Fig. 4.1
Effectiveness of exercise only or exercise as part of a comprehensive cardiac rehabilitation program on all-cause mortality and cardiac mortality (According to Jolliffe et al. [3])
4.1 Definition of Terms
Any muscle contraction resulting in an energy metabolism above basal metabolic rate is characterized as physical activity [6]. Exercise or exercise training is any physical activity that is planned, structured, performed repeatedly, and specifically aimed at improving the physical fitness level [6]. Physical fitness comprises the ability of performance including cardiopulmonary endurance, muscle strength, flexibility, and coordination [6, 7]. Cardiorespiratory fitness is determined by the maximal cardiovascular exercise capacity and is dependent on oxygen transport via lung diffusion, cardiocirculation to the muscle fiber, where it is used in the mitochondria for energy production (ATP synthase). Assessment of maximal oxygen uptake (VO2peak/max) is the gold standard for evaluating cardiorespiratory fitness, typically assessed during a maximal exercise tolerance test performed on a bicycle or treadmill ergometer [8]. Maximal exercise capacity is the highest power output a person can sustain during an exercise tolerance [8]. Exercise tolerance is defined as the highest power output possible before any pathological symptoms and/or medical indications occur [9]. In a healthy person both terms can be used interchangeably, but in a patient the range can differ substantially [8]. For the definition of the amount of physical activity or exercise, the interrelation between the total dose of activity and the intensity at which the activity is performed have to be considered (volume of exercise = duration × intensity). While the dose refers to the total energy expended, intensity reflects to the rate of energy expenditure during the physical activity. Absolute intensity reflects the rate of energy expenditure during exercise, usually expressed in metabolic equivalent tasks (MET). One MET is the energy expenditure or oxygen consumption (VO2) measured during sitting, which equals 3.5 mL O2 kg−1 min−1. MET-hours are the product of exercise intensity and exercise time [6]. Relative intensity refers to the percent of aerobic power utilized during exercise. It is expressed as percent of maximal heart rate or percent of VO2peak. In this context, activities performed at a relative intensity of <40 % VO2peak are considered to be of light intensity, those performed at 40–60 % VO2peak to be of moderate intensity, and those performed at relative intensity of >60 % VO2peak to be of vigorous intensity [6]. For the estimation of intensity, the person’s individual premises have to be taken into account. For example, brisk walking at 4.8 km h−1 has an absolute intensity of ~4 MET. For a young and healthy person, this intensity is low in relative terms, but represents a vigorous intensity for an 80-year-old person.
Exercise therapy “is medically indicated and prescribed exercise, planned and dosed by therapists, controlled together with the physician and carried out with the patient either alone or in a group” [10]. Sport and exercise therapy “is an exercise based therapeutic measure which compensates for destroyed physical, mental and social functions with suitable sports remedies, regenerates, guards against secondary damage and supports health oriented behaviour. Sport therapy is based on biological principles; especially includes physiological, medical, pedagogic-psychological as well as social therapeutic elements and attempts to create enduring health competence” [10].
4.2 Objective of Exercise-Based Training Intervention
The primary objective of an exercise-based training intervention in cardiac rehabilitation is to positively influence disease progression and prognosis. This is most successfully achieved in coronary heart disease (CHD) and its pathological consequences (acute coronary syndrome, sudden death, ischemic heart failure) and in nonischemic chronic heart failure [1, 2, 6, 11–17]. The main secondary objectives are an improvement in the symptom-free exercise tolerance and overall quality of life [6, 12–14]. Further secondary objectives are overcoming cardiovascular and musculoskeletal limitations caused by inactivity (in particular in chronic heart failure and after open-heart surgery), as well as to improve mobility, independence, psychological well-being, social and occupational reintegration, and cardiovascular risk factors and thereby reduce the need for future home care, enhance participation, and enable the patient to take up his further life. In order to achieve these objectives, an extensive physical activity counseling including individual instructions is of crucial importance, in addition to the supervised exercise training [6, 11, 12, 14, 16–19].
Individual objectives should be based on the patient’s cardiac diagnosis, exercise capacity, possible exercise-limiting comorbidities, age, gender, exercise experience, as well as the patient’s motivation, personal exercise goals, and preferences. Respecting somatic, psychosocial, and educative objectives, they should aim to support the patient’s health-oriented behavior, to create his/her persistent health competence, and to improve his/her self-efficacy (Table 4.1 and Fig. 4.2).
