Exercise + Chronic Heart Diseases
1. Myocardial Ischemia
Coronary heart disease (CHD) or ischemic myocardial disease occurs when the blood supply (and oxygen) to the myocardium is reduced due to narrowing of the lumen of the coronary arteries. This blood flow reduction in the myocardium is normally caused by atherosclerotic plaques, which are formed in the inner lining of blood vessels and project to the lumen of the arteries. The main components of atherosclerotic plaques are lipids (mainly cholesterol), as well as inflammatory cells, smooth muscle cells, fibrous tissue, etc.
When the cardiac workload is increased, as happens during physical activity, then the myocardial requirements for blood and oxygen are also increased. Therefore, the problem occurs when the balance between oxygen supply, due to coronary arteries lesions, and demand is agitated.
Thus, the ischemic myocardial disease appears to the patient either in the form of angina (which is usually presented with short duration, chest pain symptoms in fatigue or mental tension or even at rest), or in the form of acute myocardial infarction. The main symptom of acute myocardial infarction is severe pain, which is lasting more than half an hour, usually located in the chest (posterior) without excluding other localizations and/or reflections, and often accompanied by other symptoms (cold sweating, vomiting, vomiting), feeling of pulses, etc.). It has been found that there are certain risk factors, that are directly related to the appearance of atherosclerotic plaques in the coronary arteries and therefore to the occurrence of ischemic heart disease. The limitation of some of these factors has led to a dramatic reduction in the incidence of the disease in countries that preventive medicine has been created.
And the fact that about 85% of the modern middle-aged man has one or more than one risk factors for coronary artery insufficiency, is very common. The classical risk factors are:
- Gender. Large statistical studies have shown that the incidence of the disease is significantly higher in men compared to women, who are still menstruating. This is mainly due to the protective role of female hormones (mainly estrogen) against the onset of atherosclerosis, which is ceases with menopause (normal or induced after surgery).
- Age. Men have increased risk for ischemic myocardial disease after the age of 40 and this risk reaches its highest percentage in the decade of 50-60 years. As concerns as women, myocardial infarction is twice more frequent after the menopause (45-55 years old) than during the premenopausal period.
- Heredity. It has been proved that ischemic myocardial disease is more frequent in individuals with compromised family history of myocardial infarction. This is mainly due to the inherited transmission of certain risk factors, such as hyperlipidemia, hypertension, etc.
- Hypertension. Increased blood pressure is largely associated with the highly frequency of atherosclerosis and CHD.
- Hyperlipidemia and especially hypercholesterolemia. The goal of primary and secondary CHD prevention is to maintain the HDL (high- density lipoprotein) in high levels and LDL (low-density lipoprotein) in low levels. Current guidelines recommend the levels of total cholesterol to be <200 mg / dl, the HDL levels to be > 40 mg / dl and LDL levels to be<100 mg / dl, in individuals with CHD, diabetes mellitus or more than three risk factors.
- Nutrition. Obese individuals have twice the risk for a myocardial infarction, rather than individuals with normal BMI. This is mainly due to the cholesterol and other lipids levels increasing, as a result of malnutrition. Large body adipose tissue deposition and especially in the abdomen cavity, is an independent risk factor for CHD. Proper nutrition is characterized by the following conditions:
- 1) The calories should be so as not to increase the weight.
- 2) Total fat should not provide more than 30% of calories.
- 3) Cholesterol intake should not exceed 250 mg daily.
- 4) The number of calories supplied by the dietary fat, should not exceed 8% in saturated (animal) lipids, 10% for mono-unsaturated lipids and 10% or more in polyunsaturated lipids.
- 5) Proteins should be consumed at a rate that does not provide more than 15% of calories, and
- 6) salt intake should be less than 4 g per day.
- Smoking. The association of smoking with CHD, as well as with lung cancer, has been recognized globally. 40% of regular smokers have highly risk of dying from CHD or lung diseases, while only 15% of non- smokers are at similar risk. According to recent statistics, 40% of Greek population are smokers, with a significant predominance of men (46%) over women (34%).
- Non-mobility. Regular exercise prevents from CHD, since it improves blood perfusion and myocardial function and reduces many of the other risk factors.
- Stress. It has been found that daily stress, especially in individuals with type A personality, increases the probability of CHD.
- Diabetes mellitus. The frequency of diabetes mellitus is now equivalent to CHD. One of the most common complications of diabetes mellitus is vascular disease. In vascular disease there is either a direct damage to the coronary arteries or an indirectly onset of atherosclerosis, as diabetes is accompanied by other risk factors (hypercholesterolemia, hypertension, obesity, etc.). Diabetic patients also develop hyperinsulinemia and insulin resistance, which contribute independently to the onset of coronary heart disease.
