Low intensity exercise training in patients with chronic heart failure

Low-intensity exercise training improves systolic function of heart during metastatic melanoma-induced cachexia in mice

Cardiac dysfunction frequently emerges in the initial stages of cancer cachexia, posing a significant complication of the disease. Physical fitness is commonly recommended in these early stages of cancer cachexia due to its beneficial impacts on various aspects of the condition, including cardiac dysfunction. However, the direct functional impacts of exercise on the heart during cancer cachexia largely remain unexplored. In this study, we induced cancer cachexia in mice using a metastatic B16F10 melanoma model. Concurrently, these mice underwent a low-intensity exercise regimen to investigate its potential role in cardiac function during cachexia. Our findings indicate that exercise training can help prevent metastatic melanoma-induced muscle loss without significant alterations to body and fat weight. Moreover, exercise improved the melanoma-induced decline in left ventricular ejection fraction and fractional shortening, while also mitigating the increase in high-sensitive cardiac troponin T levels caused by metastatic melanoma in mice. Transcriptome analysis revealed that exercise significantly reversed the transcriptional alterations in the heart induced by melanoma, which were primarily enriched in pathways related to heart contraction. These results suggest that exercise can improve systolic heart function and directly influence the transcriptome of the heart during metastatic melanoma-induced cachexia.

Knee Extension Exercise Effects on Physiological and Psychophysical Performance: Normal Weight Versus Obese Office Workers

BACKGROUND

Knee extension exercise is useful and practical for obese and overweight people as this form of exercise is effective in minimizing body weight loading on joints and improving the body's physiological function. This study aimed to compare the physiological and psychophysical parameters of office workers while computer-based working in an active workstation equipped with an active footrest (AFR) prototype with a mechanism for performing knee extension exercises in a sitting position, and also to compare the physiological and psychophysical parameters among normal-weight and obese office workers.

METHODS

In this quasi-experimental study, the physiological parameters of heart rate (HR) and energy expenditure (EE) (measured with the Fitbit Charge HR smartwatch) were measured in two cross-over random sessions for 32 office workers (16 normal-weight and 16 obese) aged 28 to 50 years (M = 42.72, standard deviation [SD] = 4.37) while performing office tasks in sitting and active workstations (equipped with AFR). Perceived physical exertion, comfort, fatigue, and liking were also measured by rating the participants.

FINDINGS

Short-term activity of the participants with AFR performing computer tasks significantly improved physiological and psychophysical parameters compared with the participants in sitting workstations. However, there was no significant difference in the effect of AFR on physiological and psychophysical parameters between normal-weight and obese participants.

CONCLUSIONS/APPLICATION TO PRACTICE

Given the significant increase in EE and HR resulting from exercise with AFR compared with the conventional workstation, the use of AFR can help office workers achieve the minimum standard of physical activity at their workplace.

Standardised Exercise Prescription for Patients with Chronic Coronary Syndrome and/or Heart Failure: A Consensus Statement from the EXPERT Working Group

Whereas exercise training, as part of multidisciplinary rehabilitation, is a key component in the management of patients with chronic coronary syndrome (CCS) and/or congestive heart failure (CHF), physicians and exercise professionals disagree among themselves on the type and characteristics of the exercise to be prescribed to these patients, and the exercise prescriptions are not consistent with the international guidelines. This impacts the efficacy and quality of the intervention of rehabilitation. To overcome these barriers, a digital training and decision support system [i.e. EXercise Prescription in Everyday practice & Rehabilitative Training (EXPERT) tool], i.e. a stepwise aid to exercise prescription in patients with CCS and/or CHF, affected by concomitant risk factors and comorbidities, in the setting of multidisciplinary rehabilitation, was developed. The EXPERT working group members reviewed the literature and formulated exercise recommendations (exercise training intensity, frequency, volume, type, session and programme duration) and safety precautions for CCS and/or CHF (including heart transplantation). Also, highly prevalent comorbidities (e.g. peripheral arterial disease) or cardiac devices (e.g. pacemaker, implanted cardioverter defibrillator, left-ventricular assist device) were considered, as well as indications for the in-hospital phase (e.g. after coronary revascularisation or hospitalisation for CHF). The contributions of physical fitness, medications and adverse events during exercise testing were also considered. The EXPERT tool was developed on the basis of this evidence. In this paper, the exercise prescriptions for patients with CCS and/or CHF formulated for the EXPERT tool are presented. Finally, to demonstrate how the EXPERT tool proposes exercise prescriptions in patients with CCS and/or CHF with different combinations of CVD risk factors, three patient cases with solutions are presented.

Operational Modal Analysis of Near-Infrared Spectroscopy Measure of 2-Month Exercise Intervention Effects in Sedentary Older Adults with Diabetes and Cognitive Impairment

The Global Burden of Disease Study (GBD 2019 Diseases and Injuries Collaborators) found that diabetes significantly increases the overall burden of disease, leading to a 24.4% increase in disability-adjusted life years. Persistently high glucose levels in diabetes can cause structural and functional changes in proteins throughout the body, and the accumulation of protein aggregates in the brain that can be associated with the progression of Alzheimer's Disease (AD). To address this burden in type 2 diabetes mellitus (T2DM), a combined aerobic and resistance exercise program was developed based on the recommendations of the American College of Sports Medicine. The prospectively registered clinical trials (NCT04626453, NCT04812288) involved two groups: an Intervention group of older sedentary adults with T2DM and a Control group of healthy older adults who could be either active or sedentary. The completion rate for the 2-month exercise program was high, with participants completing on an average of 89.14% of the exercise sessions. This indicated that the program was practical, feasible, and well tolerated, even during the COVID-19 pandemic. It was also safe, requiring minimal equipment and no supervision. Our paper presents portable near-infrared spectroscopy (NIRS) based measures that showed muscle oxygen saturation (SmO2), i.e., the balance between oxygen delivery and oxygen consumption in muscle, drop during bilateral heel rise task (BHR) and the 6 min walk task (6MWT) significantly (p < 0.05) changed at the post-intervention follow-up from the pre-intervention baseline in the T2DM Intervention group participants. Moreover, post-intervention changes from pre-intervention baseline for the prefrontal activation (both oxyhemoglobin and deoxyhemoglobin) showed statistically significant (p < 0.05, q < 0.05) effect at the right superior frontal gyrus, dorsolateral, during the Mini-Cog task. Here, operational modal analysis provided further insights into the 2-month exercise intervention effects on the very-low-frequency oscillations (<0.05 Hz) during the Mini-Cog task that improved post-intervention in the sedentary T2DM Intervention group from their pre-intervention baseline when compared to active healthy Control group. Then, the 6MWT distance significantly (p < 0.01) improved in the T2DM Intervention group at post-intervention follow-up from pre-intervention baseline that showed improved aerobic capacity and endurance. Our portable NIRS based measures have practical implications at the point of care for the therapists as they can monitor muscle and brain oxygenation changes during physical and cognitive tests to prescribe personalized physical exercise doses without triggering individual stress response, thereby, enhancing vascular health in T2DM.

