The role of exercise training in heart failure

The effects of Baduanjin exercise on fatigue and quality of life in patients with heart failure: A randomized controlled trial

AIMS

The purpose of this study was to examine the effects of Baduanjin exercise on fatigue and quality of life in patients with heart failure.

METHODS

The study was a randomized controlled trial. Participants diagnosed with heart failure were recruited from two large medical centers in northern Taiwan. Participants were randomly assigned to the intervention ( n=39) or control ( n=41) groups. Patients in the intervention group underwent a 12-week Baduanjin exercise program, which included Baduanjin exercise three times per week for 12 weeks at home, a 35-minute Baduanjin exercise demonstration video, a picture-based educational brochure, and a performance record form. The control group received usual care and received no intervention. Fatigue and quality of life were assessed using a structural questionnaire at baseline, four weeks, eight weeks, and 12 weeks after the intervention.

RESULTS

Participants in the Baduanjin exercise group showed significant improvement in fatigue ( F=5.08, p=0.009) and quality of life ( F=9.11, p=0.001) over time from baseline to week 12 after the intervention. Those in the control group showed significantly worse fatigue ( F=3.46, p=0.033) over time from baseline to week 12 and no significant changes in quality of life ( F=0.70, p=0.518). Compared to the control group, the exercise group demonstrated significantly greater improvement in fatigue and quality of life at four weeks, eight weeks, and 12 weeks.

CONCLUSIONS

This simple traditional exercise is recommended for Taiwanese patients with heart failure in order to improve their fatigue and quality of life.

Voluntary Exercise Improves Cardiac Function and Prevents Cardiac Remodeling in a Mouse Model of Dilated Cardiomyopathy

Objective: Despite the indubitable beneficial effect of exercise to prevent of cardiovascular diseases, there is still a lack of studies investigating the impact of exercise in non-ischemic dilated cardiomyopathy. Here, we investigated the impact of voluntary exercise on cardiac function in a mouse model of non-ischemic dilated cardiomyopathy (αMHC-MerCreMer:Sf/Sf), induced by cardiac-specific inactivation of the Serum Response Factor.

Materials and Methods: Seven days after tamoxifen injection, 20 αMHC-MerCreMer:Sf/Sf mice were assigned to sedentary (n = 8) and exercise (n = 12) groups. Seven additional αMHC-MerCreMer:Sf/Sf mice without tamoxifen injection were used as control. The exercise group performed 4 weeks of voluntary running on wheel (1.8 ± 0.12 km/day). Cardiac function, myocardial fibrosis, and mitochondrial energetic pathways were then blindly assessed.

Results: Exercised mice exhibited a smaller decrease of left ventricular (LV) fractional shortening and ejection fraction compared to control mice. This was associated with a lower degree of LV remodeling in exercised mice, as shown by a lower LV end-systolic intrerventricular septal and posterior wall thickness decrease from baseline values compared to sedentary mice. Moreover, exercised mice displayed a reduced gene expression of atrial and brain natriuretic factors. These benefits were associated by a reduced level of myocardial fibrosis. In addition, exercised mice exhibited a higher mitochondrial aconitase, voltage-dependent anion-selective channel 1 and PPAR gamma coactivators-1 alpha proteins levels suggesting that the increase of mitochondrial biogenesis and/or metabolism slowed the progression of dilated cardiomyopathy in exercised animals.

Conclusions: In conclusion, our results support the role of voluntary exercise to improve outcomes in non-ischemic dilated heart failure (HF) and also support its potential for a routine clinical use in the future.

Inflammation and oxidative stress in heart failure: effects of exercise intensity and duration

Although acute exercise is apparently pro-inflammatory and increases oxidative stress, it can promote the necessary stress stimulus to train chronic adaptations in patients with chronic heart failure (CHF). This study aimed to compare the effects of exercise intensity and duration on the inflammatory markers soluble tumor necrosis factor receptor (sTNFR1) and interleukin-6 (IL-6), and on oxidative stress [malondialdehyde (MDA) and antioxidant enzymes: catalase (CAT) and superoxide dismutase (SOD)] in individuals with CHF. Eighteen patients performed three exercise sessions: 30 min of moderate-intensity (M30) exercise, 30 min of low-intensity (L30) exercise, and 45 min of low-intensity (L45) exercise. Blood analysis was performed before exercise (baseline), immediately after each session (after), and 1 h after the end of each session (1h after). Thirty min of M30 exercise promoted a larger stressor stimulus, both pro-inflammatory and pro-oxidative, than that promoted by exercises L30 and L45. This was evidenced by increased sTNFR1 and MDA levels after exercise M30. In response to this stressor stimulus, 1 h after exercise, there was an increase in IL-6 and CAT levels, and a return of sTNFR1 to baseline levels. These findings suggest that compared with the duration of exercise, the exercise intensity was an important factor of physiologic adjustments.

Exercise training in Diastolic Heart Failure (Ex-DHF): rationale and design of a multicentre, prospective, randomized, controlled, parallel group trial

Heart failure with preserved ejection fraction (HFpEF) is a common disease with high incidence and increasing prevalence. Patients suffer from functional limitation, poor health-related quality of life, and reduced prognosis. A pilot study in a smaller group of HFpEF patients showed that structured, supervised exercise training (ET) improves maximal exercise capacity, diastolic function, and physical quality of life. However, the long-term effects of ET on patient-related outcomes remain unclear in HFpEF. The primary objective of the Exercise training in Diastolic Heart Failure (Ex-DHF) trial is to investigate whether a 12 month supervised ET can improve a clinically meaningful composite outcome score in HFpEF patients. Components of the outcome score are all-cause mortality, hospitalizations, NYHA functional class, global self-rated health, maximal exercise capacity, and diastolic function. After undergoing baseline assessments to determine whether ET can be performed safely, 320 patients at 11 trial sites with stable HFpEF are randomized 1:1 to supervised ET in addition to usual care or to usual care alone. Patients randomized to ET perform supervised endurance/resistance ET (3 times/week at a certified training centre) for 12 months. At baseline and during follow-up, anthropometry, echocardiography, cardiopulmonary exercise testing, and health-related quality of life evaluation are performed. Blood samples are collected to examine various biomarkers. Overall physical activity, training sessions, and adherence are monitored and documented throughout the study using patient diaries, heart rate monitors, and accelerometers. The Ex-DHF trial is the first multicentre trial to assess the long-term effects of a supervised ET programme on different outcome measures in patients with HFpEF.

