Chapter 14 Patterns in Health and Disease: Epidemiology and Physiology

1. Chapter 14Patterns in Health and Disease:Epidemiology and Physiology EXERCISE PHYSIOLOGY Theory and Application to Fitness and Performance, 6th edition Scott K. Powers & Edward T. Howley

2. Epidemiology • The study of the distribution and determinants of health states and the use of this information in the control of disease • Uses of epidemiology: • Establish the cause of disease • Trace the natural history of disease • Describe the health status of populations • Evaluate an intervention • Epidemiologic triad • Shows connections between the environment, agent, and host that cause disease

3. The Epidemiologic Triad Figure 14.1

4. Disease Control • Destroying or removing the agent at its source • Altering the environment to reduce transmission of the agent • Improving the host’s resistance to the agent • Altering the host’s behaviors • Improved nutrition • Immunization • Exercise

5. Web of Causation • Difficult to establish the cause of chronic diseases • Cardiovascular disease • Complex involvement of factors • Risk factors • Genetic • Heredity • Environmental • Stress • Behavioral • Diet • Smoking • Physical activity

6. Web of Causation Figure 14.2

7. Major Risk Factor Categories Figure 14.3

8. Leading causes of death Heart disease Cancer Stroke Chronic lung disease Unintentional injuries Diabetes Actual causes of death Tobacco Diet and physical inactivity Alcohol consumption Infection Toxic agents Motor vehicles Firearms Leading and Actual Causes of Death

9. Coronary Heart Disease (CHD) • Associated with atherosclerosis • Thickening of the inner lining of arteries • Contributor to heart attack and stroke death • Diseases of the heart and blood vessels are the leading cause of death in the U.S. • Associated with risk factors • Each risk factor magnifies the risk of CHD • Eliminating a risk factor causes a disproportionate reduction in risk

10. CHD Risk Factors • Primary • Increases risk of CHD in and of itself • Secondary • Increases risk of CHD if primary risk factor is present • Can’t be changed • Can be changed

11. Can’t be changed Heredity Gender Age Race Can be changed Cigarette smoking High serum cholesterol High blood pressure Physical inactivity Diabetes Obesity Stress Risk Factors for CHD

12. Determining Association Between Risk Factor and Disease • Temporal Association • Plausibility • Consistency • Strength of association (relative risk) • Dose-response relationship • Reversibility • Study design • Judging the evidence

13. Physical Inactivity as a Risk Factor • Independent risk factor for CHD • Relative risk of CHD is similar to other risk factors • Smoking • High cholesterol • High blood pressure • High population attributable risk • Percentage of population at risk • Due to large number of inactive individuals

14. U.S. Population at Risk Figure 14.4

15. Metabolic Syndrome • Potential causative connections between risk factors • Hypertension • Obesity • Insulin resistance • Dyslipidemia • Leads to additional conditions • Hyperinsulinemia • Increased SNS activity • Increased blood volume • Increased resistance to blood flow

16. Metabolic Syndrome Figure 14.5

17. Risk Factors for Metabolic Syndrome • Abdominal obesity • Waist circumference >102 cm (men) and >88 cm (women) • Hypertriglyceridemia • ≥150 mg/dl • Low HDL cholesterol • <40 mg/dl (men) and <50 mg/dl (women) • High blood pressure • ≥130/85 mmHg • High fasting blood glucose • ≥110 mg/dl

18. Obesity • Prevalence in US adults • 65% are overweight (BMI = 25.0–29.9 kg/m2) • 30% are obese (BMI = ≥30.0 kg/m2) • Linked to risk of CHD and metabolic syndrome • Healthy People 2010 objectives for control of overweight and obesity • Nutrition objectives • Physical activity objectives