You are in: eMedicine Specialties > Sports Medicine > Introductory Topics in Sports Medicine Exercise PrescriptionArticle Last Updated: Sep 12, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 11
 
Author: Amer Suleman, MD, Consultant in Electrophysiology and Cardiovascular Medicine, Department of Internal Medicine, Division of Cardiology, Medical City Dallas Hospital Amer Suleman is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Society of Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions Coauthor(s): Kyle D Heffner, MS, CPFT, Consultant and Director of Clinical Operations, Frontera Strategies Editors: Joseph P Garry, MD, Director of Sports Medicine and Sports Medicine Fellowship, Associate Professor of Family Medicine and Exercise & Sport Science, Department of Family Medicine, East Carolina University Brody School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Jon B Whitehurst, MD, Clinical Instructor of Surgery, University of Illinois College of Medicine; Partner and Executive Board Member, Rockford Orthopedic Associates; Orthopedic Chairman, Rockford Memorial Hospital; Sherwin SW Ho, MD, Associate Professor, Department of Surgery, Section of Orthopedic Surgery and Rehabilitation Medicine, University of Chicago Author and Editor Disclosure Synonyms and related keywords: exercise training, physical fitness, physical fitness training program, fitness program, exercise training program, Borg scale, Borg's scale, symptom-limited exercise test, exercise test, estimated rate of perceived exertion, rate of perceived exertion, RPE, target heart rate, THR, resting heart rate, HR rest, maximal heart rate, HR max, RHR, exercise physiology EXERCISE PRESCRIPTIONSection 2 of 11
 
Exercise prescription commonly refers to the specific plan of fitness-related activities that are designed for a specified purpose, which is often developed by a fitness or rehabilitation specialist for the client or patient. Due to the specific and unique needs and interests of the client/patient, the goal of exercise prescription should be successful integration of exercise principles and behavioral techniques that motivates the participant to be compliant, thus achieving their goals. Components of exercise prescription An exercise prescription generally includes the following specific recommendations:
For an explanation of terms, see Glossary of Terms. INTRODUCTIONSection 3 of 11
Substantial data are available regarding the benefits of physical activity. For primary preventative benefits, physical activity patterns should begin in the early school years and continue throughout an individual's life. Schools must specifically designate physical education programs with aerobic activities for children at early ages. Programs should include recreational sports (eg, running, dancing, swimming). Support at home for an active lifestyle for children helps to promote healthy physical activity patterns. In the clinical setting, discuss physical activity and provide exercise prescriptions for patients and their families. In some instances, suggestions could be made about implementing physical activity recommendations at the work site. Consider intensity, duration, frequency, mode, and progression in all types of physical activity programs. As children and adolescents become adults and discontinue the athletic endeavors of school and college, primary prevention must include a plan for a lifetime of appropriate physical activity. Ideally, this activity should be performed for at least 30-60 minutes, 4-6 times weekly or 30 minutes on most days of the week. The frequency, duration, and intensity of activity should be individualized to personal satisfaction, mode, and progression. Subjects may use individual end points of exercise, such as breathlessness and/or a fatigue level ranging from somewhat hard to hard on the Borg perceived exertion scale (see Glossary of Terms, Borg rating of perceived exertion). Standardized charts that designate heart rates may help by providing heart rate end points that can be measured immediately after exercise, but these are not necessary. Exercise should include aerobic activities, such as bicycling (stationary or routine), walk-jog protocols, swimming, and other active recreational or leisure sports. Shoes and clothing should be appropriate for extremes of heat, cold, and humidity. Resistive exercises using free weights or standard equipment should be performed 2-3 times per week. These exercises should include 8-10 exercise sets that consist of 10-15 repetitions per set (including arms, shoulders, chest, trunk, back, hips, and legs) and are performed at a moderate intensity. If free weights are used, 15-30 lb is generally adequate or resistance that requires a perceived effort that is relatively hard (ie, an RPE 15-16). Resistive exercises tend to complement aerobic exercise in that some training effect is realized. However, development of muscle tone