Physical Activity and Reduced Risk of Cardiovascular Disease Chicago, IL November 21, 2008 3:30 PM 4:45 PM
Session 7: Physical Activity and Reduced Risk of Cardiovascular Disease Learning Objectives Discuss the effects of physical activity on cardiovascular disease (CVD) risk factors. Explain the magnitude of benefit of physical activity on reducing CVD events in both primary and secondary prevention patients. Describe the mechanisms of the benefit of physical activity on reducing CVD events. Faculty Samia Mora, MD, MHS, FACC Assistant Professor of Medicine Brigham and Women s Hospital Harvard Medical School Dr Samia Mora is a board-certified internist and cardiologist with specialized training in cardiovascular epidemiology and echocardiography. Dr Mora has appointments in the Divisions of Cardiovascular Disease and Preventive Medicine, Department of Medicine, at the Brigham and Women s Hospital, and is an assistant professor of medicine at Harvard Medical School. She also serves the American Heart Association as chair of the Women in Cardiology Committee, scientific advisor to the Choose to Move Program and member of the Executive Database Steering Committee. She is also a Writing Member of the American College of Cardiology/American Heart Association Primary Prevention of Cardiovascular Disease Performance Measures Writing Committee. Faculty Financial Disclosure Statement Dr Mora has no financial relationships to disclose. Drug List There are no drugs mentioned in this presentation. Suggested Reading List Haskell WL, Lee IM, Pate RR, et al. Physical activity and public health: updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Med Sci Sports Exerc. 2007;39(8):1423-1434. Mora S, Lee IM, Buring JE, Ridker PM. Association of physical activity and body mass index with novel and traditional cardiovascular biomarkers in women. JAMA. 2006;295(12):1412-1419. Mora S, Cook N, Buring JE, Ridker PM, Lee IM. Physical activity and reduced risk of cardiovascular events: potential mediating mechanisms. Circulation. 2007 Nov 6;116(19):2110-2118. Taylor RS, Brown A, Ebrahim S, et al. Exercise-based rehabilitation for patients with coronary heart disease: systematic review and meta-analysis of randomized controlled trials. Am J Med. 2004;116(10):682-692. Session 7
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Physical Activity and Reduced Risk of Cardiovascular Disease Samia Mora, MD, MHS, FACC Assistant Professor of Medicine Brigham and Women s Hospital Harvard Medical School Topics to be covered Why bother with physical activity? Physical activity and CVD reduction Primary Prevention Secondary Prevention How does physical activity prevent CVD? Fat vs unfit: which is worse? What dose of physical activity? What proportion of US adults report NO leisure-time physical activity?? Why bother with physical activity? 1. 10% 2. 20% 3. 40% 4. 60% Prevalence of Metabolic Syndrome / Lifetime risk for Diabetes in U.S. Findings from NHANES III for metabolic syndrome 24% of adults 42% of individuals > age 60 Lifetime risk of diabetes if born in yr 2000 33% men 39% women Underscores urgent need to control obesity epidemic and improve physical activity Narayan, et al JAMA 2003;290:1884 Ford Et al, JAMA.2002;287:356-359. Percent of Population Trends in Health Conditions 70 60 56 65 50 48 47 40 40 40 30 20 29 28 10 24 20 29 18 0 1971-74 1976-80 1988-94 1999-00 Overweight/Obesity Hypertension High Blood Cholesterol Trends in the age-adjusted adjusted prevalence of health conditions, U.S. adults ages 20-74 (NHANES 1971-74 74 to 1999-2000). Briefel and Johnson. Annu Rev Nutr. 2004;24:401-431 431 1
