What is the necessity of doing cardiac rehabilitation?
Cardiac rehabilitation refers to the comprehensive use of medical and related discipline methods to help heart disease patients relieve symptoms, improve cardiovascular function, regain a normal or near-normal ideal state in physiology, psychology, social life, occupation and recreation, improve quality of life through prescribed exercise and exercise, health education to control disease risk factors, and psychological, nutritional, vocational and social counseling guidance, so that Cardiac patients can return to society; at the same time, we actively intervene in various risk factors to stop or reverse the process of disease development, alleviate functional disorders, reduce the risk of recurrence of cardiovascular accidents, and reduce mortality. Exercise therapy is the core of cardiac rehabilitation programs.
For patients with heart disease, in addition to the objective functional impairment produced by the disease, patients also develop various subjective psychological barriers. They are often afraid to move around, thinking that they have become “useless” and “disabled” who cannot live without others, and are therefore depressed and even in despair. The family members and colleagues around the patients, especially the medical personnel who do not know much about the treatment and rehabilitation of heart disease, often persuade the patients to improperly “recuperate”, “recuperate” or lie in bed from the kindness of their wishes, thus aggravating the “wasted” state of the heart and the whole body function. “wasted” state. Studies have proved that: 7~10 days of bed rest, circulating blood volume is reduced by 700~800ml, with upright hypotension and reflex tachycardia; three weeks of bed rest, physical work capacity is reduced by 20% ~ 25%; low blood volume can increase blood viscosity, prone to thromboembolism; about 1/3 of myocardial infarction patients on bed rest, lower limb veins are prone to clot formation; lung volume, lung volume is reduced and pulmonary ventilation; the negative balance of nitrogen and protein is detrimental to the healing of myocardial necrosis; muscle volume and muscle contractility are reduced. If the patient is on bed rest for 1 week, muscle contractility decreases by 10-15%. When a certain amount of work is done, the muscle oxygen consumption is more and the muscle contraction capacity is poorer than that of a trained person. Patients with recent myocardial infarction are prone to accidents when subjected to greater oxygen consumption activities due to myocardial ischemia and damage to the oxygen transport system. In addition, prolonged bed rest can produce or aggravate psychological reactions such as anxiety and depression. There are also individual patients, family members and medical staff, who do not understand the sudden danger of heart disease and have a carefree attitude, allowing patients to blindly engage in activities that are beyond their heart and physical strength, resulting in aggravation of the condition and even causing a heart attack (such as angina attack or the appearance of myocardial infarction, etc.).
The theory and practice of modern cardiac rehabilitation began in the 1950s with the research on coronary heart disease in developed countries in Europe and the United States, and modern cardiac rehabilitation medicine in China has also been gradually carried out since the 1980s. After decades of development, cardiac rehabilitation medicine has become as important as preventive medicine and clinical medicine of heart disease, and is an important part of the medical model that is beneficial to all heart disease patients. Numerous studies have confirmed that exercise improves coronary blood flow, improves myocardial vascular collateral circulation, increases myocardial oxygen supply; reduces the risk of coronary thrombosis; improves cardiovascular efficiency and coronary blood flow reserve capacity, increases the functional capacity of the heart in patients with coronary artery disease; enhances cardiac function in patients with coronary artery disease; improves patients’ symptoms; increases muscle strength; exercise reduces catecholamine levels and decreases Adrenaline secretion can reduce the susceptibility to arrhythmias, thus avoiding serious arrhythmias such as ventricular fibrillation; reduce the risk factors of coronary heart disease, including improving blood lipids, lowering blood pressure, improving insulin resistance and diabetic patients’ condition; and improving psycho-psychological status. The incidence of fatal infarction is reduced by 25% after myocardial infarction rehabilitation, and the risk of unexpected recurrence of coronary heart disease is reduced by about 20%.
What are the targets of cardiac rehabilitation?
Indications for cardiac rehabilitation include: patients with occult coronary artery disease; patients with stable angina; patients with acute myocardial infarction without comorbidity or with mild or moderate cardiac insufficiency; patients with chronic heart failure; patients with rheumatic heart disease; patients with cardiomyopathy; patients with pacemakers; patients after percutaneous transluminal coronary angioplasty or stent placement; patients after coronary artery bypass surgery; patients after heart valve replacement; patients after heart Post-transplantation patients.