The Potential of Exerkines in Women's COVID-19: A New Idea for a Better and More Accurate Understanding of the Mechanisms behind Physical Exercise

The benefits of physical exercise are well-known, but there are still many questions regarding COVID-19. Chow et al.'s 2022 study, titled Exerkines and Disease, showed that a special focus on exerkines can help to better understand the underlying mechanisms of physical exercise and disease. Exerkines are a group of promising molecules that may underlie the beneficial effects of physical exercise in diseases. The idea of exerkines is to understand the effects of physical exercise on diseases better. Exerkines have a high potential for the treatment of diseases and, considering that, there is still no study of the importance of exerkines on the most dangerous disease in the world in recent years, COVID-19. This raises the fundamental question of whether exerkines have the potential to manage COVID-19. Most of the studies focused on the general changes in physical exercise in patients with COVID-19, both during the illness and after discharge from the hospital, and did not investigate the basic differences. A unique look at the management of COVID-19 by exerkines, especially in obese and overweight women who experience high severity of COVID-19 and whose recovery period is long after discharge from the hospital, can help to understand the basic mechanisms. In this review, we explore the potential of exerkines in COVID-19 by practicing physical exercise to provide compelling practice recommendations with new insights.

Plasma-Derived microRNAs Are Influenced by Acute and Chronic Exercise in Patients With Heart Failure With Reduced Ejection Fraction

Background: Exercise training improves VO2peak in heart failure with reduced ejection fraction (HFrEF), but the effect is highly variable as it is dependent on peripheral adaptations. We evaluated changes in plasma-derived miRNAs by acute and chronic exercise to investigate whether these can mechanistically be involved in the variability of exercise-induced adaptations. Methods: Twenty-five male HFrEF patients (left ventricular ejection fraction < 40%, New York Heart Association class ≥ II) participated in a 15-week combined strength and aerobic training program. The effect of training on plasma miRNA levels was compared to 21 male age-matched sedentary HFrEF controls. Additionally, the effect of a single acute exercise bout on plasma miRNA levels was assessed. Levels of 5 miRNAs involved in pathways relevant for exercise adaptation (miR-23a, miR-140, miR-146a, miR-191, and miR-210) were quantified using RT-qPCR and correlated with cardiopulmonary exercise test (CPET), echocardiographic, vascular function, and muscle strength variables. Results: Expression levels of miR-146a decreased with training compared to controls. Acute exercise resulted in a decrease in miR-191 before, but not after training. Baseline miR-23a predicted change in VO2peak independent of age and left ventricular ejection fraction (LVEF). Baseline miR-140 was independently correlated with change in load at the respiratory compensation point and change in body mass index, and baseline miR-146a with change in left ventricular mass index. Conclusion: Plasma-derived miRNAs may reflect the underlying mechanisms of exercise-induced adaptation. In HFrEF patients, baseline miR-23a predicted VO2peak response to training. Several miRNAs were influenced by acute or repeated exercise. These findings warrant exploration in larger patient populations and further mechanistic in vitro studies on their molecular involvement.

The ergoreflex: how the skeletal muscle modulates ventilation and cardiovascular function in health and disease

The control of ventilation and cardiovascular function during physical activity is partially regulated by the ergoreflex, a cardiorespiratory reflex activated by physical activity. Two components of the ergoreflex have been identified: the mechanoreflex, which is activated early by muscle contraction and tendon stretch, and the metaboreflex, which responds to the accumulation of metabolites in the exercising muscles. Patients with heart failure (HF) often develop a skeletal myopathy with varying degrees of severity, from a subclinical disease to cardiac cachexia. HF‐related myopathy has been associated with increased ergoreflex sensitivity, which is believed to contribute to dyspnoea on effort, fatigue and sympatho‐vagal imbalance, which are hallmarks of HF. Ergoreflex sensitivity increases significantly also in patients with neuromuscular disorders. Exercise training is a valuable therapeutic option for both HF and neuromuscular disorders to blunt ergoreflex sensitivity, restore the sympatho‐vagal balance, and increase tolerance to physical exercise. A deeper knowledge of the mechanisms mediating ergoreflex sensitivity might enable a drug or device modulation of this reflex when patients cannot exercise because of advanced skeletal myopathy.

Exercise Training for Patients With Severe Aortic Stenosis in a Convalescent Rehabilitation Ward - A Retrospective Cohort Study

Background: Exercise loading is contraindicated for patients with severe aortic stenosis (AS); however, everyday activities mandate the inclusion of a light load. The aim of this study was to investigate the efficacy and safety of exercise training for patients with severe AS who were admitted to a rehabilitation ward because of physical disability. Methods and Results: This historical cohort study was conducted at a single rehabilitation center in Japan. Patients admitted for rehabilitation of physical disability and those who met the definition of severe AS were analyzed. An exercise training program was implemented for patients with disability and severe AS. Cardiovascular symptoms during hospitalization were evaluated. Improvements in the performance of activities of daily living were assessed using the Functional Independence Measure (FIM). Eighteen patients undertook an exercise training program. The median patient age was 87 years (range 76-95 years). Of these patients, 3 died and another 3 were transferred to another hospital due to causes other than the exercise training program. None of the other patients experienced cardiovascular symptoms, and the FIM scores of 12 patients were significantly improved (median [range] scores at admission and discharge of 63 [32-88] and 87 [51-104], respectively; P<0.001). Conclusions: An exercise training program could be applied to patients with severe AS who were admitted for convalescent rehabilitation, because it can improve FIM scores.

Mitochondrial impairments in aetiopathology of multifactorial diseases: common origin but individual outcomes in context of 3P medicine

Mitochondrial injury plays a key role in the aetiopathology of multifactorial diseases exhibiting a "vicious circle" characteristic for pathomechanisms of the mitochondrial and multi-organ damage frequently developed in a reciprocal manner. Although the origin of the damage is common (uncontrolled ROS release, diminished energy production and extensive oxidative stress to life-important biomolecules such as mtDNA and chrDNA), individual outcomes differ significantly representing a spectrum of associated pathologies including but not restricted to neurodegeneration, cardiovascular diseases and cancers. Contextually, the role of predictive, preventive and personalised (PPPM/3P) medicine is to introduce predictive analytical approaches which allow for distinguishing between individual outcomes under circumstance of mitochondrial impairments followed by cost-effective targeted prevention and personalisation of medical services. Current article considers innovative concepts and analytical instruments to advance management of mitochondriopathies and associated pathologies.

Training intensity and improvements in exercise capacity in elderly patients undergoing European cardiac rehabilitation - the EU-CaRE multicenter cohort study

OBJECTIVES

Guidelines for exercise intensity prescription in Cardiac Rehabilitation (CR) are inconsistent and have recently been discussed controversially. We aimed (1) to compare training intensities between European CR centres and (2) to assess associations between training intensity and improvement in peak oxygen consumption ([Formula: see text]O2) in elderly CR patients.

METHODS

Peak [Formula: see text]O2, heart rate and work rate (WR) at the first and second ventilatory thresholds were measured at start of CR. Training heart rate was measured during three sessions spread over the CR. Multivariate models were used to compare training characteristics between centres and to assess the effect of training intensity on change in peak [Formula: see text]O2.

RESULTS

Training intensity was measured in 1011 out of 1633 EU-CaRE patients in 7 of 8 centers and the first and secondary ventilatory threshold were identified in 1166 and 817 patients, respectively. The first and second ventilatory threshold were found at 44% (SD 16%) and 78% (SD 9%) of peak WR and 78% (SD 9%) and 89% (SD 5%) of peak heart rate, respectively. Training intensity and session duration varied significantly between centres but change in peak [Formula: see text]O2 over CR did not. Training above the first individual threshold (β 0.62, 95% confidence interval [0.25-1.02]) and increase in training volume per hour (β 0.06, 95%CI [0.01-0.12]) were associated with a higher change in peak [Formula: see text]O2.

CONCLUSION

While training intensity and volume varied greatly amongst current European CR programs, changes in peak [Formula: see text]O2 were similar and the effect of training characteristics on these changes were small.