Trends in CVD Risk Factors, British Men, 1978-1980 to 1998-2000 Smoking 73% Systolic BP 6.6 mmhg HDL-cholesterol 0.16 mmol/l Non-HDL cholesterol 0.28 mmol/l BMI 1.89 kg/m 2 Current Perspective Physical inactivity and increased body weight are major public health epidemics 38% no physical activity 66% overweight or obese 32% obese Hardoon et al, Circulation 2008;117:598-604 AHA Heart Disease and Stroke Statistics, 2008 Update Historical Perspective Health benefits of physical activity known for a long time ~ 2500 BCE, Chinese physicians advocated regular exercise, Kung fu developed to avoid illness Hippocrates (460-370 BCE): To keep well, avoid too much food, too little toil Historical Perspective Beginning in the 1940 s, epidemiologic studies, using comparison groups, documented inverse relation between physical activity and risk of CVD (active persons had lower disease rates) Ancient Olympic Games: winners only awarded an olive branch wreath, physical fitness seen as its own reward Early Morris Studies But drivers were also fatter! CHD Rate, per 1,000 3.0 2.5 2.0 1.5 0.5 P <1 P <1 Drivers Conductors Clerks Postmen % with trouser waist 36+ inches % with jacket chest 40+ inches Age, years Drivers Conductors Drivers Conductors 25-29 8 3 11 5 35-39 22 13 19 10 45-49 40 23 33 18 55-59 63 43 51 26 Transport workers Postal workers Morris et al, Lancet Nov 21, 1953: 1053-57 Morris et al, Lancet Sep 15, 1956: pp 569-70 2
~2.25 to 3 hr/wk of purposeful walking can lower CVD rates by? Physical activity and CVD reduction Primary Prevention 1. 10-20% 2. 15-30% 3. 40-50% Physical Activity and CHD Risk Harvard Alumni Health Study Harvard Alumni Health Study, Men <60y 1.2 ~40% risk, comparing extreme fifths 6.0 RR* of CHD 0.8 0.6 0.4 0.2 P, trend = 4 <1000 1000-1999 2000-2999 3000-3999 4000+ Physical Activity, Kcal/Wk Age-adjusted RR of CHD 5.0 4.0 3.0 2.0 Ref Inactive Ref Active No RF 1 RF 2 RF 3 RF 4+ RF * adjusted for age, smoking, alcohol, diet, family history, vitamins/minerals, hypertension, diabetes Lee et al; Circulation 2000;102:981-6 RF = smoking, hypertension, diabetes, overweight, no alcohol, parental history Sesso et al, Circulation 2000:102:975-80 Harvard Alumni Health Study, Men 60+y Women s Health Initiative Observational Study Age-adjusted RR of CHD 3.0 2.5 2.0 1.5 0.5 Ref Inactive RF = smoking, hypertension, diabetes, overweight, no alcohol, parental history Ref Active No RF 1 RF 2 RF 3 RF 4+ RF Sesso et al, Circulation 2000:102:975-80 Relative Risk of CHD 0.8 0.6 0.4 0.2 Vigorous exercise* P=08 1 2 3 4 5 1 2 3 4 5 Quintiles of activity (MET-hour/week**) CHD=Coronary heart disease Relative Risk of CHD 0.8 0.6 0.4 0.2 *Includes aerobics, aerobic dancing, jogging, tennis, and swimming laps **Average active hours per week energy expenditure per activity Walking P=04 Manson JE et al. NEJM 2002;347:716-25 3
Nurses Health Study, Diabetic Women Aerobics Center Longitudinal Study Multivariate RR* of CVD 1.2 0.8 0.6 0.4 0.2 <1 1-1.9 2-3.9 4-6.9 7+ Physical Activity, Hr/Wk Age-adjusted RR of CVD Mortality 3.5 3.0 2.5 2.0 1.5 0.5 T2 DM High Chol High BP Smoker Unfit RF absent RF present * adjusted for age, smoking, BMI, menopausal status, diet, hypertension, high cholesterol, aspirin use, parental history Hu et al, Ann Intern Med 2001;134:96-105 Among normal weight men; similar associations in overweight and obese Blair et al, JAMA 1999;282:1547-53 Exercise-based cardiac rehabilitation in patients with CHD reduces total mortality by? Physical activity and CVD reduction Secondary Prevention 1. 