Linking To And Excerpting From Circulation’s “Exercise Training in High-Risk Populations: A Scientific Statement From the American Heart Association”

Posted on July 27, 2026 by Tom Wade MD

Today, I review, link to, and excerpt from Circulation’s “Exercise Training in High-Risk Populations: A Scientific Statement From the American Heart Association“. [PubMed Abstract] [Full-Text HTML] [Full-Text PDF]. Circulation. 2026 Jul 9. doi: 10.1161/CIR.0000000000001456. Online ahead of print.

All that follows is from the above resource.

Abstract

There is broad consensus on the benefits of aerobic exercise training in patients with cardiovascular disease to improve cardiorespiratory fitness and lower the risk of adverse cardiovascular events. However, certain high-risk populations such as those with frailty, stroke, spinal cord injury, rheumatological conditions, or genetic cardiomyopathies and recipients of advanced heart failure therapies or cardiac implantable electronic devices warrant special considerations with regard to exercise training. This scientific statement summarizes the present state and future directions of exercise training for these high-risk populations, including functional deficits, responses to exercise training, modifications in training programs required to maximize safety and efficacy, and knowledge gaps in this field. Key findings common across most of these high-risk populations include (1) increased barriers to participation in exercise training at multiple levels; (2) low baseline cardiorespiratory fitness, creating heightened need for exercise interventions; (3) modifications to exercise prescription, frequently emphasizing strength, balance, and flexibility in addition to aerobic training, as well as accommodations with enhanced supervision and specialized equipment as needed; and (4) functional and quality-of-life gains in response to appropriately designed exercise programs that match or exceed those in more traditional populations. Future research is needed to further develop patient-centered training regimens designed to address the unique and heterogeneous needs of these populations, evaluate their impact on clinical and patient-centered outcomes, and advance scalable and equitable delivery of exercise therapies proven safe and effective.
Prior studies have shown that higher cardiorespiratory fitness (CRF) is associated with greater longevity and lower risk of adverse cardiovascular outcomes, both in apparently healthy populations and those with chronic diseases.1–5 For both populations, exercise training has been shown to be effective in improving CRF, mitigating cardiovascular risk factors, and improving quality of life.1 Although there is a clear consensus on the benefits of regular aerobic exercise for patients with cardiovascular and other major disorders, individuals with complex, higher-risk chronic diseases have a generally low likelihood of participating in such activities. For example, patients with frailty, stroke, spinal cord injury (SCI), rheumatological conditions, or genetic cardiomyopathies and recipients of advanced heart failure (HF) therapies may be less likely to participate in or complete exercise training programs than individuals without those conditions.1,6,7
Among patients with complex, higher-risk conditions, lack of participation in exercise training programs is likely multifactorial, due in part to failure of clinician referrals to cardiac rehabilitation (CR), patient reluctance or fear of exercise (ie, kinesiophobia), disease-related exercise limitations, and socioeconomic issues.1 However, exercise training studies generally show substantial clinical benefits in these high-risk populations, with the greatest relative benefit in those with the lowest initial fitness levels.2,8 The inclusion of strength, balance, and flexibility interventions often results in even larger benefits in performing daily activities, although most training programs do not devote significant time to these modalities.
The goals of this scientific statement are to highlight the prevalence and functional deficits of the aforementioned high-risk populations, their responses to exercise training, the modifications in training programs required to maximize safety and efficacy, and the knowledge gaps in this field, with future directions that address these gaps. This document is not intended to include all high-risk populations but rather was developed to assist clinicians in managing such patients and motivate future research, particularly for those conditions for which little guidance is available.