The effectiveness of low intensity exercise and blood flow restriction without exercise on exercise induced muscle damage: A systematic review

OBJECTIVE

To investigate the evidence and provide clinical recommendations for low intensity exercises(LIE) and blood flow restriction(BFR) without exercise on reducing the effects of exercise induced muscle damage(EIMD).

METHOD

PubMed, Embase, Web of science, and PEDro(Physiotherapy Evidence Database) were searched up to December 2019 for studies that included LIE or BFR without exercise and their effect on EIMD.

RESULTS

Out of 3192 studies, 23 were included with 17 on LIE and 6 on BFR without exercise. 11 studies demonstrated positive effects for LIE on EIMD, with two level 2 and nine level 3 studies. Two level 2 and two level 3 studies found benefits for BFR without exercise on reducing the negative effects of EIMD, while two level 2 studies found did not find benefits for BFR without exercise.

CONCLUSION

Moderate to low levels of evidence supported LIE, particularly in the form of protective low load eccentric exercise, in reducing the negative effects of EIMD. Conflicting moderate to low levels of evidence was found regarding BFR without exercise. There does seem to be potential benefit for BFR without exercise in untrained individuals. Clinicians can provide clinical recommendations as LIE and BFR without exercise reducing EIMD.

Validity of simplified, calibration-less exercise intensity measurement using resting heart rate during sleep: a method-comparison study with respiratory gas analysis

Background

The recent development of wearable devices has enabled easy and continuous measurement of heart rate (HR). Exercise intensity can be calculated from HR with indices such as percent HR reserve (%HRR); however, this requires an accurate measurement of resting HR, which can be time-consuming. The use of HR during sleep may be a substitute that considers the calibration-less measurement of %HRR. This study examined the validity of %HRR on resting HR during sleep in comparison to percent oxygen consumption reserve (%VO₂R) as a gold standard. Additionally, a 24/7%HRR measurement using this method is demonstrated.

Methods

Twelve healthy adults aged 29 ± 5 years underwent treadmill testing using the Bruce protocol and a 6-min walk test (6MWT). The %VO₂R during each test was calculated according to a standard protocol. The %HRR during each exercise test was calculated either from resting HR in a sitting position (%HRR_sitting), when lying awake (%HRR_lying), or during sleep (%HRR_sleeping). Differences between %VO₂R and %HRR values were examined using Bland-Altman plots. A 180-day, 24/7%HRR measurement with three healthy adults was also conducted. The %HRR values during working days and holidays were compared.

Results

In the treadmill testing, the mean difference between %VO₂R and %HRR_sleeping was 1.7% (95% confidence interval [CI], − 0.2 to 3.6%). The %HRR_sitting and %HRR_lying values were 10.8% (95% CI, 8.8 to 12.7%) and 7.7% (95% CI, 5.4 to 9.9%), respectively. In the 6MWT, mean differences between %VO₂R and %HRR_sitting, %HRR_lying and %HRR_sleeping were 12.7% (95% CI, 10.0 to 15.5%), 7.0% (95% CI, 4.0 to 10.0%) and − 2.9% (95% CI, − 5.0% to − 0.7%), respectively. The 180-day, 24/7%HRR measurement presented significant differences in %HRR patterns between working days and holidays in all three participants.

Conclusions

The results suggest %HRR_sleeping is valid in comparison to %VO₂R. The results may encourage a calibration-less, 24/7 measurement model of exercise intensity using wearable devices.

Trial registration

UMIN000034967.

Registered 21 November 2018 (retrospectively registered).

Exercise training upregulates Nrf2 protein in the rostral ventrolateral medulla of mice with heart failure

Chronic heart failure (CHF) is associated with global oxidative stress, which contributes to sympathoexcitation. Increased reactive oxygen species in the brain accumulate within neurons and lead to enhanced neuronal excitability. Exercise training (ExT) is associated with a reduction of oxidative stress by upregulation of antioxidant enzymes. The link between ExT and antioxidant enzyme expression in the brain of animals with CHF is not clear. We hypothesized that ExT enhances transcription and translation of the nuclear factor erythroid 2-related factor 2 (Nrf2) gene, a master transcription factor that modulates antioxidant enzyme gene expression, in the rostral ventrolateral medulla (RVLM) of mice with CHF. Mice were divided into the following groups: Sham sedentary (Sham-Sed), Sham-ExT, CHF-Sed, and CHF-ExT. After 8 wk of ExT, we measured Nrf2 and NAD(P)H dehydrogenase [quinone] 1 (NQO-1) message and protein expression along with maximal exercise tolerance and urinary norepinephrine (NE) excretion. We found that Nrf2 and NQO-1 mRNA and protein expression in the RVLM were lower in CHF-Sed mice compared with Sham-Sed. ExT attenuated the CHF-induced reduction of Nrf2 and NQO-1 mRNA and protein expression in the RVLM. NE excretion was higher in CHF-Sed mice compared with Sham-Sed (666.8 ± 79.3 ng/24 h, n = 6 vs. 397.8 ± 43.7 ng/24 h, P = 0.04). CHF-ExT mice exhibited reduced urinary NE excretion compared with CHF-Sed (360.7 ± 41.7 ng, n = 4 vs. 666.8 ± 79.3 ng, n = 6; P = 0.03). We conclude that ExT-induced upregulation of Nrf2 in the RVLM contributes to the beneficial effects of ExT on sympathetic function in the heart failure state.NEW & NOTEWORTHY This study provide evidence for an important role for exercise training in the modulation of antioxidant enzyme production in the rostral ventrolateral medulla (RVLM) in the heart failure state. We show here a correlation between exercise training and the expression of the antioxidant transcription factor Nrf2 in the RVLM. Exercise training reduced sympathetic function (norepinephrine excretion) and upregulated both Nrf2 and the antioxidant enzyme NQO-1. We conclude that Nrf2 in the RVLM may be an important target for controlling sympathetic outflow in heart failure.

Combining Ubiquinol With a Statin May Benefit Hypercholesterolaemic Patients With Chronic Heart Failure

Heart failure (HF) is one of the most common causes of death in Western society. Recent results underscore the utility of coenzyme Q₁₀ (CoQ₁₀) addition to standard medications in order to reduce mortality and to improve quality of life and functional capacity in chronic heart failure (CHF). The rationale for CoQ₁₀ supplementation in CHF is two-fold. One is the well-known role of CoQ₁₀ in myocardial bioenergetics, and the second is its antioxidant property. Redox balance is also improved by oral supplementation of CoQ₁₀, and this effect contributes to enhanced endothelium-dependent relaxation. Previous reports have shown that CoQ₁₀ concentration is decreased in myocardial tissue in CHF and by statin therapy, and the greater the CoQ₁₀ deficiency the more severe is the cardiocirculatory impairment. In patients with CHF and hypercholesterolaemia being treated with statins, the combination of CoQ₁₀ with a statin may be useful for two reasons: decreasing skeletal muscle injury and improving myocardial function. Ubiquinol, the active reduced form of CoQ₁₀, presents higher bioavailability than the oxidised form ubiquinone, and should be the preferred form to be added to a statin. The combination ezetimibe/simvastatin may have advantages over single statins. Since ezetimibe reduces absorption of cholesterol and does not affect CoQ₁₀ synthesis in the liver, the impact of this combination on CoQ₁₀ tissue levels will be much less than that of high dose statin monotherapy at any target low density lipoprotein-cholesterol (LDL-C) level to be reached. This consideration makes the ezetimibe/statin combination the ideal LDL-lowering agent to be combined with ubiquinol in CHF patients. However, particular caution is advisable with the use of strategies of extreme lowering of cholesterol that may negatively impact on myocardial function. All in all there is a strong case for considering co-administration of ubiquinol with statin therapy in patients with depressed or borderline myocardial function.