- Substance intake such as alcohol or drugs, redispose to the occurrence of atherosclerosis.
From these risk factors, some are modifiable, and some other are non- modifiable, such as heredity and sex.
Thus, the purpose of modern therapy guidelines, is to identify individuals who are considered to have an increased cardiovascular risk and to address the modifiable factors.
2. Heart Failure
Heart failure is the heart inability to maintain the adequate blood circulation, in order to cover the tissues metabolic needs.
Thus, heart failure can be characterized as the efficiency degree of heart left ventricle, which cannot meet the exercise functional body requirements.
Other possible causes that can lead to heart failure are
- anatomical causes (such as valvular diseases, congenital heart diseases),
- endogenous myocardial diseases (cardiomyopathies, amyloidosis, etc.),
- increased workload (hypertension, anemia, etc.),
- medical myocardial damage, such as from drugs (eg disopyramide) etc.
Hypertension is one of the major health problems, as it is associated with increased morbidity and mortality.
Unfortunately, hypertension is now under-diagnosed and under-treated, as many individuals are unaware that they have high blood pressure. Hypertension, i.e. the maintenance of blood pressure at higher levels than normal (140/90mmHg), is a common pathological condition, especially in adults.
Its frequency is around 10-20% of the population in Europe and the USA. According to recent guidelines there is a gradation of hypertension according to its rest values. 90% of cases of hypertension have an unknown cause (idiopathic hypertension).
Risk factors are hereditary factors, poor diet (obesity), stress, etc., but its noteworthy that there is no pathological background of any disease.
Major pathophysiological mechanisms leading to increase of arterial blood pressure, is the increase of pulse volume (sodium and water retention) and the increase of peripheral vascular resistance.
EXERCISE AND CARDIOVASCULAR HEALTH - PRIMARY PREVENTION
Systematic aerobic exercise adequately protects the myocardium from ischemic disease, inhibiting or slowing its onset. The mechanisms by which systematic exercise can provide primary protection against CHD, can be divided into two categories:
- in those who reduce myocardial oxygen requirements (such as decline of resting heart rate at rest and submaximal exercise) and
- in those which can improve the modifiable risk factors, such as hypertension, hyperlipidemia, obesity, etc..
According to recent guidelines, regular exercise contributes significantly to maintenance of cardiovascular health, when it contains the following characteristics:
- A) Type:
Mixed type exercises.
Aerobic exercises, such as walking, running, cycling, swimming, dancing, etc. and
Strengthening exercises either on machines or with adjusted weights, tires or resistance.
- B) Frequency.
Aerobic exercise most days of the week or (at least 4-5 times per week and preferably daily exercise: 6-7 times per week).
Strengthening exercises: 2-3 sessions per week with at least one day off.
- C) Intensity.
Aerobic exercises near to the respiratory anaerobic threshold:
- 50-70% of VO 2peak ,
- 65-86% of HR max ,
- 13-14 of Borg scale, or corresponds to
- 60-90% of the maximum predicted heart rate or
- 50-85% of the maximum oxygen uptake.
Strengthening exercises: moderate intensity.
- D) Duration
Aerobic exercises at least 20-30 min (preferably 30-45 min)
All healthy adults are recommended to participate for at least 150 min per week at moderate intensity or 75 min per week in high-intensity aerobic activities and/or a combination thereof.
Strengthening exercises: 10-15 repetitions /1-3 sets of 8-10 upper and lower limb exercises.
Additionally, it is recommended to do strength training at least two or more (but not consecutive) days per week.
Exercise should be continued throughout the year, with the aim of lifelong exercise.
It has been found that a person's physical fitness decreases significantly 2-3 weeks after cessation of systematic physical activity, while 3-8 months after cessation the person returns to the physical state that it was before the training onset.
EXERCISE AND CORONARY HEART DISEASE - SECONDARY PREVENTION
Exercise rehabilitation programs were initially applied to patients following acute myocardial infarction, without angina events. Today, they are also addressed to patients with stable angina, after angioplasty, coronary artery reperfusion surgery, implantation of a pacemaker or defibrillator, with mild or moderate heart failure, heart transplantation, etc.
Exercise rehabilitation programs for cardiac patients aim at their professional and social reactivation and the improvement of their quality of life.
In the last twenty years it has additionally been shown that the increased physical activity in patients after myocardial infarction contributes to slowing and/or inhibiting the progression of atherosclerosis in the coronary vessels and decrease mortality in a significant proportion.