OLDER ADULTS WITH FRAILTY

Frailty is a syndrome of diminished intrinsic and allostatic reserve that manifests across physical, mental, and social domains. Although many different scales and criteria are available to assess frailty, the most commonly used approach to assess physical frailty requires at least 3 of the following: unintentional weight loss, weakness (measured by grip strength), slowness (measured by gait speed), low physical activity, and exhaustion.9,10 Although frailty can occur throughout a lifetime, prevalence increases dramatically with age, particularly in older adults with cardiovascular disease (CVD), in whom the prevalence of frailty may reach 60%, depending on the definition used (Table 1).9 A prime example of a CVD highly associated with frailty is HF with preserved ejection fraction. These patients are typically older, are more often women, and have multiple comorbid conditions, including hypertension, obesity, and diabetes.6 Multimorbidity, sarcopenia, and cognitive impairment often coexist, worsening prognosis and undercutting capacities for physical performance and autonomous daily activity. Although a growing body of literature indicates benefits of exercise and physical activity to slow and even reverse frailty,44 implementation requires a distinctive approach.
Hemodynamic improvement after revascularization, medical optimization, or valve interventions creates a window in which patients with frailty may be more capable of improving CRF. However, up to 40% of patients report fair or poor functional status after such interventions, regardless of their technical success,45 suggesting that treating CVD alone is insufficient. Randomized trials in hospitalized older adults and community-dwelling older adults have proven that multicomponent exercise training can help prevent or mitigate functional decline (Supplemental Table).7,46 TARGET‑EFT (The Multicomponent Acute Intervention in Frail Geriatric Patients With CVD Using the Essential Frailty Toolset) and REHAB-HF (Physical Rehabilitation for Older Patients Hospitalized for Heart Failure) extended such benefits to patients with frailty with acute cardiovascular conditions, improving multiple domains of physical function (strength, balance, functional mobility, endurance), frailty measures (“defrailing”), and postdischarge quality of life using simple exercises for mobility and lower-extremity strength.44,47 Restoring self‑efficacy or the confidence and capacity for rudimentary physical function (strength, balance, endurance) is a key goal for patients with frailty, particularly because hospitalizations tends to exacerbate functional declines. Patients with frailty who achieve early, meaningful improvements in physical function and self-efficacy after a hospitalization are more likely to progress to restore mobility, daily activity, CRF, and independence.2 The REHAB-HF trial showed that older patients hospitalized for HF derived significant functional improvement after a multicomponent exercise program that began in hospital.6,44 Furthermore, the subset with HF with preserved ejection fraction had greater functional limitations at baseline than those with HF with reduced ejection fraction but experienced greater improvement in function as assessed by the Short Physical Performance Battery and 6-minute walk distance and nominally lower rates of subsequent hospitalization or mortality over the 3-month follow-up period.48
Exercise prescriptions for patients with frailty typically prioritize lower-extremity strength, balance, and rapid‑force development (ie, brief, purposeful bursts to improve transfer ability), which may be essential to minimize fall risk before aerobic modalities are feasible or safe (Table 2).44 Prescriptions should be tailored to functional status with the use of performance measures such as the Short Physical Performance Battery to stratify patients and guide progression.49 Exercise training workloads that would be considered low intensity for more fit individuals are often perceived and physiologically experienced as high intensity in patients with frailty. Initially, body weight resistance exercises and slow-movement aerobic exercises may be the most that can be tolerated, but they are still sufficient to achieve meaningful training gains that may exceed those of less frail individuals.6,84 Aerobic training often must start with short bouts of exercise, with progressive increases in frequency and duration as tolerated before intensity or speed is increased. Notably, although many CR programs commonly default to recumbent devices for frail adults, with the rationale that they are safe and reassuring to patients (and staff), the CR core components emphasize the importance of resistance and balance training,1 with corroborating studies highlighting the utility of unsupported standing training, over‑ground ambulation, and plyometric-type exercises like step-ups for greater translational gain.85,86
Table 2. Training Modifications and Outcomes
Home training programs such as Vivifrail and supervised center-based programs such as REHAB-HF exemplify programs of progressive resistance, balance, and interval walking matched to baseline capacity that have successfully improved physical function and quality of life in older adults with frailty.44,85 Adequate exercise supervision and care alignment with comorbid conditions and medications are also critical factors in ensuring safety, progression, and adherence. For older adults with frailty, exercise training is potentiated by protein‑rich foods or supplements, targeting a daily intake of 1.5 g/kg body weight, to optimize muscle strengthening.50
Although CRF is usually regarded as the gold standard physiological assessment for patients with CVD, this benchmark becomes less practical and relevant for patients with frailty. Assessments of strength, balance, and submaximal endurance both are more feasible and provide greater utility for such functionally limited individuals. Sit-to-Stand repetitions, Timed Up and Go, and the Short Physical Performance Battery are among the tests that are useful to quantify lower‑extremity strength and balance, particularly because these are more strongly linked to functional independence than cardiopulmonary exercise test. For those with greater CRF, endurance and mobility for everyday activities are more accurately measured with 6-minute walk distance or 400‑m corridor walk than by cardiopulmonary exercise test. Serial testing with these instruments and patient-reported quality of life (eg, EQ-5D or Kansas City Cardiomyopathy Questionnaire) can be used to evaluate clinical changes. Given the role of sarcopenia and sarcopenic obesity as contributors to physical frailty and suboptimal responsiveness to training, assessments of muscle mass and body composition should be considered, assessed with upper-arm circumference, dual‑energy x‑ray absorptiometry, or computed tomography.12 Moreover, assessments of basic and instrumental activities of daily living, together with cognition and mood, should be considered with brief screening tools to expose limiting factors beyond physical functional status.
In summary, exercise training for patients with frailty and CVD begins with a pragmatic, multidimensional assessment; progresses through individualized, multicomponent prescription; and targets outcomes that resonate with older adults, often enabling them to reclaim roles, routines, and self-efficacy.87