Participation in Cardiac Rehabilitation Among Patients With Heart Failure

BACKGROUND

Cardiac rehabilitation (CR) is linked to reduced mortality and morbidity, including improvements in cardiorespiratory fitness, psychosocial state, and quality of life in patients with heart failure (HF). However, little is known about CR utilization among patients with HF.

OBJECTIVE

We sought to determine (a) the proportion of patients with HF who participated in CR and (b) patient characteristics associated with participation.

METHODS

A retrospective study was conducted with the use of national data from the Centers for Medicare and Medicaid Services and the Veterans Health Administration. We used primary discharge ICD-9 codes to identify patients hospitalized for HF during 2007-2011 and identified CR participation with the use of current procedure terminology codes from claims data. Multivariate logistic regression was used to identify patient characteristics associated with CR participation.

RESULTS

There were 66,710 veterans and 243,208 Medicare beneficiaries hospitalized for HF and 1554 (2.3%) and 6280 (2.6%), respectively, who attended ≥1 sessions of outpatient CR. Among Medicare beneficiaries, men were more likely than women to participate in CR (3.7% vs 1.8%; P < .001), but there was no gender difference among veterans (2.3% vs 2.8%; P = .40). Characteristics associated with participation in CR in both groups included younger age, white race, and history of ischemic heart disease.

CONCLUSIONS

Very few HF patients participated in CR, with lower rates among older non-white women with a history of depression or other chronic medical conditions. Because Medicare has recently introduced coverage for CR in patients with systolic HF, we must increase efforts to improve CR participation, especially among these vulnerable groups.

Acute impact of conventional and eccentric cycling on platelet and vascular function in patients with chronic heart failure

Evidence-based guidelines recommend exercise therapy for patients with chronic heart failure (CHF). Such patients have increased atherothrombotic risk. Exercise can transiently increase platelet activation and reactivity and decrease vascular function in healthy participants, although data in CHF are scant. Eccentric (ECC) cycling is a novel exercise modality that may be particularly suited to patients with CHF, but the acute impacts of ECC cycling on platelet and vascular function are currently unknown. Our null hypothesis was that ECC and concentric (CON) cycling, performed at matched external workloads, would not induce changes in platelet or vascular function in patients with CHF. Eleven patients with heart failure with reduced ejection fraction (HFrEF) took part in discrete bouts of ECC and CON cycling. Before and immediately after exercise, vascular function was assessed by measuring diameter and flow-mediated dilation (FMD) of the brachial artery. Platelet function was measured by the flow cytometric determination of glycoprotein IIb/IIIa activation and granule exocytosis in the presence and absence of platelet agonists. ECC cycling increased baseline artery diameter (pre: 4.0 ± 0.8 mm vs. post: 4.2 ± 0.7 mm; P = 0.04) and decreased FMD%. When changes in baseline artery diameter were accounted for, the decrease in FMD post-ECC cycling was no longer significant. No changes were apparent after CON. Neither ECC nor CON cycling resulted in changes to any platelet-function measures (all P > 0.05). These results suggest that both ECC and CON cycling, at a moderate intensity and short duration, can be performed by patients with HFrEF without detrimental impacts on vascular or platelet function.NEW & NOTEWORTHY This is the first evidence to indicate that eccentric (ECC) cycling can be performed relatively safely by patients with chronic heart failure (CHF), as it did not result in impaired vascular or platelet function compared with conventional cycling. This is important, as acute exercise can transiently increase atherothrombotic risk, and ECC cycling is a novel exercise modality that may be particularly suited to patients with CHF.

Effect of functional electrical stimulation on cardiovascular outcomes in patients with chronic heart failure

Background/design Functional electrical stimulation of lower limb muscles is an alternative method of training in patients with chronic heart failure (CHF). Although it improves exercise capacity in CHF, we performed a randomised, placebo-controlled study to investigate its effects on long-term clinical outcomes. Methods We randomly assigned 120 patients, aged 71 ± 8 years, with stable CHF (New York Heart Association (NYHA) class II/III (63%/37%), mean left ventricular ejection fraction 28 ± 5%), to either a 6-week functional electrical stimulation training programme or placebo. Patients were followed for up to 19 months for death and/or hospitalisation due to CHF decompensation. Results At baseline, there were no significant differences in demographic parameters, CHF severity and medications between groups. During a median follow-up of 383 days, 14 patients died (11 cardiac, three non-cardiac deaths), while 40 patients were hospitalised for CHF decompensation. Mortality did not differ between groups (log rank test P = 0.680), while the heart failure-related hospitalisation rate was significantly lower in the functional electrical stimulation group (hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.21-0.78, P = 0.007). The latter difference remained significant after adjustment for prognostic factors: age, gender, baseline NYHA class and left ventricular ejection fraction (HR 0.22, 95% CI 0.10-0.46, P < 0.001). Compared to placebo, functional electrical stimulation training was associated with a lower occurrence of the composite endpoint (death or heart failure-related hospitalisation) after adjustment for the above-mentioned prognostic factors (HR 0.21, 95% CI 0.103-0.435, P < 0.001). However, that effect was mostly driven by the favourable change in hospitalisation rates. Conclusions In CHF patients, 6 weeks functional electrical stimulation training reduced the risk of heart failure-related hospitalisations, without affecting the mortality rate. The beneficial long-term effects of this alternative method of training require further investigation.

High-Intensity Training Improves Global and Segmental Strains in Severe Congestive Heart Failure

BACKGROUND

High-intensity training (HIT) is superior to moderate aerobic training (MAT) for improving quality of life in congestive heart failure (CHF) patients. Speckle-tracking echocardiography (STE) has recently been suggested for estimation of left ventricle global and regional function. We evaluated the utility of STE for characterizing differences in cardiac function following MAT or HIT in a CHF rat model.

