Abstract
The benefits of physical activity are well established, leading to both cardiovascular and non-cardiovascular benefits, improving quality of life and reducing mortality. Despite such striking body of evidence, patients with hypertrophic cardiomyopathy are often discouraged by health professionals to practice physical activity and personalised exercise prescription is an exception rather than the rule. As a result, hypertrophic cardiomyopathy patients are on average less active and spend significantly less time at work or recreational physical activity than the general population. Exercise restriction derives from the evidence that vigorous exercise may occasionally trigger life-threatening arrhythmias and sudden cardiac death. However, while participation in competitive sports should be prudentially denied, hypertrophic cardiomyopathy patients can benefit from the positive effects of regular physical activity, aimed to reduce the risk of comorbidities and improve the quality of life. Based on this rationale, exercise should be prescribed and titrated just like a drug in hypertrophic cardiomyopathy patients, considering individual characteristics, symptoms, past medical history, objective individual response to exercise, previous training experience and stage of disease. Type, frequency, duration, and intensity should be defined on a personal basis. Yet exercise prescription in hypertrophic cardiomyopathy and its long-term effects represent major gaps in our current knowledge and require extensive research. We here review existing evidence regarding benefits and hazards of physical activity, with specific focus on viable modalities for tailored and safe exercise prescription in these patients, highlighting future developments and relevant research targets.
Introduction
The benefits of physical activity (PA) are well established, leading to both cardiovascular and non-cardiovascular benefits, improving quality of life, reducing mortality1–3 and promoting a favourable cardiac risk profile.4,5 Conversely, the body rapidly maladapts to physical inactivity which, when prolonged, may result in substantial decrease in total and ‘quality’ years of life.1,8 As a consequence, regular PA is highly recommended by international guidelines and should be considered in all regards as therapeutic strategy deserving to be prescribed – like any other drug – in a tailored approach based on patients’ characteristics, personal and medical history, and individual response. Despite the striking body of evidence in favour of PA, cardiac patients are often physically inactive, PA is not encouraged by health professionals and a personalised prescription is an exception rather than the rule.6 Indeed, patients with hypertrophic cardiomyopathy (HCM) are known to be less active and spend significantly less time at work or in recreational PA than the general population.7 Notably, this trend is not limited to the minority forced to inactivity due to objective functional limitation in the setting of advanced disease progression or severe outflow obstruction, but extends to individuals who are young, have little or no symptoms and previously been involved in competitive sports. As a result, HCM patients are often overweight,7 with a prevalence of obesity as high as 40%.8 In turn, obesity is a public health epidemic with multifactorial impact on cardiac structure and function. In HCM patients, obesity is independently associated with adverse cardiac remodelling, increased left ventricle (LV) mass and higher likelihood of dynamic obstruction and congestive symptoms.8,9 These effects appear to be partly direct and partly mediated by the increased prevalence of diabetes and hypertension.8 Long-term, physical inactivity and weight excess are expected to bear a major impact in term of cardiovascular morbidity and mortality, sleep apnoea, arrhythmias and diabetic complications, adding to the natural burden of HCM progression. Of note, most HCM-related complications are now known to peak in the 6th–7th decade of life, at a time when classic cardiovascular risk factors – including sedentary lifestyle – generally take their toll.10 Therefore, although exercise cannot ‘heal’ HCM, the benefits of PA may help patients to improve their wellbeing and life expectancy.
Why are most HCM patients inactive?