STROKE

Annually, >795 000 individuals in the United States experience a stroke, and ≈50% of stroke survivors have significant long-term disabilities (Table 1).13 Patients with stroke demonstrate significant impairments in balance, mobility, strength, coordination, and cognitive function, as well as decreased CRF, exhibiting ≈60% of age- and sex-related normative values for sedentary healthy adults.88 Consequently, they engage in less than half the recommended physical activity for their age group and spend ≈80% of their time sedentary.8,89 Considering the substantial benefits that exercise training can provide, there is little reason to exclude it from rehabilitation strategies for most stroke patients once they are medically stable, regardless of stroke severity.8,52,89 Engaging in physical activity after a stroke is associated with a significantly lower risk of subsequent myocardial infarction compared with a sedentary lifestyle.90 In addition, participation in a moderate-intensity aerobic exercise program has been shown to decrease all-cause readmission rates and mortality.53,54
The American Heart Association and American Stroke Association endorse physical activity and exercise for stroke survivors throughout all phases of recovery to aid with the restoration of function, secondary stroke prevention, and reduction of cardiac events.8 Current American Heart Association/American Stroke Association exercise guidelines for stroke patients recommend incorporating regular aerobic exercise (moderate intensity, lasting 20–60 minutes, 3–5 times a week), resistance training, flexibility exercises, and neuromuscular training into poststroke rehabilitation programs (Table 2).8,51,91 However, stroke patients generally do not participate in these activities because of a lack of funding and program availability. Furthermore, current stroke rehabilitation programs provide only ≈3 minutes of low-intensity aerobic exercise per session.8
Many stroke survivors present with significant deficits, including hemiparesis, balance deficits, cognitive impairment, fatigue, speech impediments, attention deficits, and impulsivity, in addition to underlying CVD. The timing of initiation, rate of progression, and associated parameters of exercise training depend on neurobiological (ie, cerebral autoregulation, ischemic penumbra, hemorrhagic stroke parameters) and cardiovascular recovery and should be individualized to account for the unique deficits and comorbidities of each patient.92
Before an exercise program is initiated, obtaining medical clearance from a clinician is the essential first step to ensure that the program is safe and suitable for the patient’s needs. A symptom-limited or submaximal exercise test should be considered before engaging in higher-intensity exercise. Accommodations for the physical impairments of stroke patients are essential for safe and effective participation. For hemiplegia or balance issues, seated equipment such as a recumbent cross-trainer or cycle ergometer should be used. Leg stabilizers, hand mitts, and torso belts may be needed for some patients to provide additional support. A harness apparatus, balance bars, or partial weight support systems can be incorporated for treadmill exercise to reduce the risk of injury. When strength training is incorporated, exercises should be selected to prevent excessive blood pressure increases and avoid the Valsalva maneuver. For stroke patients with speech or cognitive deficits, individualized methods to track pain and rate perceived exertion may be needed. Patients with dysphagia require close supervision for pulmonary status and oxygen saturation, and regular blood glucose checks are needed for patients with diabetes. In addition, immediate access to emergency medical response should be available during exercise for high-risk individuals. Research indicates that stroke patients can effectively engage in aerobic exercise programs in both group and individual settings.91,93 However, patients with more severe impairments may benefit from a personalized approach based on their physical capabilities. The exercise format should be guided by the severity of the patient’s neurological and cardiac issues, the timing of exercise initiation, and the intended mode and intensity of exercise.94
The acute poststroke phase is a critical and dynamic period for physiological recovery, requiring careful attention for cardiovascular and neurological stability, including resting blood pressure, cerebral autoregulation, blood-brain barrier function, the ischemic penumbra, and any hemorrhagic complications. Current evidence supports a phased approach to physical activity after stroke in which patients may begin light-intensity aerobic exercise within 30 days after stroke, progress to moderate-intensity exercise by 3 months, and advance to high-intensity exercise thereafter as appropriate, according to recovery and health status.92 Research indicates that at least 8 weeks of exercise training is required for meaningful improvements, and ongoing physical activity is essential to maintain these benefits.91 Exercise training, including aerobic and strength training and walking-based interventions, results in significant improvements in CRF, physical function (gait speed, walking distance, muscle strength, balance), cognitive function, and cardiometabolic profile (blood pressure, lipids, glycemic control) among stroke survivors (Supplemental Table).52,89
Aerobic exercise programs can be implemented in a range of settings such as outpatient clinics, community centers, and private residences. It is essential for high-risk individuals to have immediate access to emergency medical services. For patients at lower risk, home-based or virtual delivery programs can serve as a safe and effective alternative, depending on the mode and intensity of the exercise. In the United States, aerobic exercise programs are not currently funded for patients recovering from stroke despite evidence to support their benefit in this population.