10% 2. 20% 3. 40% 4. 60% Pooled Odds Ratio 1.5 1 0.5 0 Effect of Cardiac Rehabilitation randomized controlled trials following a MI 1.15 0.76* 0.75* All Cause Death CV Mortality Nonfatal Recurrence Exercise-Based Cardiac Rehabilitation in CHD Patients Meta-analysis of 48 trials with ~9,000 patients (19 exercise only trials) ~80% men, 20% women 2/3 MI patients only; remainder included revascularization patients On average, 3.7 times/week, 53 min, 76% VO 2 max/max heart rate CV=Cardiovascular, MI=Myocardial infarction, *p<125 Oldridge NB et al. JAMA 1988;260:945-950 Taylor et al, Am J Med 2004;116:682-92 4
Exercise-Based Cardiac Rehabilitation in CHD Patients Outcome Results (95% CI) Total mortality 20% ( 7% to 32%)* Cardiac mortality 26% ( 10% to 39%)* Total cholesterol 14 mg/dl ( 4 to 23)* LDL cholesterol 8 mg/dl ( 24 to 5) HDL cholesterol 2 mg/dl ( 1 to 5 ) Triglycerides 20 mg/dl ( 6 to 35)* Systolic BP 3.19 mmhg ( 0.95 to 5.44)* Diastolic BP 1.16 mmhg ( 2.66 to 0.32) Exercise-Only vs. Comprehensive Rehabilitation Exercise-only: Total mortality Comprehensive: Total mortality 24% ( 2% to 41%)* 16% ( 1% to 28%)* Limitations Moderate Exercise and Reduced Mortality Observational study of self-reported physical activity in 772 men with CHD Few women (20% of total) Patients tended to be young (median, 55 y; range, 48-71 y) Majority lacked major co-morbidity (e.g., heart failure) Variation in intervention length Follow-up short (6-69 months; average 2.4 y) Trial quality poorly reported (details on randomization, blinded assessment, follow-up) Moderate exercise is associated with reduced mortality CHD=Coronary heart disease, CVD=Cardiovascular disease Wannamethee SG et al. Circulation 2000;102:1358-1363 CHD Patients, Cardiovascular Health Study Estimated Mortality Risk Reductions, CHD Patients Intervention Low-dose aspirin Statins Beta-blockers ACE inhibitors Risk Reduction (95% CI) 13% ( 1% to 30%) 21% ( 14% to 28%) 23% ( 15% to 31%) 26% ( 16% to 35%) RR adjusted for age, sex, race, smoking, alcohol, SES, adiposity, prevalent disease, type of CAD Janssen et al, MSSE 2006;38:418-23 Iestra et al, Circulation 2005;112:924-34 5
Estimated Mortality Risk Reductions, CHD Patients Intervention Physical activity Smoking cessation Moderate alcohol Dietary changes Estimated Risk Reduction 25% 35% 20% 45% How does physical activity prevent CVD? Iestra et al, Circulation 2005;112:924-34 Physical activity reduces CVD events by favorable effects on body weight more so than on inflammation or blood pressure. 1. True 2. False? Physical Activity Improves traditional CVD risk factors myocardial oxygen demand Improves endothelial function Effects on coagulation/clotting factors Effects on inflammatory markers Effects on autonomic tone Effects of Physical Inactivity Inflammation Physical Inactivity Dyslipidemia Effect on Body Composition 173 sedentary, overweight (BMI >24 kg/m2) post-menopausal women randomized to moderate intensity exercise vs. stretching for 1 year Total Body Fat Intra-abdominal Fat Age Hypertension Diabetes Mellitus Smoking Obesity Hypercoagulability Genetics Atherosclerosis Novel Risk Factors Moderate exercise reduces total and intra-abdominal fat Minutes per week spent in moderate-intensity sports activity (low-active, 135 min/wk; intermediately active, 136-195 min/wk; and highly active, >195 min/wk) Irwin ML et al. JAMA 2003;289:323-330 6