Contraindications include: unstable angina; hemodynamic instability, including abnormal blood pressure, severe arrhythmias, heart failure or cardiogenic shock; severe comorbidities, including temperature over 38°C, acute myocarditis or pericarditis, uncontrolled diabetes mellitus, thrombosis or embolism; abnormal surgical incisions; new myocardial ischemic changes on the electrocardiogram; and patients who do not understand or cooperate with rehabilitation.
How to perform cardiac rehabilitation?
The following focuses on the rehabilitation procedures for patients with acute myocardial infarction in coronary artery disease, and the basic principles of rehabilitation for other cardiac diseases are the same.
1.Introduce several concepts
① Metabolic equivalents (METs): The vast majority of energy required for human activities comes from the oxidation of carbohydrates and fats, thus the release of energy is based on the consumption of oxygen, so the oxygen consumption can be used to express the intensity of exercise, the more oxygen consumption, the greater the intensity of exercise. At present, most of the exercise cardiorespiratory function instrument is used to directly determine the oxygen consumption in the active state, and since the oxygen consumption is related to the body weight, it is often expressed in its absolute value (ml/(kg.min)). In the quiet state, the average oxygen consumption per minute is 3.5 ml/kg, which is 1 MET, and the oxygen consumption during different activities is calculated as a multiple of 3.5 ml/(kg.min), which can accurately quantify the capacity of physical activities and the functional capacity of the heart, quantitatively determine the energy consumption during various daily life activities and production work, and guide the daily activities and occupational activities of patients. It is also possible to stratify the risk of patients and guide them in rehabilitation exercise training. For example, the functional capacity of the heart of a post-acute myocardial infarction patient is 5 METs, which is equivalent to 5 times the oxygen consumption in a quiet sitting position, i.e. 17.5 ml/(kg.min), which is equivalent to 17.5 ml of oxygen consumption per minute per kilogram of body weight, indicating that his heart can withstand 5 times the oxygen consumption in a quiet sitting position, so a household activity such as making the bed (average energy demand 3.4 METs) would be manageable for him, while lifting 20 kg of heavy objects upstairs (average energy requirement 7.1 METs) would be clearly beyond his ability and dangerous.
②Grading of subjective exertion (RPE): It was proposed by Gunnar Borg, a Swede, to classify patients’ subjective exertional sensations into 15 grades (Table 1). It is like a ruler, where the left end is 6 for very light exercise intensity and the right end is 20 for very tired. the RPE provides a valid and credible index of immediate exertion that reflects exercise intensity well, even when certain heart rate affecting drugs are used.
2.Rehab assessment
① Exercise test: Exercise test for cardiac rehabilitation assessment often uses cardiopulmonary exercise apparatus to perform gas metabolic exercise test, which directly measures the change of oxygen and carbon dioxide concentration, metabolic equivalent and other indices during exercise. Graded rehabilitation exercise test is not only safe and feasible but also necessary during the rehabilitation medical treatment of coronary artery disease. The first one is performed mostly before hospital discharge and every 2-3 weeks thereafter, depending on the situation. The purpose of this test is mainly to understand the patient’s physical activity capacity in order to develop and adjust the rehabilitation exercise prescription, to guide the physical activity during rehabilitation, to determine the rehabilitation efficacy, to foresee the future risk and prognosis, and to decide whether to return to work.
②Risk stratification: Risk stratification of patients with acute myocardial infarction is the basis of exercise rehabilitation training. According to the clinical characteristics of patients, patients with acute myocardial infarction from coronary artery disease are classified into low risk stratum, intermediate risk stratum and high risk stratum.
Low-risk stratum (low risk when each of these is present): no clinical complications at the time of hospitalization; no evidence of myocardial ischemia; cardiac functional capacity ≥7 METs; normal left ventricular function (LVEF ≥50%); and no rest or exercise-induced complex arrhythmias.
Intermediate-risk tier (those who did not meet the typical low- or high-risk criteria were classified as intermediate-risk): horizontal or oblique depression of the ST segment ≥2 mm; reversible abnormalities of coronary nuclear myocardial perfusion imaging; moderate or better left ventricular function (LVEF 35% – 49%); altered form of angina attack or new onset of angina.