SPINAL CORD INJURY

More than 18 000 SCI cases occur in the United States each year, and >300 000 individuals live with an SCI (Table 1).18 Most often, SCI has no antecedent, occurring through accident or unrecognized pathology. It occurs across the life span without specificity, except that in young male individuals, it is more often due to traumatic injuries.
Without predisposing risk factors, the most important predictor of future health is the SCI lesion itself. Lesion level and severity determine functional impact: musculoskeletal paralysis, pulmonary insufficiency, cardiac limitations, and autonomic dysfunction, among others.18 Hence, exercise interventions are critical to maximize function and maintain long-term health. The loss of muscle function and ensuing immobility typically result in a sedentary lifestyle that is difficult to overcome. Early access to appropriate forms of exercise is critical. However, individuals with SCI participate in exercise less than their able-bodied peers, and only 12% to 30% meet population-specific exercise guidelines.19,95 As a result, individuals with SCI have high rates of cardiovascular and metabolic disease,19 underscoring the need for regular exercise as a lifelong habit.
CRF decreases with higher and more complete SCIs (eg, cervical complete versus lumbar incomplete lesions). As a result, individuals with incomplete paraplegia may be able to achieve aerobic exercise recommendations designed for the able bodied but require greater focus on balance and strength. In contrast, those with higher-level SCI often require significant training modifications to achieve even population-specific aerobic exercise recommendations (Table 2).18,19 Across all levels of injury, resistance training is recommended to improve strength and balance, with the broad consensus of 2 to 3 training sessions per week. Aerobic exercise training sessions range from 2 to 5 sessions per week at moderate to vigorous intensities for a total of 40 to 300 minutes of exercise (Table 2).19 The optimal intensity can be difficult to ascertain because heart rate is an inadequate guide for exercise intensity in those individuals with injuries causing chronotropic incompetence. Therefore, perceptually based intensity has been suggested (eg, 10–11 on a 20-point scale or 2–3 on a 10-point scale). Meta-analyses suggest that across aerobic exercise training trials, typically lasting 6 to 12 weeks, the average improvement in peak V̇O2 is ≈3 mL·kg−1·min−1, a substantial improvement given the low pretraining peak V̇O2 in this population, with baseline values averaging 18 mL·kg−1·min−1 in otherwise young, healthy individuals.3 However, aerobic exercise training over 6 to 24 weeks may not affect body composition or metabolic function and does not appear to alter CVD risk factors (Supplemental Table). Predicting the effects of aerobic exercise training in SCI is difficult in the context of nonstandardized exercise testing/intervention protocols, patient heterogeneity (eg, incomplete paraplegia versus complete tetraplegia, time since injury, age, sex), and sparse research on high-intensity interval training (HIIT).96 Higher volumes and greater intensities of exercise than recommended,19 perhaps through whole-body hybrid electrical stimulation and initiated subacutely after injury, are likely to result in the greatest improvements in exercise capacity and CVD risk factors.3,96
To initiate exercise without specialized equipment, individuals with SCI should perform low-intensity, short-duration seated or wheeling activities 2 to 3 times per week, with time and intensity increasing gradually with perceived exertion used as a guide. Proper seated positioning (if necessary); slow, controlled movements; and light resistance should be used, and exercise should be discontinued if significant symptoms (eg, dizziness, chest pain, or disproportionate shortness of breath) arise.

