Prescription of Exercise for Health and Fitness. CHAPTER 20 Overview Health benefits of exercise...

Prescription of Exercise for Health

and Fitness

CHAPTER 20 CHAPTER 20 OverviewOverview

• Health benefits of exercise

• Medical clearance

• Exercise prescription

• Monitoring exercise intensity

• Exercise program

• Exercise and rehabilitation of people with diseases

Health Benefits of ExerciseHealth Benefits of Exercise

• 1960s: Dr. Kenneth Cooper• 1970s to 1980s: fitness boom• 1990s: The Great Awakening

– 1992: inactivity major risk for CAD (AHA)– 1994: exercise public health initiative (CDCP/ACSM)– 1995/1996: statement on exercise and

cardiovascular health (NIH)– 1996: report on health benefits of exercise (Surgeon

General)– 2000: identification of sedentary death syndrome

Health Benefits of ExerciseHealth Benefits of Exercise

• Exercise not a priority in US population– Awareness of health benefits high– Application of knowledge low

• Exercise should not intimidate– 30 min brisk walking, 15 min running– Every day or almost every day– Health benefits as duration and intensity

Medical ClearanceMedical Clearance

• Medical evaluation useful and important prior to starting exercise program– Medical information can be used to develop exercise

prescription– Provides baseline to measure progress

• High-risk individuals should exercise only under medical supervision

Medical ClearanceMedical Clearance

• Medical evaluation provides motivation– Blood pressure– Percent body fat– Blood lipid values

• Periodic medical evaluations can identify dangerous conditions earlier

Medical Clearance:Medical Clearance:Medical EvaluationMedical Evaluation

• Low-risk/healthy individuals– Medical evaluation not required– Medical system could not handle patient load

• Moderate-risk individuals– 2+ risk factors for cardiovascular, pulmonary, or

metabolic disease, no signs or symptoms– Medical evaluation recommended

• High-risk individuals– 1 or more signs or symptoms of disease– Medical evaluation recommended

Table 20.1Table 20.1

Medical Clearance:Medical Clearance:Risk StratificationRisk Stratification

• Used by health and fitness professionals during screening process

• Risk stratification helps identify– Individuals with medical contraindications– Individuals with clinical conditions who need a

medically supervised exercise program– Individuals at risk for disease who need medical

evaluation and exercise testing prior to exercise– Special needs that affect testing and prescription

Risk Stratification for Risk Stratification for Exercise PrescriptionExercise Prescription

Medical Clearance:Medical Clearance:Graded Exercise TestingGraded Exercise Testing

• Graded exercise test (GXT)– Treadmill most common– Increase intensity gradually to maximal– Monitor subject for discomfort, warning signs

• Exercising ECG necessary– Resting ECG may not reveal all abnormalities– Exercising ECG can unmask coronary artery

disease (CAD)

Medical Clearance:Medical Clearance: Graded Exercise Testing Graded Exercise Testing

• Can detect– Arrhythmias– ST segment changes (myocardial ischemia)– Results positive or negative, possibility of false

negative or false positive

• Positive ECG requires follow-up tests– Coronary arteriogram– CT, MRI scans of heart

Figure 20.3Figure 20.3


• Sensitivity of exercise ECG– Can GXT correctly identify clinical populations?– Low (66% identified) for asymptomatic CAD

• Specificity of exercise ECG– Can test correctly identify healthy individuals?– Higher (84%) specificity

• Predictive value of abnormal exercise ECG– Do abnormal results actually indicate disease?– Low (~24%) for asymptomatic CAD


• GXT has limited value in young and healthy– Accuracy of ECG questionable– Actual risk of cardiac arrest low– Expensive, less accessible test

• GXT recommended for– Moderate-risk cohorts– High-risk cohorts

Exercise PrescriptionExercise Prescription

• Exercise program designed to improve aerobic capacity in untrained individuals

• Four basic factors of exercise prescription– Mode or type of exercise– Frequency of participation– Duration of each exercise bout– Intensity of exercise bout

Exercise PrescriptionExercise Prescription

• Minimum threshold– Point below which no improvements occur– Exists for frequency, duration, and intensity– Varies with each individual

• Once minimum threshold exceeded, aerobic capacity increases

Exercise Prescription:Exercise Prescription:ModeMode

• Modes most frequently prescribed– Walking/hiking/jogging/running– Cycling– Rowing– Swimming

• Less common modes– Spinning, aerobic dance– Racket sports


• For competitive sports, precondition using common modes– Improves aerobic fitness prior to sport training– Improves success in sport performance