Exercise-based cardiac rehabilitation for adult patients with an implantable cardioverter defibrillator

BACKGROUND

An effective way of preventing sudden cardiac death is the use of an implantable cardioverter defibrillator (ICD). In spite of the potential mortality benefits of receiving an ICD device, psychological problems experienced by patients after receiving an ICD may negatively impact their health-related quality of life, and lead to increased readmission to hospital and healthcare needs, loss of productivity and employment earnings, and increased morbidity and mortality. Evidence from other heart conditions suggests that cardiac rehabilitation should consist of both exercise training and psychoeducational interventions; such rehabilitation may benefit patients with an ICD. Prior systematic reviews of cardiac rehabilitation have excluded participants with an ICD. A systematic review was therefore conducted to assess the evidence for the use of exercise-based intervention programmes following implantation of an ICD.

OBJECTIVES

To assess the benefits and harms of exercise-based cardiac rehabilitation programmes (exercise-based interventions alone or in combination with psychoeducational components) compared with control (group of no intervention, treatment as usual or another rehabilitation programme with no physical exercise element) in adults with an ICD.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and four other databases on 30 August 2018 and three trials registers on 14 November 2017. We also undertook reference checking, citation searching and contacted study authors for missing data.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) if they investigated exercise-based cardiac rehabilitation interventions compared with no intervention, treatment as usual or another rehabilitation programme. The trial participants were adults (aged 18 years or older), who had been treated with an ICD regardless of type or indication.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias. The primary outcomes were all-cause mortality, serious adverse events and health-related quality of life. The secondary outcomes were exercise capacity, antitachycardia pacing, shock, non-serious adverse events, employment or loss of employment and costs and cost-effectiveness. Risk of systematic errors (bias) was assessed by evaluation of predefined bias risk domains. Clinical and statistical heterogeneity were assessed. Meta-analyses were undertaken using both fixed-effect and random-effects models. We used the GRADE approach to assess the quality of evidence.

MAIN RESULTS

We identified eight trials published from 2004 to 2017 randomising a total of 1730 participants, with mean intervention duration of 12 weeks. All eight trials were judged to be at overall high risk of bias and effect estimates are reported at the end of the intervention with a follow-up range of eight to 24 weeks.Seven trials reported all-cause mortality, but deaths only occurred in one trial with no evidence of a difference between exercise-based cardiac rehabilitation and control (risk ratio (RR) 1.96, 95% confidence interval (CI) 0.18 to 21.26; participants = 196; trials = 1; quality of evidence: low). There was also no evidence of a difference in serious adverse events between exercise-based cardiac rehabilitation and control (RR 1.05, 95% CI 0.77 to 1.44; participants = 356; trials = 2; quality of evidence: low). Due to the variation in reporting of health-related quality of life outcomes, it was not possible to pool data. However, the five trials reporting health-related quality of life at the end of the intervention, each showed little or no evidence of a difference between exercise-based cardiac rehabilitation and control.For secondary outcomes, there was evidence of a higher pooled exercise capacity (peak VO₂) at the end of the intervention (mean difference (MD) 0.91 mL/kg/min, 95% CI 0.60 to 1.21; participants = 1485; trials = 7; quality of evidence: very low) favouring exercise-based cardiac rehabilitation, albeit there was evidence of substantial statistical heterogeneity (I² = 78%). There was no evidence of a difference in the risk of requiring antitachycardia pacing (RR 1.26, 95% CI 0.84 to 1.90; participants = 356; trials = 2; quality of evidence: moderate), appropriate shock (RR 0.56, 95% CI 0.20 to 1.58; participants = 428; studies = 3; quality of evidence: low) or inappropriate shock (RR 0.60, 95% CI 0.10 to 3.51; participants = 160; studies = 1; quality of evidence: moderate).

AUTHORS' CONCLUSIONS

Due to a lack of evidence, we were unable to definitively assess the impact of exercise-based cardiac rehabilitation on all-cause mortality, serious adverse events and health-related quality of life in adults with an ICD. However, our findings do provide very low-quality evidence that patients following exercise-based cardiac rehabilitation experience a higher exercise capacity compared with the no exercise control. Further high-quality randomised trials are needed in order to assess the impact of exercise-based cardiac rehabilitation in this population on all-cause mortality, serious adverse events, health-related quality of life, antitachycardia pacing and shock.

Resistance exercise enhances oxygen uptake without worsening cardiac function in patients with systolic heart failure: a systematic review and meta-analysis

Recent literature suggests that resistance training (RT) improves peak oxygen uptake ([Formula: see text] peak), similarly to aerobic exercise (AE) in patients with heart failure (HF), but its effect on cardiac remodeling is controversial. Thus, we examined the effects of RT and AE on [Formula: see text] peak and cardiac remodeling in patients with heart failure (HF) via a systematic review and meta-analysis. MEDLINE, EMBASE, Cochrane Library and CINAHL, AMEDEO and PEDro databases search were extracted study characteristics, exercise type, and ventricular outcomes. The main outcomes were [Formula: see text] peak (ml kg^-1 min^-1), LVEF (%) and LVEDV (mL). Fifty-nine RCTs were included. RT produced a greater increase in [Formula: see text] peak (3.57 ml kg^-1 min^-1, P < 0.00001, I ² = 0%) compared to AE (2.63 ml kg^-1 min^-1, P < 0.00001, I ² = 58%) while combined RT and AE produced a 2.48 ml kg^-1 min^-1 increase in [Formula: see text]; I ² = 69%) compared to control group. Comparison among the three forms of exercise revealed similar effects on [Formula: see text] peak (P = 0.84 and 1.00, respectively; I ² = 0%). AE was associated with a greater gain in LVEF (3.15%; P < 0.00001, I ² = 17%) compared to RT alone or combined exercise which produced similar gains compared to control groups. Subgroup analysis revealed that AE reduced LVEDV (- 10.21 ml; P = 0.007, I ² = 0%), while RT and combined RT and AE had no effect on LVEDV compared with control participants. RT results in a greater gain in [Formula: see text] peak, and induces no deleterious effects on cardiac function in HF patients.

Benefits of exercise training on cardiovascular dysfunction: molecular and integrative

Exercise training has been shown to ameliorate a wide variety of cardiovascular disorders. The mechanisms by which long-term benefits of exercise training are mediated remains incomplete, despite intense research in this area. Exactly how the act of chronic exercise improves function in every tissue is unknown, but many of the cellular, molecular, and genetic mechanisms are becoming progressively clearer. This "Perspectives" article reviews the contributions of 15 articles published in the American Journal of Physiology-Heart and Circulatory Physiology in response to a Call for Papers in this area. Here, we summarize the contributions of these studies at the cardiac, vascular, immune, and molecular levels. We discuss the translational benefit of these studies and conclude that the beneficial effects of exercise training in cardiovascular disease is due to a large interplay of cellular and molecular mediators in the heart and peripheral vasculature as well as changes in neural elements that regulate blood pressure and blood flow. Readers are encouraged to evaluate and learn from this collection of novel studies.