METHODS AND RESULTS

After baseline physiologic assessment, CHF was induced by means of coronary artery ligation in Sprague-Dawley rats. Repeated measurements confirmed the presence of CHF (ejection fraction 52 ± 10%, global circumferential strain (GCS) 10.5 ± 4, and maximal oxygen uptake (V˙O_2max) 71 ± 11 mL⋅min^-1⋅kg^-1; P < .001 vs baseline for all). Subsequently, rats were divided into training protocols: sedentary (SED), MAT, or HIT. After the training period, rats underwent the same measurements and were killed. Training intensity improved V˙O_2max (73 ± 13 mL⋅min^-1⋅kg^-1 in MAT [P < .01 vs baseline] and 82 ± 6 mL⋅min^-1⋅kg^-1 in HIT [P < .05 vs baseline or SED] and ejection fraction (50 ± 21% in MAT [P < .001 vs baseline] and 66 ± 7% in HIT [P > .05 vs baseline]). In addition, strains of specific segments adjacent to the infarct zone regained basal values (P > .05 vs baseline), whereas global cardiac functional parameters as assessed with the use of 2-dimensional echocardiography did not improve.

CONCLUSIONS

High-intensity exercise training improved function in myocardial segments remote from the scar, which resulted in compensatory cardiac remodeling. This effect is prominent, yet it could be detected only with the use of STE.

Impaired High-Density Lipoprotein Anti-Oxidative Function Is Associated With Outcome in Patients With Chronic Heart Failure

Background

Oxidative stress is mechanistically linked to the pathogenesis of chronic heart failure (CHF). Antioxidative functions of high‐density lipoprotein (HDL) particles have been found impaired in patients with ischemic cardiomyopathy; however, the impact of antioxidative HDL capacities on clinical outcome in CHF patients is unknown. We therefore investigated the predictive value of antioxidative HDL function on mortality in a representative cohort of patients with CHF.

Methods and Results

We prospectively enrolled 320 consecutive patients admitted to our outpatient department for heart failure and determined antioxidative HDL function using the HDL oxidative index (HOI). During a median follow‐up time of 2.8 (IQR: 1.8‐4.9) years, 88 (27.5%) patients reached the combined cardiovascular endpoint defined as the combination of death due to cardiovascular events and heart transplantation. An HOI ≥1 was significantly associated with survival free of cardiovascular events in Cox regression analysis with a hazard ratio (HR) of 2.28 (95% CI 1.48‐3.51, P<0.001). This association remained significant after comprehensive multivariable adjustment for potential confounders with an adjusted HR of 1.83 (95% CI 1.1‐2.92, P=0.012). Determination of HOI significantly enhanced risk prediction beyond that achievable with N‐terminal pro‐B‐type natriuretic peptide indicated by improvements in net reclassification index (32.4%, P=0.009) and integrated discrimination improvement (1.4%, P=0.04).

Conclusions

Impaired antioxidative HDL function represents a strong and independent predictor of mortality in patients with CHF. Implementation of HOI leads to a substantial improvement of risk prediction in patients with CHF.

The mechanisms of breathlessness in heart failure as the basis of therapy

PURPOSE OF REVIEW

The review provides an overview of recent understanding in relation to the mechanisms relating to skeletal muscle and the sympathetic nervous system, and therapies for breathlessness which target these mechanisms. These are set in the context of established knowledge in this field.

RECENT FINDINGS

Despite strong evidence to support exercise training programmes, and recommendations in international guidelines, programmes are implemented poorly. Electrical stimulation appears to be a way of exercising people too frail to undertake a full exercise programme. There is evidence to support the use of opioids for breathlessness in other conditions, but as yet the evidence in chronic heart failure is mixed.

SUMMARY

Previous work in relation to the role of skeletal muscle and sympathetic nervous system has set the scene for targeted therapies for the relief of breathlessness in people with heart failure.

Exercise intolerance in pulmonary hypertension: mechanism, evaluation and clinical implications

INTRODUCTION

Exercise intolerance in pulmonary hypertension (PH) is a major factor affecting activities of daily living and quality of life. Evaluation strategies (i.e., non-invasive and invasive tests) are integral to providing a comprehensive assessment of clinical and functional status. Despite a growing body of literature on the clinical consequences of PH, there are limited studies discussing the contribution of various physiological systems to exercise intolerance in this patient population.

AREAS COVERED

This review, through a search of various databases, describes the physiological basis for exercise intolerance across the various PH etiologies, highlights the various exercise evaluation methods and discusses the rationale for exercise training amongst those diagnosed with PH. Expert commentary: With the growing importance of evaluating exercise capacity in PH (class 1, Level C recommendation), understanding why exercise performance is altered in PH is crucial. Thus, the further study is required for better quality evidence in this area.

Changes in derived measures from six-minute walk distance following home-based exercise training in congestive heart failure: A preliminary report

The response of derived parameters from six-minute walk distance (6MWD), like 6MW work (6MWW), to exercise training and its correlation with quality of life (QoL) in congestive heart failure (CHF) is not known. A secondary analysis from a randomized controlled trial on 30 patients (23 males; mean age 57.7 ± 10.4 years; mean ejection fraction 31 ± 10%) with CHF in NYHA class I–IV who completed an eight-week home-based exercise training program found a significant improvement in 6MWW (p < 0.05), with similar correlations between 6MWD and 6MWW with QoL. 6MWW does not appear to provide additional benefit to 6MWD in cardiac rehabilitation for CHF.

Team-based Care for Cardiac Rehabilitation and Exercise Training in Heart Failure

The estimated cost of treating patients with HF in the United States is expected to more than double by 2030.65 This forecast of the impact of HF in the United States should serve as a call to action. Despite well-documented benefits, participation in exercise training and CR programs by patients with HF remains low. In this article, standards and guidelines for exercise and CR in HF were reviewed. Although traditional CR had core components, it lacked care management specific for HF. Chronic stable HF patients can safely exercise; however, there are many unique needs that are not currently addressed at the patient, system, and provider levels. As we face economic and political forces that are expected to require major change to the health care delivery system, it becomes even more important to capitalize on the advantages that come with team-based care. CR has always served as a model of team-based care; however, the model must now include professionals with HF expertise to guide patients in safe exercise and self-management strategies appropriate for this chronically ill population.

