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| REVIEW ARTICLE |
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| Year : 2017 | Volume
: 6
| Issue : 3 | Page : 109-114 |
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Exercise for prevention of cardiovascular disease: Evidence-based recommendations
Geevar Zachariah1, Anoop George Alex2
1 Department of Cardiology, Mother Hospital, Thrissur, Kerala, India
2 Department of Cardiology, Christian Medical College, Vellore, Tamil Nadu, India
| Date of Web Publication | 4-Jul-2017 |
Correspondence Address:
Geevar Zachariah
Chief of Cardiology and Chairman Mother Heart Care, Mother Hospital, Pantheon, Remadevi Mandir Lane, Punkunnam, Thrissur - 680 002, Kerala
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/JCPC.JCPC_9_17
Sedentary lifestyle is one of the major risk factors for cardiovascular disease (CVD). In India, a large percentage of the people are physically inactive with fewer than 10% engaging in recreational physical activity. Physical activity has many beneficial effects on the risk factors for CVD. Apart from improving fitness level, it decreases myocardial oxygen demand and improves myocardial perfusion. There is an inverse association between physical activity and all-cause mortality. In primary prevention, physical inactivity is associated with a two-fold increase in the risk for coronary events. In secondary prevention, data confirm the existence of an inverse dose–response relationship between cardiovascular fitness and the all-cause mortality in large populations of cardiovascular patients. Guidelines from the American authorities as well as the European Society of Cardiology provide specific recommendations for exercise depending on the clinical setting (primary or secondary prevention of CVD) and the patient-specific factors (the patient's physical activity level and the perceived CVD risk). The present review summarizes the clinical evidence regarding the role of exercise in CVD prevention and the exercise recommendations from the leading Cardiac societies. Keywords: Aerobic exercise program, European Society of Cardiology guidelines, exercise intensity, physical activity, US guidelines
How to cite this article:
Zachariah G, Alex AG. Exercise for prevention of cardiovascular disease: Evidence-based recommendations. J Clin Prev Cardiol 2017;6:109-14 |
| Introduction | |  |
Regular physical activity and exercise are important in reducing risk of death and cardiovascular events in the primary as well as in the secondary prevention.[1],[2],[3],[4] A sedentary lifestyle is one of the major risk factors for cardiovascular disease (CVD).[5] More than 25% of the population attributable risk for myocardial infarction (MI) is due to physical inactivity.[6] Most international guidelines emphasize the importance of regular exercise as a valuable nonpharmacological tool for prevention of CVD.[7],[8],[9] In India, a large percentage of the people are physically inactive with fewer than 10% engaging in recreational physical activity.[10] India is now facing a huge burden of CAD and efforts to promote physical activity and reduce sedentary lifestyle plays an important role containing the problem.
| Definitions | | |
Physical activity is any bodily movement produced by the contraction of skeletal muscle that increases energy expenditure above the basal level.[9] Exercise is a subcategory of physical activity, that is, planned, structured, repetitive, and purposeful with the objective of improving or maintaining one or more components of physical fitness. Physical fitness is defined as the ability to carry out daily tasks with vigor and alertness, without undue fatigue, and with ample energy to enjoy leisure-time pursuits and meet unforeseen emergencies.
Exercise can be dynamic (isotonic) where there is a movement of the limb or static (isometric) which is not associated with movement of the limb. Dynamic exercise is further classified as either concentric (associated with shortening of muscle fibers) or eccentric (associated with lengthening of muscle fibers as that which occur when weight is lowered against gravity). Exercise can also be classified as aerobic when oxygen is available and anaerobic in the absence of oxygen. Most physical activities have dynamic and static components as well as aerobic and anaerobic metabolism. A particular physical activity is classified based on dominant, mechanical, or metabolic characteristics. Dynamic aerobic exercise cause volume load on heart whereas isometric exercise cause pressure overload. Both kinds of exercise increase physical fitness. Endurance training leads to improvements in aerobic capacity and favorable effects on cardiopulmonary and metabolic variables. Isometric exercise and resistance training enhances muscular strength, endurance, and muscle mass.[11]
| Types of Physical Activity and Intensity | | |
