Physical training improves skeletal muscle metabolism in patients with chronic heart failure

The effects of regular exercise on cognitive and cardiometabolic health in testicular cancer survivors subjected to platinum-based chemotherapy

BACKGROUND

Platinum-based chemotherapy provides curative treatment to more than 95% of patients with testicular germ cell tumor but it has negative cardiometabolic and neurological effects. Regular exercise can alleviate late chemotherapy-related toxicities. We examined the impact of a 6-month supervised aerobic-strength training on cognitive and cardiometabolic health and residual level of platinum in cancer survivors.

METHODS

Twenty-eight middle-aged (42.1 ± 7.6 years) testicular germ cell tumor survivors subjected to platinum-based chemotherapy (1-8 cycles, 0-24 years ago) were recruited into exercise (n = 20) and control (n = 8) groups. Effects of 6-month exercise training on the whole-body and muscle metabolism, cognitive functions, cardiopulmonary fitness, residual plasma platinum, and plasma adiponectin were examined.

RESULTS

Exercise intervention improved cardiopulmonary fitness and cognitive functions, reduced residual plasma platinum, visceral adiposity and muscle lipids, improved glucose (glycosylated hemoglobin) and lipid (high-density lipoprotein cholesterol) metabolism, and enhanced dynamics of muscle post-exercise phosphocreatine recovery. Exercise-related decline in plasma platinum was paralleled by decline of muscle glycerophosphocholines and by the enhanced metabolic flexibility during low-intensity exercise, and predicted training-induced increase in cognitive functions.

CONCLUSIONS

The 6-month exercise intervention resulted in improved cognitive and cardiometabolic health in testicular germ cell tumor survivors, which was paralleled by reduced plasma platinum, providing evidence that structured supervised exercise brings multiple health benefits to testicular germ cell tumor survivors.

Calcium ATPase (PMCA) and GLUT-4 Upregulation in the Transverse Tubule Membrane of Skeletal Muscle from a Rat Model of Chronic Heart Failure

Intolerance to exercise is a symptom associated with chronic heart failure (CHF) resulting in SM waste and weakness in humans. The effect of CHF on skeletal muscle (SM) arose from experimental evidence in rat models to explain the underlying mechanism. We investigated SM mechanical and metabolic properties in sham rats and with coronary ligation-induced CHF. After twelve weeks of CHF, rats were catheterized to measure right auricular pressure, SM mechanical properties, SERCA-ATPase activity and plasma membrane Ca2+-ATPase (PMCA) hydrolytic activity in isolated sarcoplasmic reticulum (SR) and transverse tubule (TT membrane), respectively, in the sham and CHF. The right auricular pressure and plasma nitrite concentration in CHF increased two-fold with respect to the sham. Pleural effusion and ascites were detected in CHF, confirming CHF. SERCA activity was conserved in CHF. In TT membranes from CHF, the glucose transporter GLUT4 increased seven-fold, and the PMCA hydrolytic activity increased five-fold, but in isolated muscle, the mechanical properties were unaffected. The absence of a deleterious effect of coronary ligation-induced CHF in the rat model on SM could be explained by the increased activity of PMCA and increased presence of GLUT-4 on the TT membrane, which may be involved in the mechanical outcome of the EDL.

Contribution of reduced skeletal muscle perfusion reserve to exercise intolerance in heart failure with preserved ejection fraction

BACKGROUND

Skeletal muscle (SM)-associated mechanisms of exercise intolerance in HFpEF are insufficiently defined, and inadequate augmentation of SM blood flow during physical effort may be one of the contributors. Therefore, we sought to investigate the association of SM perfusion response to exertion with exercise capacity in this clinical condition.

METHODS

Echocardiography and SM microvascular perfusion by contrast-enhanced ultrasound were performed at rest and immediately post-exercise test in 77 HFpEF patients in NYHA class II and III, and in 25 subjects with normal exercise tolerance (stage B). Exercise reserve of cardiac function and SM perfusion was calculated by subtracting resting value from exercise value.

RESULTS

In addition to decreased cardiac functional reserve, HFpEF patients demonstrated significantly reduced SM perfusion reserve as compared to HF stage B, with the degree of impairment being greater in the subgroup with more profound left ventricular (LV) diastolic abnormalities (E/e' > 15 and TRV > 2.8 m/s). SM perfusion reserve was significantly associated with exercise capacity (beta = 0.33; SE 0.11; p = 0.003), cardiac output reserve (beta = 0.24; SE 0.12; p = 0.039), resting E/e' (beta = -0.33; SE 0.11; p = 0.006), and patient frailty expressed by the PRISMA 7 score (beta = -0.30; SE 0.11; p = 0.008). In multivariable analysis including clinical, demographic and cardiac functional variables, SM perfusion reserve was in addition to patient frailty, sex and LV longitudinal strain reserve among the independent correlates of exercise capacity.

CONCLUSIONS

SM perfusion reserve is impaired in HFpEF, and is associated with reduced exercise capacity independent of clinical, demographic and "central" cardiac factors. This supports the need to consider the SM domain in patient management strategies in HFpEF.