Table 4.1
Somatic, psychosocial, and educative objectives of individually prescribed and supervised exercise training in cardiac rehabilitation
Somatic objectives: |
To positively influence disease progression and prognosis |
To overcome cardiovascular and musculoskeletal limitations caused by inactivity |
To improve symptom-free exercise tolerance |
To improve cardiopulmonary exercise tolerance |
To improve coordination, flexibility, agility, and muscular strength |
To positively influence cardiovascular risk factors |
Psychosocial objectives: |
To improve body awareness and perception, especially the patient’s perception of stress during exercise training |
To reduce the patient’s anxiety for overload during exercise training |
To improve the patient’s realistic judgment of his/her individual exercise tolerance |
To improve overall well-being |
To improve psychosocial well-being and coping with the disease |
To improve overall social integration |
To increase level of independency |
To improve quality of life |
Educative objectives: |
To improve knowledge in the impact and health benefits of regular physical activity and exercise training |
To improve practical skills of self-control and adequate handling during physical activity and/or exercise training to the patient |
To improve long-term compliance to lifestyle changes |
To implement a physically active lifestyle |
Fig. 4.2
Objectives of exercise-based training intervention
4.3 How to Set Up an Exercise Training Program in Cardiac Rehabilitation
Exercise training in cardiac rehabilitation should be medically supervised and led by an experienced exercise therapist (or physiotherapist). During the initial phase after an acute event, the exercise program should be started under careful medical supervision. The supervision should include physical examination, monitoring of heart rate, blood pressure, and rhythm before, during, and after the exercise training [12, 14, 17]. A careful supervision allows to verify individual responses and tolerability, clinical stability, and promptly identifying signs and symptoms indicating necessary modification or termination of the program. The supervision should be prolonged in patients with high risk of cardiovascular events (severe coronary heart disease, heart failure NYHA III, ventricular arrhythmias, implantable cardioverter defibrillator (ICD), heart transplantation). In these patients an inpatient cardiac rehabilitation setting is recommended [12].
Exercise training in cardiac rehabilitation should be prescribed on an individualized approach after a careful clinical evaluation including: risk stratification, symptom-limited exercise testing (either on bicycle or on treadmill), assessment of possible exercise-limiting comorbidities, assessment of functional capacity (especially in groups at risk to have reduced functional capacity, e.g., older patients, females, and/or heart failure patients), assessment of behavioral characteristics (movement and exercise experiences, physical activity level, readiness to change behavior, self-confidence, barriers to increase physical activity, as well as social support in making positive changes), and patient’s personal goals and exercise preferences. The type and severity of the disease also have to receive similar attention such as personal characteristics like age and gender [12, 14, 17] (Fig. 4.3).
Fig. 4.3
Contents of comprehensive exercise based training intervention in cardiac rehabilitation
Exercise training in cardiac rehabilitation should be based on aerobic endurance training. On its basis, further components such as resistance exercise and gymnastics including exercises for coordination (inclusive balance and sensorimotoric), flexibility, agility, and strength as well as perceptional training, are to be added. In frail and older patients, special exercise elements for preventing falls should be a part of the exercise program (Fig. 4.4).
Fig. 4.4
Components that have to be considered by planning and implementation of an individually dosed, adapted and controlled exercise program in cardiac rehabilitation
Based on the results of the clinical evaluation, every person should receive individualized exercise training recommendations containing the following information [14] (Fig. 4.5):
Exercise training goals (i.e., improvement of exercise capacity, muscular strength)
Exercise training mode (i.e., aerobic endurance training, moderate resistance training)
Exercise training content, with reference to the preferred type of exercise (i.e., bicycle ergometer, treadmill, walking, Nordic walking, etc.; resistance training using weight machines, elastic bands, etc.)
Exercise training method (steady-state training, interval training, etc.)
Exercise training intensity (i.e., % HRpeak, % VO2peak, % of one repetition maximum)
Exercise training duration (duration of the individual training unit [i.e., 30–60 min] and the supervised training program [i.e., 3–6 months])
Exercise training frequency (i.e., 3–7 exercise units per week) [12]
Fig. 4.5
How to set up an individually dosed and adapted, and controlled exercise training program in cardiac rehabilitation
Exercise training duration, intensity, and frequency should start at a low level and be increased incrementally. Especially in patients taking up an exercise training after a long period of inactivity, it is important to pay close attention to the variation in time each organ system needs in order to adapt to the training process. While the cardiovascular and muscular systems show a fast adaptation, bones, tendons, ligaments, and joints adapt very slowly. The primary goal should be to increase training duration and frequency [12]. If these are well tolerated, then the intensity can also be increased.
Exercise training should be planned in three stages: initial stage, improvement stage, and maintaining stage (Fig. 4.6) [12, 14, 17].