High-risk stratum (high risk when any risk factor is present): previous or recent myocardial infarction affecting the left ventricle ≥35%; LVEF <35% at rest; fall in systolic blood pressure or rise in systolic blood pressure ≤10 mmHg on exercise stress test; persistent or recurrent ischemic chest pain ≥24 h after admission; functional cardiac volume <5 METs with hypotensive response or ST-segment drop >1 mm on exercise test. Symptoms of congestive heart failure during hospitalization; ST-segment depression ≥2 mm at a peak heart rate ≤135 beats/min; complex ventricular arrhythmias induced by rest or exercise.
Stratification of coronary heart patients according to their risk of myocardial infarction and death is important for determining prognosis and guiding secondary prevention, treatment, and rehabilitation exercises. For example, low-risk patients with myocardial infarction can mostly complete shorter rehabilitation procedures successfully, and rehabilitation activities after discharge are usually performed without cardiac monitoring; whereas rehabilitation activities for high-risk patients must be performed under continuous cardiac monitoring.
It should be added that: the risk is greater when the age is older than 70 years; the risk is higher in patients with severe and prolonged episodes of myocardial ischemia (angina or asymptomatic) and poor response to medical therapy; the risk is greater in patients with old myocardial infarction, which should be considered a high-risk group if the angina is caused by myocardial ischemia in the non-infarcted area; the combination of other organic diseases such as hypertensive disease, uncontrolled diabetes mellitus, The combination of other organic diseases such as hypertension, uncontrolled diabetes mellitus, chronic obstructive pulmonary disease, renal failure, etc. also obviously affects the medium and long-term prognosis of patients and increases the risk; the application of potassium and magnesium excreting drugs that may cause hypokalemia combined with the application of antidepressants or antipsychotics should be classified as medium risk, and high risk when hypokalemia occurs.
3. Rehabilitation treatment
The rehabilitation treatment of acute myocardial infarction is divided into 3 phases: inpatient rehabilitation (Phase I), post-discharge rehabilitation (Phase II), and chronic coronary heart disease or chronic phase rehabilitation (Phase III).
3.1 Inpatient rehabilitation (Phase I)
This phase of rehabilitation is performed within 2 weeks of acute myocardial infarction. It includes two phases in cardiac care ward and general ward. The indications are that the patient has stable vital signs, no obvious angina, quiet heart rate of 110 beats/min, no heart failure, serious arrhythmia and cardiogenic shock, basic normal blood pressure
The patient should have normal blood pressure and normal body temperature. Contraindications are unstable angina; hemodynamic instability, including abnormal blood pressure, severe arrhythmias, heart failure or cardiogenic shock; serious comorbidities, including temperature over 38°C, acute myocarditis or pericarditis, uncontrolled diabetes mellitus, thrombosis or embolism; abnormal surgical incision; new myocardial ischemic changes on the electrocardiogram; and patients who do not understand or do not
rehabilitation. The goals of rehabilitation in this period are to make patients and family members understand the knowledge about coronary heart disease; to eliminate fear and increase confidence; to start physical activities at an early stage, to maintain the existing level of function, to prevent wasting, to improve physical strength, and to gradually transition to self-care of daily life at discharge, or to walk 200 meters continuously or go up and down 1-2 floors at a normal pace without symptoms and signs, and to achieve 2-3 METs of exercise capacity.
The following procedures for acute myocardial infarction stage I rehabilitation treatment, 1 to 2 days for each stage and 7 to 14 days for discharge, can be used as reference.
Phase 1: Practice abdominal breathing in bed for 10 minutes, once a day. Active or passive movement of the non-resistant wrist and ankle 10 times, once a day. Sitting back in bed for 5 minutes, once daily. Mission and psychological adjustment includes introduction to the cardiac care unit, disposition of the individual in case of emergency, and social services if needed.
Phase 2: Practice abdominal breathing in bed for 20 minutes, once daily. Non-resistant wrist and ankle active or passive movements for 20 sessions, once daily. Resisted wrist and ankle activities 10 times, once daily. 10 minutes of sitting in bed, once daily. 5 minutes of unrestrained sitting in bed, 1 time per day. The mission includes introduction to the rehabilitation team, rehabilitation procedures, smoking cessation, distribution of information materials, and preparation for transfer to the general ward.
