (See 'Surveillance of the adult exerciser' above.)

●Supporting patients starting to exercise – Attrition rates among sedentary individuals embarking on a new exercise program are high, particularly during the initial conditioning stage (first 5 to 10 weeks). Interventions during this period, such as phone calls from office staff or clinicians to encourage patients, can reduce attrition. We suggest making a scheduled office visit during this period to reinforce the new behavior and to help overcome any obstacles to exercising. (See 'Beginning exerciser' above.)

ACKNOWLEDGEMENT — The authors wish to thank Ms. Brenda White for her invaluable assistance preparing and revising the manuscript.