Examples of physical activity involve not only sport-related activities but also lifestyle-common activities such as walking briskly, climbing stairs, doing more housework and gardening work, and engaging in active recreational pursuits.[12] Absolute intensity of physical activity is the amount of energy expended per minute of activity. This can be assessed by oxygen uptake per unit of time (mL/min) or by metabolic equivalent (MET). One MET is the rate of energy expenditure of an adult while sitting at rest. It is taken by convention to be an oxygen uptake of 3.5 mL/kg of body weight per minute. Moderate intensity physical activity implies activity performed at an intensity of 3–6 METs and vigorous intensity physical activity includes that performed at >6 METs.[13]
Absolute intensity does not take into account of individual factors such as body weight, sex, and fitness level. An older person exercising at the vigorous intensity of 6 METs may be exercising at their maximum intensity while a younger person working at the same absolute intensity may be exercising moderately.[7] Relative intensity is the level of effort required to perform an activity. Less-fit individuals require higher level of effort than fitter people. Relative intensity is determined relative to an individual's level of cardio-respiratory fitness (VO2 max) or as a percentage of a person's measured or estimated heart rate (HR) (%max HR) which is 220-age. It is also expressed as an index of the individual rate of effort (how hard the person feels he is exercising), that is, the rating of perceived exertion or by frequency of breathing.[7] Moderate-intensity physical activity should be defined in relative terms as an activity performed at 40%–59% of VO2 or HR reserve, or at a rate of perceived exertion of 5–6 in CR10 Borg scale, which would correspond to an absolute energy expenditure of 4.8–7.1 METs in the young, 4.0–5.9 METs in the middle-aged, 3.2–4.7 METs in the old, and 2.0–2.9 METs in the very old.[14] Analogously, vigorous-intensity physical activity is performed at 60%–85% of VO2 or HR reserve, or at a rate of perceived exertion of 7–8 in the CR10 Borg scale, corresponding to an absolute energy expenditure of 7.2–10.1 METs in the young, 6.0–8.4 METs in the middle-aged, 4.8–6.7 METs in the old, and 3.0–4.2 METs in the very old.[14]
| Mechanism of Benefit of Exercise | | |
Regular aerobic physical activity improves exercise performance. Ideally, one should exercise to the intensity of 40%–85% of VO2.[15] Exercise improves fitness level and thereby quality of life.[16] It also decreases myocardial oxygen demand by decreasing the product of HR and systolic blood pressure and reducing myocardial ischemia. Regular exercise also improves myocardial perfusion. It increases the diameter of epicardial coronary arteries and also has favorable effects on microcirculation and endothelial function. Regular exercise has antithrombotic effects and helps to prevent coronary occlusion. Antithrombotic effects are mediated through increased plasma volume, reduced viscosity of blood, decreased platelet aggregation, and increased thrombolytic activity.[17] Regular exercise also reduces risk of an arrhythmic event by affecting the autonomic function.[18] Physical activity has many beneficial effects on the risk factors for coronary artery disease. Regular physical activity not only reduces blood pressure in established hypertension but also helpful in preventing development of hypertension. It is well known to increase protective HDL cholesterol, improve glycemic control in diabetics, prevents onset of diabetes, and helpful in maintaining ideal bodyweight.[9] Regular exercise also helps in ischemic preconditioning, by which transient myocardial ischemia during exercise protects the myocardium from subsequent more prolonged ischemia.[19]
| Evidence of Benefit of Exercise in Primary Prevention | | |
Randomized trials to observe the effects of physical activity and exercise on the primary prevention of cardiovascular outcomes has been scarce due to many factors such as ethical issues in assigning people to control group and nonadherence to long-term exercise regimen. The available randomized trials are not very informative because they enrolled only small number of participants. Hence, most data come from observational trials.
| Physical Activity and Coronary Events | | |
Physical inactivity is associated with at least a two-fold increase in the risk for coronary events.[20] Prolonged sitting or sedentary time has also been associated with an increased risk for diabetes and CVD.[21] The results of studies investigating the relation between habitual physical activity and morbidity and/or mortality associated with CVD, published since 1996 quite consistently show lower event rates in more physically active men and women than for their least active counterparts.[1]
A systemic review of 16 prospective, cohort studies and 4 case-control studies on coronary heart disease (CHD) in men, involving 124,000 men aged 15–96 years, clearly showed the benefit of regular exercise in preventing cardiovascular events.[1] Among the prospective cohort studies, the median RR was 0.81 for moderate intensity activity versus no or light activity, and 0.68 for vigorous intensity activity versus light or no activity. For the 6 case-control studies, the median RR was 0.65 for moderate intensity versus no or light activity, and 0.53 for vigorous intensity activity versus no or light activity.