Lipids Effect of Physical Activity on Lipids TC Men Women LDL-C Men Women HDL-C Men Women TG Men Women Baseline 214 239 138 155 37 47 200 188 *P=001 for change in women vs men P=3 for change in women vs men Year and Lipid Level (mg/dl) 1 213 223 134 135 40 50 197 190 Warner JG et al. Circulation 1995;92:773-777 3 210 209 131 120 41 55 199 174 5 196 193 118 102 39 56 202 171 Change from Baseline 8% 20%* 15% 34%* 5% 20% HDL-C=High density lipoprotein cholesterol, LDL-C=Low density lipoprotein cholesterol, TC=Total cholesterol, TG=Triglyceride NS Effect of Exercise on Obesity and Diabetes 35% 30% 25% 20% 15% 10% 5% 0% DM=Diabetes mellitus Reduction: Each hour a day spent walking briskly Hu FB et al. JAMA 2003;289:1785-91 Nurse s Health Study Increase: Each two hours a day spent watching TV Risk of obesity Risk of DM Increase: Each two hours a day spent sitting or driving Exercise reduces the incidence of obesity and DM Exercise Reduces Incidence of Diabetes: Diabetes Prevention Program (DPP) 3234 subjects with fasting and postload glucose levels Lifestyle modification, metformin, or placebo Goals for 2-yr follow-up: 7% weight loss 150 min activity/week Incidence of diabetes (per 100 person-years) Placebo 1 Metformin 7.8 NNT = 14 Lifestyle modification 4.8 NNT = 7 Reduction in incidence Lifestyle 58% vs metformin 31% (P<5) Both lifestyle and metformin vs placebo (P<5) Effect of Fitness on Blood Pressure and HTN 4,884 healthy women examined at the Cooper Clinic, 1970-98 157 developed hypertension over 5 years Risk adjusted for age, exam year, alcohol intake, smoking, BP, family history of hypertension, waist girth, glucose, & triglycerides Risk of Developing Hypertension 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 P for trend <1 Low Moderate High Fitness Groups Diabetes Prevention Program Research Group. N Engl J Med. 2002;346:393-403. Barlow CE et al. Am J Epidemiol 2006; 163:142-50 Effect of Fitness on Inflammation (CRP) *p<5 after adjusting for fatness Hamer, Preventive Medicine 2007; 44:3-11 * * * * * * * * Physical Activity RCT s CVD Risk Factors (BP, lipids, glucose, etc.) CVD Observational epi studies 7
Potential Biologic Mechanisms Epidemiologic studies (and not just lab studies) can inform about potential biologic mechanisms underlying the protective effect of PA on chronic diseases One way to assess this is to look at statistical models that do not, and that do, adjust for the mechanism of interest E.g., we can look at the RR of CVD associated with being active, in a model that does NOT and that does adjust for blood pressure The degree to which the RR is attenuated can be attributed to the effect of blood pressure in mediating the relation between PA and CVD Mora et al, Circulation 2007;116 : 2110-8 Physical Activity and CVD Risk % of Risk Reduction Explained by Various Risk Factors Risk Reduction in CVD by Activity Level Women s s Health Study All Risk Factors 59% Inflammatory Markers Blood Pressure/ Hypertension 32.6% 27.1% Reference <200 kcal/wk N=6,789 200-599 kcal/wk N=6,732 600-1499 kcal/wk N=7,681 1500 kcal/wk N=5,853 Traditional Lipids Novel Lipids 19.1% 15.5% -27% -32% Body Mass Index Hemoglobin A1c/ Diabetes Homocysteine 10.1% 8.9% 0.7% Age and treatment adjusted relative risk, 11 year follow-up -41% Mora et al, Circulation 2007;116 : 2110-8 0 10 20 30 40 50 60 70 % Risk Reduction Mora et al, Circulation 2007;116:2110 Physical Activity and CVD Risk in Women % of Risk Reduction Explained by Various Risk Factors Heart Rate Recovery All Risk Factors 59% Inflammatory Markers Blood Pressure/ Hypertension Traditional Lipids Novel Lipids Body Mass Index Hemoglobin A1c/ Diabetes Homocysteine 32.6% 27.1% 19.1% 15.5% 10.1% 8.9% 0.7% Mora et al, Circ 2007;116: 2110 0 10 20 30 40 50 60 70 % Risk Reduction Lauer MS, ACC Current Journal Review 2001;10 8