Most HCM patients admit an intentional reduction in PA following the diagnosis of HCM, despite a negative impact on their emotional well-being and mental health. Others continue to practise moderate or vigorous exercise, but the duration and frequency of activity is significantly lower than the general population.7 The potential reasons include physician or self-imposed restrictions owing to safety concerns or physical limitations to exercise, or both. Sweeting et al. aimed to establish the prevalence of physical inactivity in 198 HCM patients and to elucidate the barriers to PA in this specific population.11 They found that more than a half (54.8%) of HCM patients did not meet the minimum amount of PA recommended; notably, some authors reported a lower percentage of adults physically inactive in the general population, i.e. 31.1%.12 Older age, poor health and a higher number of perceived barriers reduced the likelihood of meeting guidelines, while better physical health-related quality of life and having a tertiary education increased the likelihood of meeting guidelines.11 The most commonly identified barriers to exercise included ‘pain interferes with my exercise’ (32.8%), ‘I have an injury/disability that stops me’ (29.3%), ‘I don’t have time’ (27.9%) and 16.2% of patients indicated they had been advised not to exercise.11 In an indirect comparison with the general population, perceived barriers to exercise for HCM patients were more likely related to health rather than to time or motivation.11,13 Furthermore, information via social media on sudden cardiac death (SCD) related to HCM in competitive athletes14 may have generated anxiety and fear in HCM patients and may have played a role as barrier also to practice PA. The medical advice to generalised exercise restriction in HCM patients derives from early evidence that vigorous exercise may trigger life-threatening arrhythmias and SCD. Indeed, previous evidences demonstrated that HCM was a frequent cause of SCD in young athletes in the USA.15,16 A lower prevalence of HCM-associated SCD (i.e. 8%) was then demonstrated by Harmon et al. in a database of National Collegiate Athletic Association deaths (2003–2013), with another 8% due to ‘idiopathic left ventricular hypertrophy/possible cardiomyopathy’.17 In the UK, Finocchiaro et al. confirmed that 6% of SCDs were due to HCM with the highest percentage (8%) observed in the range of age between 18–35 years.18 However, the approach assessing solely individuals who have died on the field provides a very skewed perspective, lacking a clinical denominator and not taking into account relevant demographic differences such as ethnicity, age and definition of ‘athlete’. When the issue is analysed by assessing the circumstances and triggers of all SCD in HCM cohorts, the association of arrhythmic events with PA is less compelling. In the study by Finocchiaro et al.,18 13 HCM individuals died while exercising, while seven events occurred at rest. If idiopathic LV hypertrophy is also considered, 34 cases occurred during exertion and 25 cases died at rest. Therefore, while intensive exercise and competitive sport participation may certainly trigger SCD, due to accompanying alterations in hydration, electrolyte and acid-base status and surges in catecholamine levels, other mechanisms also seem to be at play in HCM, and the risk associated with less intense PA appears dubious.18–20 Although a level of uncertainty still exists regarding the long-term safety of exercise at different levels of intensity and training goals in HCM patients, mounting evidence suggests that the risks are considerably lower than initially estimated more than a decade ago.21 Furthermore, in the setting of submaximal, tailored activity, estimated risk is expected to be even lower and possibly not different from that associated with HCM in resting conditions or during routine daily activities.
Exercise prescription in HCM: a review of the evidence
Current international guidelines and expert consensus documents agree that HCM patients should be excluded from high-intensity competitive sports.22,23 However, there are endless alternative options between maximal, competitive engagement and complete inactivity. Asymptomatic HCM individuals who are disqualified from competitions often enter a grey zone where little or no information is provided about what they can or cannot do to stay active. This paradox reflects the fact that physicians are often reluctant to provide guidance, due to lack of data and limited confidence with the issue.
Rather than vague advice, or no advice at all, the best approach to active HCM patients is represented by tailored exercise prescription. Unfortunately, few trials on exercise training in HCM patients are there to help guide clinical practice.24 The Randomized Exploratory Study of Exercise Training in Hypertrophic Cardiomyopathy (RESET-HCM) was a clinical trial investigating the effects of individualised moderate-intensity aerobic exercise training versus usual activity in 136 patients with HCM.25 The training group participated in a structured, unsupervised exercise programme individually prescribed based on heart rate (HR) reserve derived from the cardiopulmonary exercise test (CPET). Patients initially performed exercise at a HR corresponding to 60% of HR reserve (resting HR +0.6 (maximal HR minus resting HR)). Exercise was initiated at a minimum of three sessions per week, 20 min per session, and then increased progressively to a goal of 70% of HR reserve, to be maintained until the 16th week of the protocol. The type of exercise included cycling, walk-jog protocols and elliptical training. After 16 weeks, average peak oxygen consumption (VO2) increased slightly but significantly in the exercise training group but not in the usual-activity group (p = 0.02). There were no occurrences of sustained ventricular arrhythmia, SCD or appropriate defibrillator shock in either subset.