Insulin-like growth factor 1 prevents diastolic and systolic dysfunction associated with cardiomyopathy and preserves adrenergic sensitivity

AIMS

Insulin-like growth factor 1 (IGF-1)-dependent signalling promotes exercise-induced physiological cardiac hypertrophy. However, the in vivo therapeutic potential of IGF-1 for heart disease is not well established. Here, we test the potential therapeutic benefits of IGF-1 on cardiac function using an in vivo model of chronic catecholamine-induced cardiomyopathy.

METHODS

Rats were perfused with isoproterenol via osmotic pump (1 mg kg(-1) per day) and treated with 2 mg kg(-1) IGF-1 (2 mg kg(-1) per day, 6 days a week) for 2 or 4 weeks. Echocardiography, ECG, and blood pressure were assessed. In vivo pressure-volume loop studies were conducted at 4 weeks. Heart sections were analysed for fibrosis and apoptosis, and relevant biochemical signalling cascades were assessed.

RESULTS

After 4 weeks, diastolic function (EDPVR, EDP, tau, E/A ratio), systolic function (PRSW, ESPVR, dP/dtmax) and structural remodelling (LV chamber diameter, wall thickness) were all adversely affected in isoproterenol-treated rats. All these detrimental effects were attenuated in rats treated with Iso+IGF-1. Isoproterenol-dependent effects on BP were attenuated by IGF-1 treatment. Adrenergic sensitivity was blunted in isoproterenol-treated rats but was preserved by IGF-1 treatment. Immunoblots indicate that cardioprotective p110α signalling and activated Akt are selectively upregulated in Iso+IGF-1-treated hearts. Expression of iNOS was significantly increased in both the Iso and Iso+IGF-1 groups; however, tetrahydrobiopterin (BH4) levels were decreased in the Iso group and maintained by IGF-1 treatment.

CONCLUSION

IGF-1 treatment attenuates diastolic and systolic dysfunction associated with chronic catecholamine-induced cardiomyopathy while preserving adrenergic sensitivity and promoting BH4 production. These data support the potential use of IGF-1 therapy for clinical applications for cardiomyopathies.

Exercise and sports in cardiac patients and athletes at risk: Balance between benefit and harm

Physical training has a well-established role in the primary and secondary prevention of coronary artery disease. Moderate exercise has been shown to be beneficial in chronic stable heart failure. Competitive sports, however, is contraindicated in most forms of hypertrophic cardiomyopathy (HCM), in myocarditis, in pericarditis, and in right ventricular cardiomyopathy/dysplasia. In most European countries, the recommendations of medical societies or public bodies state that these diseases have to be ruled out by prescreening before an individual can take up competitive sports. But the intensity and quality of this health check vary considerably from country to country, from the type of sports activity, and from the individuals who want to participate in sports. Prescreening on an individual basis should also be considered for leisure sports, particularly in people who decide to start training in middle age after years of physical inactivity to regain physical fitness. In leisure sports the initiative for a medical check-up lies primarily in the hands of the "healthy" individual. If she or he plans to participate in extreme forms of endurance sports with excessive training periods such as a marathon or ultramarathon and competitive cycling or rowing, they should be aware that high-intensity endurance sports can lead to structural alterations of the heart muscle even in healthy individuals. Physical exercise in patients with heart disease should be accompanied by regular medical check-ups. Most rehabilitation programs in Europe perform physical activity and training schedules according to current guidelines. Little is known about athletes who are physically handicapped and participate in competitive sports or the Paralympics, and even less is known about individuals with intellectual disabilities (ID) who participate in local, regional, international competitions or the Special Olympics or just in leisure sport activities.

Beneficial Effects of Physical Exercise on Functional Capacity and Skeletal Muscle Oxidative Stress in Rats with Aortic Stenosis-Induced Heart Failure

Objective. We evaluated the influence of exercise on functional capacity, cardiac remodeling, and skeletal muscle oxidative stress, MAPK, and NF-κB pathway in rats with aortic stenosis- (AS-) induced heart failure (HF). Methods and Results. Eighteen weeks after AS induction, rats were assigned into sedentary control (C-Sed), exercised control (C-Ex), sedentary AS (AS-Sed), and exercised AS (AS-Ex) groups. Exercise was performed on treadmill for eight weeks. Statistical analyses were performed with Goodman and ANOVA or Mann-Whitney. HF features frequency and mortality did not differ between AS groups. Exercise improved functional capacity, assessed by maximal exercise test on treadmill, without changing echocardiographic parameters. Soleus cross-sectional areas did not differ between groups. Lipid hydroperoxide concentration was higher in AS-Sed than C-Sed and AS-Ex. Activity of antioxidant enzymes superoxide dismutase and glutathione peroxidase was changed in AS-Sed and restored in AS-Ex. NADPH oxidase activity and gene expression of its subunits did not differ between AS groups. Total ROS generation was lower in AS-Ex than C-Ex. Exercise modulated MAPK in AS-Ex and did not change NF-κB pathway proteins. Conclusion. Exercise improves functional capacity in rats with AS-induced HF regardless of echocardiographic parameter changes. In soleus, exercise reduces oxidative stress, preserves antioxidant enzyme activity, and modulates MAPK expression.

Cardiac Rehabilitation in Patients With Heart Failure: New Perspectives in Exercise Training

Exercise training is recommended to patients with chronic heart failure (CHF) and reduced ejection fraction at a class 1 evidence level. Currently the 'dose' of exercise (dose being both volume and intensity) still remains uncertain and the best form of aerobic exercise training has not been defined. Guidelines commonly use heart rate (HR) as a target factor for both moderate continuous and interval training exercises. However, exercise training guided by HR can be limited in CHF patients due to chronotropic incompetence and beta-blocker treatment. In our study, we systematically addressed the above issues by applying a training method that takes into account both the volume and intensity of exercise on an individual basis. This method is referred to as individual TRaining IMPulses (TRIMPi). In this review, we summarise a series of investigations that used TRIMPi and different exercise forms to quantify the optimum training load in CHF patients. This review also highlights the way TRIMPi and the individual exercise dose affects cardiorespiratory, metabolic and autonomic cardiac adaptations.