Fig. 4.6
Stages of exercise training in cardiac rehabilitation
The objectives of the initial stage are to prepare the patient for the exercise training and to verify the individual response and tolerability to a low-intensity exercise program. This phase also includes improvement of coordination and flexibility as well as developing the patient’s perception for exercise intensity. Previously physically inactive people and older patients have to receive special attention. In the initial stage the intensity of exercise should be kept at a low level. According to perceived symptoms and clinical status, the duration of the exercise unit can be prolonged (i.e., from 15 to 30 min). The duration of the initial stage depends on the patient’s clinical status and exercise tolerance, but should not exceed 4–6 exercise units during 1–2 weeks, respectively.
The objectives of the improvement stage are to gradually increase exercise capacity and other components of physical fitness such as coordination, flexibility, muscular strength, and endurance capacity. During this stage, the exercise intensity should be gradually increased according to the patient’s exercise prescription and exercise goals. Likewise, each exercise session can be prolonged up to 30–60 min and even beyond as well as exercise frequency can be increased up to daily sessions. However, this has to be adapted to the patient’s objective medical status and subjective health status.
The objectives of the maintenance stage are to stabilize and preserve the improvements achieved as well as extend them over a long period of time. Exercise intensity, exercise duration, and exercise frequency can be gradually increased if tolerated. In this stage, special attention has to be paid to the patient’s motivation as well as education to increase and or stabilize adherence to regular physical activity and exercise training. It is mandatory to provide the patient with the necessary practical skills of self-control and adequate handling during physical activity and/or exercise training. Careful instruction about the impact and health benefits of regular physical activity and exercise training might be helpful to improve his/her adherence to a physically active lifestyle.
Overall, during cardiac rehabilitation the individual exercise training recommendations have to be adapted individually and reevaluated after change of medical status, change of medication, hospitalization, or other illnesses.
4.4 Physical Activity Counseling: Motivation to a Physically Active Lifestyle
Provided they are performed on a regular and a long-term basis, physical activity and exercise training are valuable sources of multiple health benefits. The patient’s motivation to take up an active lifestyle and start regular exercise training on a sustained basis is therefore an important goal of the cardiac rehabilitation program. Investigations have shown that the patient’s thorough information and motivation provided by the attending physician is the most effective instrument to achieve such behavioral changes [21]. Based on this initial encouragement by the physician, the motivation achieved has to be stabilized and augmented through individual as well as group counseling during the rehabilitation process.
The primary preventive role of regular physical activity is well established by large epidemiological studies. Results of meta-analyses demonstrate regular physical activity compared with sedentary behavior to be associated with reduction of overall mortality rate by 22–36 % and reduction of cardiovascular mortality rate by 25–35 % [22–25]. The impact of regular physical activity in the secondary prevention of CHD is less well established. The results of smaller prospective studies demonstrate the prognostic importance of regular physical activities after diagnosis of the CHD, showing regular physical activity to be associated with a relative risk reduction of overall mortality by 19–58 % and cardiovascular mortality and/or morbidity by 20–62 % [26–35]. These prospective cohort studies [27, 32] also showed that it is never too late to take up an active lifestyle. They found reduced overall mortality rate by 29–50 % in former inactive CHD patients that increased their activity levels after the diagnosis of the disease [27, 32]. A relative reduction for overall mortality by 34–79 % was found in anciently physically active patients that maintained active, compared to those who were sedentary before and after the diagnosis of the disease [27, 32]. These results have to be established by studies with greater cohorts. Thereby in cardiac rehabilitation, it is important to emphasize sedentary lifestyle as an independent risk factor and explain the health benefits achieved by any increase in physical activity to the patients. However, the exercise therapist should keep in mind that it is not sufficient to inform the patient about the achievable health benefits. During the rehabilitation process, the patient’s perceptions, attitude, and health esteem regarding physical activity and exercise training have to be influenced positively. It is important that he/she experiences the exercise training provided during cardiac rehabilitation as a convenient task that he/she can cope with as well as an activity that is associated with well-being, fun, and social contacts. On a long-term basis, the patient will only integrate physical activity and exercise training into his/her daily life, if medical benefits are associated with personal values. The motivation to be physically active for health benefits usually only lasts for few months [36]. It is essential to change the patient’s secondary motivation (exercise training for health) into a primary motivation (e.g., I like exercise training, it is associated with fun, well-being, and/or meeting friends); otherwise he/she will return to his/her inactive lifestyle within a short period of time.
During the cardiac rehabilitation program, the patient should receive individual advices and exercise prescription for his/her physical activity and exercise training after the termination of the program and get the opportunity to put those into practice under supervision. These individual advises should take into consideration the patient’s age, gender, past habits, comorbidities, preferences, and goals. The patient’s readiness to change behavior, his/her self-confidence, and/or social support in making positive changes as well as possible barriers to increase and take up independent exercise training should be addressed. The participation in long-term maintenance programs like heart groups should be recommended if available.