A prospective non-randomised intervention study by Klempfner et al.26 enrolled 20 patients with symptomatic HCM, significantly limited in everyday activity despite optimised medical therapy, into a supervised cardiac rehabilitation exercise program. Patients were 62 ± 13 years old, in New York Heart Association (NYHA) functional class II or III, 35% had a left ventricular outflow gradient at rest >30 mm Hg and 25% had LV systolic dysfunction (left ventricular ejection fraction (LVEF)< 50%). The exercise training programme was determined based on the results of a graded exercise test. Exercise was initiated at a minimum of sessions twice per week, 60 min per session, at 50–60% of the HR reserve, increasing progressively to 65–85% as permitted by the trainee’s perceived exertion (13–15 on the Borg scale). During the training sessions, performed in a cardiac rehabilitation setting, HCM patients were continuously monitored using wireless telemetry and supervised by physicians and nurses. Patients completed an average of 41 ± 8 h of aerobic exercise training, with no adverse events or sustained ventricular arrhythmias. Functional capacity, assessed by the change in maximally attained metabolic equivalent of task (METs), improved by 46% (p = 0.01). NYHA functional class improved by ≥1 grade in 10 patients (50%) and the majority reported subjective improvement in their clinical condition. Despite the short-term duration, small number of enrolled patients and lack of non-exercising control HCM group, this study supports the view that symptomatic patients benefit from supervised exercise programmes and can exercise safely. Deigaard et al.27 investigated whether a history of vigorous exercise (defined as ≥6 METs) correlated with changes in LV function, morphology and arrhythmias in HCM genotype-positive, phenotype-negative (genotype+/hypertrophy (LVH)–) and in phenotype-positive (HCM LVH+) patients. A questionnaire on PA, including a detailed history of exercise from school age to present time, or to age 60 years, was administered. Retrospective data on echocardiograms were analysed and ventricular arrhythmias were collected from medical records, Holter recording, telemetry observations during hospital stays and internal cardioverter defibrillator interrogations. A history of vigorous exercise was associated with larger LV end-diastolic volumes in both genotype+/LVH– and HCM LVH+ patients and correlated with better diastolic function in LVH+ individuals. Notably, a history of vigorous exercise was not associated with occurrence of ventricular arrhythmias in both groups. The current evidence on this field is evolving. Indeed, a recent randomised controlled trial, Dallas High Intensity Exercise for Increasing Fitness in Patients with Hypertrophic Cardiomyopathy (HIIT-HCM) Pilot Study, NCT03335332) is ongoing.28 It has been designed firstly to examine the efficacy of a supervised high-intensity exercise (HIE) in adults with HCM, comparing the ability of HIE and moderate intensity exercise intervention to improve cardiorespiratory fitness and functional stroke volume reserve. Secondly, the trial will evaluate the safety of HIE training in patients with HCM.
Summary of the existing research
Collectively, the small number of studies and their inherent limitations, such as paucity of patients enrolled and/or short follow-up duration, constitute proof that the issue of PA in HCM has been neglected. Nevertheless, increasing and consistent evidence shows that exercise programmes in HCM patients are safe and the promotion of favourable outcome and benefits in terms of exercise capacity and quality of life suggest that it is high time to translate such evidence into clinical practice. However, the lack of large-scale studies with long-term follow-up necessitates the monitoring of the long-term effects of exercise programmes in HCM patients and an international registry should be developed for systematic data collection in the field.