[Exercise training as a key component of heart failure therapy]

Physical exercise has been recognized as a standard therapy in the guidelines for secondary prevention of chronic heart failure. In clinical practice its benefits are widely underestimated. It is still too rarely applied as a therapeutic component, despite overwhelming scientific evidence, including meta-analyses illustrating the positive effect on exercise capacity, quality of life and hospitalization. It is crucial that patients undergo a thorough clinical investigation, including exercise testing and are in a clinically stable condition for at least 6 weeks under optimal guideline-conform medicinal therapy before exercise training is initiated. Moreover, it is important that only approved exercise regimens should be prescribed and exercise sessions should be appropriately monitored. Both moderate continuous endurance training and recently developed interval training have been shown to be safe and effective in chronic heart failure. Ideally, endurance training should be combined with moderate resistance training. Current evidence clearly demonstrates a dose-response relationship in the way that beneficial effects of exercise training are strongly related to factors such as exercise duration and intensity. Development of strategies that support long-term adherence to exercise training are a crucial challenge for both daily practice and future research.

Exercise training normalizes renal blood flow responses to acute hypoxia in experimental heart failure: role of the α1-adrenergic receptor

Recent data suggest that exercise training (ExT) is beneficial in chronic heart failure (CHF) because it improves autonomic and peripheral vascular function. In this study, we hypothesized that ExT in the CHF state ameliorates the renal vasoconstrictor responses to hypoxia and that this beneficial effect is mediated by changes in α1-adrenergic receptor activation. CHF was induced in rabbits. Renal blood flow (RBF) and renal vascular conductance (RVC) responses to 6 min of 5% isocapnic hypoxia were assessed in the conscious state in sedentary (SED) and ExT rabbits with CHF with and without α1-adrenergic blockade. α1-adrenergic receptor expression in the kidney cortex was also evaluated. A significant decline in baseline RBF and RVC and an exaggerated renal vasoconstriction during acute hypoxia occurred in CHF-SED rabbits compared with the prepaced state (P < 0.05). ExT diminished the decline in baseline RBF and RVC and restored changes during hypoxia to those of the prepaced state. α1-adrenergic blockade partially prevented the decline in RBF and RVC in CHF-SED rabbits and eliminated the differences in hypoxia responses between SED and ExT animals. Unilateral renal denervation (DnX) blocked the hypoxia-induced renal vasoconstriction in CHF-SED rabbits. α1-adrenergic protein in the renal cortex of animals with CHF was increased in SED animals and normalized after ExT. These data provide evidence that the acute decline in RBF during hypoxia is caused entirely by the renal nerves but is only partially mediated by α1-adrenergic receptors. Nonetheless, α1-adrenergic receptors play an important role in the beneficial effects of ExT in the kidney.

Exercise Training in Group 2 Pulmonary Hypertension: Which Intensity and What Modality

Pulmonary hypertension (PH) due to left-sided heart disease (LSHD) is a common and disconcerting occurrence. For example, both heart failure (HF) with preserved and reduced ejection fraction (HFpEF and HFrEF) often lead to PH as a consequence of a chronic elevation in left atrial filling pressure. A wealth of literature demonstrates the value of exercise training (ET) in patients with LSHD, which is particularly robust in patients with HFrEF and growing in patients with HFpEF. While the effects of ET have not been specifically explored in the LSHD-PH phenotype (i.e., composite pathophysiologic characteristics of patients in this advanced disease state), the overall body of evidence supports clinical application in this subgroup. Moderate intensity aerobic ET significantly improves peak oxygen consumption, quality of life and prognosis in patients with HF. Resistance ET significantly improves muscle strength and endurance in patients with HF, which further enhance functional capacity. When warranted, inspiratory muscle training and neuromuscular electrical stimulation are becoming recognized as important components of a comprehensive rehabilitation program. This review will provide a detailed account of ET programing considerations in patients with LSHD with a particular focus on those concomitantly diagnosed with PH.

"I Just Can't Do It Anymore" Patterns of Physical Activity and Cardiac Rehabilitation in African Americans with Heart Failure: A Mixed Method Study

Physical activity and cardiac rehabilitation (CR) are components of heart failure (HF) self-care. The aims of this study were to describe patterns of physical activity in African Americans (n = 30) with HF and to explore experience in CR. This was a mixed method, concurrent nested, predominantly qualitative study. Qualitative data were collected via interviews exploring typical physical activity, and CR experience. It was augmented by quantitative data measuring HF severity, self-care, functional capacity and depressive symptoms. Mean age was 60 ± 15 years; 65% were New York Heart Association (NYHA) class III HF. Forty-three percent reported that they did less than 30 min of exercise in the past week; 23% were told “nothing” about exercise by their provider, and 53% were told to do “minimal exercise”. A measure of functional capacity indicated the ability to do moderate activity. Two related themes stemmed from the narratives describing current physical activity: “given up” and “still trying”. Six participants recalled referral to CR with one person participating. There was high concordance between qualitative and quantitative data, and evidence that depression may play a role in low levels of physical activity. Findings highlight the need for strategies to increase adherence to current physical activity guidelines in this older minority population with HF.

Heart Failure as a Newly Approved Diagnosis for Cardiac Rehabilitation: Challenges and Opportunities

Many see the broadened eligibility of cardiac rehabilitation (CR) to include heart failure with reduced ejection fraction (HFrEF) as a likely catalyst to high CR enrollment and improved care. However, such expectation contrasts with the reality that CR enrollment of eligible coronary heart disease patients has remained low for decades. In this review, entrenched obstacles impeding utilization of CR are considered, particularly in relation to potential HFrEF management. The strengths and limitations of the HF-ACTION (Heart Failure-A Controlled Trial Investigating Outcomes of Exercise Training) trial to advance precepts of CR are considered, as well as gaps that this trial failed to address, such as the utility of CR for patients with heart failure with preserved ejection fraction and the conundrum of poor patient adherence.