Changes in pulmonary oxygen uptake and muscle deoxygenation kinetics during cycling exercise in older women performing walking training for 12 weeks

PURPOSE

This study examined the hypothesis that walking training (WT) could accelerate the slowed time constant (τ) of phase II in pulmonary oxygen uptake ([Formula: see text]O₂) on-kinetics in older women. Also, we aimed to demonstrate that O₂ delivery and O₂ utilization were better matched at the site of gas exchange in exercising muscles when τ[Formula: see text]O₂ was shortened.

METHODS

20 recreationally active older women underwent WT sessions of approximately 60 min, 3-4 times a week for 12 weeks. We assessed [Formula: see text]O₂, heart rate (HR) and deoxygenated-hemoglobin concentration ([HHb]) kinetics during a constant-load exercise test before training (0 week-Pre), and at 6 and 12 weeks (6 weeks-Mid, 12 weeks-Post) throughout the training period.

RESULTS

Maximal oxygen uptake ([Formula: see text]O_2max) was unchanged throughout the training program. τHR tended to decline at Mid (58.6 ± 22.0 s), and was significantly shorter at Post (51.7 ± 21.7 s, p = 0.01) compared to Pre (67.1 ± 23.8 s). τ[Formula: see text]O₂ significantly decreased from 38.9 ± 8.6 s for Pre, to 31.5 ± 7.9 s for Mid (p = 0.02), and 32.3 ± 10.5 s for Post (p = 0.03). The normalized [HHb] to [Formula: see text]O₂ ratio (Δ[HHb]/Δ[Formula: see text]O₂) at Pre (1.32 ± 0.93) gradually approached the perfectly matched value (= 1.0) at Mid (1.15 ± 0.61) and Post (1.07 ± 0.52).

CONCLUSIONS

The restoration to baseline (≒ 30 s) of the slower τ[Formula: see text]O₂ due to WT, which may reflect better matching of O₂ delivery and O₂ utilization at the site of gas exchange, suggests that a longer period of WT could be a useful tool for improving exercise tolerance in older individuals.

Effects of exercise modalities on central hemodynamics, arterial stiffness and cardiac function in cardiovascular disease: Systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Exercise is accepted as an important contribution to the rehabilitation of patients with cardiovascular disease (CVD). This study aims to better understand the possible causes for lack of consensus and reviews the effects of three exercise modalities (aerobic, resistance and combined exercise) on central hemodynamics, arterial stiffness and cardiac function for better rehabilitation strategies in CVD.

METHODS

The electronic data sources, Cochrane Library, MEDLINE, Web of Science, EBSCO (CINAHL), and ScienceDirect from inception to July 2017 were searched for randomized controlled trials (RCTs) investigating the effect of exercise modalities in adult patients with CVD. The effect size was estimated as mean differences (MD) with 95% confidence intervals (CI). Subgroup analysis and meta-regression were used to study potential moderating factors.

RESULTS

Thirty-eight articles describing RCTs with a total of 2089 patients with CVD were included. The pooling revealed that aerobic exercise [MD(95%CI) = -5.87 (-8.85, -2.88), P = 0.0001] and resistance exercise [MD(95%CI) = -7.62 (-10.69, -4.54), P<0.00001] significantly decreased aortic systolic pressure (ASP). Resistance exercise significantly decreased aortic diastolic pressure [MD(95%CI) = -4(-5.63, -2.37), P<0.00001]. Aerobic exercise significantly decreased augmentation index (AIx) based on 24-week exercise duration and patients aged 50-60 years. Meanwhile, aerobic exercise significantly improved carotid-femoral pulse wave velocity (cf-PWV) [MD(95%CI) = -0.42 (-0.83, -0.01), P = 0.04], cardiac output (CO) [MD(95% CI) = 0.36(0.08, 0.64), P = 0.01] and left ventricular ejection fraction (LVEF) [MD(95%CI) = 3.02 (2.11, 3.93), P<0.00001]. Combined exercise significantly improved cf-PWV [MD(95%CI) = -1.15 (-1.95, -0.36), P = 0.004] and CO [MD(95% CI) = 0.9 (0.39, 1.41), P = 0.0006].

CONCLUSIONS

Aerobic and resistance exercise significantly decreased ASP, and long-term aerobic exercise reduced AIx. Meanwhile, aerobic and combined exercise significantly improved central arterial stiffness and cardiac function in patients with CVD. These findings suggest that a well-planned regime could optimize the beneficial effects of exercise and can provide some evidence-based guidance for those involved in cardiovascular rehabilitation of patients with CVD.

Combinatorial therapy of exercise-preconditioning and nanocurcumin formulation supplementation improves cardiac adaptation under hypobaric hypoxia

BACKGROUND

Chronic hypobaric hypoxia (cHH) mediated cardiac insufficiencies are associated with pathological damage. Sustained redox stress and work load are major causative agents of cardiac insufficiencies under cHH. Despite the advancements made in pharmacological (anti-oxidants, vasodilators) and non-pharmacological therapeutics (acclimatization strategies and schedules), only partial success has been achieved in improving cardiac acclimatization to cHH. This necessitates the need for potent combinatorial therapies to improve cardiac acclimatization at high altitudes. We hypothesize that a combinatorial therapy comprising preconditioning to mild aerobic treadmill exercise and supplementation with nanocurcumin formulation (NCF) consisting of nanocurcumin (NC) and pyrroloquinoline quinone (PQQ) might improve cardiac adaptation at high altitudes.

METHODS

Adult Sprague-Dawley rats pre-conditioned to treadmill exercise and supplemented with NCF were exposed to cHH (7620 m altitude corresponding to pO2~8% at 28±2°C, relative humidity 55%±1%) for 3 weeks. The rat hearts were analyzed for changes in markers of oxidative stress (free radical leakage, lipid peroxidation, manganese-superoxide dismutase [MnSOD] activity), cardiac injury (circulating cardiac troponin I [TnI] and T [cTnT], myocardial creatine kinase [CK-MB]), metabolic damage (lactate dehydrogenase [LDH] and acetyl-coenzyme A levels, lactate and pyruvate levels) and bio-energetic insufficiency (ATP, p-AMPKα).

RESULTS

Significant modulations (p≤0.05) in cardiac redox status, metabolic damage, cardiac injury and bio-energetics were observed in rats receiving both NCF supplementation and treadmill exercise-preconditioning compared with rats receiving only one of the treatments.

CONCLUSIONS

The combinatorial therapeutic strategy showed a tremendous improvement in cardiac acclimatization to cHH compared to either exercise-preconditioning or NCF supplementation alone which was evident from the effective modulation in redox, metabolic, contractile and bio-energetic homeostasis.

Molecular effects of exercise training in patients with cardiovascular disease: focus on skeletal muscle, endothelium, and myocardium

For decades, we have known that exercise training exerts beneficial effects on the human body, and clear evidence is available that a higher fitness level is associated with a lower incidence of suffering premature cardiovascular death. Despite this knowledge, it took some time to also incorporate physical exercise training into the treatment plan for patients with cardiovascular disease (CVD). In recent years, in addition to continuous exercise training, further training modalities such as high-intensity interval training and pyramid training have been introduced for coronary artery disease patients. The beneficial effect for patients with CVD is clearly documented, and during the last years, we have also started to understand the molecular mechanisms occurring in the skeletal muscle (limb muscle and diaphragm) and endothelium, two systems contributing to exercise intolerance in these patients. In the present review, we describe the effects of the different training modalities in CVD and summarize the molecular effects mainly in the skeletal muscle and cardiovascular system.