Electromyogram Power Spectrum and Cardiac Function Changes After Combined Aerobic Interval Training and Inspiratory Muscle Training in Chronic Heart Failure Patients

Exercise intolerance and dyspnea are the major symptoms of patients with chronic heart failure (CHF) and are associated with a poor quality of life. In addition to impaired central hemodynamics, symptoms may be attributed to changes in peripheral skeletal muscles. This study aimed to evaluate the effects of aerobic interval training (AIT) combined with inspiratory muscle training (IMT) on cardiac and skeletal muscle function and on functional capacity and dyspnea in patients with CHF and inspiratory muscle weakness.Left ventricle ejection fraction was improved significantly after AIT and AIT & IMT with a high percentage of amelioration (17%, P < 0.042) in the combined group compared to the control group. Therefore, we showed a significant improvement in maximal voluntary isometric force, isometric endurance time, root mean square, and frequency median in both strength and endurance manipulations in the aerobic and combined group; however, the improvement was superior in the combined group compared to the control group. Significant amelioration was proved in functional capacity and dyspnea after all types of training but was performed at 18% higher in 6 minutes' walk test and 43% lower in dyspnea for the combined group compared to the control group.Combining AIT to IMT had optimized exercise training benefits in reversing the cardiac remodeling process and improving skeletal muscle function, functional capacity, and dyspnea in patients with CHF.

Influence of Daily Aerobic Exercise Duration on Phase 2 Cardiac Rehabilitation at a Rehabilitation Hospital and Health-Related Quality of Life After Discharge

Background

Phase 2 in-patient cardiac rehabilitation (CR) at a rehabilitation hospital is now added the medical service fees in Japan and in light of the recent reimbursement for CR, a study needed to be performed to determine exertional exercise on its effectiveness and benefits to patients. We examined the effects of daily aerobic exercise duration on health-related quality of life (HR-QoL) at 6 months after discharge from phase 2 CR.

Methods

Of the 54 consecutive cardiovascular disease patients admitted to a rehabilitation hospital after acute care, 43 were considered acceptable candidates for enrollment according to predetermined inclusion and exclusion criteria. Of these, 40 patients completed study requirements, including return of a questionnaire on HR-QoL survey 6 months after discharge. The primary outcome was HR-QoL as evaluated using the EuroQol five-dimension five-level (EQ-5D-5L). Two multiple regression models were constructed to assess the influences of daily aerobic exercise duration (content of rehabilitation) and other clinicodemographic variables assessed during acute care (model 1) or at transfer from acute care to a rehabilitation hospital (model 2).

Results

Both model 1, which included age, Barthel index of daily function before hospitalization, and daily aerobic exercise duration in the rehabilitation hospital (R2 = 0.553, P < 0.001), and model 2, which included New York Heart Association functional classification at transfer, Charlson comorbidity index at transfer, and daily aerobic exercise duration (R2 = 0.336, P = 0.002) identified aerobic exercise duration as a significant independent factor influencing HR-QoL at 6 months post-discharge (model 1: P = 0.041; model 2: P = 0.010).

Conclusions

Enhanced daily aerobic exercise content during phase 2 in-hospital CR can significantly improve longer-term HR-QoL among cardiovascular disease patients independently of other clinicodemographic factors, including age, activities of daily living before treatment, and baseline condition at rehabilitation onset. These findings, that in the small sample size, support the continued expansion of phase 2 CR at a rehabilitation hospital in Japan.

The Association of Physical Activity with Glaucoma and Related Traits in the UK Biobank

PURPOSE

To examine the association of physical activity (PA) with glaucoma and related traits, to assess whether genetic predisposition to glaucoma modified these associations, and to probe causal relationships using Mendelian randomization (MR).

DESIGN

Cross-sectional observational and gene-environment interaction analyses in the UK Biobank. Two-sample MR experiments using summary statistics from large genetic consortia.

PARTICIPANTS

UK Biobank participants with data on self-reported or accelerometer-derived PA and intraocular pressure (IOP; n = 94 206 and n = 27 777, respectively), macular inner retinal OCT measurements (n = 36 274 and n = 9991, respectively), and glaucoma status (n = 86 803 and n = 23 556, respectively).

METHODS

We evaluated multivariable-adjusted associations of self-reported (International Physical Activity Questionnaire) and accelerometer-derived PA with IOP and macular inner retinal OCT parameters using linear regression and with glaucoma status using logistic regression. For all outcomes, we examined gene-PA interactions using a polygenic risk score (PRS) that combined the effects of 2673 genetic variants associated with glaucoma.

MAIN OUTCOME MEASURES

Intraocular pressure, macular retinal nerve fiber layer (mRNFL) thickness, macular ganglion cell-inner plexiform layer (mGCIPL) thickness, and glaucoma status.