The safe inclusion of a patient in a carefully designed therapeutic exercise training or exercise therapy of a rehabilitation program, can be done only after a complete check of her/his cardiovascular system.
Special care and continuous monitoring are required in patients, with coexisting pathological conditions, such as severe hypertension, lung disease, anemia, renal failure, etc., or those receiving strong doses of certain drugs, such as diuretics, vasodilators, β-blockers, etc. Patients with unstable angina, malignant hypertension, severe aortic stenosis, unregulated diabetes, etc. are contraindicated in these programs.
Each exercise program should be individualized based on the age, gender, condition, degree of physical fitness and goals of each patient and should be done under the supervision of medical or properly trained paramedical staff.
If the necessary conditions are met, the risk of complications during exercise is small. It is necessary to inform the patients and their relatives about the program purposes, the methodology to be followed and its possible risks.
The main exercise programs element is the properly planned systematic physical exercise, based on the results of the functional evaluation of each patient. Programs should consist of a variety of exercises to keep the patient interested.
Advisement on proper nutrition, suppression of high-risk factors, etc. should also be given.
Cardiac rehabilitation programs
Cardiac rehabilitation programs include four phases, aimed at improving their physical fitness, psychological support and encouraging a healthy lifestyle.
The first phase concerns the hospitalization period of the patient in the hospital.
The patient’s mobilization starts approximately two days after the onset of acute myocardial infarction, which is not accompanied by complications, and aims to restore the problems created by immobilization in the intensive care unit. The patient's mobilization is usually started by the physiotherapist by mobilizing him from the bed, breathing exercises, maintaining the flexibility of the joints and massaging the lower extremities. Progressive mobilization is more systematic and extensive and includes gait of the patient and lifting and lowering of a few steps. At the end of this phase, the patient's cardiac function is necessarily assessed.
After the patient leaves the hospital, the second phase begins, which lasts 2-3 months and it must be done in a well-organized rehabilitation center. The rehabilitation center staff consists of a specialist cardiologist, occupational physiologist, dietitian, psychologist, social counselor and specialized exercise therapists. During that period, all the exercise programs are done under the guidance of specialized trainers and include aerobic type exercises, such as walking, swimming and cycling, with a frequency of 3 times per week and duration of each exercise session 30-60 min. moreover, during the first 4 weeks the intensity of exercise is set at 70-85% of the highest heart rate achieved during the submaximal fatigue test at the end of phase I (usually 90-120 rpm). If the patient is unable to undergo a fatigue test, then the exercise intensity should increase the heart rate by 20-30 b/min than the resting heart rate. In the next four weeks of the exercise program the intensity and duration of the exercise is progressively increasing. During the exercise the heart rate can be recorded by various techniques (telemetry, Holter monitoring, sport tester, etc.).
A typical exercise session during this phase includes:
- a) 10 min of mild intensity cycling and 10 min of warm-up with various exercises,
- b) 30 min of aerobic type exercises that lead to the heart rate mentioned above.
The warm-up period is necessary for the proper preparation of the musculoskeletal system to accept the burden and to avoid injuries. Walking, jogging, swimming, cycling and aerobic type exercises in steps are the most popular aerobic type exercises, in which large muscle groups participate without significantly burdening the cardiovascular system.
The aim of phase II rehabilitation program is for the patient to spend at least 8 hourly energy equivalents (METs) per week, in order to achieve the expected benefits, at the end of the week. The patient should not only be content with the prescribed programs, but to achieve a satisfactory physical activity during the rest of the hours or days.
The patient’s inclusion in the third phase, which can be performed in general gyms, should be done, after a period of 6-12 weeks after acute myocardial infarction or 8-14 weeks after reperfusion surgery. The third phase totally lasts 4-6 months and the exercise program should be done 3-5 times per week. The exercise’s intensity should correspond to 60- 90% of the maximum heart rate or 50-85% of the maximum O 2 intake. The duration depends mainly on the intensity. So, the duration will be longer, when the intensity is low and vice versa. The average duration, however, should be 30-60 min with low intensity, in order to avoid any complications. In this phase there are also aerobic exercises with static character of moderate intensity, which aim at the increase and maintenance of the muscular strength. Examples of such exercises are the muscular stretching with resistances, the execution of exercises with dumbbells adapted to the upper and/or lower extremities, etc. 8-10 different isometric exercises should be performed at least 2 times per week for 10-15 minutes, with each containing about 8 repetitions.
The fourth phase is an integral part of the previous one and aims at the complete reintegration of the individual into the previous levels of normal life. Any cessation of regular exercise may lead to loss of cardiovascular benefits that have previously achieved. More specifically, a cessation for 4-12 weeks reduces by 50% the initial improvement in VO 2max .