Phase 3: Practice abdominal breathing in bed for 30 minutes, once daily. Non-resistant wrist and ankle active movement for 30 sessions, once daily. Resisted wrist and ankle joint activity 20 times, once daily. 10 non-resistant knee and elbow movements, 1 time per day Feeding, washing and toileting on your own with assistance. Sitting leaning in bed for 20 minutes, once a day. Sitting unsupported in bed for 10 minutes, once a day. Sitting with support at the bedside for 5 minutes and standing with support for 5 minutes. The education includes introduction to the anatomy and function of the normal heart and the development of atherosclerosis.
Phase 4: 30 minutes of abdominal breathing in bed, twice a day. Non-resistant wrist and ankle active movement for 30 sessions, twice daily. Resisted wrist and ankle activity 30 times, 1 time per day. 20 non-resistant knee and elbow activities, 1 time daily Resisted knee and elbow joint activity 10 times, 1 time per day. Eating independently, washing and toileting with assistance. Sitting in bed for 30 minutes, once a day. Sitting without support in bed for 20 minutes, once a day. Sitting with support at bedside for 10 minutes, sitting without support for 5 minutes, standing with support for 10 minutes, standing without support for 5 minutes, once a day. Bedside walking for 5 minutes once a day. Conduct education on risk factors for coronary artery disease and their control.
Phase 5: Resisted wrist and ankle activities 30 times, twice daily. Non-resistant knee and elbow activities 30 times, 1 time daily. Resisted knee and elbow activities 20 times, 1 time per day. Independent eating, washing and toileting. Sitting leaning in bed for 30 minutes, twice a day. Sitting unsupported in bed for 30 minutes, once daily. Sitting with support at the bedside for 20 minutes, sitting without support for 20 minutes, standing with support for 10 minutes, standing without support for 10 minutes, once a day. Bedside walking for 10 minutes, corridor walking for 5 minutes, once a day. Introduction to healthy and rational diet and energy expenditure.
Phase 6: 30 non-resistant knee and elbow activities, twice daily. Resisted knee and elbow activities 30 times, 1 time per day. Independent eating, washing and toileting. Sitting without support in bed for 30 minutes, twice daily. Sitting with support at bedside for 30 minutes, sitting without support for 20 minutes, standing with support for 30 minutes, standing without support for 20 minutes, once daily. Bedside walking for 20 minutes, hallway walking for 10 minutes, 1 time per day. Go down one floor once. The mission includes management in case of heart attack recurrence, medication, exercise, surgery and symptomatic management, family and social adjustment after going home.
Stage 7: Resist blocking knee and elbow movement 30 times, twice daily. Independent feeding, washing and toileting. Bedside sitting with support for 30 minutes, twice daily. Sitting without support for 30 minutes and standing without support for 30 minutes, 1 time per day. Bedside walking for 30 minutes and hallway walking for 20 minutes once a day. Go down one floor twice a day and up one floor 1-2 times a day. Pre-discharge education, including post-discharge advice regarding medications, diet, activity self-monitoring, psychological adjustment, family life, return to work issues, and return to society.
It is important to note that the rehabilitation treatment plan must be developed according to the principle of individualization of the patient. For patients who have no complications or whose complications have been controlled and whose condition is stable, while providing education on relevant knowledge, gradually start low-load (1-2 METs) activities, such as passive and active movements of the limbs, bed or bedside washing, and eating, according to the rehabilitation program. After transferring to a general ward, gradually start activities such as walking, going up and down stairs, and bicycling. Early activity movements should be performed slowly and for a short period of time, and gradually increase the amount of activity until the entire rehabilitation procedure is completed. Patients with no adverse reactions during training and exercise heart rate increase <10 beats/min can move to the next stage of training the next day. An exercise heart rate increase of around 20 beats/min requires continuation of the same level of exercise. An increase in heart rate of more than 20 beats/min or any adverse reactions should result in a return to the previous phase of exercise or even a temporary cessation of exercise training. Medical personnel must be present for all rehabilitation activities during this period. Blood pressure and ECG monitoring is required before, during and after each activity, and the patient's symptoms and signs should be noted.
3.2 Post-discharge rehabilitation (Phase II)
The period of time from the patient’s discharge from the hospital until the condition is completely stabilized is 6-12 weeks. The indications and contraindications of this period are similar to those of the inpatient period, and the patient achieves more than 3METs of motor ability and is in stable condition.