In the Nurses' Health Study of 72488 women between 40 and 65 years of age, it was found that brisk walking or vigorous exercise was inversely related to the risk of a coronary event.[22] In a review of over 70,000 postmenopausal women in the Women's Health Initiative Observational Study, prolonged sitting predicted an increase in cardiovascular risk.[23]
In a systemic review of studies of women reporting CHD clinical events which included more than 200,000 participants aged 20–85 years, the median RR of having a CHD clinical event for women reporting participation in moderate intensity of physical activity compared to women reporting no or only light intensity activity was 0.78, while the RR for women performing vigorous or high amounts of activity as compared to women reporting no or light activity was 0.62.[1]
| Physical Activity and Mortality | | |
Available data strongly support an inverse association between physical activity and all-cause mortality.[1] Active individuals have approximately a 30% lower risk of dying during follow-up, compared with inactive individuals. This inverse relationship has been observed irrespective of country of residence, age, race, and ethnicity. In one study, even in persons with impaired mobility (unable to walk 2 km or climb one flight of stairs without difficulty), physical activity was associated with lower all-cause mortality rates. A 2014 meta-analysis of cohort studies in elite athletes found that compared with the general population, athletes have 67 percent lower mortality.[24]
In a retrospective study of over 12 years, physical activity habits were analyzed in 10,269 Harvard alumni (mean age 58).[25] Those engaged in moderately vigorous sports activity (defined as total physical activity levels >4200 kJ/week or brisk walking, recreational cycling or swimming, home repair, and yard work for 30 min/day on most days) had a 23% lower risk of death than those who were less active.
In a systematic review of studies looking at the relationship between physical activity and premature mortality, 31% of lower risk for all-cause mortality was observed in the most active individuals. The median risk reduction was 32%.[1] The greatest differences in risk occurred between the lowest adjacent activity and fitness categories, suggesting that sedentary individuals can markedly reduce their risk for all-cause mortality with relatively minor increments in physical activity.
It has been estimated that by eliminating physical inactivity, 6% of CVD worldwide may be eliminated and life expectancy of the world may be increased by 0.68 years.[26]
| Recommendations for Primary Prevention of Cardiovascular Disease | | |
Based on the available literature, there is compelling evidence that the recommendation of 30 min of moderate intensity exercise on most days of the week (equivalent to 4.2 MJ/week or 1,000 kcal/week) reaches a threshold associated with significant reductions in cardiovascular-related mortality.[27],[28]
Brisk walking has also been shown to be preferable to a slower pace.[29] Current recommendations require at least 1000 kcal of caloric expenditure per week to achieve exercise-induced protection against premature cardiovascular death.[30] Evidence also suggests that the benefits of exercise on reducing mortality may plateau after a certain activity level.[31]
Doses above 100 min/day for moderate-intensity physical activity in healthy individuals do not appear to be associated with additional reductions in mortality rates.[32]
| Us Recommendations for Physical Activity for Primary Prevention of Cardiovascular Disease | | |
Following are the recommendations from the American Heart Associations and the American College of Sports Medicine.[33],[34]
- All adults aged 18–65 years should perform moderate-intensity aerobic (endurance) physical activity for a minimum of 30 min on 5 days each week or vigorous-intensity aerobic activity for a minimum of 20 min on 3 days each week (I [A])
- Combinations of moderate- and vigorous-intensity activity can be performed to meet this recommendation (IIa [B])
- Above activities are in addition to the light intensity activities frequently performed during daily life
- Multiple bouts of exercise each lasting 10 or more minutes can be performed to satisfy the goal of minimum 30 min moderate intensity physical activity (I [B])
- In addition, at least twice each week adults will benefit by performing activities using the major muscles of the body that maintain or increase muscular strength and endurance (Ia [A])
- Exceeding the minimum recommended amount of physical activity may provide additional benefit (I [A]).
For older adults, recommendations for moderate- and vigorous-intensity physical activity are the same as for younger adults. They should also perform muscle strengthening activities. Like younger adults, they can also if desired further exceed the minimum recommended amount of physical activity.
However, to maintain the flexibility necessary for regular physical activity and daily life, older adults should perform activities that maintain or increase flexibility on at least 2 days each week for at least 10 min each day (IIb [B]) and to reduce risk of injury from falls, community-dwelling older adults with substantial risk of falls should perform exercises that maintain or improve balance (IIa [A]) Many months of activity at less than recommended levels is appropriate for some older adults (e.g., those with low fitness) as they increase activity in a stepwise manner.
| European Society of Cardiology Recommendations for Physical Activity for Primary Prevention of Cardiovascular Disease | | |
- Healthy adults of all ages should perform at least 150 min a week of moderate-intensity or 75 min a week of vigorous-intensity aerobic physical activity or an equivalent combination thereof (I [A])[7]
- For additional benefit, a gradual increase to 300 min a week of moderate-intensity or 150 min a week of vigorous-intensity aerobic physical activity or an equivalent combination is recommended (I [A])
- Regular assessment and counseling are recommended to support an increase in volume of exercise over time (I [B]). For low-risk individuals, further assessment is not required
- Multiple sessions of physical activity should be considered each lasting >10 min, preferably every day of the week (IIa [B]).
