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Benefits and Risks Associated with Exercise and Exercise Testing. Is Exercise Good For You?. Physical Activity vs. Exercise. Definition of Physical Activity Body movement that increases energy expenditure Examples – walking and gardening Definition of Exercise
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Benefits and Risks Associated with Exercise and Exercise Testing
Physical Activity vs. Exercise • Definition of Physical Activity • Body movement that increases energy expenditure • Examples – walking and gardening • Definition of Exercise • Specific physical tasks to elicit specific physiological responses – planned and structured • Time and tasks have goals – health or performance • Examples – jogging and strength training
Physical Activity vs. Exercise • Surgeon General Says…. • Health benefits from moderate amount of physical activity to improve quality of life • 30 min. brisk walking or raking leaves • 15 min. running • 45 min. playing volleyball • Most if not all days of the week
Physical Activity vs. Exercise • Surgeon General Says…. • Additional health benefits from more physical activity • Longer duration • More vigorous intensity • Likely to derive greater benefit
Implications • Quantity and quality of life improve through movement (PA or EX.) • Dose response occurs - greater dose, greater response • Public Health Policy • Recommend movement
Specific Health Changes Resulting From PA/EX • Improvement in cardiovascular and respiratory function (Box 1-1). • Increased maximal oxygen consumption • Lower myocardial oxygen cost per intensity • Increased capillary density in skeletal muscle • Lower HR and BP per intensity
Specific Health Changes Resulting From PA/EX • Reduced Risk • Certain disease processes occur less in physically fit people – inverse dose response relationship • All-cause mortality • Cardiovascular mortality • Type II diabetes • Hypertension • Colon cancer • Osteoporosis • Obesity
Specific Health Changes Resulting From PA/EX • Decreased mortality and morbidity (Box 1-1). • Primary prevention – to prevent heart attack • Fewer deaths from coronary artery disease (CAD) • Fewer diseases combined (CAD, colon cancer, Type II diabetes) • Secondary prevention – to prevent another • Conflicting results • Other benefits • Emotional, psychological, work / sport improvement
Specific Health Changes Resulting From PA/EX • Reduced coronary artery disease risk factors (Box 1-1). • Lower systolic and diastolic BP • Decreased serum triglycerides • Increased serum HDL • Lower body fat • Lower insulin needs
Determining Risk • Statistical Relationship • Large group studies • Nurses & medical personnel – bias: select group • Cities – Framingham, MA – bias: features of city, SES • Longitudinal studies • Single cohort – group selection bias • 5, 10, 15 year, etc. deaths and diseases • Meta-analysis studies • Pooled studies • Effect size
Do You Feel Lucky? • What level of risk / chance are you willing to accept? • Winning vs. Losing • 1 in 100, 1 in 1000, 1 in 100,000
Risks of Exercise • “Negative” event • Some people die during exercise • Apparently healthy vs. known disease • Risk of death during exercise • Higher than during sedentary • Highest for least frequent exercisers – least fit • Lowest for most frequent exercisers – most fit
What’s Dangerous About Exercise? • Arrhythmia – ventricular ectopic activity • Acute Exercise Stress • Increased myocardial O2 consumption • Shortened diastole – less time for perfusion • Sodium/potassium change • Increased catecholemines • Immediate Post Exercise • Decreased venous return • Decreased blood pressure
What’s Dangerous About Exercise? • Couple exercise with blocked coronary arteries • Even less blood flow – ischemia • Exercise is transient so ischemia is too • For some the injury is too great – not transient
If Exercise is Risky, Isn’t Exercise Testing Risky? • Various studies • Risk of death during or after exercise test (XT) is < .01% • Risk of “event” during or after XT is < .04%
How is Disease Detected? • Subjective symptoms • Chest pain – angina pectoris • Low exercise tolerance – fatigue & SOB • Graded Exercise Test (GXT) – stress the heart • ST segment changes (depression of 1mm or more) • Angina pectoris • Both
Diagnostic Value of Exercise GXTs(Remember?) • Sensitivity: percentage of people with CAD who have a positive exercise EKG test. • 68% for ECG stress test = TP/(TP + FN) • Specificity: percentage of people without CAD who have a negative exercise EKG test. • 77% for ECG stress test = TN/(TN + FP)
So Why Exercise? • Benefits outweigh risks • Feeling lucky?