RESULTS

In multivariable-adjusted regression models, we found no association of PA level or time spent in PA with glaucoma status. Higher overall levels and greater time spent in higher levels of both self-reported and accelerometer-derived PA were associated positively with thicker mGCIPL (P < 0.001 for trend for each). Compared with the lowest quartile of PA, participants in the highest quartiles of accelerometer-derived moderate- and vigorous-intensity PA showed a thicker mGCIPL by +0.57 μm (P < 0.001) and +0.42 μm (P = 0.005). No association was found with mRNFL thickness. High overall level of self-reported PA was associated with a modestly higher IOP of +0.08 mmHg (P = 0.01), but this was not replicated in the accelerometry data. No associations were modified by a glaucoma PRS, and MR analyses did not support a causal relationship between PA and any glaucoma-related outcome.

CONCLUSIONS

Higher overall PA level and greater time spent in moderate and vigorous PA were not associated with glaucoma status but were associated with thicker mGCIPL. Associations with IOP were modest and inconsistent. Despite the well-documented acute reduction in IOP after PA, we found no evidence that high levels of habitual PA are associated with glaucoma status or IOP in the general population.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Cardiac rehabilitation in heart failure with severely reduced ejection fraction: effects on mortality

Thirty years ago, patients with low ejection fraction (EF) have often been excluded from rehabilitation programs due to concern about possibility of sudden death or other adverse cardiovascular events during exercise sessions. Recent studies have highlighted the fact that cardiac rehabilitation could improve exercise capacity, cardiac function, and health-related quality of life in congestive heart failure patients. This encouraged us to write a review article and update our latest knowledge about the outcome of rehabilitation program in patients with severely depressed cardiac function. We were particularly interested in effect of cardiac rehabilitation on exercise capacity, quality of life, vascular effects, neuro-hormonal changes, and mortality. We also conducted a mini-systematic review and meta-analysis on randomized controlled trials comparing exercise training with usual care in patients with severely reduced left ventricular ejection fraction, for the mortality subsection to obtain precise estimates of overall treatment benefit on mortality. It is our privilege to submit our manuscript for possible publication in your prestigious journal.

The Effects of Exercise Training on Mitochondrial Function in Cardiovascular Diseases: A Systematic Review and Meta-Analysis

Mitochondria dysfunction is implicated in the pathogenesis of cardiovascular diseases (CVD). Exercise training is potentially an effective non-pharmacological strategy to restore mitochondrial health in CVD. However, how exercise modifies mitochondrial functionality is inconclusive. We conducted a systematic review using the PubMed; Scopus and Web of Science databases to investigate the effect of exercise training on mitochondrial function in CVD patients. Search terms included “mitochondria”, “exercise”, “aerobic capacity”, and “cardiovascular disease” in varied combination. The search yielded 821 records for abstract screening, of which 20 articles met the inclusion criteria. We summarized the effect of exercise training on mitochondrial morphology, biogenesis, dynamics, oxidative capacity, antioxidant capacity, and quality. Amongst these parameters, only oxidative capacity was suitable for a meta-analysis, which demonstrated a significant effect size of exercise in improving mitochondrial oxidative capacity in CVD patients (SMD = 4.78; CI = 2.99 to 6.57; p < 0.01), but with high heterogeneity among the studies (I2 = 75%, p = 0.003). Notably, aerobic exercise enhanced succinate-involved oxidative phosphorylation. The majority of the results suggested that exercise improves morphology and biogenesis, whereas findings on dynamic, antioxidant capacity, and quality, were inadequate or inconclusive. A further randomized controlled trial is clearly required to explain how exercise modifies the pathway of mitochondrial quantity and quality in CVD patients.

Efficacy and safety of different modes of exercise-based cardiac rehabilitation delivery for patients with heart failure: a protocol for a systematic review and network meta-analysis

INTRODUCTION

The prevalence of heart failure (HF) is increasing. Exercise-based cardiac rehabilitation (CR) reduces mortality and further improves the prognosis of patients with HF. However, the effect of different modes of CR delivery on HF remains unclear. Thus, the purpose of this study is to find out the relative efficacy and safety of different modes of CR delivery for individuals with HF using a network meta-analysis.

METHODS AND ANALYSIS

We will perform a systematic review and network meta-analysis of randomised controlled trials which compare different modes of exercise-based CR delivery for patients with HF. Databases including Embase, Medline, the Cochrane Central Register of Controlled Trials and Web of Science will be searched up to May 2022. The primary outcomes will focus on the functional capacity and the health-related quality of life (hr-QOL). Functional capacity will be evaluated by peak oxygen consumption (mL/kg/min) and 6 min walking test (metres). The Minnesota Living with Heart Failure questionnaire, Short Form-36, Psychometric properties of the Kansas City cardiomyopathy questionnaire and EuroQol five dimensions questionnaire will serve as measures of hr-QOL. As secondary outcomes, we will assess hospital admissions (all-cause and cardiac) and all-cause mortality, which required a minimum follow-up of 6 months, as well as adverse events during exercise training. The risk of bias for individual studies will be evaluated according to the Cochrane Handbook. The quality of evidence will be assessed by the Grading of Recommendations, Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

This study does not require ethics approval as it is based on published trials. Results of this systematic review and network meta-analysis will be submitted to a peer-reviewed journal for future publication.

TRIAL REGISTRATION NUMBER

CRD42021278351.