A working proposal for personalised exercise prescription and titration
A tailored exercise prescription must take into account individual characteristics, past medical history, objective individual response to exercise, and previous training experience in the general population as well as in the patients, and stage of disease for cardiac patients. Although the main principles behind exercise prescription are universal, HCM patients can exhibit certain disease-specific features that constitute contraindications to PA, including a history of syncope/hypotension during effort, clinically relevant arrhythmias (particularly during effort), LV outflow tract obstruction ≥50 mm Hg at rest or during effort, recent history of acute heart failure and extensive late gadolinium enhancement within the LV. It is important to limit PA in patients with severe provocable obstruction during effort and recovery by exercise echocardiography; however, such indication may be re-evaluated after appropriate pharmacological or interventional relief of the gradient. In addition, during preadolescence and adolescence, when the disease is often discovered for the first time, a period of detraining may be useful to reach a definitive diagnosis and to avoid potential effects of intense PA on cardiac remodelling in a dynamic phase of phenotype development. Although the impact on the final HCM phenotype is unresolved, a promoter effect of PA on LVH development in very young individuals cannot be ruled out.
Once an exercise programme is prescribed, strict compliance must be stressed for all HCM patients who would like to participate, in order to avoid inappropriate practices counterbalancing the benefits of PA. The frequency, intensity, duration and type of exercise have been established in the general population for primary prevention29 as well as for general patients with cardiovascular and non-cardiovascular disorders.30–32 Similarly, HCM patients are most likely to benefit from regular aerobic exercise, by which most body muscles move in a cyclic manner to allow human locomotion, e.g. walking, brisk walking, running, or cycling. Precise indications should be provided with regard to frequency, duration, and intensity (e.g. light, moderate, or vigorous).
Intensity of exercise
Different methods can be used to define the intensity of exercise: these include the Borg scale, percentage of max HR, HR reserve, peak VO2, and the aerobic and anaerobic thresholds derived from lactate test or from CPET,33,34 the latter allowing particularly accurate individualised exercise prescription based on objective parameters. Conversely, the Borg scale may be used to quantify the subjective intensity of exertion.35
The use of CPET is well-established for tailored exercise prescription, as VO2 at ventilatory threshold helps set exercise intensity in a highly individualised manner.36 CPET has the potential to define training intensity for each specific patient, determining the peak of VO2, the VO2 reserve, max HR and ventilatory thresholds, identifying the most appropriate target for aerobic exercise,37–39 in different setting of patients and particularly in heart failure.40,41 Unfortunately, the nomenclature introduced to define the ventilatory threshold is conflicting and, as a result, misunderstandings exist concerning the non-invasive determination of lactate threshold.33 For the purpose of exercise prescription, the first (‘aerobic’) threshold (VT1) and the second (‘anaerobic’) threshold (VT2) can be determined, representing a useful and widely applicable tool to establish the intensity of exercise, especially in cardiac patients with different degrees of functional impairment.32,33,42 VT1 and VT2 can be determined by CPET using the V-slope method, the minute ventilation (VE)/VO2 plot, the VE/VCO2 slope versus workload relationship, the VE versus workload relationship, and the partial pressure of end-tidal carbon dioxide (PetCO2) and partial pressure of end-tidal oxygen (PetO2) versus workload relationship.33,43 The different plots used to determine VT1 by CPET in a patient with HCM referred to our centre for a tailored exercise prescription are shown in Figure 1. The aerobic and anaerobic thresholds can also be easily identified through the determination of lactate levels in the blood via withdrawal from the ear lobe and subsequent analysis of the lactate-intensity curve. The first lactate or aerobic threshold can be set at 2 mmol/l of blood lactate, while the second lactate or anaerobic threshold can be identified at 4 mmol/l. Although a general consensus on the definition of intensity of exercise has not been reached, a classification considered acceptable by most is reported in Table 1. Exercise intensity is classified in light, moderate, vigorous and very hard, according to the determination of VT1 and VT2 by CPET; the corresponding values obtained by different methods are also shown in Table 1. When VT1 and VT2 are identified, the corresponding HR values can be derived and used as an objective indicator for tailored exercise. We propose that HCM patients should maintain an average HR corresponding to VT1 identified by CPET (i.e. moderate PA) and generally avoid exceeding the HR corresponding to VT2. These are empiric indications requiring prospective validation but appear reasonable based on experience on other cardiac conditions.42,44 Notably, while beta-blockers – a common drug therapy in HCM patients – may affect HR, the intensity of exercise based on VT1 and VT2 can be determined irrespective of beta-blocker treatment and takes into account also its impact on HR, while the use of theoretical HR targets in beta-blocker users can be misleading.