Exercise-Based Rehabilitation for Heart Failure: Clinical Evidence

People with heart failure experience marked reduction in their exercise capacity which has detrimental effects on their activities of daily living, health-related quality of life, and ultimately their hospital ad-mission rate and mortality. Numerous cardiac rehabilitation studies have demonstrated functional benefits, improvement in quality of life and clinical outcomes from exercise training in patients with HFrEF. Based on evidences, the American College of Cardiology/American Heart Association, European Society of Cardiology, and National Institute for Health and Care Excellence(NICE) consistently recommend exercise-based cardiac rehabilitation(CR) as an effective and safe adjunct for patients with stable class II to III heart failure (HF) who do not have advanced arrhythmias and who do not have other limitations to exercise. This recommendation applies to patients with HFrEF as well as to patients with HFpEF besides patients with class IV HF, although the data are not as robust for patients with HFpEF. In this article, the clinical evidence on effects of exercise for HFrEF and HFpEF as well as end-stage heart failure were separately reviewed.

Effects of High-Intensity Interval Exercise Training on Skeletal Myopathy of Chronic Heart Failure

BACKGROUND

It remains controversial which type of exercise elicits optimum adaptations on skeletal myopathy of heart failure (HF). Our aim was to evaluate the effect of high-intensity interval training (HIIT), with or without the addition of strength training, on skeletal muscle of HF patients.

METHODS AND RESULTS

Thirteen male HF patients (age 51 ± 13 years, body mass index 27 ± 4 kg/m²) participated in either an HIIT (AER) or an HIIT combined with strength training (COM) 3-month program. Biopsy samples were obtained from the vastus lateralis. Analyses were performed on muscle fiber type, cross-section area (CSA), capillary density, and mRNA expression of insulin-like growth factor (IGF) 1 isoforms (ie, IGF-1Ea, IGF-1Eb, IGF-1Ec), type-1 receptor (IGF-1R), and binding protein 3 (IGFBP-3). Increased expression of IGF-1Ea, IGF-1Eb, IGF-1Ec, and IGFBP-3 transcripts was found (1.7 ± 0.8, 1.5 ± 0.8, 2.0 ± 1.32.4 ± 1.4 fold changes, respectively; P < .05). Type I fibers increased by 21% (42 ± 10% to 51 ± 7%; P < .001) and capillary/fiber ratio increased by 24% (1.27 ± 0.22 to 1.57 ± 0.41; P = .005) in both groups as a whole. Fibers' mean CSA increased by 10% in total, but the increase in type I fibers' CSA was greater after AER than COM (15% vs 6%; P < .05). The increased CSA correlated with the increased expression of IGF-1Ea and IGF-1Εb.

CONCLUSIONS

HIIT reverses skeletal myopathy of HF patients, with the adaptive responses of the IGF-1 bioregulation system possibly contributing to these effects. AER program seemed to be superior to COM to induce muscle hypertrophy.

Moderate exercise training improves functional capacity, quality of life, and endothelium-dependent vasodilation in chronic heart failure patients with implantable cardioverter defibrillators and cardiac resynchronization therapy

BACKGROUND

The objective of this study was to determine the effects of a moderate exercise training program on functional capacity, quality of life, and hospital readmission rate in chronic heart failure patients with implantable cardioverter defibrillators and cardiac resynchronization therapy.

METHODS AND RESULTS

We studied 52 men (mean age 55+/-10 years, ejection fraction 31+/-7%) in chronic heart failure II (n=29) and III (n=23) NYHA functional class with ischemic cardiomyopathy who received implantable cardioverter defibrillators with or without cardiac resynchronization therapy. Patients were randomized into two groups. Group T (n=30 patients, 15 implantable cardioverter defibrillator, 15 implantable cardioverter defibrillator+cardiac resynchronization therapy) underwent a supervised exercise training program at 60% of peak VO2 three times a week for 8 weeks. Group C (n=22 patients, 12 implantable cardioverter defibrillator, 10 implantable cardioverter defibrillator+cardiac resynchronization therapy) avoided physical training. At 8 weeks, only trained patients had improvements in peak VO2 (P<0.01 versus C), endothelium-dependent dilatation of the brachial artery (P<0.001 versus C) and quality of life (P<0.001 versus C). Among trained patients, those with cardiac resynchronization therapy had greater improvements in peak VO2 and quality of life. During the follow-up (24+/-6 months), eight controls had sustained ventricular tachycardia requiring hospital readmission, while no trained patients had adverse events (log rank 8.56; P<0.001). The improvement in peak VO2 was correlated with the improvement in endothelium-dependent dilatation (r=0.65).

CONCLUSION

Moderate exercise training is safe and has beneficial effects after implantable cardioverter defibrillator implantation, especially when cardiac resynchronization therapy is present. These effects are associated with improvement in quality of life and outcome.

Determinants of maximal exercise performance in chronic heart failure

BACKGROUND

Chronic heart failure (CHF) is characterized by symptoms like fatigue, dyspnoea and limited exercise performance. It has been postulated that maximal exercise performance (Wmax) is predominantly limited by skeletal muscle function and less by heart function.

AIM

To study the interrelation between most relevant muscle and anthropometrical variables and Wmax in CHF patients in order to develop a model that describes the impact of these variables for maximal exercise performance.

DESIGN

In 77 patients with CHF Wmax was assessed by incremental cycle ergometry until exhaustion (20 Watt/3 min). Peak torque (strength) and total work (endurance) for the quadriceps and hamstrings were assessed by isokinetic dynamometry. Isometric strength was measured by hand dynamometry. Relevant muscle areas were calculated by computerized tomography scan.

RESULTS

Significant correlations between Wmax and isokinetic muscle parameters (peak torque and total work) ranged from 0.41-0.65 (P<0.01). Other significant relationships (P<0.01) with Wmax were obtained for age (r=-0.22), gender (r=0.45), fat free mass (FFM) (r=0.51), quadriceps muscle area (r=0.73), hamstrings muscle area (r=0.50), upper leg muscle function (i.e., a combination of muscle strength and muscle endurance) (r=0.71) and isometric strength (r=0.63). Multiple regression analysis showed that upper leg muscle function and quadriceps muscle area could predict 57% of the variance in Wmax.

CONCLUSION

Muscle strength and muscle endurance, combined with quadriceps muscle area are the main predictors of maximal exercise performance in patients with CHF.

Statement on cardiopulmonary exercise testing in chronic heart failure due to left ventricular dysfunction: recommendations for performance and interpretation Part III: Interpretation of cardiopulmonary exercise testing in chronic heart failure and future applications: Task Force of the Italian Working Group on Cardiac Rehabilitation and Prevention (Gruppo Italiano di Cardiologia Riabilitativa e Prevenzione, GICR), endorsed by Working Group on Cardiac Rehabilitation and Exercise Physiology of the European Society of Cardiology

Optimal use of cardiopulmonary exercise testing (CPET) in clinical practice and chronic heart failure (CHF) requires appropriate data presentation and a flexible interpretative strategy. The greatest potential impact on the decision-making process may rest not on the value of any individual measurement, although some are obviously more important than others, but rather on their integrative use. Such an integrative approach relies on interrelationship, trending phenomena and patterns of key gas exchange variable responses. An multiparametric approach will be discussed in different clinical applications, for exercise prescription and monitoring, functional evaluation of drug therapy or cardiac resynchronisation therapy efficacy, and risk stratification. The role of CPET in the daily clinical decision-making process will be underscored. Future indications of CPET will be addressed, suggesting and promoting an extended candidacy either to all CHF patients, including those at high risk or most vulnerable, such as female, elderly patients, and patients with implantable cardioverter defibrillator or in every clinical setting where objective definition of exercise capacity provides implications for medical, surgical, and social decision making.