Relationship of arterial tonometry and exercise in patients with chronic heart failure: a systematic review with meta-analysis and trial sequential analysis

BACKGROUND

Arterial stiffness is a common characteristic in patients with chronic heart failure (CHF), and arterial tonometric technologies related to arterial stiffness are novel and effective methods and have an important value in the diagnosis and prognosis of CHF. In terms of ameliorating arterial stiffness in patients with CHF, exercise training is considered an adjuvant treatment and also an effective means in the diagnosis and judgment of prognosis. However, there are huge controversies and inconsistencies in these aspects. The objective of this meta-analysis was to systematically test the connection of arterial tonometry and exercise in patients with CHF.

METHODS

Databases, including MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, were accessed from inception to 7 March 2022. The meta-analysis was then conducted, and trial sequential analysis (TSA) was performed jointly to further verify our tests and reach more convincing conclusions by using RevMan version 5.4 software, STATA version 16.0 software, and TSA version 0.9.5.10 Beta software.

RESULTS

Eighteen articles were included, with a total of 876 participants satisfying the inclusion criteria. The pooling revealed that flow-mediated dilation (FMD) was lower in basal condition [standardized mean difference (SMD): - 2.28%, 95% confidence interval (CI) - 3.47 to - 1.08, P < 0.001] and improved significantly after exercise (SMD: 5.96%, 95% CI 2.81 to 9.05, P < 0.001) in patients with heart failure with reduced ejection fraction (HFrEF) compared with healthy participants. The high-intensity training exercise was more beneficial (SMD: 2.88%, 95% CI 1.78 to 3.97, P < 0.001) than the moderate-intensity training exercise to improve FMD in patients with CHF. For augmentation index (AIx), our study indicated no significant differences (SMD: 0.50%, 95% CI - 0.05 to 1.05, P = 0.074) in patients with heart failure with preserved ejection fraction (HFpEF) compared with healthy participants. However, other outcomes of our study were not identified after further verification using TSA, and more high-quality studies are needed to reach definitive conclusions in the future.

CONCLUSIONS

This review shows that FMD is lower in basal condition and improves significantly after exercise in patients with HFrEF compared with healthy population; high-intensity training exercise is more beneficial than moderate-intensity training exercise to improve FMD in patients with CHF; besides, there are no significant differences in AIx in patients with HFpEF compared with the healthy population. More high-quality studies on this topic are warranted.

Intermittent aerobic-resistance interval training versus continues aerobic training: Improvement in cardiac electrophysiologic and anthropometric measures in male patients post myocadiac infarction, a randomized control trial

Purpose

Exercise is a valuable intervention modality for patients post-myocardial infarction (MI). Aerobic and resistance training are both commonly used separately in cardiac rehabilitation. However, the effect of aerobic interval exercise combined with alternating sets of resistance training (super-circuit training, SCT) on cardiac electrophysiologic and anthropometric measures had not been thoroughly investigated.

Aim

The primary objective of this study was to compare the effectiveness of moderate-intensity continuous-aerobic training (CAT) vs. SCT on cardiac electrical measures (resting electrocardiographic, ECG; a nd heart rate variability, HRV) in patients’ post-MI presenting reduced left ventricular function. Second, to examine its effect on anthropometric measures.

Material and methods

Twenty-nine men post-MI with reduced left ventricular function were assigned randomly to either 12 weeks of CAT (n = 15) or SCT (n = 14). CAT group performed moderate-intensity activity. SCT group performed high-intensity exercise, alternating between resistance and aerobic training. Differences between CAT and SCT groups were done using independent t-tests, paired t-tests and effect size (ES).

Results

Participants in both groups improved their HRV measures (increase in HFnu; p < 0.05; ES > 0.51) and ECG (reduction in QT-dispersion; p < 0.05; ES > 0.51). Only the SCT group had significant improvements in waist circumference (p < 0.05).

Conclusion

Exercise improves cardiac electrical measures post-MI. However, in comparison to CAT, SCT may yield greater anthropometric changes. In order to have improvements in cardiac electrical stability, clinicians working with post-MI patients may use both CAT and SCT. However, SCT might result in greater improvements.

Impaired skeletal muscle fatigue resistance during cardiac hypertrophy is prevented by functional overload- or exercise-induced functional capillarity

KEY POINTS

Capillary rarefaction is hypothesized to contribute to impaired exercise tolerance in cardiovascular disease, but it remains a poorly exploited therapeutic target for improving skeletal muscle performance. Using an abdominal aortic coarctation rat model of compensatory cardiac hypertrophy, we determine the efficacy of aerobic exercise for the prevention of, and mechanical overload for, restoration of hindlimb muscle fatigue resistance and microvascular impairment in the early stages of heart disease. Impaired muscle fatigue resistance was found after development of cardiac hypertrophy, but this impairment was prevented by low-intensity aerobic exercise and recovered after mechanical stretch due to muscle overload. Changes in muscle fatigue resistance were closely related to functional (i.e. perfused) microvascular density, independent of arterial blood flow, emphasizing the critical importance of optimal capillary diffusion for skeletal muscle function. Pro-angiogenic therapies are an important tool for improving skeletal muscle function in the incipient stages of heart disease.