The figure shows the determination of the first (‘aerobic’) ventilatory threshold (‘AT’) by cardiopulmonary exercise testing (CPET) in a 24-year-old woman affected by hypertrophic cardiomyopathy and referred to our centre for exercise prescription. CPET allowed us to prescribe a tailored exercise programme based on the determination of the thresholds. The figure shows the first aerobic threshold, identified in the different panels by the dashed line.VCO2: carbon dioxide production; VO2: oxygen consumption; VE: minute ventilation; PetO2: partial pressure of end-tidal oxygen; PetCO2: partial pressure of end-tidal carbon dioxide.
Definition of intensity of exercise according to first ‘aerobic’ and second ‘anaerobic’ thresholds (VT1 and VT2 respectively) determined by cardiopulmonary exercise testing (CPET) and correspondence to parameters obtained by different methods currently available.
| Light | Moderate | Vigorous | Very hard | |
|---|---|---|---|---|
| Ventilatory thresholds by CPET | Below VT1 | Slightly above or around VT1 | Slightly below or around VT2 | Above VT2 |
| Lactate test, mmol/l | < 2 | 2–4 | 3–5 | ≥5 |
| Original Borg scale (6–20) | 8–10 | 11–13 | 14–16 | ≥17 |
| Revised Borg scale (0–10) | 1–2 | 3–4 | 5–6 | ≥7 |
| Maximum HR, % | 45–60 | 60–80 | 70–90 | ≥90 |
| HR reserve, % | 20–40 | 40–60 | 60–85 | ≥85 |
| VO2 peak, % | 30–50 | 50–75 | 70–90 | >90 |
| VO2 R, % | 20–40 | 40–60 | 60–85 | ≥85 |
| Light | Moderate | Vigorous | Very hard | |
|---|---|---|---|---|
| Ventilatory thresholds by CPET | Below VT1 | Slightly above or around VT1 | Slightly below or around VT2 | Above VT2 |
| Lactate test, mmol/l | < 2 | 2–4 | 3–5 | ≥5 |
| Original Borg scale (6–20) | 8–10 | 11–13 | 14–16 | ≥17 |
| Revised Borg scale (0–10) | 1–2 | 3–4 | 5–6 | ≥7 |
| Maximum HR, % | 45–60 | 60–80 | 70–90 | ≥90 |
| HR reserve, % | 20–40 | 40–60 | 60–85 | ≥85 |
| VO2 peak, % | 30–50 | 50–75 | 70–90 | >90 |
| VO2 R, % | 20–40 | 40–60 | 60–85 | ≥85 |
HR: heart rate; VO2: oxygen consumption; VO2R: VO2 reserve.