SEVERE ARTHRITIS

Severe arthritis is characterized by joint pain, stiffness, swelling, and joint deformities that substantially limit daily function. Approximately 24% of US adults and >50% of adults ≥65 years have arthritis, with 44% of those reporting activity limitations constituting severe arthritis.20 Among the many types of arthritis, osteoarthritis and rheumatoid arthritis (RA) are most common. Adults with severe arthritis are more likely to have poor health, overweight/obesity, psychological distress, low education and income, and disabilities preventing employment.20 Furthermore, compared with the general population, adults with RA are almost twice as likely to develop CVD.97 Arthritis is associated with reduced CRF (peak V̇O2), endurance, strength, flexibility, and physical function. In a study of 404 older patients with knee osteoarthritis, 71% women (age, 68±10 years), mean peak V̇O2 was 17 mL·kg−1·min−1.98 Among 67 patients with RA, 64% women (age, 53±10 years), lower-extremity strength was 65% to 75%, and estimated peak V̇O2 was 80% that of matched controls.99 Fortunately, arthritis-related pain and physical function can be improved with exercise training.58
For RA, clinical guidelines strongly recommend regular exercise to improve CRF, strength, and physical function and reduce pain (Table 2).56 Improvements in CRF and strength occur regardless of age and severity of functional deficits with minimal adverse events.57,59,100 Multiple types of exercise programs improve physical functioning, including combined aerobic and resistance training (with and without flexibility and neuromuscular exercises) and aquatic exercise, with water providing movement resistance (Supplemental Table).57,61,62 Aerobic exercise training, with and without resistance training, reduces fatigue.101–103 Aquatic exercise, resistance training, and combined aerobic and resistance training reduce RA inflammatory disease activity (eg, Disease Activity Score for 28 Joints).61–63 For example, meta-analyses show that resistance training improves the Disease Activity Score for 28 Joints (standardized mean difference, −0.69 [95% CI, −1.26 to −0.11]).63 Furthermore, combined aerobic and resistance training with or without HIIT improves multiple measures of CVD risk, including peak V̇O2, blood pressure, triglycerides, high-density lipoprotein cholesterol, and endothelial function (Supplemental Table).64–66 Although both aerobic training and resistance training reduce fat mass, resistance training may provide superior fat reduction, along with increases in lean mass.60 Although HIIT interventions improve CRF, HIIT alone provides minimal improvements for inflammatory disease activity or traditional CVD risk factors (eg, lipid profiles and blood pressure) among patients with RA.104
For individuals with osteoarthritis of the hip or knee, meta-analyses support that multiple types of exercise training interventions improve osteoarthritis pain, function, physical performance, and quality of life with minimal adverse effects (Table 2).69 Exercise effects for osteoarthritis pain reduction and functional improvement are similar in magnitude to those resulting from standard pharmacological therapy.105 Strength training is a key part of knee osteoarthritis treatment, with lower-extremity strength increases underlying improvements in self-reported function and pain.106 Although prior osteoarthritis recommendations focused on non–weight-bearing exercise, both non–weight-bearing and weight-bearing strength training improves pain and function, with weight-bearing exercise offering potentially greater benefits in quality of life with fewer adverse events.107
Guidelines for specific amounts and intensities of exercise for patients with arthritis are based on expert opinion and typically follow those for the general population and older adults; randomized controlled trials of specific modifications are lacking (Table 2). Patients with severe arthritis should be evaluated by a physical therapist or a clinical exercise physiologist to discern activity limitations, develop modifications as needed, and provide a period (eg, 3 months) of supervised exercise training. Regardless of arthritis type or severity, exercise training individualized according to functional limitations should be a key component of arthritis management. Individuals without access to specialized equipment or supervision are encouraged to perform enjoyable, pain-free activities such as walking, cycling, and aquatic exercises that promote CRF, balance, and mobility with low risk of injury.