Clinical evaluation should be considered for sedentary people with CV risk factors who intent to engage in vigorous physical activity or sports [IIa (C)]. Starting with a low-intensity activity is recommended in sedentary individuals and those with cardiovascular risk factors.
| Physical Activity and Exercise for Secondary Prevention of Cardiovascular Disease | | |
Evidence of benefit of exercise in secondary prevention
Aerobic physical activity in patients with known CVD is usually considered as part of the cardiac rehabilitation program. Hence, data on influence of habitual physical activity level on cardiovascular outcomes in cardiac patients is scarce. Further, effects of physical activity alone on cardiovascular risk may not be easily discernible. However, a meta-analysis which included mainly middle-aged men, with a previous acute MI, prior coronary artery bypass grafting (CABG), prior percutaneous transluminal coronary angioplasty or stable angina pectoris, showed around 30% reduction in total cardiovascular mortality with aerobic exercise training programs of at least 3-months' duration.[12] However, aerobic exercise training did not show any effect on the occurrence of nonfatal MI. In the recent years, wide spread use of revascularization procedures and drug treatments has reduced the overall risks of mortality in cardiac patients, and hence, it is difficult to demonstrate significant survival advantage with interventions such as regular physical activity. Yet, data confirms the existence of an inverse dose–response relationship between cardiovascular fitness (evaluated by treadmill stress testing and expressed in METs) and all-cause mortality in large populations of both male and female cardiovascular patients (a history of angiographically documented CHD, MI, CABG, coronary angioplasty, percutaneous coronary intervention (PCI), or stable angina).[12] Finally, aerobic exercise training in low-risk patients has been shown to be at least as effective as an invasive strategy such as a PCI, in improving clinical status and myocardial perfusion, and is also associated with fewer cardiovascular events.[12]
European society of cardiology recommendations for physical activity for secondary prevention of cardiovascular disease
European society of cardiology guidelines emphasize that unlike in primary prevention, providing a specific exercise prescription is not possible in secondary prevention and recommendations must be individualized.[12] Low-risk patients with a previous acute MI, CABG, PCI, or affected by stable angina pectoris or chronic heart failure should be advised to undergo an aerobic exercise training program of moderate to vigorous intensity of 3–5 sessions/week, 30 min/session. The patients with moderate to high clinical risk should be given an exercise prescription based on metabolic load known to cause symptoms. Even in patients with symptoms with ordinary level of activities, small amount of supervised exercise is beneficial.
Risk stratification tools can be used to identify the patients at increased risk for exercise-related cardiovascular events. Safety of medically supervised exercise programs is well established. Possibility of major cardiovascular events occurring during supervised aerobic exercise training is rare and varies from 1 in 50,000 to 1 in 120,000 patient-hours of exercise. Chance of a fatal event occurring during exercise is extremely rare at 1 in 340,000–1 in 750,000 patient hours of exercise.[12]
American College of Cardiology/American Heart Associations recommendations for physical activity for secondary prevention of cardiovascular disease
- Assess patient's risk with a physical activity history and/or an exercise test (I [B])[35]
- Advise 30–60 min of moderate-intensity aerobic activity, such as brisk walking on most, preferably all days of the week supplemented by an increase in daily lifestyle activities (e.g., walking breaks at work, gardening, and household work) (I [B])
- Encourage resistance training 2 days/week (IIb [C])
- Advise medically supervised programs for high-risk patients (e.g. recent acute coronary syndrome or revascularization, heart failure (I [B]).
| Conclusions | | |
It is well-known that a sedentary lifestyle is one of the major risk factors for CVD. A large percentage of Indians are physically inactive and <10% of our adult population engages in recreational physical activity. Promoting physical activity is of paramount importance to reduce cardiovascular burden in India. Even though there are only very few randomized clinical trials showing benefit of physical activity in reducing cardiovascular events and mortality, large number of observational studies both in men and women have shown benefits of regular physical activity. Regular physical activity exerts its beneficial effects primarily by reducing risk factors for coronary artery disease. In addition, it enhances fitness level, reduces myocardial oxygen demand, improves myocardial perfusion, and has antithrombotic effects. Most professional societies recommend 150 min of moderate-intensity physical activity or 75 min of vigorous physical activity per week along with 2 days/week of muscle-strengthening exercises for primary prevention. Less-fit individuals should start with less strenuous exercise and gradually increase activity. For secondary prevention, recommendations should be individualized. The patients should be evaluated by history and exercise stress test before recommending regular physical activity. It is preferable for patients with established CVD to go for a medically supervised exercise program. Based on the robust evidence for the benefit of exercise in primary and secondary prevention, there is urgent need promote physical activity in our population.
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Conflicts of interest
There are no conflicts of interest.
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