and strengthening of body musculature is more important as adults age. The long-term effect of any physical activity program is affected by compliance. In today's mobile society, an exercise plan must include activities for business trips and vacations. Exercise facilities may not be convenient in such settings, which may mean improvising. For example, a walk-jogger should bring walking or running shoes and find a safe place to walk or run at a pace that approximates the usual activity level. Many hotels or motels have exercise facilities with a track or treadmill, exercise cycle, and weights, enabling travelers or others away from their usual routine to maintain an exercise program. Physical activity measured in total time or kilocalories (kcal) or kilojoules (kJ) per week is appropriate and may be achieved with various combinations of scheduling, such as 10-15 minutes in the morning, at noon, and/or an afternoon/evening session. Many persons may schedule longer, less frequent periods of exercise. As intensity decreases, frequency and duration should increase and vice versa. The dosage or total energy (calorie) expenditure per week must be individualized. Persons with influenza syndromes or respiratory illnesses should decrease or stop exercise until they have recovered. If the recovery time is greater than 2-3 weeks, activity should be resumed at a lower level to compensate for the slight loss in training level. Maintenance of the cardiovascular training effects of exercise has been shown to be more related to the exercise intensity than to exercise frequency or duration. In other words, if the intensity is maintained, even though the exercise sessions are less frequent or shorter in duration, transient reductions in conditioning from the decreased exercise appears to be minimized. Various exercise testing measures of functional capacity should be used in special populations but are not necessary for primary prevention. Traditionally, many athletically inclined persons like to have periodic oxygen-uptake (VO2) measurements to assess their level of training. However, recent technologic advances have not only made cardiopulmonary (CPX) or metabolic (CMET) testing more commonplace among medical practices, but have also become increasingly popular as a part of a routine physical and stress test evaluation, especially for individuals who are considered at high risk for cardiovascular disease (eg, those with hypertension, shortness of breath, chest discomfort, or abnormal blood lipid levels). A lifestyle of physical activity from childhood throughout the adult years fosters health and longevity. Even brisk walking as a physical activity/exercise habit promotes health benefits. This is the simplest program for most individuals and has clear benefits. This improved state of health is enhanced by weight control, restricted intake of saturated fat and cholesterol, abstinence from cigarette smoking, and control of high blood pressure and glucose intolerance. For excellent patient education resources, visit eMedicine's Public Health Center. Also, see eMedicine's patient education articles Walking for Fitness and Strength Training. BENEFITS OF EXERCISESection 4 of 11
Routine exercise improves tissue VO2 affects the following:
Middle-aged men and women who work in physically demanding jobs or perform moderate to strenuous recreational activities have fewer manifestations of coronary artery disease than their less active peers. Meta-analysis studies of clinical trials reveal that medically prescribed and supervised exercise can reduce mortality rates for persons with coronary artery disease. In addition to the physical benefits of exercise, both short- and long-term aerobic exercise training are associated with improvements in various indexes of psychologic functioning. Cross-sectional studies reveal that compared with sedentary individuals, active persons are more likely to be better adjusted, to perform better on tests of cognitive functioning, to exhibit reduced cardiovascular responses to stress, and to report fewer symptoms of anxiety and depression. In one report, persons who increased their activity levels from 1965-1974 were at no greater risk for depression than those individuals who were active all along; however, persons who were active and became inactive were 1.5 times as likely to become depressed by 1983 compared with those who maintained an active lifestyle. Longitudinal studies have also documented significant improvement in psychologic functioning. Exercise training reduces depression in healthy older men and in persons with cardiac disease or major depression. Exercise also improves self-confidence and self-esteem, attenuates cardiovascular and neurohumoral responses to mental stress, and reduces some type A behaviors. Although exercise training generally has not been found to improve cognitive performance, short bouts of exercise may have short-term