Training improves the oxidative phenotype of muscle during the transition from cardiac hypertrophy to heart failure without altering MyoD and myogenin

NEW FINDINGS

What is the central question of this study? We investigated the effects of physical training on phenotypic (fibre-type content) and myogenic features (MyoD and myogenin expression) in skeletal muscle during the transition from cardiac hypertrophy to heart failure. What is the main finding and its importance? We provide new insight into skeletal muscle adaptations by showing that physical training increases the type I fibre content during the transition from cardiac hypertrophy to heart failure, without altering MyoD and myogenin expression. These results have important clinical implications for patients with heart failure, because this population has reduced muscle oxidative capacity. The purpose of this study was to investigate the effects of physical training (PT) on phenotypic features (fibre-type content) and myogenic regulatory factors (MyoD and myogenin) in rat skeletal muscle during the transition from cardiac hypertrophy to heart failure. We used the model of ascending aortic stenosis (AS) to induce heart failure in male Wistar rats. Sham-operated animals were used as age-matched controls. At 18 weeks after surgery, rats with ventricular dysfunction were randomized into the following four groups: sham-operated, untrained (Sham-U; n = 8); sham-operated, trained (Sham-T; n = 6); aortic stenosis, untrained (AS-U; n = 6); and aortic stenosis, trained (AS-T; n = 8). The AS-T and Sham-T groups were submitted to a 10 week aerobic PT programme, while the AS-U and Sham-U groups remained untrained for the same period of time. After the PT programme, the animals were killed and the soleus muscles collected for phenotypic and molecular analyses. Physical training promoted type IIa-to-I fibre conversion in the trained groups (Sham-T and AS-T) compared with the untrained groups (Sham-U and AS-U). No significant (P > 0.05) differences were found in type I or IIa fibre content in the AS-U group compared with the Sham-U group. Additionally, there were no significant (P > 0.05) differences in the myogenic regulatory factors MyoD and myogenin (gene and protein) expression between the groups. Therefore, our results indicate that PT may be a suitable strategy to improve the oxidative phenotype in skeletal muscle during the transition from cardiac hypertrophy to heart failure, without altering MyoD and myogenin.

Aerobic training enhances muscle deoxygenation in early post-myocardial infarction

Purpose

Exercise-induced skeletal muscle deoxygenation is startling by its absence in early post-myocardial infarction (MI) patients. Exercise training early post-MI is associated with reduced cardiovascular risk and increased aerobic capacity. We therefore investigated whether aerobic training could enhance the muscle deoxygenation in early post-MI patients.

Methods

21 ± 8 days after the first MI patients (n = 16) were divided into 12-week aerobic training (TR, n = 10) or non-training (CON, n = 6) groups. Before and after intervention, patients performed ramp bicycle exercise until exhaustion. Muscle deoxygenation was measured at vastus lateralis by near-infrared spectroscopy during exercise.

Results

Aerobic training significantly increased peak oxygen uptake (VO₂) (18.1 ± 3.0 vs. 22.9 ± 2.8 mL/kg/min), decreased the change in muscle oxygen saturation from rest to submaximal and peak exercise (∆SmO₂; 2.4 ± 5.7 vs. −7.0 ± 3.4 %), and increased the relative change in deoxygenated hemoglobin/myoglobin concentration from rest to submaximal (−1.5 ± 2.3 vs. 3.0 ± 3.6 μmol/L) and peak exercise (1.1 ± 4.5 vs. 8.2 ± 3.5 μmol/L). Change in total hemoglobin/myoglobin concentration in muscle was not significantly affected by training. In CON, no significant alterations were found after 12 weeks in either muscle deoxygenation or peak VO₂ (18.6 ± 3.8 vs. 18.9 ± 4.6 mL/kg/min). An increase in peak VO₂ was significantly negatively correlated with change in ∆SmO₂ (r = −0.65) and positively associated with change in ∆deoxy-Hb/Mb at peak exercise (r = 0.64) in TR.

Conclusions

In early post-MI patients, aerobic training enhanced skeletal muscle deoxygenation, and the enhancement was related to increased aerobic capacity.

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.

Effects of Cardiopulmonary Exercise Rehabilitation on Left Ventricular Mechanical Efficiency and Ventricular-Arterial Coupling in Patients With Systolic Heart Failure

BACKGROUND

Success of cardiac rehabilitation (CR) is generally assessed by the objective improvement in peak volume of inhaled oxygen (VO2) measured by cardiopulmonary exercise test (CPX). However, cardiac mechanical efficiency and ventricular-arterial coupling (VAC) are the other important dimensions of the heart failure pathophysiology, which are not included in CPX-derived data. The effect of cardiac rehabilitation on left ventricular (LV) efficiency or VAC in unselected heart failure patients has not been studied thus far.

METHODS AND RESULTS

Thirty patients with an ejection fraction of ≤45% were recruited for 20 sessions of exercise-based CR. Noninvasive LV pressure-volume loops were constructed and VAC was calculated with the help of applanation tonometry and echocardiography before and after CR. VAC showed an improved mechanical efficiency profile and increased significantly from 0.56±0.18 to 0.67±0.21 (P=0.02). LV mechanical efficiency improved from 43.9±9.1% to 48.8±9.1% (P=0.01). The change in peak VO2 was not in a significant correlation with the change in VAC (r=-0.18; P=0.31), mechanical efficiency (r=-0.16, P=0.39), or the change in ejection fraction (r=-0.07; P=0.68).

CONCLUSIONS

CR is associated with an improvement in VAC and LV mechanical efficiency in heart failure patients. Further studies are needed to determine the incremental value of VAC and mechanical efficiency over CPX-derived data in predicting clinical outcomes.

Skeletal Muscle Changes in Chronic Cardiac Disease and Failure

Peak exercise performance in healthy man is limited not only by pulmonary or skeletal muscle function but also by cardiac function. Thus, abnormalities in cardiac function will have a major impact on exercise performance. Many cardiac diseases affect exercise performance and indeed for some cardiac conditions such as atherosclerotic heart disease, exercise testing is frequently used not only to measure functional capacity but also to make a diagnosis of heart disease, evaluate the efficacy of treatment, and predict prognosis. Early in the course of cardiac diseases, exercise performance will be minimally affected but with disease progression impairment in exercise capacity will become apparent. Ejection fraction, that is, the percent of blood volume ejected with each cardiac cycle is often used as a measure of cardiac performance but frequently there is a dissociation between the ejection fraction and exercise capacity in patients with heart disease. How abnormalities in cardiac function impacts the muscles, vasculature, and lungs to impact exercise performance will here be reviewed. The focus of this work will be on patients with systolic heart failure as the incidence and prevalence of heart failure is reaching epidemic proportions and heart failure is the end result of many other chronic cardiac diseases. The prognostic role of exercise and benefits of exercise training will also be discussed.