4.5 Perception Training, Body Awareness, and Practical Skills of Self-Control
After an acute cardiac event (acute coronary syndrome, PCI, or cardiac surgery), most of the patients are uncertain regarding physical activity overall and, particularly, how much physical stress they are able to tolerate and what kind of physical activity they are allowed to perform. This uncertainty in combination with the experience of the vulnerability of the heart results in the avoidance of any physical strain and foster physical inactivity. Other patients rather tend to mentally suppress the cardiac event that might assimilate a danger of overload. During the exercise training, the patient has to learn the limit of his/her exercise tolerance and his/her exercise limits. The goal is to achieve the patient’s realistic judgment as well as his/her acceptance of the often considerable reduced exercise tolerance. The exercise training is an optimal instrument to improve the patient’s body awareness and perception. The experience of subjective and objective symptoms that occur during exercise training should be used to help the patient to recognize such symptoms as well as estimate their relevance for the load achieved. Improving body awareness and perception should therefore be an integral component of each exercise training, explaining the exercise procedure and its beneficial as well as possible adverse effects on the body to the patient. Through the exercise training, the patient should learn to perceive and observe his/her local and systemic reactions (i.e., increased heart rate, respiration, level of exertion of the muscle, subjective well-being, etc.) and to interconnect them to the objective exertion performed. By gradually increased exercise intensity, the patient should perceive the limit of his/her exercise tolerance in order to be able to recognize it. The exercise therapist should communicate with the patient asking him/her to prescribe his/her perceptions of objective and subjective symptoms during exercise. These practical skills of self-control are the fundamental instruments for the patient’s safe and effective approach to physical activity and training. This will reduce anxiety and improve a certainty regarding physical exertion during occupation, recreation, or daily life (Fig. 4.7).
Fig. 4.7
Patient should learn to perceive and observe his/her local and systemic reactions, i.e. increased heart rate
4.6 Aerobic Endurance Training
Oxygen consumption (VO2peak) assessed by means of cardiopulmonary exercise testing is one of the strongest predictors of disease prognosis in patients with coronary artery disease and chronic heart failure [36–42] (Fig. 4.8). In CHD patients every 1.0 ml/kg1 min1 increase in VO2peak is associated with 15 % decrease in risk of death, 14 % (in women) and 17 % (in men) decrease in risk of overall mortality, and 10–14 % (in women) and 9–16 % (in men) decrease in risk of cardiovascular mortality [42]. Martin et al. [43] demonstrated in a retrospective analysis of a cohort of 5641 CHD patients that improvements in VO2peak achieved during cardiac rehabilitation have prognostic value. They found every increase in exercise capacity in one MET achieved during 12-week CR to be associated with 13 % reduction of overall mortality. In patients who started the CR program in the lowest fitness group, the benefit on exercise capacity was even of greater value. In this group an increase in one MET was associated with 30 % reduction of overall mortality.
Fig. 4.8
The relative risk of death from any cause according to quintile of exercise capacity among subjects with and without cardiovascular disease (According to Myers et al. [41])
A systematically carried out aerobic endurance exercise program leads to an increase in exercise capacity and symptom-free exercise tolerance [13, 42–46]. In patients with cardiovascular disease, the increase in exercise capacity gained has been reported to range between 11 and 36 % [13, 45, 46] depending on the patient’s exercise tolerance, clinical status, as well as intensity and dose of the exercise training [13, 47–49]. Sedentary untrained and deconditioned patients have been shown to achieve the greatest benefits [13, 47–49]. In addition, long-term regular aerobic endurance training positively influences well-known cardiovascular risk factors such as hypertension, type 2 diabetes mellitus, dyslipidemia, and abdominal obesity [50–59] (Fig. 4.9).
Fig. 4.9
Potential cardioprotective effects of regular physical activity, especially aerobic endurance training
4.6.1 Exercise Prescription and Definition of Individual Exercise Intensity
Based on careful clinical evaluation and risk stratification, including symptom-limited exercise testing, aerobic endurance training can be performed in a safe and an effective manner [3, 4, 46].
In addition to the maximal achieved exercise capacity, the intensity that the patient is able to tolerate without any pathology (exercise tolerance) is to be well defined and taken into account when exercise prescription is given.
Absolute contraindications to aerobic endurance training are summarized in Table 4.2 [14].