• Preconditioning required for several weeks or months before sport training starts– Sport maintains aerobic fitness– Sport may further improve aerobic fitness


• Mode should be enjoyable and motivating

• Mode should be challenging

• Mode should produce needed benefits

• Multiple modes helpful– Inclement weather– Boredom

Exercise Prescription:Exercise Prescription:Frequency and DurationFrequency and Duration

• Frequency– Optimal: 3 to 5 days per week– Start gradually, avoid burnout/fatigue– Less important than intensity or duration

• Duration– Optimal: 20 to 30 min per day– One long bout or multiple shorter bouts– Inverse relationship between duration and intensity

Exercise Prescription:Exercise Prescription:IntensityIntensity

• Intensity most important factor– Minimum recommended: 50 to 60% VO2max

– Upper limit depends on purpose of training

– Upper limit seldom exceeds 80% VO2max

• High-intensity, low-volume interval training– Markedly increases aerobic capacity– Results seen in 2 weeks

Monitoring Exercise IntensityMonitoring Exercise Intensity

• Training heart rate (THR)– Based on linear relationship between HR, VO2

– Use target HR corresponding to target % VO2max

– 75% VO2max = 87% HRmax (not 75% HRmax)

• Karvonen method for THR– Maximal HR reserve = HRmax – HRrest

– THR calculated as percent of maximal HR reserve

– THR75% = HRrest + 0.75(HRmax – HRrest)


• Training HR range– Example: 50 to 75% maximal HR reserve– Will ensure training response– Start at low end and move up

• HR correlated with cardiac work– THR ensures constant rate of work done by heart

regardless of environmental conditions– Safe for high-risk patients– Allows for improved aerobic fitness


• Metabolic equivalent (MET)– Gauges intensity based on O2 consumption

– 1 MET = 3.5 ml O2/kg/min

– 1 MET = resting metabolic rate

• Published MET values for activities but– MET can vary considerably among individuals– Values fail to account for environmental conditions– Values fail to account for physical conditioning


• VO2 reserve (VO2R) method– ACSM position stand

– VO2R = VO2max – VO2rest

– Prescribe exercise as % VO2R

– Assumes 1 MET = universal resting VO2

• % Maximal HR reserve versus % VO2R


• Ratings of perceived exertion (RPEs)– Individuals rate how hard exercise feels– Numerical rating scale

• Borg RPE scale– Scale 6 to 20– Corresponds with HR– Very accurate when used correctly

Table 20.3Table 20.3

Exercise ProgramExercise Program

• Total exercise program includes1. Warm-up, stretching activities

2. Endurance training

3. Cool-down, stretching activities

4. Flexibility training

5. Resistance training

6. Recreational activities

• First three activities, 3 to 4 times per week


• Warm-up and stretching activities– Start with low-intensity calisthenics, stretching– Gradually increase HR, breathing– Prepare exerciser for more vigorous exercise– Can reduce muscle soreness

• Sample warm-up– 5 to 10 min stretching– 5 to 10 min low-intensity activity


• Endurance training– Develops cardiovascular endurance– Improves capacity and efficiency of cardiovascular,

respiratory, and metabolic systems– Controls body weight

• Best modes: walk/jog/run, cycle, swim, row

• Poor modes: golf, bowling, softball


• Cool-down and stretching– Should conclude every endurance workout– Reduced intensity– Do not stop abruptly

• Stretching after exercise flexibility


• Flexibility training– Supplements warm-up and cool-down periods– Useful for those with poor flexibility, joint pain– Should be performed slowly

• Timing of flexibility training– Best after workout– Tissues may be more adaptable and responsive

after exercise


• Resistance training– Starting point: 10 repetitions at 1/2 1RM– Proper starting weight: fatigue at repetitions 8 to 10– If 15 repetitions reached, increase weight

• 2 to 3 sets per day, 2 to 3 times per week

• Can reduce to 1 to 2 sets if needed (still see results in untrained people)


• Recreational activities important aspect of comprehensive exercise program

• Guidelines for selecting recreation: Will the activity– Be learned and performed with moderate success?– Provide opportunities for social development?– Keep costs within budget?– Maintain long-term interest?– Be safe given health and age?

Exercise and Rehabilitation Exercise and Rehabilitation for People With Diseasesfor People With Diseases

• Exercise a major component of rehabilitation

• Used in rehabilitation programs for– Cardiopulmonary disease– Cancer– Obesity, diabetes– Renal disease– Osteoporosis– Arthritis, chronic fatigue, fibromyalgia– Cystic fibrosis

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