Exercise and the cardiovascular system: clinical science and cardiovascular outcomes

Substantial evidence has established the value of high levels of physical activity, exercise training (ET), and overall cardiorespiratory fitness in the prevention and treatment of cardiovascular diseases. This article reviews some basics of exercise physiology and the acute and chronic responses of ET, as well as the effect of physical activity and cardiorespiratory fitness on cardiovascular diseases. This review also surveys data from epidemiological and ET studies in the primary and secondary prevention of cardiovascular diseases, particularly coronary heart disease and heart failure. These data strongly support the routine prescription of ET to all patients and referrals for patients with cardiovascular diseases, especially coronary heart disease and heart failure, to specific cardiac rehabilitation and ET programs.

Improving functional capacity in heart failure: the need for a multifaceted approach

PURPOSE OF REVIEW

Functional capacity is a broad term that describes a person's ability to perform the daily activities that require physical exertion. Patients diagnosed with heart failure, regardless of cause, demonstrate a compromised functional capacity. The ability to perform aerobic activities is a central, but not complete, determinant of functional capacity. Muscular strength and endurance are other important elements of functional capacity. It is well established that patients with heart failure demonstrate attenuated muscular strength and endurance as a consequence of their disease process. Typically, a heart failure patient's ability to perform daily activities that are either aerobic or resistive in nature is compromised and contributes to the decline in functional capacity.

RECENT FINDINGS

There is an abundance of literature demonstrating that exercise training improves aerobic capacity and muscular strength and endurance in those with heart failure. These training benefits translate to an improvement in functional capacity and an enhanced ability to perform activities of daily living. There are several approaches to exercise training in the heart failure population, each of which has implications for the degree to which functional capacity can be improved.

SUMMARY

This review summarizes the current body of literature related to exercise training as a means of optimizing functional capacity in patients with heart failure.

Incorporating patients with chronic heart failure into outpatient cardiac rehabilitation: practical recommendations for exercise and self-care counseling-a clinical review

PURPOSE

A recent policy change from the Centers for Medicare and Medicaid Services includes coverage of cardiac rehabilitation (CR) for patients with chronic heart failure (CHF) with reduced ejection fraction. This article provides a framework by which CR programs can incorporate disease-specific services for patients with CHF who participate in CR.

DISCUSSION

Cardiac rehabilitation should include self-care counseling that targets improved education and skill development (eg, medication compliance, monitoring/management of body weight). Various tools are available for assessing exercise tolerance (eg, stress test with gas exchange and 6-minute walk), health-related quality of life, and other outcome-related parameters. Exercise should be prescribed in a manner that progressively increases intensity, duration, and frequency, to a volume of exercise equivalent to 3 to 7 metabolic equivalent task (MET)-hr per week. The benefits of exercise training are limited by patient adherence; therefore, CR providers need to identify the adherence challenges unique to each patient and address each accordingly. To optimize the referral of patients with CHF to CR, program staff should develop strategies to raise both health care provider and patient awareness about the benefits of CR, as well as work collaboratively to set up system-based approaches to CR referral.

CONCLUSIONS

The referral of patients with CHF to CR will increase in 2014 and beyond, due partly to a policy change from the Centers for Medicare and Medicaid Services that allows coverage for CR. These patients should be integrated into existing programs, with the intent of providing both standard CR services and CHF-specific education and disease management activities that target improved outcomes.

Protein post-translational modifications and misfolding: new concepts in heart failure

A new concept in the field of heart-failure (HF) research points to a role of misfolded proteins, forming preamyloid oligomers (PAOs), in cardiac toxicity. This is largely based on few studies reporting the presence of PAOs, similar to those observed in neurodegenerative diseases, in experimental and human HF. As the majority of proteinopathies are sporadic in nature, protein post-translational modifications (PTMs) likely play a major role in this growing class of diseases. In fact, PTMs are known regulators of protein folding and of the formation of amyloid species in well-established proteinopathies. Proteomics has been instrumental in identifying both chemical and enzymatic PTMs, with a potential impact on protein mis-/folding. Here we provide the basics on how proteins fold along with a few examples of PTMs known to modulate protein misfolding and aggregation, with particular focus on the heart. Due to its innovative content and the growing awareness of the toxicity of misfolded proteins, an "Alzheimer's theory of HF" is timely. Moreover, the continuous innovations in proteomic technologies will help pinpoint PTMs that could contribute to the process. This nuptial between biology and technology could greatly assist in identifying biomarkers with increased specificity as well as more effective therapies.

Exercise training prevents the deterioration in the arterial baroreflex control of sympathetic nerve activity in chronic heart failure patients

Arterial baroreflex control of muscle sympathetic nerve activity (ABRMSNA) is impaired in chronic systolic heart failure (CHF). The purpose of the study was to test the hypothesis that exercise training would improve the gain and reduce the time delay of ABRMSNA in CHF patients. Twenty-six CHF patients, New York Heart Association Functional Class II-III, EF ≤ 40%, peak V̇o2 ≤ 20 ml·kg(-1)·min(-1) were divided into two groups: untrained (UT, n = 13, 57 ± 3 years) and exercise trained (ET, n = 13, 49 ± 3 years). Muscle sympathetic nerve activity (MSNA) was directly recorded by microneurography technique. Arterial pressure was measured on a beat-to-beat basis. Time series of MSNA and systolic arterial pressure were analyzed by autoregressive spectral analysis. The gain and time delay of ABRMSNA was obtained by bivariate autoregressive analysis. Exercise training was performed on a cycle ergometer at moderate intensity, three 60-min sessions per week for 16 wk. Baseline MSNA, gain and time delay of ABRMSNA, and low frequency of MSNA (LFMSNA) to high-frequency ratio (HFMSNA) (LFMSNA/HFMSNA) were similar between groups. ET significantly decreased MSNA. MSNA was unchanged in the UT patients. The gain and time delay of ABRMSNA were unchanged in the ET patients. In contrast, the gain of ABRMSNA was significantly reduced [3.5 ± 0.7 vs. 1.8 ± 0.2, arbitrary units (au)/mmHg, P = 0.04] and the time delay of ABRMSNA was significantly increased (4.6 ± 0.8 vs. 7.9 ± 1.0 s, P = 0.05) in the UT patients. LFMSNA-to-HFMSNA ratio tended to be lower in the ET patients (P < 0.08). Exercise training prevents the deterioration of ABRMSNA in CHF patients.