Acute coronary syndrome (ACS) |
Malignant hypertension with systolic blood pressure >190 mmHg during exercise training despite exhaustive antihypertensive medication therapy |
Drop in systolic blood pressure by ≥20 mmHg during exercise, in particular in patients with CHD |
Severe secondary mitral valve insufficiency or more specifically moderate mitral valve insufficiency with evidence of increased regurgitation during exercise |
Heart failure NYHA IV |
Supraventricular and ventricular arrhythmias causing symptoms or hemodynamic compromise, continual ventricular tachycardia |
Frequent ventricular extrasystoles, noncontinual ventricular tachycardia in advanced left ventricular dysfunction or more specifically after myocardial infarct as well as in response to exercise or during the postexercise regeneration phase |
Cardiovascular diseases that have not been risk evaluated and that have not been treated according to guideline requirements in terms of best possible prognosis outcome (i.e., beta-blocker in patients with CHD, angiotensin-converting enzyme inhibitor in patients with heart failure) or, more specifically, hemodynamic control (i.e., maximal medication therapy for blood pressure regulation in severe arterial hypertension). Patients with contraindications to exercise training due to malignant arrhythmias, on the other hand, can be introduced to a training program after antiarrhythmic measures have been taken (i.e., implantable cardioverter defibrillator (ICD), proven efficacy of medication therapy) |
4.6.1.1 How to Define Exercise Intensity
Training intensity should be established and controlled based on the results of a maximal exercise stress test done on a bicycle/treadmill ergometer including ECG and blood pressure monitoring. This should yield maximal heart rate, maximal exercise load in watts, possible ischemic threshold, and blood pressure response to exercise. These data will form the basis for determining the individual training load and training heart rate. Additional cardiovascular examinations or improvement of therapy has to be included, if cardiac complaints and/or symptoms arise during the exercise stress test. If complaints or symptom limitations persist, despite maximal therapeutic efforts, it is advised to keep the exercise load at a level free of symptoms and ischemia. It is generally recommended that the training intensity should be clearly below the ischemic threshold [11–13, 17].
The heart rate is an objective, easily determined parameter used to regulate and control exercise load in cardiac rehabilitation. The maximal heart rate (HR peak ) is the highest heart rate achieved prior to termination of an incremental exercise tolerance test due to subjective exhaustion or objective indications [8]. The training heart rate can be determined as percent of maximal heart rate (HRpeak). In cardiac rehabilitation a training heart rate of 65–75 % (if tolerated 80–85 %) HRpeak is recommended [17]. It is important to keep in mind that only the heart rate response to an exercise stress test performed under the patients actual medication can be used for exercise prescription. This applies especially to the use of ß-receptor blockers (Fig. 4.10).
Fig. 4.10
How to determine a target heart rate and exercise load (watt) for exercise training in cardiac rehabilitation
The training heart rate can also be determined mathematically by using the Karvonen formula, in which the heart rate reserve (HRR) is calculated. The heart rate reserve is the difference between maximal heart rate and resting heart rate, as determined in maximal exercise stress test (Fig. 4.11).
Fig. 4.11
How to determine the target heart rate for exercise training in cardiac rehabilitation using the Karvonen formula
In cardiac patients training heart rate of 40–60 % (if tolerated 65–70 %) of heart rate reserve is recommended [17]. The heart rate reserve method should especially be used in patients with chronotropic incompetence. The training heart rate should always be determined clearly below the ischemic threshold (i.e., 10 beats/min).
Maximal exercise capacity measured in watt is a reliable and reproducible parameter in order to regulate exercise training performed on a bicycle ergometer [11]. In cardiac rehabilitation exercise intensity at 40–60 % (if tolerated up to 70–80 %) of maximal load (watt) achieved in a symptom limited exercise test is recommended [17]. In patients with very low exercise tolerance, very low heart rate reserve, as well as with the inability of the sinus node to react adequately to exercise stress by increasing heart rate (i.e., patients with chronotropic incompetence, atrial fibrillation, pacemakers, and post-heart transplant), training intensity should be controlled according to exercise load in watts and by using the Borg scale.
The Borg scale (rate of perceived exertion (RPE)) is used to subjectively assess how the individual perceives the intensity of the performed exercise on a scale from 6 to 20 points [60] (Fig. 4.12). It is not advisable, however, to solely rely on the Borg scale to advise on training load as it contains too many influencing factors from the patient’s perspective (i.e., unfamiliar method, poor body awareness, over motivation, and peer pressure) [61]. The Borg scale can be used as a supplement to other training regulation options, as well as to facilitate developing body awareness to the exercise load. Target values are RPE 11–14, comparable to light to moderate exercise intensity [17].