ABSTRACT

Microvascular rarefaction may contribute to declining skeletal muscle performance in cardiac and vascular diseases. It remains uncertain to what extent microvascular rarefaction occurs in the earliest stages of these conditions, if impaired blood flow is an aggravating factor and whether angiogenesis restores muscle performance. To investigate this, the effects of aerobic exercise (voluntary wheel running) and functional muscle overload on the performance, femoral blood flow (FBF) and microvascular perfusion of the extensor digitorum longus (EDL) were determined in a chronic rat model of compensatory cardiac hypertrophy (CCH, induced by surgically imposed abdominal aortic coarctation). CCH was associated with hypertension (P = 0.001 vs. Control) and increased relative heart mass (P < 0.001). Immediately upon placing the aortic band (i.e. before development of CCH), post-fatigue test FBF was reduced (P < 0.003), coinciding with attenuated fatigue resistance (P = 0.039) indicating an acute arterial perfusion constraint on muscle performance. While FBF was normalized during CCH in chronic groups (P > 0.05) fatigue resistance remained reduced (P = 0.039) and was associated with reduced (P = 0.009) functional capillarity after development of CCH without intervention, indicating a microvascular limitation to muscle performance. Normalization of functional capillarity after aerobic exercise (P = 0.065) and overload (P = 0.329) in CCH coincided with restoration to control levels of muscle fatigue resistance (P > 0.999), although overload-induced EDL hypertrophy (P = 0.027) and wheel-running velocity and duration (both P < 0.05) were attenuated after aortic banding. These data show that reductions in skeletal muscle performance during CCH can be countered by improving functional capillarity, providing a therapeutic target to improve skeletal muscle function in chronic diseases.

Heart Failure-Induced Skeletal Muscle Wasting

PURPOSE OF REVIEW

Heart failure (HF) is a structural or functional cardiac abnormality which leads to failure of the heart to deliver oxygen commensurately with the requirements of the tissues and it may progress to a generalized wasting of skeletal muscle, fat tissue, and bone tissue (cardiac cachexia). Clinically, dyspnea, fatigue, and exercise intolerance are some typical signs and symptoms that characterize HF patients. This review focused on the phenotypic characteristics of HF-induced skeletal myopathy as well as the mechanisms of muscle wasting due to HF and highlighted possible therapeutic strategies for skeletal muscle wasting in HF.

RECENT FINDINGS

The impaired exercise capacity of those patients is not attributed to the reduced blood flow in the exercising muscles, but rather to abnormal metabolic responses, myocyte apoptosis and atrophy of skeletal muscle. Specifically, the development of skeletal muscle wasting in chronic HF is characterized by structural, metabolic, and functional abnormalities in skeletal muscle and may be a result not only of reduced physical activity, but also of metabolic or hormonal derangements that favour catabolism over anabolism. In particular, abnormal energy metabolism, mitochondrial dysfunction, transition of myofibers from type I to type II, muscle atrophy, and reduction in muscular strength are included in skeletal muscle abnormalities which play a central role in the decreased exercise capacity of HF patients. Skeletal muscle alterations and exercise intolerance observed in HF are reversible by exercise training, since it is the only demonstrated intervention able to improve skeletal muscle metabolism, growth factor activity, and functional capacity and to reverse peripheral abnormalities.

Lean Mass Abnormalities in Heart Failure: The Role of Sarcopenia, Sarcopenic Obesity, and Cachexia

The role of body composition in patients with heart failure (HF) has been receiving much attention in the last few years. Particularly, reduced lean mass (LM), the best surrogate for skeletal muscle mass, is independently associated with abnormal cardiorespiratory fitness (CRF) and muscle strength, ultimately leading to reduced quality of life and worse prognosis. While in the past, reduced CRF in patients with HF was thought to result exclusively from cardiac dysfunction leading to reduced cardiac output at peak exercise, current evidence supports the concept that abnormalities in LM may also play a critical role. Abnormalities in the LM body composition compartment are associated with the development of sarcopenia, sarcopenic obesity, and cachexia. Such conditions have been implicated in the pathophysiology and progression of HF. However, identification of such conditions remains challenging, as universal definitions for sarcopenia, sarcopenic obesity, and cachexia are lacking. In this review article, we describe the most common body composition abnormalities related to the LM compartment, including skeletal and respiratory muscle mass abnormalities, and the consequences of such anomalies on CRF and muscle strength in patients with HF. Finally, we discuss the potential nonpharmacologic therapeutic strategies such as exercise training (ie, aerobic exercise and resistance exercise) and dietary interventions (ie, dietary supplementation and dietary patterns) that have been implemented to target body composition, with a focus on HF.