Identifying biomarker patterns and predictors of inflammation and myocardial stress

BACKGROUND

Regular exercise is recommended to improve outcomes in patients with heart failure. Exercise is known to decrease inflammation and thought to decrease myocardial stress; however, studies of exercise in heart failure have had mixed results on levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity C-reactive protein (hsCRP). A multimarker analysis may help to identify distinct subgroups of patients who respond to exercise. Our primary study objective was to identify common and distinct patterns of change in hsCRP and NT-proBNP and to quantify the influence of exercise therapy on the observed patterns of change.

METHODS AND RESULTS

NT-proBNP and hsCRP were assessed in a random sample of 320 participants from the biomarker substudy of HF-ACTION, a randomized clinical trial of exercise training versus usual care in patients with stable and chronic heart failure. Growth mixture modeling was used to identify unique biomarker patterns over 12 months. Three statistically independent and clinically meaningful biomarker patterns of NT-proBNP and hsCRP were identified. Two patterns were combined and compared with the "low/stable" pattern, which was characterized by the lowest levels of NT-proBNP and hsCRP over time. Participants who were taking a loop diuretic and had hypertension or ischemic etiology were ∼2 times as likely to be in the "elevated/worsening" biomarker pattern. Participants randomized to the exercise intervention were less likely to be in the elevated/worsening pattern of NT-proBNP and hsCRP (relative risk ratio 0.56, 95% confidence interval 0.32-0.98; P = .04).

CONCLUSIONS

Exercise therapy was protective for reducing the frequency of membership in the elevated/worsening biomarker pattern, indicating that exercise may be helpful in delaying the progression of heart failure.

Mechanisms of carotid body chemoreflex dysfunction during heart failure

NEW FINDINGS

What is the topic of this review? Carotid body chemoreceptor activity is tonically elevated in heart failure and contributes to morbidity due to the reflex activation of sympathetic nerve activity and destabilization of breathing. The potential causes for the enhanced chemoreceptor activation in heart failure are discussed. What advances does it highlight? The role of a chronic reduction in blood flow to the carotid body due to cardiac failure and its impact on signalling pathways in the carotid body is discussed. Recent advances have attracted interest in the potential for carotid body (CB) ablation or desensitization as an effective strategy for clinical treatment and management of cardiorespiratory diseases, including hypertension, heart failure, diabetes mellitus, metabolic syndrome and renal failure. These disease states have in common sympathetic overactivity, which plays an important role in the development and progression of the disease and is often associated with breathing dysregulation, which in turn is likely to mediate or aggravate the autonomic imbalance. Evidence from both chronic heart failure (CHF) patients and animal models indicates that the CB chemoreflex is enhanced in CHF and contributes to the tonic elevation in sympathetic activity and the development of periodic breathing associated with the disease. Although this maladaptive change is likely to derive from altered function at all levels of the reflex arc, a tonic increase in afferent activity from CB glomus cells is likely to be a main driving force. This report focuses on our understanding of mechanisms that alter CB function in CHF and their potential translational impact on treatment of CHF.

Role of the Carotid Body Chemoreflex in the Pathophysiology of Heart Failure: A Perspective from Animal Studies

The treatment and management of chronic heart failure (CHF) remains an important focus for new and more effective clinical strategies. This important goal, however, is dependent upon advancing our understanding of the underlying pathophysiology. In CHF, sympathetic overactivity plays an important role in the development and progression of the cardiac and renal dysfunction and is often associated with breathing dysregulation, which in turn likely mediates or aggravates the autonomic imbalance. In this review we will summarize evidence that in CHF, the elevation in sympathetic activity and breathing instability that ultimately lead to cardiac and renal failure are driven, at least in part, by maladaptive activation of the carotid body (CB) chemoreflex. This maladaptive change derives from a tonic increase in CB afferent activity. We will focus our discussion on an understanding of mechanisms that alter CB afferent activity in CHF and its consequence on reflex control of autonomic, respiratory, renal, and cardiac function in animal models of CHF. We will also discuss the potential translational impact of targeting the CB in the treatment of CHF in humans, with relevance to other cardio-respiratory diseases.

Central mechanisms for exercise training-induced reduction in sympatho-excitation in chronic heart failure

The control of sympathetic outflow in the chronic heart failure (CHF) state is markedly abnormal. Patients with heart failure present with increased plasma norepinephrine and increased sympathetic nerve activity. The mechanism for this sympatho-excitation is multiple and varied. Both depression in negative feedback sensory control mechanisms and augmentation of excitatory reflexes contribute to this sympatho-excitation. These include the arterial baroreflex, cardiac reflexes, arterial chemoreflexes and cardiac sympathetic afferent reflexes. In addition, abnormalities in central signaling in autonomic pathways have been implicated in the sympatho-excitatory process in CHF. These mechanisms include increases in central Angiotensin II and the Type 1 receptor, increased in reactive oxygen stress, upregulation in glutamate signaling and NR1 (N-methyl-D-aspartate subtype 1) receptors and others. Exercise training in the CHF state has been shown to reduce sympathetic outflow and result in increased survival and reduced cardiac events. Exercise training has been shown to reduce central Angiotensin II signaling including the Type 1 receptor and reduce oxidative stress by lowering the expression of many of the subunits of NADPH oxidase. In addition, there are profound effects on the central generation of nitric oxide and nitric oxide synthase in sympatho-regulatory areas of the brain. Recent studies have pointed to the balance between Angiotensin Converting Enzyme (ACE) and ACE2, translating into Angiotensin II and Angiotensin 1-7 as important regulators of sympathetic outflow. These enzymes appear to be normalized following exercise training in CHF. Understanding the precise molecular mechanisms by which exercise training is sympatho-inhibitory will uncover new targets for therapy.