CARDIAC IMPLANTABLE ELECTRONIC DEVICES

More than 3 million Americans live with pacemakers, and ≈800 000 have implantable cardioverter defibrillators (ICDs),28 with 100 000 to 300 000 new implantations each year (Table 1).13 Peak V̇O2 in this population is highly variable although low at 17.4 mL·kg−1·min−1 on average.29–37,108 Multiple studies have shown that aerobic exercise training after receipt of an ICD or cardiac resynchronization therapy pacemaker or defibrillator is effective at improving CRF with few ICD shocks or antitachycardia pacings, deaths, or hospitalizations (Supplemental Table).109–114 However, many ICD recipients are reluctant to participate in vigorous physical activity for fear of activating arrhythmias and ICD shocks.
Pacemaker recipients require careful monitoring of their heart rate response to exercise and possible pacemaker adjustments to ensure appropriate response. Approximately 3000 individuals with cardiac implantable electronic devices (CIEDs) have participated in structured clinical trials of exercise interventions.114,115 These trials have included mostly men with an average age of ≈60 years. Although the majority of programs were conducted within a supervised outpatient exercise center, 3 studies of home exercise have been completed,32,35,36 with all reporting improvements in CRF similar to those of supervised programs.109–115 The mode of exercise prescribed is typically cycling or walking for 30 to 60 minutes on 3 to 5 d/wk at 60% to 80% of maximal heart rate for a minimum of 6 weeks (Table 2). Peak V̇O2, as measured by cardiopulmonary exercise test, improved by 2 mL·kg−1·min−1 (range, 0–2 mL·kg−1·min−1) on average among individuals with CIEDs following a structured exercise program.109–116 Despite demonstrated improvements in CRF, the impact of exercise on quality of life, psychological adjustment, patient-centered outcomes, and other biomarkers is rarely reported for individuals with CIEDs. Little has been written about the techniques, protocols, costs, and expert knowledge needed to bring exercise training to larger populations with CIEDs.
For patients with ICDs initiating an exercise program, a symptom-limited exercise test is recommended before exercise to monitor for cardiac arrhythmias.117–119 The ICD should be deactivated during the exercise test to prevent ICD shocks. Thereafter, exercise should be prescribed to achieve a peak heart rate at least 10 to 15 bpm below the ICD activation rate to avoid delivery of ICD therapies (shocks or antitachycardia pacing) during exercise. Heart rate should be tracked and recorded with each exercise session, noting the highest heart rate achieved during exercise and ensuring ongoing safety in performing the specific exercise type. For patients prescribed medications that act at the sinus or atrioventricular node (eg, β-blockers), it is recommended that these be taken 1 to 2 hours before exercise.
For patients with pacemakers, including those with an ICD, the following adaptations are recommended to maximize performance and comfort.117–119 First, the rate-response feature should be turned on, and the upper tracking rate should be set to a heart rate that the patient can achieve while exercising. Second, heart rate and symptoms should be tracked and recorded with each exercise session, ensuring that the heart rate rises with increasing levels of exertion. Last, if the heart rate achieved during exercise is inappropriate (ie, too fast or too slow), the rate-response feature on the pacemaker should be adjusted accordingly.