facilitative effects. Despite the positive physical and mental health benefits of exercise, long-term adherence to exercise programs remains problematic. Overall physical activity levels decrease with aging, in minority populations, in females, in disabled persons, and in those with chronic disease. Only an estimated 50% of all persons who initiate an exercise program continue the habit for more than 6 months. The issue of nonadherence is particularly important because exercise is only beneficial if it is maintained for extended periods. Thus, developing strategies to improve exercise initiation and adherence, especially for persons who are among the least active (eg, 75% of black women; less educated, obese, elderly persons), is important. DIFFERENT TYPES OF EXERCISESection 5 of 11
Exercise has been defined as an activity for the express purpose of improving fitness or health. Physical activity includes all forms of activity (eg, occupational, recreational, sports-related) that are performed without the specific purpose of fitness or health. Different types of exercise are as follows:
GENERAL GUIDELINESSection 6 of 11
Resistance and repetitions
Type of exercise (mode)
Energy (caloric) expenditure
Lifetime activities
Selecting the right physical activities
EXERCISE PRESCRIPTION FOR SPECIAL POPULATIONSSection 7 of 11
Advanced age
Pulmonary disease
Diabetes
Obesity
Maternity
Osteoporosis
Tips for trouble-free exercise
EXERCISE PRESCRIPTION FOR INDIVIDUALS WITH CORONARY ARTERY DISEASESection 8 of 11
Physical inactivity is recognized as a risk factor for coronary artery disease. Regular aerobic physical activity increases exercise capacity and plays a role in both primary and secondary prevention of cardiovascular disease. The known benefits of regular aerobic exercise and recommendations for implementation of exercise programs are discussed. Exercise training increases cardiovascular functional capacity and decreases myocardial oxygen demand at any level of physical activity in apparently healthy persons and in most individuals with cardiovascular disease. Regular physical activity is required to maintain these training effects. Myocardial work can be affected by caffeine intake, and caffeine intake has been shown to increase blood pressure response to exercise. The potential risks of physical activity can be reduced by receiving a medical evaluation, risk stratification, supervision, and education. Exercise can help control blood lipid abnormalities, diabetes, and obesity. In addition, aerobic exercise adds an independent blood pressure–lowering effect in certain hypertensive patient groups, with a decrease of 8-10 mm Hg in both systolic and diastolic blood pressure measurements. A direct relationship exists between physical inactivity and cardiovascular mortality, and physical inactivity is an independent risk factor for the development of coronary artery disease. A dose response relationship exists between the amount of exercise performed (from approximately 700-2000 kcal/wk [2940-8400 kJ/wk] energy expenditure) and all-cause mortality and cardiovascular disease mortality in middle-aged and elderly populations. The greatest potential for reduced mortality is in sedentary persons who become moderately active. Most beneficial effects of physical activity on cardiovascular disease mortality can be attained through moderate-intensity activity (40-60% of maximal VQ, depending on the participant's age). The activity can be accrued through formal training programs or leisure-time physical activities. Although most supporting data are based on studies in men, more recent findings show similar results for women. Results of pooled studies reveal that persons who modify their behavior after myocardial infarction to include regular exercise have improved rates of survival. Studies have revealed that intensive multiple interventions, such as smoking cessation, blood lipid reduction, weight control, and physical activity, significantly decreased the rate of progression—and, in some cases, lead to regression—in the severity of atherosclerotic lesions in persons with coronary disease. In addition, limited data indicate that higher-intensity exercise, compared with lower-intensity exercise, improves left ventricular ejection fractions in persons with coronary artery disease. Current activity status (eg, persons remaining physically active or having been sedentary and becoming physically active) revealed the greatest decline in coronary artery disease risk. Persons who remain sedentary have the highest risk for cardiovascular disease mortality. Exercise intensity should approximate 40-85% of VO2 reserve (VO2R) or HR reserve (HRR), as determined by an exercise test. If a test is not performed initially, a reasonable estimate of 20-30 beats per minute (bpm) above HR rest is generally appropriate until testing is performed. Activities can be prescribed according to the work