Usefulness of 500-m walk electrocardiogram test on clinical outcomes in patients with ST-segment elevation myocardial infarction

The current Japanese guideline for ST-segment elevation myocardial infarction (STEMI) recommends 500-m walk electrocardiogram (ECG) test for patients with STEMI during hospitalization. However, little is known regarding the association between acute phase 500-m walk ECG test and clinical outcomes. The purpose of this study was to investigate the association between 500-m walk ECG test and mid-term clinical outcomes in patients with STEMI. A total of 313 STEMI patients who underwent primary percutaneous coronary interventions were included, and were divided into the successful 500-m group (n = 263) and the unsuccessful 500-m group (n = 50). The primary endpoint was the major adverse cardiovascular events (MACE), which were defined as the composite of all cause death, acute myocardial infarction, readmission for heart failure, and ischemia-driven target vessel revascularization (TVR). During the follow-up period (median 223 days), a total of 55 MACE were observed. The log-rank test revealed that MACE, all cause death, readmission for heart failure, and ischemia-driven TVR were more frequently observed in the unsuccessful 500-m group than the successful 500-m group. In the multivariate Cox proportional hazard model, the unsuccessful 500-m walk ECG test was significantly associated with MACE (OR 5.62, 95% CI 3.08-10.08, P < 0.01) after controlling confounding factors such as age, and serum creatinine levels. In conclusion, the unsuccessful 500-m walk ECG test was significantly associated with poor mid-term outcomes in patients with STEMI. Our results suggest the usefulness of 500-m walk ECG test to stratify the high-risk group from patients with STEMI.

Impaired Exercise Tolerance in Heart Failure: Role of Skeletal Muscle Morphology and Function

PURPOSE OF REVIEW

To discuss the impact of deleterious changes in skeletal muscle morphology and function on exercise intolerance in patients with heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF), as well as the utility of exercise training and the potential of novel treatment strategies to preserve or improve skeletal muscle morphology and function.

RECENT FINDINGS

Both HFrEF and HFpEF patients exhibit a reduction in percent of type I (oxidative) muscle fibers and oxidative enzymes coupled with abnormal mitochondrial respiration. These skeletal muscle abnormalities contribute to impaired oxidative metabolism with an earlier shift towards glycolytic metabolism during exercise that is strongly associated with exercise intolerance. In both HFrEF and HFpEF patients, peripheral "non-cardiac" factors are important determinants of the improvement in exercise tolerance following aerobic exercise training. Adjunctive strategies that include nutritional supplementation with amino acids and/or anabolic drugs to stimulate anabolic molecular pathways in skeletal muscle show great promise for improving exercise tolerance and treating heart failure-associated sarcopenia, but these efforts remain early in their evolution, with no immediate clinical applications. There is consistent evidence that heart failure is associated with multiple skeletal muscle abnormalities which impair oxygen uptake and utilization and contribute greatly to exercise intolerance. Exercise training induces favorable adaptations in skeletal muscle morphology and function that contribute to improvements in exercise tolerance in patients with HFrEF. The contribution of skeletal muscle adaptations to improved exercise tolerance following exercise training in HFpEF remains unknown and warrants further investigation.

Endothelial Dysfunction in Chronic Heart Failure: Assessment, Findings, Significance, and Potential Therapeutic Targets

Chronic heart failure (CHF) is a complex syndrome that results from structural and functional disturbances that affect the ability of the heart to supply oxygen to tissues. It largely affects and reduces the patient's quality of life, socio-economic status, and imposes great costs on health care systems worldwide. Endothelial dysfunction (ED) is a newly discovered phenomenon that contributes greatly to the pathophysiology of numerous cardiovascular conditions and commonly co-exists with chronic heart failure. However, the literature lacks clarity as to which heart failure patients might be affected, its significance in CHF patients, and its reversibility with pharmacological and non-pharmacological means. This review will emphasize all these points and summarize them for future researchers interested in vascular pathophysiology in this particular patient population. It will help to direct future studies for better characterization of these two phenomena for the potential discovery of therapeutic targets that might reduce future morbidity and mortality in this "at risk" population.

Sexual dimorphism in the control of skeletal muscle interstitial Po2 of heart failure rats: effects of dietary nitrate supplementation