ADVANCED HF

Left Ventricular Assist Devices

Although HF remains epidemic in the United States, only 2512 left ventricular assist devices (LVADs) were implanted in 2022, representing ≈3% of patients with stage D HF (Table 1).25 With improvements in technology, continuous-flow LVADs have significantly increased survival, with current 1- and 5-year survival rates of 86% and 64%, respectively.25 Most patients are supported with intravenous inotropic therapy, temporary mechanical circulatory support, or a combination of inotropic therapy and temporary mechanical circulatory support at the time of LVAD implantation. Thus, these patients are often immobile, frail, and malnourished in the immediate postoperative period. After device implantation, they require intensive in-hospital physical therapy and medical optimization before ambulatory CR or other exercise interventions can begin.76
CRF for patients supported with an LVAD is limited by right ventricular dysfunction, pulmonary hypertension, anemia, residual skeletal muscle abnormalities, chronotropic incompetence, inability of the LVAD to respond to increased workloads, and sensitivity of the LVAD to increased afterload during exercise.26 Peak V̇O2 remains depressed in the range of 11 to 20 mL·kg−1·min−1, and native left ventricular contractility frequently provides a significant contribution to peak exercise performance.26
The general approach to CR in patients with an LVAD includes supervised aerobic (bicycle or treadmill) exercise at 50% to 70% of peak V̇O2, 60% to 80% of heart rate reserve, or Borg Rating of Perceived Exertion at 11 to 13 for those who are paced for 20 to 30 minutes, combined with strength training of limb muscles with 2 to 3 sets of 10 to 15 repetitions at 50% of maximum voluntary contraction.120 There are also reports of HIIT with 3 to 4 minutes at 80% to 90% of peak V̇O2 followed by moderate-intensity exercise (50% peak V̇O2).121 There is no formal LVAD guideline recommendation for CR, although guidance exists from the American Association of Cardiovascular and Pulmonary Rehabilitation and American College of Sports Medicine. Because all patients with LVAD have severe HF, however, insurance coverage for CR is provided on that basis. An analysis of 2014 Medicare beneficiaries who received an LVAD revealed that 30% of 1164 such patients underwent CR. These patients had 23% lower first-year hospitalizations and 47% lower mortality rate after multivariable adjustment than those not participating in CR.122 Although there are few randomized CR trials of patients with LVAD,77 most studies have shown a significant increase in peak V̇O2 of 10% to 40% with endurance exercise with or without strength training, although this increase has not been consistently greater than improvement in peak V̇O2 in the usual-care arm (Supplemental Table).77,123–129 Furthermore, CR has been shown to be safe in these patients, with the most common adverse events being arrhythmias.76
Monitoring of patients with an LVAD during CR or structured exercise requires familiarity with the LVAD and its peripheral components (ie, external batteries, controller, driveline, device alarms, and power base units; Table 2). Exercise should not be performed in the setting of low-flow alarms for which the differential diagnosis includes hypertension, hypovolemia, right ventricular failure, bleeding, arrhythmias, pump failure, obstruction, or pulmonary embolus. The presence of these alarms should be reported to the clinical care team. Continuous-flow LVADs produce a pulseless circulation for which heart rate and blood pressure monitoring is challenging. Electrocardiographic monitoring is needed to detect arrhythmias, and Doppler measurement is required to ensure a resting mean arterial pressure of 70 to 90 mm Hg, with exercise contraindicated with a mean arterial pressure >90 mm Hg In summary, exercise training in patients with LVAD begins with early mobilization with physical therapy in hemodynamically stable, ambulatory patients who can easily manage device peripheral components.130 Formal CR usually begins after wound healing 8 to 12 weeks after LVAD implantation. Exercise prescriptions should be individualized by the clinical exercise physiologist and physician, depending on the type of device, time since implantation, and patient age and comorbidities. Group or individual training can be performed. A baseline 6-minute walk test or cardiopulmonary exercise test may be helpful to guide the initial exercise prescription.

Heart Transplantation

There has been recent growth in heart transplantation (HTx) procedures, with >4000 adult HTx procedures performed in the United States and 5887 globally in 2023 (Table 1).21 Median survival exceeds 13 years for recipients who survive the first year after HTx.21 Exercise responses after an HTx are significantly altered because of physiological changes resulting from surgery and the long-term effects of immunosuppressive therapy. The transplanted heart is initially decentralized (often referred to as denervated), lacking autonomic nervous system input. This leads to elevated resting heart rate (typically 90–110 bpm), blunted heart rate response during exercise (chronotropic incompetence), and delayed peak heart rate, often occurring during recovery rather than at peak exertion.23,70 Most HTx recipients experience some degree of reinnervation and improvement of chronotropic response in the months to years after HTx but to a variable extent.23
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