Fig. 4.12
The Borg scale – rate of perceived exertion (RPE)
The maximal oxygen consumption (VO 2peak ) reached during an exercise stress test and the oxygen consumption at the anaerobic threshold (VO2-AT) are meaningful parameters in regulating exercise load during training [62]. The latter can also be determined during submaximal exercise testing, independent of the individual’s motivation level [63]. If a cardiopulmonary exercise test is used to determine aerobic training intensity then 40–70 % of VO2peak (up to 80 % if tolerated) should be targeted, close to the individual’s anaerobic threshold (1st VAT) [17, 64] (Fig. 4.13).
Fig. 4.13
An exemplary result from a cardiopulmonary exercise testing in a 62-year-old man with coronary artery disease and type 2 diabetes
4.6.1.2 Aerobic Endurance Training Duration and Frequency
Health benefits can only be reached and maintained with long-term aerobic endurance training done on a regular basis. Aerobic endurance training should be performed for ≥30 min 3–5 times per week, preferably everyday, resulting in a total exercise time of ≥150 min per week (or 21/2 h/week). Ideally, exercise time should be around 3–4 h/week. The initial aerobic endurance exercise phase should last around 5–10 min in untrained individuals and gradually increase to ≥30 min per training session during the course of the training program. Low-intensity physical activities, such as walking in plane, can and should be done on a daily basis (preferably more than once a day) [12, 14, 17].
4.6.1.3 How to Perform Aerobic Exercise Training
The most common training forms used in cardiac rehabilitation to improve aerobic endurance are ergometer training on a cycle or treadmill. Additional common aerobic exercise modes include walking, Nordic walking, and biking. Jogging may be performed in those with good exercise capacity. This holds also true for swimming, as only those with stable cardiac condition without ischemia or potential for life-threatening should perform swimming. The decisive factors in choosing an appropriate training form in cardiac rehabilitation should be the ability to exactly dose, control, and gradually increase the appropriate exercise intensity, and the availability to monitor vital parameters (i.e., ECG, heart rate, blood pressure) is necessary.
When choosing a training form, an individual’s baseline characteristics (such as age, gender, exercise experience, exercise tolerance, and concomitant diseases) as well as preference and motivation must be considered. For overweight and obese individuals, non-weight-bearing exercise modes should be chosen (i.e., biking, bicycle ergometer training, and swimming). Walking and Nordic walking can be considered, if there are no pre-existing joint problems.
Aerobic Endurance Training on a Cycle Ergometer
In phase II of cardiac rehabilitation, aerobic endurance training on a cycle ergometer is recommended as standard procedure. The advantages of this training form are that it is non-weight bearing and enables the exercise load to be precisely dosed, independent of the patient’s body weight. Moreover, the minimal upper body motion enables blood pressure and ECG to be monitored at a high-quality standard during exercise. This type of exercise can be performed in an upright or supine position, and special safety equipment is available to facilitate patients with special needs, for example, extremely obese subjects, elderly insecure patients, or patients with history of stroke (Fig. 4.14). Computer-controlled cycle ergometer training and monitoring systems, specially designed for the use in cardiac rehabilitation, are available. Cycle ergometry can be performed as group training or at an individual basis. Training should be performed on an electrically braked cycle ergometer 3–5 times per week. If possible, it should be taken advantage of everyday the cardiac rehabilitation program is offered.
Fig. 4.14
Supervised exercise training on a cycle ergometer
Endurance training (i.e., 10–30 min) is the most effective method to improve aerobic endurance capacity. Every exercise unit on the cycle ergometer should be constructed in four phases (Table 4.3 and Fig. 4.15).
Table 4.3
Recommendations for moderate-intensity-continuous-endurance training on a cycle ergometer
Phase I (warm-up phase I) | |
Exercise intensity: | <50 % of target exercise intensity |
Exercise duration: | >2 min |
Phase II (warm-up phase II) | |
Exercise intensity: | Gradually increase in exercise load by 1–10 watt/min (depending on patient’s exercise tolerance) until target exercise intensity has been reached |
Exercise duration: | 5–10 min |
Phase III (exercise phase) | |
Exercise intensity: | 100 % of the target exercise intensity in watt and/or of the target training heart rate |
Exercise duration: | >5 min and gradually prolong the exercise duration up to 20–30 min (up to 45–60 min) |
Phase IV (cool down phase) | Gradually reduce the exercise load to 0 watt within the time of 3 min. |
Fig. 4.15
Aerobic endurance training on a cycle ergometer. The graphic shows the composition of an exemplary exercise session
Table 4.4 shows the recommendation for the implementation of moderate-intensity-continuous-endurance training in cardiac rehabilitation [17].
