How Much Exercise Is Necessary to Prevent CV Disease?

Thomas G. Allison, PhD, MPH

Mayo Clinic, Rochester, MN, USA

ExercisePrevention

of CHD

Amount of exercise?

Exercise intensity?

Type of exercise?

The relationship between exercise or physical fitness and CHD is curvilinear

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kcal of Exercise per Week

– CHD risk = f(1/x)

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Age 70-84 Age 60-69 Age 50-59 Age 35-49

Relationship of Leisure-Time Physical Activity to All-Cause Mortality in Male Harvard Alumni

< 500 kcal/week

500-1999 kcal/week

2000+ kcal/week

Benefits of Exercise Increase with Age (and Risk)

CHD Risk Factor Trends in US

Risk factors declining since 1980

• Smoking• LDL cholesterol

Risk factors increasing since 1980

• Obesity• Diabetes/IFG• Low HDL cholesterol• High triglycerides• Sedentary lifestyleNot strongly associated with

exercise/physical activity

Strongly associated with exercise/physical activity

Physical Activity and All-cause Mortality In Iowa Women

• Prospective cohort study of 40,417 women

• Aged 55-69 years at baseline

• Followed 7 years

• Physical activity assessed by mailed questionnaire

Kushi et al, JAMA 1997;277:1287-1292

All-cause Mortality In Iowa Women Related to Moderate and Vigorous Activity

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CHD and Exercise in Women

• Women’s Health Initiative Observational Study

• 73,743 women reporting amount and intensity of exercise, including walking, and amount of time sitting– age 50-79 years– no baseline CHD or cancer– followed from 1994-1998 through August 27, 2000

Manson et al, NEJM 2002;347:716-725

Age-Adjusted Rate of CV Events According to Quintiles of Total Physical Activity

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MET-hours/week

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(1000 kcal/week 16.7 MET-hours/week)

CHD and Exercise in Men

• Health Professionals Follow-up Study

• 44,452 male health professionals

• Baseline age 40-72 years

• Excluding baseline CHD and cancer

• Biennial questionnaire reporting amount and type of physical activity

• Followed 1986 to January 31, 1998

Tanasescu et al, JAMA 2002;288:1994-2000

Rate of New CHD According to Quintiles of Total Physical Activity

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MET-hours/week

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(2000 kcal/week 33.3 MET-hours/week)

Types of Exercise

• Significant reductions in risk seen with – total physical activity– running– jogging– walking– rowing– weight training > 30 minutes per week

CHD and Exercise Intensity

• New analysis of Harvard Alumni Study

• 7337 men reporting amount and absolute and relative exercise intensity– average age 66 years– no baseline CHD or cancer– followed from 1988 to 1995– CHD = angina pectoris, MI, PTCA, CABG,

CHD deathLee et al, Circ 2003;107:1110-1116

Exercise Classification

• Amount of exercise:[< 1000] vs [1000-2499] vs [ 2500 kcal/week]

• Absolute intensity of exercise:[< 3] vs [3-6] vs [> 6 METs]

• Relative intensity of exercise (based on 10-point Borg Scale):[Weak or less (0-2)] vs [Moderate (3)] vs

[Somewhat Strong (4)] vs [Strong or greater (5+)]

0 Nothing at all0.5 Very, very weak1 Very weak2 Weak3 Moderate4 Somewhat strong5 Strong67 Very strong8910 Very, very strong• Maximal

Results

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Amount Absolute Intensity Relative Intensity

Exercise Classification

Age-adjusted relative risk of CHD (n = 551) by ascending categories of exercise amount, absolute intensity, and relative intensity

How Does CV Fitness Contribute to Risk Stratification?

FAC Group (% predicted)

FRS Group

>110%90-109%

70-89% 50-69% <50%

< 5% 0.7 1.2 1.7 5.0 14.1

5 - 9.9% 1.7 2.4 3.6 9.6 22.1

10 – 14.9% 2.3 4.0 7.2 11.5 22.3

15 – 19.9% 5.6 6.7 10.6 13.9 32.5

≥ 20% 5.4 10.8 15.5 20.0 27.2

Al Badarin FJ, Kopecky SL, Allison TG.  JACC 2009 Mar; 53(10 Suppl 1):A258.  (Abstract)

8-Year All-Cause Mortality

Recommendations

• Start with a level of exercise appropriate to the baseline fitness and activity level of the patient

• Progressively advance the exercise prescription until risk factors are optimally controlled … or limits of tolerance are reached

Recommendations

Amount of exercise

• To “get on the flat tail” of the CHD:exercise curve, it appears that one or more of the following are needed:– “vigorous” exercise at least 2-4 times per week– at least 2000 kcal/week in leisure-time physical activity– exercise capacity of 10 METs for men or 9 METs for

women

Recommendations

Exercise intensity

• Relative exercise intensity of 4 (“somewhat strong”) on the 10-point Borg scale– probably 12-14 on the older 6-20 Borg scale

Type of exercise

• Running, jogging, walking, rowing, weight training have all been validated

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