VO2R = VO2 max–VO2 at rest, assuming rest VO2 = 3.5 ml/kg/min); it has been reported that %HR reserve is a better estimate of %VO2R than %VO2 peak (see Brawner et al.).39
Definition of intensity of exercise according to first ‘aerobic’ and second ‘anaerobic’ thresholds (VT1 and VT2 respectively) determined by cardiopulmonary exercise testing (CPET) and correspondence to parameters obtained by different methods currently available.
| Light | Moderate | Vigorous | Very hard | |
|---|---|---|---|---|
| Ventilatory thresholds by CPET | Below VT1 | Slightly above or around VT1 | Slightly below or around VT2 | Above VT2 |
| Lactate test, mmol/l | < 2 | 2–4 | 3–5 | ≥5 |
| Original Borg scale (6–20) | 8–10 | 11–13 | 14–16 | ≥17 |
| Revised Borg scale (0–10) | 1–2 | 3–4 | 5–6 | ≥7 |
| Maximum HR, % | 45–60 | 60–80 | 70–90 | ≥90 |
| HR reserve, % | 20–40 | 40–60 | 60–85 | ≥85 |
| VO2 peak, % | 30–50 | 50–75 | 70–90 | >90 |
| VO2 R, % | 20–40 | 40–60 | 60–85 | ≥85 |
| Light | Moderate | Vigorous | Very hard | |
|---|---|---|---|---|
| Ventilatory thresholds by CPET | Below VT1 | Slightly above or around VT1 | Slightly below or around VT2 | Above VT2 |
| Lactate test, mmol/l | < 2 | 2–4 | 3–5 | ≥5 |
| Original Borg scale (6–20) | 8–10 | 11–13 | 14–16 | ≥17 |
| Revised Borg scale (0–10) | 1–2 | 3–4 | 5–6 | ≥7 |
| Maximum HR, % | 45–60 | 60–80 | 70–90 | ≥90 |
| HR reserve, % | 20–40 | 40–60 | 60–85 | ≥85 |
| VO2 peak, % | 30–50 | 50–75 | 70–90 | >90 |
| VO2 R, % | 20–40 | 40–60 | 60–85 | ≥85 |
HR: heart rate; VO2: oxygen consumption; VO2R: VO2 reserve.
VO2R = VO2 max–VO2 at rest, assuming rest VO2 = 3.5 ml/kg/min); it has been reported that %HR reserve is a better estimate of %VO2R than %VO2 peak (see Brawner et al.).39
Preliminary evidence supports the view that HCM patients should be engaged in low-to-moderate intensity endurance PA. In patients with mild non-obstructive HCM, a study was conducted using CPET coupled with serial phlebotomy to define the relationship between exercise intensity and plasma catecholamine levels compared to age-matched controls.45In this study, concentrations of adrenaline and noradrenaline were unchanged through low- and moderate-exercise intensity until reaching a ‘catecholamine’ HR threshold at 82 ± 4% of peak HR in HCM patients (comparable to that of controls at 85 ± 3% of peak HR, p = 0.86). At greater intensities, the levels of both molecules rose rapidly. In patients with mild non-obstructive HCM, plasma catecholamine levels remained stably low at exercise intensities below the second ventilatory threshold but rose rapidly at higher intensities.45
Frequency and duration of exercise and progression
Key recommendations for exercise prescription in HCM are reported in Table 2. In terms of frequency, 3–4 sessions per week of endurance exercise represent the optimal frequency of weekly exercise according to current recommendations for the general population. Initially, 150 min/week of low-to-moderate endurance PA may be prescribed to HCM patients, aimed at control of cardiovascular risk factors. To this aim, HCM patients not able to jog (e.g. sedentary and/or obese patients, patients with functional capacity limited by muscle-skeletal symptoms, etc.) should practice at least 300 min of brisk walking per week. In order to impact the metabolic profile and reduce risk of comorbidities, established thresholds occur for instance at exercise volumes of 24–32 km per week of brisk walking (15–20 miles, corresponding to 900–1200 kcal for a patient weighting 75 kg).46 In terms of hours of practice per week, at a speed of 5 km/h of brisk walking, the training volume corresponds to 5–6 h. If the characteristics of HCM patients permit higher intensity at low-to-moderate intensity (i.e. jogging), exercise volume may be reduced to 3–4 h per week: for a speed of 8 km/h, this corresponds to 1800–2400 kcal for a patient weighting 75 kg, obtaining a higher impact on the cardiovascular risk profile.