Table 4.4
Recommendations for moderate-intensity-continuous-endurance training on a cycle ergometer
Aerobic endurance training on a cycle ergometer training with monitoring | |||
|---|---|---|---|
Stages | Exercise intensity | Exercise duration | Exercise frequency |
Initial stage | Low intensity, that is, 40–50 % VO2peak, 60 % HRpeak 40 % HRR Below 1st VAT RPE < 11 | Starting with ca. 5 min (in the exercise phase) and gradually increase to 10 min | 3–5 days/week Target: daily |
Improvement stage | Gradually increase the exercise intensity from low to moderate up to target values, depending on the patient’s exercise tolerance and clinical status, that is, 50, 60, 70, (80 %) VO2peak 65, 70, 75 (80–85 %) HRpeak 45, 50, 55, 60 % (65–70 %) HRR RPE 12–14 | Gradually prolong the exercise training from 10 to 20 (up to 30–45) min | 3–5 days/week Target: ≥5 days/week |
Maintenance stage | Long-term stabilization of the exercise intensity and exercise duration achieved during the improvement stage; gradually increase exercise intensity and especially exercise duration and frequency if intended and well tolerated | Gradually prolong the exercise training from 20–45 (up to >60) min if tolerated | 3–5 days/week Target: most days/week |
The safety and efficiency of moderate-intensity-continuous-aerobic training in patients with cardiac diseases is well established and therefore recommended as a standard training modality in cardiac rehabilitation in international guidelines and position papers. In primary prevention it is well known that higher exercise volume aerobic exercise training is more effective to improve exercise capacity and to reduce overall mortality. On the other hand by increasing the intensity similar effects can be achieved by shorter exercise boots [66]. Results of a meta-analyses [22] demonstrate an inverse relationship between exercise intensity and overall mortality, which was independent of age and gender. The question is if vigorous aerobic exercise training is also safe, effective, and well tolerated in cardiac patients. An interval-training mode would allow to exercise with at least short high-intensity bouts alternating to bouts of low or moderate intensity. In fact in the last decade, some studies with high-intensity interval training (HIIT) in cardiac patients have been carried out. The results prove HIIT to be beneficial [67, 68] and safe [69] in CHD patients [67–75] as well as in patients with markedly reduced exercise capacity (i.e., severe chronic heart failure) [76–80]; however long-term effects are still equivocal. In cardiac rehabilitation mainly two types of interval trainings protocols have been in focus of science and implementation: sprint or short-term interval training and high-intensity interval training (HIIT).
The type of sprint or short (term) interval training mostly used in cardiac rehabilitation is characterized by alternating short bouts of high-intensity exercise (20–30s) followed by a long recovery phase at minimal load typically twice the length of the exercise bout (ratio of exercise time: recovery time = 1:2) (Fig. 4.16 and Table 4.5). The advantage of this type of training is that the short bout of high-intensity exercise stimulates peripheral adaptations in the leg muscles to take place without compromising an overload in central mediation. The exercise intensity can be determined as a percentage of maximum load (wattpeak) achieved during a symptom-limited exercise stress test. An intensity as high as 85–90 % of wattpeak is usually recommended. Conclusive evidence base concerning the safety and efficiency of this type of training is only preliminary and must be confirmed by randomized controlled studies [14, 17].
Fig. 4.16
Interval training on a cycle ergometer. The graph shows the composition of an exemplary exercise session
Table 4.5
Exercise protocol commonly used for interval training in cardiac rehabilitation: sprint or short (term) interval training and high–intensity interval training to be performed on a cycle or treadmill ergometer
Sprint or short (term) interval traininga | High-intensity interval training (HIIT) |
|---|---|
Phase I (warm-up phase) | Phase I (warm-up phase) |
> 2 min without or with very low load | 10 min with 60 % of the heart ratepeak |
Phase II (exercise phase) | Phase II (exercise phase) |
Alternating short (20–30 s) exercise bouts with 100 % of the target exercise intensity and twice as long (40–60 s) recovery bouts without or with very low load ≥10 repetitions of the intervals – to be prolonged up to ≥20 repetitions. | Alternating 4 × 4 min exercise bouts with 85–95 of HRpeak and 3 × 3 min recovery bouts with 60–70 % of HRpeak |
Phase III (recovery phase) | Phase III (recovery phase) |
< 3 min without or with very low load | 3–5 min with 60–70 % of HRpeak |