intensity at which the training HR is achieved after 5-10 minutes at the same workload (steady state). This may be expressed as watts on an ergometer, speed on a treadmill, or METs. If an individual cannot assess intensity, HR counting (manually or with a pulse meter or cardiotachometer) is especially useful. HR counters are widely available and generally accurate for low- to moderate-intensity exercise. If an individual intends to walk on a level surface, activity can be prescribed as the treadmill step rate that generates the desirable HR. The step rate is the number of steps taken in 15 seconds while walking at the desired speed on the treadmill. Step rate can be counted easily because it requires less skill than counting HR. If this approach is used, caution individuals to avoid hills. Walking in shopping malls or gymnasiums allows individuals to avoid inclement weather and to exercise on a flat surface. Exercise should be supervised for the first few sessions to ensure that instructions are understood and the activity is well tolerated. Individuals can also judge the intensity of exercise by the RPE, which can be equated with the desired HR during laboratory exercise and activities. The original scale is a 15-grade category scale that ranges from 6-20, with a verbal description at every odd number, beginning at 7 (very, very light) and progressing to 19 (very, very hard). RPE values should be rated as follows:
Activities can progress as tolerance is demonstrated. An appropriate initial intensity of training is 60-75% of HR max (moderate) or an RPE of 12-13. However, many individuals may need to begin at 40-60% of HR max (light). After safe activity levels have been established, duration is increased in 5-minute increments each week. Later, with increased strength and as the HR response to exercise decreases with conditioning, intensities can be increased to a frequency of 3-6 times per week. At this point, limited resistive exercises can be added, which have proved both safe and effective in secondary prevention. Exercise prescription in the presence of ischemia or arrhythmias (moderate to high risk) An exercise test and medical supervision are essential for this type of exercise prescription. The manifestations of arrhythmias or ischemia that require such precautions can vary but usually include the following:
Perform exercise testing in the usual fashion, but the conditioning work intensity is derived from the HR associated with the abnormality. If the exercise test continues to a high level of effort, the HR at 50-60% of maximum can be used if it falls at least 10 bpm below the abnormal level. Otherwise, the recommended peak training HR is 10 bpm less than that associated with the abnormality. These individuals are recommended to have medically supervised cardiac rehabilitation and reevaluation to restratify them to a lower risk. Repeat exercise testing at least yearly. As the population ages and more elderly persons survive coronary events, increasing numbers need appropriate physical activity. Most of these persons initially demonstrate benefits from supervised exercise for a brief period. This is performed primarily to introduce the patient to exercise (which the individual may not have performed before) and to evaluate the patient for possible complications of exercise, such as arrhythmias, evidence of heart failure, anginal chest pain, or abnormal ECG ST segments. On the basis of the evaluation, the person can be categorized as low risk or moderate to high risk, and appropriate cardiac rehabilitation precautions can be taken. Most individuals in secondary prevention can soon be restratified as low risk and can implement their exercise prescription at home or in a community program. In this setting, the previously mentioned primary prevention guidelines also apply. The intensity may be much less, and the frequency may be more, with appropriate changes in duration. Interval exercise testing is recommended at least yearly, and coronary risk factor modification should be aggressive. In summary, implementation of physical activity strategies by physicians for both primary and secondary prevention should consider the dosing effect or expenditure of kilocalories or kilojoules over a unit of time (usually a week). The guidelines above ideally should entail 5-6 hours of various physical activities weekly if possible. The exercise routine must be individualized and should include both aerobic and resistance activities. The benefits of exercise are enhanced with good to excellent compliance with exercise and appropriate lifestyle modifications. Postmyocardial infarction As the safety of early ambulation was progressively demonstrated in patients after suffering myocardial infarction, other benefits were realized, such as the prevention of the deconditioning effects of bed rest, decrease of anxiety and depression, and improved functional status at discharge.