Key recommendations for exercise prescription in hypertrophic cardiomyopathy
| Optimal targets | |
|---|---|
| Frequency and duration | • From 150–300 min per week of low-to-moderate endurance exercise, 3–5 days per week, depending on weekly volume • All sessions must be preceded by a warm-up phase and must end with a cool-down phase, each lasting about 5 min |
| • Muscle-strengthening activities of low-to-moderate intensity and that involve all major muscle groups on 2 days per week | |
| • Flexibility training should be performed at least 2–3 times per week, such as stretching (10–20 s), four times per muscle group | |
| Intensity | • Low-to-moderate endurance training (see Table 1 for the definition of moderate intensity). Training volume should be emphasised more than intensity • Resistance training: intensity should correspond to 40–70% of 1 RM; however, the set of repetitions should be stopped before the point at which it would be difficult to perform another repetition |
| Progression | |
| Frequency | • Start with a weekly session and introduce the second session when the patient is adapted (3–4 times per week of endurance exercise is considered the optimal frequency) |
| Duration | • Start with 10–30 min of endurance exercise and increase of 10 min every week to reach the optimal weekly training volume in 3–4 weeks based on individual response to exercise |
| Intensity | • During the first 3–4 weeks, start at low intensity, first increasing the volume and then progress with the suggested intensity. The progression should take into account patient’s adaptation to exercise, the previous experience of training, age and clinical characteristics • The patient should start gradually with 1–3 sets of 8–10 resistance exercise, performed at slow-moderate velocity (set duration about 40 s), increasing weekly training volume according to his/her adaptation |
| Optimal targets | |
|---|---|
| Frequency and duration | • From 150–300 min per week of low-to-moderate endurance exercise, 3–5 days per week, depending on weekly volume • All sessions must be preceded by a warm-up phase and must end with a cool-down phase, each lasting about 5 min |
| • Muscle-strengthening activities of low-to-moderate intensity and that involve all major muscle groups on 2 days per week | |
| • Flexibility training should be performed at least 2–3 times per week, such as stretching (10–20 s), four times per muscle group | |
| Intensity | • Low-to-moderate endurance training (see Table 1 for the definition of moderate intensity). Training volume should be emphasised more than intensity • Resistance training: intensity should correspond to 40–70% of 1 RM; however, the set of repetitions should be stopped before the point at which it would be difficult to perform another repetition |
| Progression | |
| Frequency | • Start with a weekly session and introduce the second session when the patient is adapted (3–4 times per week of endurance exercise is considered the optimal frequency) |
| Duration | • Start with 10–30 min of endurance exercise and increase of 10 min every week to reach the optimal weekly training volume in 3–4 weeks based on individual response to exercise |
| Intensity | • During the first 3–4 weeks, start at low intensity, first increasing the volume and then progress with the suggested intensity. The progression should take into account patient’s adaptation to exercise, the previous experience of training, age and clinical characteristics • The patient should start gradually with 1–3 sets of 8–10 resistance exercise, performed at slow-moderate velocity (set duration about 40 s), increasing weekly training volume according to his/her adaptation |
RM: repetition maximum.