After discharge, due to the loss of the security of medical staff presence, some patients have a fear of performing activities of daily living independently, and if there is occasional physical discomfort, this uneasiness and fear is often aggravated, and the patient stops rehabilitation activities, which is not conducive to recovery. Therefore, the goal of rehabilitation in this period is to enable patients to adapt to life after discharge, stabilize their emotions, gradually restore the ability of general activities of daily living, including light housework and recreational activities, etc., to improve the quality of life and return to work as soon as possible. The exercise ability will reach 4-6 METs.
The rehabilitation program includes indoor and outdoor walking, tai chi, housework, kitchen activities, gardening activities or shopping in the neighborhood. The intensity of activity was 40%-50% of maximum heart rate, with no more than 13-14 subjective exertion during activity; activity time gradually reached 20-30 min; and frequency of exercise gradually reached 3-4 times per week. Medical monitoring is not required for general activities. The rehabilitation process can be observed several times by an experienced rehabilitation therapist to establish safety when performing higher intensity activities. Patients with no complications may be gradually transitioned to unsupervised activities with the help of family members. Be careful not to have shortness of breath or fatigue during this period of activity, and prohibit excessive exertion. Outpatient follow-up is required once a week. Any discomfort should be suspended and the patient should be seen promptly. Sexual activity can be gradually resumed when you can successfully climb the second floor (about 1 min) or walk more than 1 km (4.5-5.5 METs). For intermediate or high-risk patients or those with more obvious abnormalities after increasing exercise load, especially when attempting to increase exercise volume, frequency or duration, then medically supervised exercise training should be performed at least 3 times a week at a hospital rehabilitation clinic.
The following home activity program is provided for reference.
Phase 1: Sitting activities at home. You can go up and down stairs slowly, but avoid any fatigue. Avoid guest visits if possible. There are no special restrictions on personal hygiene activities, but avoid bath water that is too hot and also avoid being in an environment where the temperature is too cold or too hot. You can wash dishes, vegetables, make beds, and lift heavy objects of about 2kg. You can play poker, play chess, watch TV, read, knit, sew, and ride in a car for a short time. Avoid lifting heavy objects over 2kg, excessive bending, emotional frustration, overexcitement and stress.
Stage 2: You can go out for haircut, wash small clothes or use washing machine (but not large clothes), dry clothes, iron small clothes in sitting position, use sewing machine, dusting, wipe table, comb hair, simple cooking, and lift heavy objects of about 4kg. When you can go up and down two flights of stairs or walk 1km without any discomfort, you can resume sexual intercourse. However, it is important to take a relatively relaxed approach. You can take or reserve nitroglycerin before sexual intercourse. If necessary, you can consult your doctor first. Avoid prolonged activities, hot environments such as perms, lifting heavy objects over 4 kg, and activities involving financial or legal issues.
Stage 3: You can iron clothes for a long time, make a bed, and lift heavy objects of about 4.5 kg. Light gardening work, indoor swimming, visiting friends and family. You can walk 1km continuously for 10-15min each time, 1-2 times a day. Avoid lifting too heavy objects and moving around for too long.
Stage 4: You can go out shopping with others, cook normally, lift heavy objects of about 5kg, do minor home repairs, clean outdoors; walk continuously for 20-25min each time, twice a day. Avoid lifting heavy objects and using power tools, such as drills and chainsaws.
Stage 5: Can go shopping independently (use wheelbarrow to carry heavy objects), vacuuming or mopping for a short time, lifting heavy objects of about 5.5 kg; fishing, bowling-type activities; walking continuously for 25-30 min each time, twice a day. Avoid lifting too heavy objects.
Stage 6: Washing the bathtub, windows, lifting heavy objects of about 9kg (if there is no discomfort). Dance calmly; go out for picnics, go to theaters and theaters. Walking is listed as an activity of daily living, 30min at a time, 2 times a day. Avoid strenuous exercise, such as weight lifting and digging, and competitive activities, such as various competitions.
Caution: (1) Each phase lasts 1-2 weeks, paying attention to gradual progress. (2) All activities of the upper limbs over the head are high-intensity exercises and should be avoided or reduced. (3) Care should be taken to maintain a certain level of activity during training, but energy conservation strategies should be used in daily life and work, such as developing reasonable work or daily activity routines and reducing unnecessary movements and physical exertion, etc., to maximize work and physical efficiency. (4) Activities should be performed in the absence of symptoms and without fatigue. The heart rate during activity should not exceed 100-110 beats/min.
