Benefits and Risks Associated with Exercise and Exercise Testing

Is Exercise Good For You?

Physical Activity vs. Exercise Definition of Physical Activity Definition of Physical Activity Body movement that increases energy expenditure Body movement that increases energy expenditure Examples – walking and gardening Examples – walking and gardening Definition of Exercise Definition of Exercise Specific physical tasks to elicit specific physiological responses – planned and structured Specific physical tasks to elicit specific physiological responses – planned and structured Time and tasks have goals – health or performance Time and tasks have goals – health or performance Examples – jogging and strength training Examples – jogging and strength training

Physical Activity vs. Exercise Surgeon General Says…. Surgeon General Says…. Health benefits from moderate amount of physical activity to improve quality of life Health benefits from moderate amount of physical activity to improve quality of life 30 min. brisk walking or raking leaves 30 min. brisk walking or raking leaves 15 min. running 15 min. running 45 min. playing volleyball 45 min. playing volleyball Most if not all days of the week Most if not all days of the week

Physical Activity vs. Exercise Surgeon General Says…. Surgeon General Says…. Additional health benefits from more physical activity Additional health benefits from more physical activity Longer duration Longer duration More vigorous intensity More vigorous intensity Likely to derive greater benefit Likely to derive greater benefit

Implications Quantity and quality of life improve through movement (PA or EX.) Quantity and quality of life improve through movement (PA or EX.) Dose response occurs - greater dose, greater response Dose response occurs - greater dose, greater response Public Health Policy Public Health Policy Recommend movement Recommend movement

Specific Health Changes Resulting From PA/EX Improvement in cardiovascular and respiratory function (Box 1-1). Improvement in cardiovascular and respiratory function (Box 1-1). Increased maximal oxygen consumption Increased maximal oxygen consumption Lower myocardial oxygen cost per intensity Lower myocardial oxygen cost per intensity Increased capillary density in skeletal muscle Increased capillary density in skeletal muscle Lower HR and BP per intensity Lower HR and BP per intensity

Specific Health Changes Resulting From PA/EX Reduced Risk Reduced Risk Certain disease processes occur less in physically fit people – inverse dose response relationship Certain disease processes occur less in physically fit people – inverse dose response relationship All-cause mortality All-cause mortality Cardiovascular mortality Cardiovascular mortality Type II diabetes Type II diabetes Hypertension Hypertension Colon cancer Colon cancer Osteoporosis Osteoporosis Obesity Obesity

Specific Health Changes Resulting From PA/EX Decreased mortality and morbidity (Box 1-1). Decreased mortality and morbidity (Box 1-1). Primary prevention – to prevent heart attack Primary prevention – to prevent heart attack Fewer deaths from coronary artery disease (CAD) Fewer deaths from coronary artery disease (CAD) Fewer diseases combined (CAD, colon cancer, Type II diabetes) Fewer diseases combined (CAD, colon cancer, Type II diabetes) Secondary prevention – to prevent another Secondary prevention – to prevent another Conflicting results Conflicting results Other benefits Other benefits Emotional, psychological, work / sport improvement Emotional, psychological, work / sport improvement

Specific Health Changes Resulting From PA/EX Reduced coronary artery disease risk factors (Box 1-1). Reduced coronary artery disease risk factors (Box 1-1). Lower systolic and diastolic BP Lower systolic and diastolic BP Decreased serum triglycerides Decreased serum triglycerides Increased serum HDL Increased serum HDL Lower body fat Lower body fat Lower insulin needs Lower insulin needs

Determining Risk Statistical Relationship Statistical Relationship Large group studies Large group studies Nurses & medical personnel – bias: select group Nurses & medical personnel – bias: select group Cities – Framingham, MA – bias: features of city, SES Cities – Framingham, MA – bias: features of city, SES Longitudinal studies Longitudinal studies Single cohort – group selection bias Single cohort – group selection bias 5, 10, 15 year, etc. deaths and diseases 5, 10, 15 year, etc. deaths and diseases Meta-analysis studies Meta-analysis studies Pooled studies Pooled studies Effect size Effect size

Do You Feel Lucky? What level of risk / chance are you willing to accept? What level of risk / chance are you willing to accept? Winning vs. Losing Winning vs. Losing 1 in 100, 1 in 1000, 1 in 100,000 1 in 100, 1 in 1000, 1 in 100,000

Risks of Exercise “Negative” event “Negative” event Some people die during exercise Some people die during exercise Apparently healthy vs. known disease Apparently healthy vs. known disease Risk of death during exercise Risk of death during exercise Higher than during sedentary Higher than during sedentary Highest for least frequent exercisers – least fit Highest for least frequent exercisers – least fit Lowest for most frequent exercisers – most fit Lowest for most frequent exercisers – most fit

What’s Dangerous About Exercise? Arrhythmia – ventricular ectopic activity Arrhythmia – ventricular ectopic activity Acute Exercise Stress Acute Exercise Stress Increased myocardial O 2 consumption Increased myocardial O 2 consumption Shortened diastole – less time for perfusion Shortened diastole – less time for perfusion Sodium/potassium change Sodium/potassium change Increased catecholemines Increased catecholemines Immediate Post Exercise Immediate Post Exercise Decreased venous return Decreased venous return Decreased blood pressure Decreased blood pressure

What’s Dangerous About Exercise? Couple exercise with blocked coronary arteries Couple exercise with blocked coronary arteries Even less blood flow – ischemia Even less blood flow – ischemia Exercise is transient so ischemia is too Exercise is transient so ischemia is too For some the injury is too great – not transient For some the injury is too great – not transient

If Exercise is Risky, Isn’t Exercise Testing Risky? Various studies Various studies Risk of death during or after exercise test (XT) is <.01% Risk of death during or after exercise test (XT) is <.01% Risk of “event” during or after XT is <.04% Risk of “event” during or after XT is <.04%

How is Disease Detected? Subjective symptoms Subjective symptoms Chest pain – angina pectoris Chest pain – angina pectoris Low exercise tolerance – fatigue & SOB Low exercise tolerance – fatigue & SOB Graded Exercise Test (GXT) – stress the heart Graded Exercise Test (GXT) – stress the heart ST segment changes (depression of 1mm or more) ST segment changes (depression of 1mm or more) Angina pectoris Angina pectoris Both Both

Diagnostic Value of Exercise GXTs (Remember?) Sensitivity: percentage of people with CAD who have a positive exercise EKG test. 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. 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 Benefits outweigh risks Feeling lucky? Feeling lucky?

Questions?

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