Low Exercise Capacity and HR Recovery Combined Substantially Increase Risk Both High One Low Both Low Women who were below the median for both exercise capacity and heart rate recovery had 3.5-fold increased risk of CVD death Mora S et al, JAMA 2003;290:1600-1607 Adjusted RR CVD Death 12 10 8 6 4 2 P P 0 FRS < 6%FRS > 6% WOMEN Mora S et al, Circulation 2005:112:1566 12 10 8 P=08 6 4 2 P 0 FRS < 6% FRS > 6% MEN Fat vs Unfit: Which is worse? Both increased body weight and physical inactivity are powerful predictors of CVD, diabetes, and death Both are associated with CVD risk factors and they often occur together This has led to some controversy over the relative contributions of each to cardiovascular risk Fitness vs Fatness debate Fit, Fat, and Healthy? Physical activity may attenuate the increased cardiovascular risk associated with overweight and obesity Maintaining healthy weight is at least as important as being active for CVD and mortality 9
Physical Activity and CHD Risk Harvard Alumni Health Study BMI and CVD Mortality Harvard Alumni Health Study 1.2 ~40% risk, comparing extreme fifths 3.0 ~60% risk, comparing extreme fifths RR* of CHD 0.8 0.6 0.4 0.2 P, trend = 4 RR* of CVD Mortality 2.5 2.0 1.5 0.5 P, trend = 03 <1000 1000-1999 2000-2999 3000-3999 4000+ <22.5 22.5-<23.5 23.5-24.5 24.5-<26.0 26.0+ Physical Activity, Kcal/Wk Body Mass Index * adjusted for age, smoking, alcohol, diet, family history, vitamins/minerals, hypertension, diabetes Lee et al; Circulation 2000;102:981-6 * Among never smokers; adjusted for age and physical activity Lee et al; JAMA 1993;270:2823-8 BMI and CVD Mortality in Koreans Aerobics Center Longitudinal Study Healthy Men Adjusted RR of CVD Death 2.5 2.0 1.5 Normal Wt Overweight Obese DM Chol HTN SMK Unfit Jee et al; N Engl J Med 2006;355:779-87 Wei et al, JAMA 1999;282:1547-53 Risk of Death 6 5 4 3 2 1 0 METS All-Cause Mortality by Fitness & Fatness 2,196 Men with Diabetes <8.8 8.8-18 18-11.7 >11.7 <8.8 8.8-18 18-11.7 >11.7 <8.8 8.8-18 >18 Normal Weight Overweight Obese Church et al, Diabetes Care. 2004 Jan;27(1):83-8. Relative Risk of CHD Women s Health Study 1 0.8 0.6 0.4 0.2 0 <200 200-599 600-1499 1500+ Physical Activity, Kcal/Wk Lee et al, JAMA 2001; 285:1447-1454 Overwt Normal wt 10
Women s Health Initiative P trend = 03 P trend P trend Age-Adjusted RR of CVD 0.8 0.6 0.4 0.2 Q1 Q1 Q1 Q5 Q5 Q5 For some diseases (particularly type 2 diabetes), healthy weight is more important Normal Wt Overweight Obese Manson et al, NEJM 2002;347:716-725 Physical Activity, BMI and Risk of Diabetes Few studies have directly compared the effects of fit vs fat on CVD biomarkers Weinstein et al, JAMA 2004;292:1188-94 Fatness More Closely Associated with Higher Risk Biomarkers than Fitness in Healthy Men Fibrinogen vs BMI dashed line: after adjusting for fitness Christou et al, Circ 2005; 111:1904-14 Total Cholesterol vs BMI Women s Health Study: Correlations of Biomarkers Physical Activity BMI CRP -0.10 0.47 Fibrinogen -9 0.33 ICAM -0.10 0.21 Homocysteine -5 5 LDL cholesterol -5 0.15 HDL cholesterol 0.10-0.38 Total cholesterol -4 0.10 Apolipoprotein A1 7-0.25 Apolipoprotein B 100-8 0.26 Lipoprotein (a) 1 1 Creatinine 4-1 Mora et al, JAMA 2006; 295:1412-1419 11