Recovery during this period usually takes 6-12 weeks. For patients who progress well without abnormal manifestations, the exercise load of 6 METs can be achieved in about 6-8 weeks and smoothly proceed to phase III of cardiac rehabilitation. Thereafter, patients can mostly return to a normal social life including occupational activities (including sexual life). However, there will be a subset of patients, such as those in the intermediate and high risk strata, who may take more than 12 weeks to reach the 6 METs mark. Individual patients at high risk may not reach this standard at all and have to continue with low levels of exercise training.
Based on the results of the Exercise Tolerance Exercise Test at the end of Phase II, a complete exercise prescription for a high level of rehabilitation is developed by the rehabilitation physician and the patient is ready to enter Phase III of cardiac rehabilitation.
3.3 Chronic Phase Rehabilitation (Phase III)
Patients with coronary artery disease in this phase are in a longer-term stable state, including old myocardial infarction
death, stable angina, occult coronary artery disease, after percutaneous transluminal coronary angioplasty or stent placement, after heart transplantation, after pacemaker installation, etc. The rehabilitation program is generally designed for 2-3 months, and the patient’s self-exercise should continue for the rest of his life. The goal of rehabilitation is to consolidate the results of phase II rehabilitation, further improve the patient’s psychological status and control risk factors, improve physical activity and cardiovascular function, and restore the life and work before the onset of the disease.
1. Safety The main factors related to the risk of exercise are age, heart disease condition and exercise intensity. The randomized incidence of sudden death during coronary heart disease training is expected to be 1 case per 80,000 to 160,000 exercise hours. The lowest rate of sudden cardiac death occurred during walking, cycling, and active planking. The higher rate of sudden death during jogging was related to exercise intensity. All individuals should undergo a thorough physical examination when participating in exercise workouts that exceed walking intensity (e.g., jogging), and coronary patients as well as normal individuals over the age of 40 must undergo a graded cardiac exercise test to establish training safety. Each exercise training must have 3 stages of warm-up activities, basic training activities and finishing activities. Most of the cardiovascular accidents during training occur during the warm-up and finishing activities, which should be sufficiently recognized.
2, training principles
(1) Individualized principle: The rehabilitation program must be developed on an individual basis according to age, gender, site and degree of heart damage, corresponding clinical manifestations, overall health level, risk factors, current cardiac functional capacity, type and degree of past rehabilitation training, past habits and hobbies, and the patient’s psychological state and needs.
(2) Principle of gradual progress: Start with low-level exercise training and gradually increase the amount of exercise according to the patient’s condition.
(3) Principle of perseverance: The effect of training is a process of quantitative to qualitative change, and the maintenance of training effects also requires long-term exercise. After 2 weeks of stopping exercise, the training effect begins to fade, and after 5 weeks of stopping exercise, about half of the training effect disappears. Therefore, the purpose of the rehabilitation exercise training program is to make patients adhere to exercise for life, even during the leave of absence, patients should continue to maintain the original exercise program or other similar activities.
(4) Principle of interest: Interest can increase the patient’s initiative and compliance to participate and adhere to rehabilitation treatment.
(5) The principle of comprehensiveness: The person is viewed as a whole.
The development and implementation of exercise prescriptions for rehabilitation of cardiac patients requires the development of exercise prescriptions, which should be treated with the same care as drug prescriptions. Exercise prescription is the guiding principle of rehabilitation exercise training, guiding the form and content of exercise training. Exercise prescription includes exercise mode, exercise intensity, exercise time, exercise frequency and precautions.
(1) Exercise mode: including aerobic training, strength training, flexibility training, homework training, medical gymnastics, taijiquan, etc. Rehabilitation training after myocardial infarction generally uses aerobic exercises with large muscle groups, long duration and rhythm, such as fast walking, jogging, stairs, cycling and swimming. Exercise forms can be divided into: ① Intermittent exercise: refers to the basic training period with several peak target intensities, with decreasing intensity between peak intensities. For example, for patients with a maximum intensity of 10 METs in the exercise test, several times of 8-9 METs intensity can be used in the training period, with a duration of no more than 2-3 min. The advantage is that a higher exercise intensity stimulus can be obtained, and because the duration of the high-intensity stimulus is not long, it is not so high as to cause irreversible pathological changes. The main disadvantage is the need to constantly adjust the intensity of movement, the operation is more troublesome. (2) continuous exercise: means that the target intensity of the training period continues unchanged, which is the traditional mode of operation. The main advantage is that it is simple and relatively easy for the patient to adapt.