EXERCISE IN CHRONIC HEART FAILURE
Specially planned chronic exercise for patients with heart failure is safe and leads to an improved overall functional capacity, morbidity and mortality. In the Sports Medicine Laboratory of TEFAA in Aristotle University of Thessaloniki, the implementation of rehabilitation programs for patients with coronary heart disease and heart failure has started since 1997. Many cardiac patients participate in these programs for free. Their training takes place in municipal gyms of Thessaloniki. Those exercise programs are properly designed for cardiac patients, in order to be safe and beneficial. The training is always done by specialized and experienced physical education teachers and under the supervision of medical staff.
The special characteristics that a fitness program for patients with chronic heart failure must have in order to lead to beneficial adjustments and not to carry risks are the following:
- a) The frequency of exercise should be at least 3-5 times per week with the aim of daily exercise,
- b) the duration of each training session should be at least 20 min at the beginning, with a gradual increase after the program, which reaches 60 min.
- c) The exercise’s intensity should initially be mild to moderate and cause an increase in heart rate up to 60% of the maximum predicted (HR max ) or 50% of the residual heart rate or 50% of the VO 2peak . This load is equivalent to intensity below the anaerobic respiratory threshold and based on the Borg RPE scale <11. Gradually the intensity should be increased, depending on the patient's ability to function and his/her clinical condition. After 2-4 weeks the intensity of the exercises may increase to a degree accompanied by an increase in heart rate to 60-70% of the remaining (RPE 12-14). As the patient makes adjustments, the duration, the frequency and finally the intensity of the exercise sessions, are gradually increased. The minimum intensity to improve aerobic capacity in patients with cardiovascular disease is 45% of VO2R (70% HR max), while in patients with heart failure the minimum required intensity can reach 23% of VO2R (or even lower). Of course, the intensity of the exercises depends on the degree of functional capacity of the left heart ventricle, as well as on the overall functional condition of the patients.
- d) The exercises are suggested to be initially isotonic type and to use mainly the large muscles of the lower extremities. Examples of such exercises are walking, light walking and cycling. Then (after 2-4 weeks) the program consists of art exercises, as well as exercises in steps under music, dance, swimming as well as exercises with balls. At the same time, it is recommended to apply muscle strengthening exercises with dynamic type exercises 2 to 3 times per week on non-consecutive days.
At the initial stage it is recommended to apply 1-3 sets of 4-8 exercises for large muscle groups, with 5-10 repetitions at low intensity (<30% MVC).
Then the repetitions are increased to 12-25, with intensity 30- 50% MVC (RPE 12-13) in order to increase muscle endurance. It is recommended to apply 5-10 min muscle stretches. In every exercise session warm up is necessary both at the beginning and recovery, at the end of the exercise session. Furthermore, at least during the first month of the exercise program, patients’ heart rate should be monitored continuously and at regular intervals of patients’ blood pressure.
In recent years we have been implementing exercise programs with an entertaining character, such as zumba, yoga, Pilates, aqua gymnastics, Greek traditional dance, etc. with the aim of increasing the motivation of patients to participate in them. Modern cardiac rehabilitation centers usually use telemetry methods for this purpose. With telemedicine, exercise can be done safely in the patient's home without the presence of a doctor and a specialized trainer in the gym.
EXERCISE IN BLOOD HYPERTENSION
Contraindications for exercise are individuals, whom hypertension is not properly regulated (systolic> 180 mmHg and diastolic> 110 mmHg), have complications from the eyes, kidneys, as well as in those who coexist with poorly regulated diabetes. Exercise should also be discontinued, when blood pressure values increase significantly during exercise (above 220 mmHg systolic and above 110 mmHg diastolic or the patient have angina, dizziness, arrhythmias or dyspnea. Patients with mild hypertension and without other special risk factors (e.g. obesity, smoking, coronary heart disease, diabetes, etc.), can participate freely in all sports activities, considering age and physical fitness. Patients with mild to moderate hypertension and moderate coexistence of certain risk factors should avoid moderate to high- intensity static exercise. Finally, patients with increased risk factors can participate in exercise programs that have low-intensity aerobic exercise (e.g. walking, cycling or swimming). Exercise programs should be individualized according to the capabilities and aims of each patient and the cooperation between the treating physician, trainer and patient, is necessary. Blood pressure should also be measured regularly during exercise to avoid complications. Exercise characteristics that offer protection against the occurrence of hypertension and / or contribute effectively to its treatment are:
- The frequency of exercise, that should be 3-5 times per week, with the aim of daily exercise and duration 20-60 min.