Median Biomarker Levels by Physical Activity Quintiles Median Biomarker Levels by BMI Quintiles CRP Fibrinogen ICAM Homocysteine LDL Cholesterol HDL Cholesterol Total Cholesterol Apolipoprotein A1 151 151 150 148 146 Apolipoprotein B 100 98 98 100 104 106 Lipoprotein (a) Creatinine Kcal/wk Q5 >1574 1.78 335 337 10.4 119 54 207 10.4 0.72 Q4 1.78 346 337 10.3 120 53 206 10.9 0.71 Q3 1.90 349 339 10.3 121 52 208 10.5 0.71 Q2 2.11 354 346 10.5 122 51 209 1 0.71 Q1 144 2.54 362 358 10.8 125 49 211 10.2 0.70 P trend 0.12 CRP Fibrinogen ICAM Homocysteine LDL Cholesterol HDL Cholesterol Total Cholesterol Apolipoprotein A1 158 154 150 146 138 Apolipoprotein B 100 90 96 103 108 111 Lipoprotein (a) Creatinine Q1 21.9 0.87 322 325 10.3 113 60 201 10.1 0.71 Q2 1.31 335 331 10.3 118 56 206 10.4 0.71 Q3 1.85 350 339 10.4 124 53 210 10.9 0.71 Q4 2.64 363 350 10.5 126 49 213 1 0.71 Q5 >29.3 4.49 393 371 10.8 126 44 211 10.7 0.70 P trend 0.13 8 Mora et al, JAMA 2006; 295:1412-1419 Adjusted Odds Ratio 1 2 4 8 Adjusted Odds Ratios for CRP P C-Reactive Protein > 3 mg/l P =1 P =03 BMI 18.5-24.9 BMI 25-29.9 BMI 30+ active inactive Adjusted Odds Ratios for LDL cholesterol Adjusted Odds Ratio 1 2 4 8 P LDL Cholesterol > 130 mg/dl BMI 18.5-24.9 BMI 25-29.9 BMI 30+ active P =7 inactive P =0.77 Mora et al, JAMA 2006; 295:1412-1419 Mora et al, JAMA 2006; 295:1412-1419 Adjusted Odds Ratios for HDL cholesterol Adjusted Odds Ratio 1 2 4 8 P HDL Cholesterol < 50 mg/dl BMI 18.5-24.9 BMI 25-29.9 BMI 30+ active P =01 inactive P =02 Pathophysiology Increased body weight is associated with inflammatory and lipid biomarkers metabolically active adipose tissue proinflammatory and prothrombotic atherogenic dyslipidemia Association of physical activity with biomarkers independent of BMI less clear regular muscle movement may suppress inflammation locally systemically via muscle-derived cytokines or leptin endothelial function (nitric oxide, progenitor cells) Mora et al, JAMA 2006; 295:1412-1419 Grundy SM, Circ 2002;105:2696 Kasapis C, Thompson PD, JACC 2005;45:1563 12
Fit-Fat Summary Both unfit and fat were associated with higher risk biomarker levels Stronger associations seen for fat compared with unfit What dose of physical activity? Most favorable biomarkers in those with normal BMI (18.5-24.9) and active (1000 kcal/wk, ~2.5 hrs/wk) Current guidelines for general health benefits of physical activity recommend at least: 1. 30 min moderate activity, 5x/wk 2. 20 min vigorous activity, 3x/wk 3. Either 1 or 2 4. None of the above? Goals Minimum: 30-60 minutes, 5 days per week Optimal: 30-60 minutes, 7 days per week I IIa IIb III Physical Activity Guidelines Recommendations Assess risk, preferably with an exercise test, to guide prescription (Class I, Level B) Encourage aerobic activity (e.g., walking, jogging, cycling) supplemented by an increase in daily activities (e.g., walking breaks at work, gardening, household work) (Class I, Level B) Encourage resistance training (e.g., weight machines, free weights) 2 days a week (Class IIb, Level C) Encourage cardiac rehabilitation for patients with stable angina, recent MI, LV systolic dysfunction, or recent CABG (Class I, Level B) No Leisure-Time Physical Activity USA 1988 2005 Physical Activity Recommendations Over the Years 13
Recommendations Before 1995 No pain, no gain Vigorous exercise for at least 20 minutes continuously, 3X/week (e.g., running or jogging) E.g., recommendations from ACSM and AHA, 1970 s to early 1990 s Recommendations After 1995 Train, don t strain Accumulate at least 30 min/day of moderate-intensity PA most days (e.g., brisk walking) First issued by CDC/ACSM 1995 Similar recommendations adopted by many countries, including the UK (NHS Physical Activity Action Plan 2005) ACSM/AHA 2007 Update International Association for the Study of Obesity, 2002 Clarifies that either moderate or vigorous PA recommendation will do