1 RM corresponds to the maximum weight that can be lifted through the entire exercise movement only one time.
Key recommendations for exercise prescription in hypertrophic cardiomyopathy
| Optimal targets | |
|---|---|
| Frequency and duration | • From 150–300 min per week of low-to-moderate endurance exercise, 3–5 days per week, depending on weekly volume • All sessions must be preceded by a warm-up phase and must end with a cool-down phase, each lasting about 5 min |
| • Muscle-strengthening activities of low-to-moderate intensity and that involve all major muscle groups on 2 days per week | |
| • Flexibility training should be performed at least 2–3 times per week, such as stretching (10–20 s), four times per muscle group | |
| Intensity | • Low-to-moderate endurance training (see Table 1 for the definition of moderate intensity). Training volume should be emphasised more than intensity • Resistance training: intensity should correspond to 40–70% of 1 RM; however, the set of repetitions should be stopped before the point at which it would be difficult to perform another repetition |
| Progression | |
| Frequency | • Start with a weekly session and introduce the second session when the patient is adapted (3–4 times per week of endurance exercise is considered the optimal frequency) |
| Duration | • Start with 10–30 min of endurance exercise and increase of 10 min every week to reach the optimal weekly training volume in 3–4 weeks based on individual response to exercise |
| Intensity | • During the first 3–4 weeks, start at low intensity, first increasing the volume and then progress with the suggested intensity. The progression should take into account patient’s adaptation to exercise, the previous experience of training, age and clinical characteristics • The patient should start gradually with 1–3 sets of 8–10 resistance exercise, performed at slow-moderate velocity (set duration about 40 s), increasing weekly training volume according to his/her adaptation |
| Optimal targets | |
|---|---|
| Frequency and duration | • From 150–300 min per week of low-to-moderate endurance exercise, 3–5 days per week, depending on weekly volume • All sessions must be preceded by a warm-up phase and must end with a cool-down phase, each lasting about 5 min |
| • Muscle-strengthening activities of low-to-moderate intensity and that involve all major muscle groups on 2 days per week | |
| • Flexibility training should be performed at least 2–3 times per week, such as stretching (10–20 s), four times per muscle group | |
| Intensity | • Low-to-moderate endurance training (see Table 1 for the definition of moderate intensity). Training volume should be emphasised more than intensity • Resistance training: intensity should correspond to 40–70% of 1 RM; however, the set of repetitions should be stopped before the point at which it would be difficult to perform another repetition |
| Progression | |
| Frequency | • Start with a weekly session and introduce the second session when the patient is adapted (3–4 times per week of endurance exercise is considered the optimal frequency) |
| Duration | • Start with 10–30 min of endurance exercise and increase of 10 min every week to reach the optimal weekly training volume in 3–4 weeks based on individual response to exercise |
| Intensity | • During the first 3–4 weeks, start at low intensity, first increasing the volume and then progress with the suggested intensity. The progression should take into account patient’s adaptation to exercise, the previous experience of training, age and clinical characteristics • The patient should start gradually with 1–3 sets of 8–10 resistance exercise, performed at slow-moderate velocity (set duration about 40 s), increasing weekly training volume according to his/her adaptation |
RM: repetition maximum.
1 RM corresponds to the maximum weight that can be lifted through the entire exercise movement only one time.
A reassessment of the exercise programmes is needed, in order to monitor the feedback of the patients, the long-term effects and safety of PA. An appropriate exercise programme may also modify the first ‘aerobic’ and second ‘anaerobic’ thresholds: therefore, the lactate test or the CPET should be repeated during follow-up in order to obtain the new thresholds, maintaining an appropriate intensity of exercise.
Conclusions
Prescribing regular PA to HCM patients has evolved in the last years to a necessity. Properly administered, exercise is the ideal drug for prevention of comorbidities and promotion of personal well-being. In young adults and adults with a recent diagnosis of genetic cardiomyopathies – an event which often undermines confidence and precipitates psychological frailty – exercise is the ultimate resource to counter these effects. Here, we have outlined potential strategies for safe, highly personalised exercise prescription. These can be considered reasonable starting points for clinical practice, largely based on the experience with other cardiac conditions. The specific features of HCM and its molecular basis, however, warrant dedicated research in the field. Only when it is properly evidence-based, will the practice of exercise prescription come of age in this complex disease.
Author contribution
LC, IO, NM, MB and FD contributed to the conception or design of the work. LC and FD drafted the manuscript. FD, IO, MB, SF, FF, NM and SM critically revised the manuscript. All gave final approval and agree to be accountable for all aspects of work ensuring integrity and accuracy.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship and/or publication of this article.
References
World Health Organization. Global recommendations on physical activity for health. WHO guidelines approved by the Guidelines Review Committee. Geneva: World Health Organization,
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