Sex differences in the mechanisms underlying cardiovascular pathophysiology of O₂ transport in heart failure (HF) remain to be explored. In HF, nitric oxide (NO) bioavailability is reduced and contributes to deficits in O₂ delivery-to-utilization matching. Females may rely more on NO for cardiovascular control and as such experience greater decrements in HF. We tested the hypotheses that moderate HF induced by myocardial infarction would attenuate the skeletal muscle interstitial Po₂ response to contractions (Po_2is; determined by O₂ delivery-to-utilization matching) compared with healthy controls and females would express greater dysfunction than male counterparts. Furthermore, we hypothesized that 5 days of dietary nitrate supplementation (Nitrate; 1 mmol·kg^-1·day^-1) would raise Po_2is in HF rats. Forty-two Sprague-Dawley rats were randomly assigned to healthy, HF, or HF + Nitrate groups (each n = 14; 7 female/7 male). Spinotrapezius Po_2is was measured via phosphorescence quenching during electrically induced twitch contractions (180 s; 1 Hz). HF reduced resting Po_2is for both sexes compared with healthy controls (P < 0.01), and females were lower than males (14 ± 1 vs. 17 ± 2 mmHg) (P < 0.05). In HF both sexes expressed reduced Po_2is amplitudes following the onset of muscle contractions compared with healthy controls (female: -41 ± 7%, male: -26 ± 12%) (P < 0.01). In HF rats, Nitrate elevated resting Po_2is to values not different from healthy rats and removed the sex difference. Female HF + Nitrate rats expressed greater resting Po_2is and amplitudes compared with female HF (P < 0.05). In this model of moderate HF, O₂ delivery-to-utilization matching in the interstitial space is diminished in a sex-specific manner and dietary nitrate supplementation may serve to offset this reduction in HF rats with greater effects in females. NEW & NOTEWORTHY Interstitial Po₂ (Po_2is; indicative of O₂ delivery-to-utilization matching) determines, in part, O₂ flux into skeletal muscle. We show that heart failure (HF) reduces Po_2is at rest and during skeletal muscle contractions in rats and this negative effect is amplified for females. However, elevating NO bioavailability with dietary nitrate supplementation increases resting Po_2is and alters the dynamic response with greater efficacy in female HF rats, particularly at rest and following the onset of muscle contractions.

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.

Exercise training in heart failure

Exercise training (ET) in heart failure (HF) has long been established as an important part of HF care. ET is known to improve quality of life and functional capacity in a number of ways. Despite its proposed benefits, evidence supporting its routine inclusion in standard rehabilitation programme is at times conflicting, partly because of the significant heterogeneity present in available randomised controlled trials. There is lack of evidence with regard to the duration of the overall benefit, the optimal exercise regimen and whether certain types of HF aetiologies benefit more than others. The aim of this review is to provide an update to date literature review of the positive and negative evidence surrounding ET in HF, while proposing an efficient novel in-hospital exercise-based rehabilitation programme for patients with HF in addition to a pre-existing HF clinic.

The evolving role of adiponectin as an additive biomarker in HFrEF

Heart failure (HF) is a growing health problem. Despite improved management and outcome, the number of patients with HF is expected to keep rising in the following years. In recent research, adiponectin was shown to exert beneficial effects in the cardiovascular system, but the protein was also implicated in the development and progression of HF. The objective of this review is to provide an overview of current knowledge on the role of adiponectin in HF with reduced ejection fraction. We discuss the cardioprotective and (anti-) inflammatory actions of adiponectin and its potential use in clinical diagnosis and prognosis.

Improvement in cardiac dysfunction with a novel circuit training method combining simultaneous aerobic-resistance exercises. A randomized trial

Introduction

Exercise is considered a valuable nonpharmacological intervention modality in cardiac rehabilitation (CR) programs in patients with ischemic heart disease. The effect of aerobic interval exercise combined with alternating sets of resistance training (super-circuit training, SCT) on cardiac patients' with reduced left ventricular function, post-myocardial infarction (MI) has not been thoroughly investigated.

Aim of study

to improve cardiac function with a novel method of combined aerobic-resistance circuit training in a randomized control trial by way of comparing the effectiveness of continuous aerobic training (CAT) to SCT on mechanical cardiac function. Secondary to compare their effect on aerobic fitness, manual strength, and quality of life in men post MI. Finally, to evaluate the safety and feasibility of SCT.

Methods

29 men post-MI participants were randomly assigned to either 12-weeks of CAT (n = 15) or SCT (n = 14). Both groups, CAT and SCT exercised at 60%-70% and 75–85% of their heart rate reserve, respectively. The SCT group also engaged in intermittently combined resistance training. Primary outcome measure was echocardiography. Secondary outcome measures were aerobic fitness, strength, and quality of life (QoL). The effectiveness of the two training programs was examined via paired t-tests and Cohen's d effect size (ES).

Results

Post-training, only the SCT group presented significant changes in echocardiography (a reduction in E/e' and an increase in ejection fraction, P<0.05). Similarly, only the SCT group presented significant changes in aerobic fitness (an increase in maximal metabolic equivalent, P<0.05). In addition, SCT improvement in the physical component of QoL was greater than this observed in the CAT group. In both training programs, no adverse events were observed.

Conclusion

Men post-MI stand to benefit from both CAT and SCT. However, in comparison to CAT, as assessed by echocardiography, SCT may yield greater benefits to the left ventricle mechanical function as well as to the patient's aerobic fitness and physical QoL. Moreover, the SCT program was found to be feasible as well as safe.

Exercise Therapy for Older Heart Failure Patients

Both the aging process and heart failure (HF) syndrome are characterized by a dramatic reduction of aerobic capacity. Significant decreases in muscle mass and strength are also common. Few HF training studies have included meaningful numbers of older individuals, especially those greater than 80 years of age and older women with HF with reduced ejection fraction. The modest data available suggest similar benefits in older patients and excellent safety. Resistance training may provide additional benefit. Whether exercise training can reduce mortality, hospitalizations, and overall health care costs in older adults with HF awaits the outcome of adequately powered multicenter trials.

