Exercise in prevention of myocardial infarction

A review states (1):

• people who are physically active reduce their risk of developing coronary heart disease, stroke and type II diabetes by up to 50%
  • people who are physically active reduce their risk of developing coronary heart disease, stroke and type II diabetes by up to 50% and reduce the risk of premature death by about 20-30%. Individuals who are active are almost two times less likely to die prematurely from a heart attack than their inactive contemporaries
• more than two-thirds of the UK population is not sufficiently active to accrue cardiovascular benefits
• primary care practitioners should identify and advise inactive adults to aim for 30 minutes of moderate intensity physical activity on 5 or more days of the week
  • healthy adults aged 18 - 65 years are recommended to participate in moderate-intensity aerobic physical activity for a minimum of 30 minutes on five days each week or vigorous intensity aerobic activity for a minimum of 20 minutes on three days each week
    • a variety of moderate and vigorous intensity activities can be combined to meet the recommendations. For example,walking briskly for 30 minutes twice a week and jogging for 20 minutes on two other days of the week

Although regular vigorous physical activity confers maximum cardiovascular benefit, it is apparent that this level of activity is unattainable and unlikely to be sustainable for the majority of the population.

Regular moderate intensity physical activity:

• reduces adiposity, particularly in those with excess upper body and abdominal fat
• reduces both systolic and diastolic blood pressure in individuals with elevated blood pressure by approximately 3.8mmHg and 2.6mmHg respectively
• reduces elevated plasma triglycerides
• increases high density lipoprotein cholesterol level
• improves insulin sensitivity and glucose use and reduces the risk of type II diabetes

Note that:

• benefits of regular moderate-to-vigorous intensity physical activity far outweigh the risks except in those with the following conditions:
  • symptomatic severe aortic stenosis
  • acute pulmonary embolus or pulmonary infarction
  • acute myocarditis or pericarditis
  • suspected or known dissecting aneurysym
  • resting SBP >= 180mmHG / DBP >=100 mmHG
  • uncontrolled / unstable angina
  • acute uncontrolled psychiatric illness
  • osteoporosis (T score >=2.5)
  • experiences significant drop in BP during exercise
  • uncontrolled resting tachycardia >=100 bpm
  • unstable or acute heart failure
  • uncontrolled diabetes
  • new or uncontrolled arrhythmias
  • experiences chest pain, dizziness or excessive breathlessness during exertion

In healthy sedentary adults, regular brisk walking improves cardiovascular fitness, body composition, and diastolic blood pressure (3):

• on average walking was done 4.4 days per week for 38 minutes per session

Reference:

• (1) British Heart Foundation Factfile (September 2008). Physical activity to reduce cardiovascular risk.
• (2) Murphy MH et al. The effect of walking on fitness, fatness and resting blood pressure: a meta-analysis of randomised, controlled trials.Prev Med. 2007
• (3) Br Heart J 1991; 66:384-394.