Clarifies that the moderate PA recommendation is on at least 5 days ( most days ) Clarifies that a combination of both moderate or vigorous activities are OK, so long as the total energy expended satisfies the minimum under either recommendation The current physical activity guideline for adults of 30 minutes of moderate intensity activity daily is of importance for limiting health risks for a number of chronic diseases For preventing weight gain or regain this guideline is likely to be insufficient for many individuals in the current environment. There is compelling evidence that prevention of weight regain in formerly obese individuals requires 60-90 minutes of moderate intensity activity or lesser amounts of vigorous intensity activity. Although definitive data are lacking, it seems likely that moderate intensity activity of approximately 45-60 minutes per day is required to prevent the transition to overweight or obesity. Major Issue to Consider Which dose is best: moderate or vigorous? Intensity of PA and total volume of energy expended are closely correlated Appropriate study design or analyses are needed to get right answer E.g., if we see these rates of disease associated with different PA intensities: no activity 15/10,000 (referent) mod intensity 12/10,000 (p=0.32) vig intensity 5/10,000 (p=2) Unclear whether it is intensity or total energy expenditure that accounts for the results 14
WHI Observational Cohort Moderate vs. Vigorous Intensity PA and CVD Risk Factors ~ 12.5 MET-hr ~ 10 MET-hr Data from RCT s show that when total energy expended is held constant: Vigorous PA confers additional benefits for fitness, DBP, glucose/insulin No additional benefit of vigorous PA for weight control, SBP, HDL Manson et al, NEJM 2002;347:716-25 Swain et al, Am J Cardiol 2006;97:141-7 Physical Activity and CVD There is a large body of evidence showing that higher volume of energy expended is associated with lower CVD rates; there is also clear evidence of a dose-response This energy expenditure can come from moderate or vigorous intensity PA There are limited data on whether vigorousintensity PA confers additional risk reduction for CVD risk, beyond its contribution to the total energy expended Physical Activity It is reasonable to follow current guidelines for general health benefits: 30 min moderate PA, 5x/wk or 20 min vigorous PA, 3x/wk or combination Choice of moderate- or vigorous-intensity PA can be dependent on patient preference Also consider risk:benefit for patient Topics covered today Why bother with physical activity? Physical activity and CVD reduction Primary Prevention Secondary Prevention How does physical activity prevent CVD? Fat vs unfit: which is worse? What dose of physical activity? Conclusions CVD is a leading cause of death world-wide Physical activity is associated with decreased risk of subsequent cardiovascular events and mortality among persons at high risk (e.g., CHD patients), and among persons at usual risk, who do and do not have CVD risk factors 15
Conclusions The magnitude of decreased risk associated with a physically active way of life is comparable to that seen with avoidance of other CVD risk factors, use of cardioprotective drugs (e.g., aspirin, beta-blockers, statins) Most of the benefit of physical activity on reducing CVD can be explained by favorable effects on risk factors, in particular inflammation and blood pressure For the same caloric intake, what dose of physical activity is the minimum required for weight loss? 1. 30-60 min moderate activity, 5x/wk 2. 60-90 min moderate activity, 5x/wk? 16