Exercise training in chronic heart failure: improving skeletal muscle O2 transport and utilization

Chronic heart failure (CHF) impairs critical structural and functional components of the O2 transport pathway resulting in exercise intolerance and, consequently, reduced quality of life. In contrast, exercise training is capable of combating many of the CHF-induced impairments and enhancing the matching between skeletal muscle O2 delivery and utilization (Q̇mO2 and V̇mO2 , respectively). The Q̇mO2 /V̇mO2 ratio determines the microvascular O2 partial pressure (PmvO2 ), which represents the ultimate force driving blood-myocyte O2 flux (see Fig. 1). Improvements in perfusive and diffusive O2 conductances are essential to support faster rates of oxidative phosphorylation (reflected as faster V̇mO2 kinetics during transitions in metabolic demand) and reduce the reliance on anaerobic glycolysis and utilization of finite energy sources (thus lowering the magnitude of the O2 deficit) in trained CHF muscle. These adaptations contribute to attenuated muscle metabolic perturbations (e.g., changes in [PCr], [Cr], [ADP], and pH) and improved physical capacity (i.e., elevated critical power and maximal V̇mO2 ). Preservation of such plasticity in response to exercise training is crucial considering the dominant role of skeletal muscle dysfunction in the pathophysiology and increased morbidity/mortality of the CHF patient. This brief review focuses on the mechanistic bases for improved Q̇mO2 /V̇mO2 matching (and enhanced PmvO2 ) with exercise training in CHF with both preserved and reduced ejection fraction (HFpEF and HFrEF, respectively). Specifically, O2 convection within the skeletal muscle microcirculation, O2 diffusion from the red blood cell to the mitochondria, and muscle metabolic control are particularly susceptive to exercise training adaptations in CHF. Alternatives to traditional whole body endurance exercise training programs such as small muscle mass and inspiratory muscle training, pharmacological treatment (e.g., sildenafil and pentoxifylline), and dietary nitrate supplementation are also presented in light of their therapeutic potential. Adaptations within the skeletal muscle O2 transport and utilization system underlie improvements in physical capacity and quality of life in CHF and thus take center stage in the therapeutic management of these patients.

Modulation of angiotensin II signaling following exercise training in heart failure

Sympathetic activation is a consistent finding in the chronic heart failure (CHF) state. Current therapy for CHF targets the renin-angiotensin II (ANG II) and adrenergic systems. Angiotensin converting enzyme (ACE) inhibitors and ANG II receptor blockers are standard treatments along with β-adrenergic blockade. However, the mortality and morbidity of this disease is still extremely high, even with good medical management. Exercise training (ExT) is currently being used in many centers as an adjunctive therapy for CHF. Clinical studies have shown that ExT is a safe, effective, and inexpensive way to improve quality of life, work capacity, and longevity in patients with CHF. This review discusses the potential neural interactions between ANG II and sympatho-excitation in CHF and the modulation of this interaction by ExT. We briefly review the current understanding of the modulation of the angiotensin type 1 receptor in sympatho-excitatory areas of the brain and in the periphery (i.e., in the carotid body and skeletal muscle). We discuss possible cellular mechanisms by which ExT may impact the sympatho-excitatory process by reducing oxidative stress, increasing nitric oxide. and reducing ANG II. We also discuss the potential role of ACE2 and Ang 1-7 in the sympathetic response to ExT. Fruitful areas of further investigation are the role and mechanisms by which pre-sympathetic neuronal metabolic activity in response to individual bouts of exercise regulate redox mechanisms and discharge at rest in CHF and other sympatho-excitatory states.

Clinical utility of exercise training in heart failure with reduced and preserved ejection fraction

Reduced exercise tolerance is an independent predictor of hospital readmission and mortality in patients with heart failure (HF). Exercise training for HF patients is well established as an adjunct therapy, and there is sufficient evidence to support the favorable role of exercise training programs for HF patients over and above the optimal medical therapy. Some of the documented benefits include improved functional capacity, quality of life (QoL), fatigue, and dyspnea. Major trials to assess exercise training in HF have, however, focused on heart failure with reduced ejection fraction (HFREF). At least half of the patients presenting with HF have heart failure with preserved ejection fraction (HFPEF) and experience similar symptoms of exercise intolerance, dyspnea, and early fatigue, and similar mortality risk and rehospitalization rates. The role of exercise training in the management of HFPEF remains less clear. This article provides a brief overview of pathophysiology of reduced exercise tolerance in HFREF and heart failure with preserved ejection fraction (HFPEF), and summarizes the evidence and mechanisms by which exercise training can improve symptoms and HF. Clinical and practical aspects of exercise training prescription are also discussed.

[Left ventricle assist device: rehabilitation and management programmes]

Progress in the medical management of patients with heart failure with systolic dysfunction has been accompanied by a significant improvement in survival and quality of life. These strategies have also resulted in changes in the clinical profile as well as an increase in the number of patients with advanced heart failure. The technological developments in left ventricular assist devices provide real hope for these patients. This article related our experience of management and the rehabilitation program realized.

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.

Muscle wasting in cancer

Skeletal muscle loss appears to be the most significant clinical event in cancer cachexia and is associated with a poor outcome. With regard to such muscle loss, despite extensive study in a range of models, there is ongoing debate as to whether a reduction in protein synthesis, an increase in degradation or a combination of both is the more relevant. Each model differs in terms of key mediators and the pathways activated in skeletal muscle. Certain models do suggest that decreased synthesis accompanied by enhanced protein degradation via the ubiquitin proteasome pathway (UPP) is important. Murine models tend to involve rapid development of cachexia and may represent more acute muscle atrophy rather than the chronic wasting observed in humans. There is a paucity of human data both at a basic descriptive level and at a molecular/mechanism level. Progress in treating the human form of cancer cachexia can only move forwards through carefully designed large randomised controlled clinical trials of specific therapies with validated biomarkers of relevance to underlying mechanisms. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.

Exercise training in chronic heart failure

The syndrome of heart failure (HF) is a growing epidemic that causes a significant socio-economic burden. Despite considerable progress in the management of patients with HF, mortality and morbidity remain a major healthcare concern and frequent hospital admissions jeopardize daily life and social activities. Exercise training is an important adjunct nonpharmacological treatment modality for patients with HF that has proven positive effects on mortality, morbidity, exercise capacity and quality of life. Different training modalities are available to target the problems with which HF patients are faced. It is essential to tailor the prescribed exercise regimen, so that both efficiency and safety are guaranteed. Electrical implanted devices and mechanical support should not exclude patients from exercise training; however, particular precautions and a specialized approach are advised. At least 50% of patients with HF, older than 65 years of age, present with HF with preserved ejection fraction (HFPEF). Although the study populations included in studies evaluating the effect of exercise training in this population are small, the results are promising and seem to support the idea that exercise training is beneficial for HFPEF patients. Both the short- and especially long-term adherence to exercise training remain a major challenge that can only be tackled by a multidisciplinary approach. Efforts should be directed towards closing the gap between recommendations and the actual implementation of training programmes.

Aerobic exercise intensity assessment and prescription in cardiac rehabilitation: a joint position statement of the European Association for Cardiovascular Prevention and Rehabilitation, the American Association of Cardiovascular and Pulmonary Rehabilitation, and the Canadian Association of Cardiac Rehabilitation

Aerobic exercise intensity prescription is a key issue in cardiac rehabilitation, being directly linked to both the amount of improvement in exercise capacity and the risk of adverse events during exercise. This joint position statement aims to provide professionals with up-to-date information regarding the identification of different exercise intensity domains, the methods of direct and indirect determination of exercise intensity for both continuous and interval aerobic training, the effects of the use of different exercise protocols on exercise intensity prescription and the indications for recommended exercise training prescription in specific cardiac patients' groups. The importance of functional evaluation through exercise testing prior to starting an aerobic training program is strongly emphasized, and ramp incremental cardiopulmonary exercise test, when available, is proposed as the gold standard for a physiologically comprehensive exercise intensity assessment and prescription. This may allow a shift from a 'range-based' to a 'threshold-based' aerobic exercise intensity prescription, which, combined with thorough clinical evaluation and exercise-related risk assessment, could maximize the benefits obtainable by the use of aerobic exercise training in cardiac rehabilitation.