Endurance-training in healthy men is associated with lesser exertional breathlessness that correlates with circulatory-muscular conditioning markers in a cross-sectional design

Whether exertional dyspnoea can be attributed to poor circulatory-muscular conditioning is a difficult clinical issue. Because criteria of poor conditioning such as low oxygen pulse, low ventilatory threshold or high heart rate/oxygen consumption slope can be observed in heart or lung diseases and are not specific to conditioning, we assessed the relationships between physical exercise, conditioning and exertional breathlessness in healthy subjects, in whom the aforementioned criteria can confidently be interpreted as reflecting conditioning.

To this end, healthy males with either low (inactive men, n = 31) or high (endurance-trained men, n = 31) physical activity evaluated using the International Physical Activity Questionnaire (IPAQ) underwent spirometry and incremental exercise testing with breathlessness assessment using Borg scale.

No significant breathlessness was reported before the ventilatory threshold in the two groups. Peak breathlessness was highly variable, did not differ between the two groups, was not related to any conditioning criterion, but correlated with peak respiratory rate. Nevertheless, endurance-trained subjects reported lower breathlessness at the same ventilation levels in comparison with inactive subjects. Significant but weak associations were observed between isoventilation breathlessness and physical activity indices (Borg at 60 L/min and total IPAQ scores, rho = -0.31, p = 0.020), which were mainly attributable to the vigorous domain of physical activity, as well as with conditioning indices (Borg score at 60 L.min^-1 and peak oxygen pulse or heart rate/oxygen consumption slope, rho = -0.31, p = 0.021 and rho = 0.31, p = 0.020; respectively).

In conclusion, our data support a weak relationship between exertional breathlessness and circulatory-muscular conditioning, the later being primarily related to vigorous physical activity.

Possible synergism of physical exercise and ghrelin-agonists in patients with cachexia associated with chronic heart failure

The occurrence of cachexia of multifactorial etiology in chronic heart failure (CHF) is a common and underestimated condition that usually leads to poor outcome and low survival rates, with high direct and indirect costs for the Health Care System. Recently, a consensus definition on cachexia has been reached, leading to a growing interest by the scientific community in this condition, which characterizes the last phase of many chronic diseases (i.e., cancer, acquired immunodeficiency syndrome). The etiology of cachexia is multifactorial and the underlying pathophysiological mechanisms are essentially the following: anorexia and malnourishment; immune overactivity and systemic inflammation; and endocrine disorders (anabolic/catabolic imbalance and resistance to growth hormone). In this paper, we review the main pathophysiological mechanisms underlying CHF cachexia, focusing also on the broad spectrum of actions of ghrelin and ghrelin agonists, and their possible use in combination with physical exercise to contrast CHF cachexia.

Central command dysfunction in rats with heart failure is mediated by brain oxidative stress and normalized by exercise training

Sympathoexcitation elicited by central command, a parallel activation of the motor and autonomic neural circuits in the brain, has been shown to become exaggerated in chronic heart failure (CHF). The present study tested the hypotheses that oxidative stress in the medulla in CHF plays a role in exaggerating central command-elicited sympathoexcitation, and that exercise training in CHF suppresses central command-elicited sympathoexcitation through its antioxidant effects in the medulla. In decerebrate rats, central command was activated by electrically stimulating the mesencephalic locomotor region (MLR) after neuromuscular blockade. The MLR stimulation at a current intensity greater than locomotion threshold in rats with CHF after myocardial infarction (MI) evoked larger (P < 0.05) increases in renal sympathetic nerve activity and arterial pressure than in sham-operated healthy rats (Sham) and rats with CHF that had completed longterm (8–12 weeks) exercise training (MI + TR). In the Sham and MI + TR rats, bilateral microinjection of a superoxide dismutase (SOD) mimetic Tempol into the rostral ventrolateral medulla (RVLM) had no effects on MLR stimulation-elicited responses. By contrast, in MI rats, Tempol treatment significantly reduced MLR stimulation-elicited responses. In a subset of MI rats, treatment with Tiron, another SOD mimetic, within the RVLM also reduced responses. Superoxide generation in the RVLM, as evaluated by dihydroethidium staining, was enhanced in MI rats compared with that in Sham and MI + TR rats. Collectively, these results support the study hypotheses. We suggest that oxidative stress in the medulla in CHF mediates central command dysfunction, and that exercise training in CHF is capable of normalizing central command dysfunction through its antioxidant effects in the medulla.

[Exercise training in heart failure]

In patients with chronic but stable heart failure (HF) exercise training is a recommended and widely accepted adjunct to an evidence-based management involving pharmacological and non-pharmacological therapies. Various pathophysiological mechanisms, such as central hemodynamics, vasculature, ventilation, skeletal muscle function as well as neurohormonal activation and inflammation are responsible for exercise intolerance described in HF patients. There is sufficient and growing evidence that exercise training in HF with reduced (HFrEF) and with preserved ejection fraction (HFpEF) is effective in improving exercise capacity, HF symptoms and quality of life. The positive effects of exercise training in HF are mediated by an improvement of central hemodynamics, endothelial function, inflammatory markers, neurohumoral activation, as well as skeletal muscle structure and function. In contrast to convincing data from a large meta-analysis, the large HF-ACTION study (Heart Failure-A Controlled Trial Investigating Outcomes of exercise TraiNing) only demonstrated a modest improvement of all cause mortality and hospitalizations in HFrEF. Outcome data in HFpEF are lacking. Whether interval training incorporating variable and higher intensities or the addition of resistance exercise to a standard aerobic prescription is superior in improving clinical status of HF patients is currently being examined. Despite increasing validation of the potential of exercise training in chronic HF, challenges remain in the routine therapeutic application, including interdisciplinary management, financing of long-term exercise programs and the need to improve short-term and long-term adherence to exercise training.