ADDITIONAL RESEARCH AND FUTURE ISSUESSection 9 of 11
The body of knowledge on exercise is large, but data on exercise and its effects on the cardiovascular system and long-term survival are still relatively limited. The responsibility for conducting research lies with government agencies, private health organizations, the insurance industry, employers, universities, and medical schools. Basic knowledge of the anatomic, biochemical, and physiologic changes that result from various patterns of physical activity (short- and long-term, sustained and intermittent, isotonic and isometric, low and high intensity) in persons of different ages is needed, as is a determination of whether a certain minimum-intensity threshold of physical activity is required for benefit. The biomedical and economic impact of participation in exercise programs on coronary artery disease, cerebrovascular and peripheral vascular disease, heart failure, and hypertension should also be evaluated. The psychosocial functioning of persons with coronary artery disease and the potential value of exercise in enhancing the quality of life for cardiac and other patients warrants further study. Future studies should include adequate numbers of women, ethnic groups, and elderly persons to better meet research objectives. Furthermore, the presence and extent of coronary risk factors in disabled and disadvantaged individuals and in minority groups must be identified and better defined. Consequently, the effect of modifications (eg, increases in physical activity on members of these groups) should be explored. Large studies should also include a significant number of these persons. Research should be continued to establish the cost-effectiveness of physical activity programs for the enhancement of cardiovascular health, with a focus on the type of promotional strategies required for initiating and maintaining physical activity (eg, insurance incentives, health personnel, public policy, media materials) and the social context of such activity (eg, industry and business, rural and urban settings, schools, churches, families). Research should also involve issues such as how physical activity can prevent (or decrease the duration of) the hospitalization of patients with chronic disease. More information is also needed to identify societal, cultural, ethnic, and personal factors that affect development or maintenance of lifelong patterns of physical activity and incorporation of these into exercise promotion strategies. Research on better and more effective physical activity interventions that improve long-term compliance to a physically active lifestyle is urgently needed. Innovative nontraditional methods of increasing physical activity in the population must be developed, implemented, and evaluated. In summary, future developments and studies should focus not only on the benefits of physical activity, but also on exercise adherence strategies and the methods used to facilitate dissemination of present and future knowledge to all members of society. GLOSSARY OF TERMSSection 10 of 11
Exercise intensity is generally expressed as a percentage of either HR or VO2. By definition, VO2 is the oxygen uptake by an individual at rest or during exertion expressed commonly in milliliters of oxygen consumed per kilogram body weight per minute (mL/kg/min) Heart rate reserve (HRR) is defined as the maximal heart rate (HR max) observed during a symptom-limited exercise stress test minus the resting heart rate (HR rest). A percentage of the HRR range is added to the HR rest to determine a target heart rate (THR) range to be used during exercise. This approach accounts for individual variability in the HR rest and better reflects the peak exercise oxygen consumption (VO2 max). VO2 max reflects the highest rate of oxygen consumption that one can achieve. Target heart rate (THR) for exercise is generally recommended from 50-85% HRR (or VO2R). For deconditioned individuals, 40-50% HRR may be more appropriate for beginning exercise, whereas physically active individuals may require higher intensities to achieve improvements in their conditioning. As an illustration in determining THR, the example below uses a resting HR (RHR) of 70 and a HR max of 180 bpm.
So, a THR range would be 136-158 bpm or a pulse count of 22-26 beats per 10 seconds. Metabolic equivalents (METs) are useful units when recommending exercise. By definition, one MET is the amount of oxygen consumed at rest or about 3.5 mL/kg/min. For most people, walking 2 mph requires 2 METs and 3 mph require 3-4 METs. Published MET tables describe many activities in terms of the estimated MET requirements. For example, if an individual has a VO2 max of 34 mL/kg/min, the VO2R is 34 minus the resting VO2 of 3.5 mL/kg/min equals 30.5 mL/kg/min. Dividing this result by 3.5 yields 8.7 METs. Using 60-80% VO2R, the recommended range of exercise METs may be determined by the following: When one consults a common MET table, an exercise intensity of 6.2-8.0 METs is equivalent to a slow walk-jog combination exercise, hiking with a backpack, hill climbing, and numerous other moderately vigorous activities. Exercise intensity may be customized to the individual based upon their metabolic response to progressive exercise if the VO2 max and the anaerobic threshold (AT) or ventilatory threshold (VT) is determined. By definition, the VT may be described as the level of oxygen consumption (VO2) at which a significant increase in anaerobiosis occurs, as evidenced by an increase in blood lactate levels and respiratory responses to the increasing exercise workload. MET is a unit of energy or level of oxygen used at rest (1 MET = VO2 of 3.5 mL/kg/min). Maximal voluntary ventilation (MVV) is defined as the maximal amount of ventilation per minute, generally determined by a 12-second hyperventilation procedure to maximal ventilation capabilities. The respiratory exchange ratio (R or RER) or respiratory quotient (RQ) is the ratio of the VO2 to the carbon dioxide produced in the body. At rest, the RER reflects the substrate's use of fuel sources (eg, carbohydrates, fats, proteins). The metabolism of fats or fatty acids yields a ratio of 0.7; of carbohydrates, 1; and of protein, 0.84. During exercise, the RER generally exceeds 1 because of the additional carbon dioxide produced as a byproduct of the bicarbonate system and because of lactate buffering. Borg ratings of perceived exertion The RPE scale is used widely in exercise science and sports medicine to monitor or prescribe levels of exercise intensity. The 95%-limits-of-agreement technique has been advocated as a better means of assessing within-subject (trial-to-trial) agreement. The perception of exertion is a monitoring behavior that uses all sources of information to govern actions that can benefit or preserve health and partake of adaptive pursuits. How a person feels about exertion moderates his or her response to exercise and effort. The perception of what is happening in exercise, and its concomitant effect on physiologic function, must be known to further understand the nature of an exercise response. How a person feels modifies reactions to exercise stress and the mechanisms that underlie them. Exercise is never a purely mechanistic physiologic reaction. The interpretation of the exercise experience governs the nature, quality, and extent of the exercise response. To fully understand and accurately assess the nature of an exercise behavior, measuring as many moderating variables as possible is necessary. Physiologic measures can be used to grade the strain for each individual, but so can exertion estimates. In an exercise response, the underlying determining mechanism may not be the pure physiologic parameter being measured. Without knowledge of the psychologic moderator variables, the physiologic measurement alone is misleading; its value as a predictor variable is usually negligible. The particular circumstances in which the physiologic measurement is taken may be more important for predicting or analyzing a response than the variable itself. To exercise only according to HR is dangerous. The aches and strain that are felt may be very important indicators of the real degree of exertion. Rigid adherence to the objective measures of physiology may cause interpretive and prescriptive errors of great magnitude. In many circumstances, the psychologic components of an exercise response are more reliable and relevant than the physiologic measures. This has been shown to be true in the assessment of long-term exercise strain for determining the early symptoms of overtraining or maladaptation. Borg's original intention was to construct a category scale from 6-20 in which scale levels were roughly one tenth of the HR for equivalent scaled exercise levels. A score of 6 (no exertion at all) should exhibit an HR somewhere in the vicinity of 60 bpm for a young to middle-aged, mildly fit individual. This correspondence is generally reserved for middle-aged people exercising at moderate to high intensity levels. At best, this is a very rough estimation of the relationship; individual variability is significant. Also, the relationship between HR and RPE within an individual varies with different forms of activity. The RPE is best reserved for intraindividual comparisons for a specific form of exercise. HRs are related linearly to the scale scores (r = 0.8-0.9). However, even with this relationship one cannot conclude that HR is a cause of the perceived exertion. The perception of exertion integrates many more exercise factors than are considered with singular or isolated physiologic variables. This integration is a truer indication of an exercise response than is depicted by restricted variables such as HRs, lactate measurements, or blood measurements. To understand a certain RPE value, knowing (1) the age and other personal characteristics of the individual, (2) what type of activity was performed, and (3) the environmental conditions that existed at the time is important. The instructions for using the scale are to "estimate how hard and strenuous you feel the work to be." The perception should be general, rather than focusing on specific parts of the body (eg, "tired arms"). The perception of exertion should include as many contributory sensations as possible. Once the verbal description is determined, the individual should choose an exact number that corresponds to the verbal descriptor. When a subject is unable to complete the highest workload, the rating should be of the work at the time of the final interruption. With athletes, the major problem with using RPE is their common tendency to underestimate the exertion level. Practice in using the scale is necessary. If the various categories can be aligned with other categories or levels of work response, an accurate level of discrimination can be developed between the categories. The RPE yields important additional data beyond those available through isolated physiologic variables. In conscientious and reliable individuals, its value exceeds that of singular parameters of performance. Instructions for use: During the exercise you are to rate your perception of exertion. Use this scale, where 6 means no exertion at all, and 20 means a totally maximum effort. The 13 on the scale is a somewhat heavy exercise but capable of being performed at steady state (ie, anaerobic threshold). When at a level of 17, the effort level requires you to push yourself hard even though it is possible to continue for some time. For many people, 19 is about as strenuous as exercise becomes because they often reserve a small amount of possible extra effort. Try to appraise the feeling of exertion as honestly as possible. Do not underestimate or overestimate it. It is of no value to underestimate the level to produce an impression of being brave or tough. Your own feeling of effort and exertion is all that is of interest. Look at the scale and wordings and decide on the word that best describes your effort level and the number alternative associated with that description. The Borg scale is as follows:
REFERENCESSection 11 of 11
Article Last Updated: Sep 12, 2007 |