Within the last few years, the safety and the efficacy of the 4 × 4 min high–intensity interval training protocol (HIIT) (Table 4.5 and Fig. 4.17) has been in the scientific focus for its use in cardiac rehabilitation. Meta-analysis including the results of few small, randomized controlled studies comparing the efficacy of HIIT to moderate-intensity-continuous-endurance training has revealed HIIT to be more effective in improving exercise capacity measured as a VO2peak. A meta-analysis of nine studies (206 CHD patients) [67] revealed HIIT to increase VO2peak a 1.60 mL/kg−1/min−1 more than moderate continuous training. High-intensity interval training resulted in a significant larger benefit in VO2peak compared to moderate continuous training (MCT) in patients with CHD (HIIT 20.5 % vs. MCT 12.8 %; p < 0.001). A second meta-analysis of six studies (229 CHD patients; EF < 40; 99 were randomized to HIIT) confirms these results [68]. Patients in the HIIT group improved their VO2peak by 1.53 mL/kg−1/min−1 more than those in the MCT group. The authors point out that small sample sizes and the large inconsistency and heterogeneity between the study results in the included studies limit the informational value of this meta-analysis. On the other hand, a recently published larger randomized controlled study (200 CHD patients; EF > 40 %) comparing HITT versus MCT does not confirm these results [74]. The results show no advantage for one of the exercise modalities (HIIT: 23.5 ± 5.7 vs. 28.6 ± 6.9 mL/kg−1/min−1; +22.7 %; MCT: 22.4 ± 5.6 vs. 26.8 ± 6.7 mL/kg−1/min−1; +20.3 %; p (time) =0.001; p (interaction) = ns) [74]. Both 12-week interventions equally improved VO2peak, peripheral endothelial function, as well as quality of life in CHD patients. Both programs seem to be safe for CHD patients, and no adverse events were reported during the exercise sessions. The authors’ experience was that the implementation of the 4 × 4 HIIT protocol with the target intensity of 90–95 % of HRpeak is hardly feasible in CHD patients. The mean intensity achieved in the HIIT group was 88 % of HRpeak compared to mean intensity of 80 % HRpeak in MCT group. These results demonstrate the impact of sufficient training intensity in continuous exercise training, which may, if tolerated, be more than the generally recommended 65–75 % of the HRpeak. Rogmore et al. [69] evaluated the risk of cardiovascular events during organized high-intensity interval exercise training (HIIT 85–95 % HRpeak) and moderate-intensity training (MCT 60–70 % HRpeak) among 4846 patients, primary with coronary heart disease. The results indicate that the risk of a cardiovascular event is overall low during both high-intensity exercise and moderate-intensity exercise in a cardiovascular rehabilitation setting (MCT, one fatal cardiac arrest (1 per 129,456 exercise hours); HIIT, two nonfatal cardiac arrests (1 per 23,182 exercise hours)). In a recently published study, a significant correlation between the changes in physical fitness during the intervention and the physical activity levels after the 1-year follow-up was found, indicating that patients who improved their physical fitness more had a higher motivation to adopt a physically active lifestyle following cardiac rehabilitation [80, 81].
A meta-analysis of seven randomized trials comparing the results of HIIT vs. MCT in heart failure patients (mean LVEF 32 % ) showed high-intensity interval training (HIIT) to be more effective for improving VO2peak than traditionally prescribed moderate-intensity continuous aerobic training (MCT) (WMD 2.14 mL VO2/kg/min, 95 % CI 0.66–3.63). The comparison of the effects on the left ventricular ejection fraction (LVEF) at rest revealed inconclusive results (HIIT vs. MCT: WMD 3.3 %, 95 % CI −0.7–7.3 %) [79]. An interesting meta-analysis stratified aerobic exercise studies in heart failure patients by activity intensity [80]. The results revealed the magnitude of improvements in cardiorespiratory fitness to be greater with increasing intensity, unrelated to baseline fitness levels or exercise volume. The largest improvement in VO2peak was observed with high-intensity training (23 %) showing a linear decrease in effect size with decreasing exercise intensity (vigorous intensity 16 %, moderate intensity 13 %, low intensity 7 %, respectively). Exercising with high or vigorous intensity seems to be well tolerated in heart failure patients, especially if interval protocol is used. Furthermore studies of continuous exercise training used a greater volume (duration) of exercises and some of them multiple daily sessions. In high-intensity exercise programs, the volume of work is completed in shorter time and may therefore require shorter session duration and lower exercise frequency that might influence the patient’s adherence to the exercise program [80]. Moreover this analysis also demonstrated exercising with higher intensity in heart failure patients to be safe, showing no increased risk of death, adverse events, or hospitalization in the high- and vigorous-intensity exercise groups [80]. These interesting results must be confirmed by more prospective randomized controlled studies, with greater cohorts and longer follow-up period, though, before definite recommendations can be given [14, 17]. Furthermore until now the prognostic value of high-intensity interval training have not yet been evaluated neither in CHD nor in heart failure patients.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