- Exercise intensity is recommended to be low to moderate (40-50% of VO 2max or 55-65% of HR max ), as higher intensity has not been found to bring better results.
- To regulate better the blood pressure, it is recommended to increase more the duration and frequency of exercise and less the intensity.
- Exercise should include exercises for endurance, muscle strengthening and flexibility.
- Exercise should include adequate warm-up at the beginning and at the end of the main exercise program.
EXERCISE BENEFITS IN PATIENTS WITH CARDIOVASCULAR DISEASES
More specifically, aerobic exercise induces:
- increase in muscle mass,
- improvement in muscle fibrils diameter,
- increase in blood capillaries and the muscle fibers diameter,
- increase in the number of mitochondria and oxidative enzymes.
Especially in patients with CHD, regular exercise provides secondary protection, by preventing the recurrence of clinical manifestations. In more detail, regular exercise reduces the CHD progression, either by direct mechanisms, such as reducing the myocardium’s oxygen demand, increasing its perfusion and having a beneficial effect both on blood lipid levels and blood coagulation function, or indirectly by suppressing known cardiovascular risk factors.
The decrease in myocardial oxygen demand with chronic exercise is due to the reduction in heart rate, systolic and mean blood pressure, both at rest and at maximal exercise, and at cardiac output during maximal exercise.
These favorable adaptations are due to:
- the tone decrease in sympathetic nervous system, because of the decrease in levels of circulating catecholamines,
- the action increase in parasympathetic nervous system,
- the inhibition of the endogenous heart rate.
Systematic exercise (SE) increases high-density lipoprotein (HDL) levels and decreases blood lipid levels. Therefore, SE improves the individual’s lipid profile (by increasing the HDL-C / LDL-C ratio) and has a beneficial effect on carbohydrate metabolism, by increasing tissue sensitivity to insulin.
The effect of exercise on inflammatory indicators is also positive. It is known that patients with CHD, heart failure, diabetes, etc. show increased levels of IL-6 and TNF-α.
Systematic long-term exercise may also lead to a reduction in these pro-inflammatory cytokines and cytokine mediators (sFas and sFasL), as well as to a reduction in myocardial and endothelial cell apoptosis.
At the same time, several studies show that SE significantly reduces the levels of C-reactive protein.
The benefits of oxidative stress are also significant, as it has been found that exercise groups have lower levels of lipid hydroperoxides (PEROXs) and thiobarbituric acid reactants (TBARs) compared to non-exercise groups.
Moreover, aerobic exercise increases the angina’s threshold during exercise and therefore reduces the symptoms of angina or heart failure in patients.
Thus, SE programs increase myocardial perfusion and create collateral circulation in the ischemic myocardium.
Both the role of aerobic exercise and endothelial function is important, as it leads to an increase in blood flow and wall tension and also increases the synthesis and secretion of nitric oxide (NO) and other vasodilators and leads to a parallel reduction of vasoconstrictors, such as endothelin-1.
Several studies have also argued that aerobic exercise improves myocardial function by increasing pulse volume, ejection fraction, left ventricular mass and myocardial contractility in both healthy and individuals with dysfunctional left ventricle of ischemic etiology.
However, for heart failure patients there is a different point of view. Many researchers support that regular exercise improves heart performance, but the beneficial effect on the overall patients’ functional capacity is due to a better functioning of skeletal muscles.
Chronic SE is also indirectly protecting against the ischemic heart disease, by suppressing the high-risk factors that lead to its occurrence. And that’s because chronic SE decreases obesity’s levels, regulates better the blood pressure and carbohydrate metabolism in diabetic patients and leads also to smoking cessation.
In conclusion, SE benefits in the psychosocial field are also important. By increasing the patient’s physical fitness, there are improvements in patients’ self-care, self-confidence and self-esteem. Furthermore, SE improves well-being, reduces stress and depression levels and increases the mood for social and professional reactivation. There is evidence that SE reduces cardiovascular mortality by 20-25%.
Complications in CHD patients during exercise are extremely rare, when the principles of safe exercise are applied.
The literature reports one episode of cardiac arrest per 30,000 hours of systematic physical activity, as well as one death per 120,000 hours in patients who had undergone rehabilitation programs and were under close medical supervision. Other, less common complications described are pulmonary embolism, pulmonary edema and cardiogenic shock.
Careful patients’ selection in exercise groups, proper training and proper exercise safety measures, are further reduce the risk. It is therefore concluded that the implementations of rehabilitation programs for heart patients are effective, affordable and safe enough, leading to improved functional performance and quality of life.