(2) Exercise volume: the basic elements of exercise volume are exercise intensity, exercise time and exercise frequency. The amount of exercise has to reach a certain threshold in order to produce a training effect. The total amount of exercise (expressed in calories) per week should be 700-2000cal (equivalent to about 10-32km of walking or jogging). Exercise less than 700 cal only maintains physical activity levels and does not improve exercise capacity. There were no significant gender differences in total exercise. Since METs eliminate the effect of body weight, they are mostly used in practical applications to express METs. The formula for converting calories to METs is: calories = METs x 3.5 x kg body weight/200. So how much exercise is considered appropriate? The main signs of an appropriate amount of exercise are: slight sweating during exercise, mildly accelerated breathing but not affecting conversation, feeling comfortable when waking up in the morning, and no persistent fatigue or other discomfort. If the patient has angina pectoris, frequent arrhythmias, abnormal tachycardia or bradycardia, dizziness, nausea, vomiting, leg pain, pallor, cyanosis, shortness of breath lasting more than 10 minutes, or prolonged fatigue and insomnia secondary to exercise, etc. during or immediately after exercise, it is a sign of exercise overload.
Exercise intensity: The intensity prescribed for exercise training is called target intensity, which can be determined by heart rate, heart rate reserve, maximum oxygen consumption, METs, anaerobic threshold, and subjective exertion scoring. The target intensity is mainly calculated based on the heart rate, maximum oxygen consumption, metabolic equivalent (METs) anaerobic threshold and subjective exertional scoring at the time of ischemic symptoms, abnormal ECG, abnormal blood pressure or reaching maximum exercise during the cardiac exercise test. That is, the highest intensity target in the exercise test is used and multiplied by the corresponding safety factor. The target intensity is generally 40%-85% of the maximum oxygen consumption or METs, or 60%-80% of the heart rate reserve, or 70%-85% of the maximum heart rate. The main ways to determine the exercise intensity are: ① Age prediction way: for those who are not in a position to perform cardiac exercise test, the formula of age prediction can be considered: target heart rate (beats/min) = 170 (180) – age (years);. The constant 170 is suitable for those who have a short recovery time after illness, or those with recurrent illness and weak constitution. 180 is suitable for rehabilitated patients and elderly people who have already had a certain basis of exercise and have a good constitution. ② Heart rate reserve mode: Heart rate reserve is the difference between maximum heart rate and quiet heart rate, which is equal to the age-expected maximum heart rate or the maximum heart rate in exercise test – quiet heart rate. Age predicted maximum heart rate = 220 – age. Target heart rate (beats/min) = heart rate reserve × (60%-80%) + quiet heart rate. (③) Maximum oxygen consumption or metabolic equivalents (METs) approach: 40%-85% of the maximum oxygen consumption or METs of the exercise test was taken as the training intensity. The reason for this approach is that heart rate has become difficult to reflect the true cardiovascular exercise response due to the widespread use of cardiovascular active drugs, while it is more difficult to monitor heart rate during exercise. In addition the application of monitoring heart rate and target heart rate is even more difficult when multiple exercise modalities are used in the exercise prescription. Since METs have been more fully studied and the METs values during various activities have been derived, it is easy to make flexible choices when developing the program, so it has been widely used in recent years. ④Anaerobic threshold mode: It means that when the tissue demand for oxygen exceeds the amount of oxygen supply that the circulation can provide after the limit amount of exercise load is reached, the tissue must carry out anaerobic metabolism to provide more energy. The threshold of oxygen consumption at which anaerobic metabolism begins to occur is called the anaerobic threshold. The anaerobic threshold is an indicator that has been developed in recent years and typically occurs at 47% – 64% of maximal oxygen consumption in untrained normal individuals and at 70% – 90% of maximal oxygen consumption in trained individuals, and at approximately 60% of maximal oxygen consumption or the equivalent of 60% – 70% of maximal heart rate in patients with coronary artery disease. Some studies have concluded that this exercise intensity provides the best training effect with the lowest risk of exercise. ⑤ Subjective exertion degree scoring method: For unmonitored exercise, the subjective exertion scoring is generally 11-13, and for those with cardiac monitoring, the intensity can be in the range of 13-15.
Exercise time: refers to the time of each exercise workout. It is generally believed that exercise to achieve the target intensity needs to last 15-30 min, but it is also believed that it can be in the range of 10-60 min. exercise volume = exercise intensity × time. Under the premise of the total rated exercise, the training time is inversely proportional to the intensity. For example, the exercise intensity is 70% of the maximum heart rate when the exercise time is 20-30min, when the exercise intensity is greater than 70% of the maximum heart rate when the exercise time is shortened to 10-15min, when the exercise intensity is less than 70% of the maximum heart rate when the exercise time can be extended to 45-60min. exercise volume can also be expressed in terms of calories consumed by exercise. Calorie consumption (kcal) = [(METs × 3.5 × kg body weight × minutes) ÷ 1000] × 5. For example, a patient weighs 60 kg, exercises at an intensity of 6 METs, and exercises for 45 minutes. Exercise calorie consumption = [(6 × 3.5 × 60 × 45) ÷ 1000] × 5 = 283.5 kcal. Since exercise training generally requires the selection of a variety of exercise modalities to enhance the patient’s interest, there must be some flexibility in the scheduling of training time. The time for warm-up and finishing activities is generally calculated separately.
Exercise frequency: refers to the number of training sessions per week. The frequency of 3-5 times per week is usually used.
(3) Precautions: ① Choose the appropriate exercise, avoid competitive sports. ② Exercise only when you feel good. After a cold or fever, do not resume exercise until the symptoms and signs have disappeared for more than 2 days. ③ Pay attention to the influence of the surrounding environmental factors on exercise response, including: cold and hot climate to relatively reduce the amount and intensity of exercise; wear loose, comfortable, breathable clothes and shoes; slow down when going uphill. Do not exercise strenuously after meals. ④ Patients need to understand the limitations of their individual abilities and should regularly check and revise their exercise prescriptions to avoid overtraining. When medication changes, take care to adjust the exercise regimen accordingly. ⑤ Be alert to symptoms. If the following symptoms are observed during exercise, stop exercising and seek prompt medical attention: upper body discomfort (including chest, arms, neck or jaw, which may manifest as soreness, burning, constriction or distension), weakness, shortness of breath, bone and joint discomfort (arthralgia or back pain), etc.
(4) Training implementation Each training must include three parts: warm-up activities, training activities and finishing activities. ①Warm-up activities: 5-10min, the main purpose is to warm up, that is, let the muscles, joints, ligaments and cardiovascular system to gradually adapt to the training period of exercise stress. Exercise intensity is small, the exercise should include stretching exercises and large muscle group activities, to ensure that the main joints and muscles of the whole body are active, generally using medical gymnastics, taijiquan, etc., can also be attached to small intensity walking. ②Training activities: activities that reach the target training intensity. ③ finishing activities: 5-10min, the main purpose is to let the highly excited cardiovascular stress gradually reduce, and adapt to the hemodynamic changes after the cessation of exercise, such as gravitational hypotension, etc.. Exercise intensity is low, the exercise can be the same as the training mode, but gradually reduce the intensity. Adequate warm-up and finishing activities are an important part of preventing training accidents. Seventy-five percent of cardiovascular accidents during training occur in these two periods. In addition, proper warm-up and conditioning activities have a positive effect on the prevention of sports injuries.
Phase III rehabilitation may take 6-12 months. This is a long and arduous training process. Many patients with myocardial infarction drop out halfway and fail to persevere, and many of them cannot follow the exercise prescriptions, and the intensity, duration and frequency of exercise fail to meet the requirements, thus greatly affecting the actual effect of rehabilitation. According to statistics in the United States, about 50% of patients are able to successfully adhere to the entire three periods of myocardial infarction rehabilitation training. This means that half of the patients drop out of the rehabilitation program halfway through. Although the reasons for dropping out of the program are multiple, there is no denying that cardiac rehabilitation is not yet widely and deeply understood as a major reason. Nonetheless, exciting results have been achieved in the rehabilitation of coronary heart disease, particularly myocardial infarction. It is now internationally recognized that cardiac rehabilitation can reduce the overall mortality rate of patients after myocardial infarction by 25% and the risk of unplanned reoccurrence of coronary heart disease by approximately 20%.