Muscle injections with lidocaine improve resting fatigue and pain in patients with chronic fatigue syndrome

OBJECTIVE

Patients with chronic fatigue syndrome (CFS) complain of long-lasting fatigue and pain which are not relieved by rest and worsened by physical exertion. Previous research has implicated metaboreceptors of muscles to play an important role for chronic fatigue and pain. Therefore, we hypothesized that blocking impulse input from deep tissues with intramuscular lidocaine injections would improve not only the pain but also fatigue of CFS patients.

METHODS

In a double-blind, placebo-controlled study, 58 CFS patients received 20 mL of 1% lidocaine (200 mg) or normal saline once into both trapezius and gluteal muscles. Study outcomes included clinical fatigue and pain, depression, and anxiety. In addition, mechanical and heat hyperalgesia were assessed and serum levels of lidocaine were obtained after the injections.

RESULTS

Fatigue ratings of CFS patients decreased significantly more after lidocaine compared to saline injections (p = 0.03). In contrast, muscle injections reduced pain, depression, and anxiety (p < 0.001), but these changes were not statistically different between lidocaine and saline (p > 0.05). Lidocaine injections increased mechanical pain thresholds of CFS patients (p = 0.04) but did not affect their heat hyperalgesia. Importantly, mood changes or lidocaine serum levels did not significantly predict fatigue reductions.

CONCLUSION

These results demonstrate that lidocaine injections reduce clinical fatigue of CFS patients significantly more than placebo, suggesting an important role of peripheral tissues for chronic fatigue. Future investigations will be necessary to evaluate the clinical benefits of such interventions.

Effects of combined exercise training and electromyostimulation treatments in chronic heart failure: A prospective multicentre study

Background Exercise training as part of a comprehensive cardiac rehabilitation is recommended for patients with cardiac heart failure. It is a valuable method for the improvement of exercise tolerance. Some studies reported a similar improvement with quadricipital electrical myostimulation, but the effect of combined exercise training and electrical myostimulation in cardiac heart failure has not been yet evaluated in a large prospective multicentre study. Purpose The aim of this study was to determine whether the addition of low frequency electrical myostimulation to exercise training may improve exercise capacity and/or muscular strength in cardiac heart failure patients. Methods Ninety-one patients were included (mean age: 58 ± 9 years; New York Heart Association II/III: 52/48%, left ventricular ejection fraction: 30 ± 7%) in a prospective French study. The patients were randomised into two groups: 41 patients in exercise training and 50 in exercise training + electrical myostimulation. All patients underwent 20 exercise training sessions. In addition, in the exercise training + electrical myostimulation group, patients underwent 20 low frequency (10 Hz) quadricipital electrical myostimulation sessions. Each patient underwent a cardiopulmonary exercise test, a six-minute walk test, a muscular function evaluation and a quality of life questionnaire, before and at the end of the study. Results A significant improvement of exercise capacity (Δ peak oxygen uptake+15% in exercise training group and +14% in exercise training + electrical myostimulation group) and of quality of life was observed in both groups without statistically significant differences between the two groups. Mean creatine kinase level increased in the exercise training group whereas it remained stable in the combined group. Conclusions This prospective multicentre study shows that electrical myostimulation on top of exercise training does not demonstrate any significant additional improvement in exercise capacity in cardiac heart failure patients.

Exercise training decreases NADPH oxidase activity and restores skeletal muscle mass in heart failure rats

We have recently demonstrated that NADPH oxidase hyperactivity, NF-κB activation, and increased p38 phosphorylation lead to atrophy of glycolytic muscle in heart failure (HF). Aerobic exercise training (AET) is an efficient strategy to counteract skeletal muscle atrophy in this syndrome. Therefore, we tested whether AET would regulate muscle redox balance and protein degradation by decreasing NADPH oxidase hyperactivity and reestablishing NF-κB signaling, p38 phosphorylation, and proteasome activity in plantaris muscle of myocardial infarcted-induced HF (MI) rats. Thirty-two male Wistar rats underwent MI or fictitious surgery (SHAM) and were randomly assigned into untrained (UNT) and trained (T; 8 wk of AET on treadmill) groups. AET prevented HF signals and skeletal muscle atrophy in MI-T, which showed an improved exercise tolerance, attenuated cardiac dysfunction and increased plantaris fiber cross-sectional area. To verify the role of inflammation and redox imbalance in triggering protein degradation, circulating TNF-α levels, NADPH oxidase profile, NF-κB signaling, p38 protein levels, and proteasome activity were assessed. MI-T showed a reduced TNF-α levels, NADPH oxidase activity, and Nox2 mRNA expression toward SHAM-UNT levels. The rescue of NADPH oxidase activity induced by AET in MI rats was paralleled by reducing nuclear binding activity of the NF-κB, p38 phosphorylation, atrogin-1, mRNA levels, and 26S chymotrypsin-like proteasome activity. Taken together our data provide evidence for AET improving plantaris redox homeostasis in HF associated with a decreased NADPH oxidase, redox-sensitive proteins activation, and proteasome hyperactivity further preventing atrophy. These data reinforce the role of AET as an efficient therapy for muscle wasting in HF.

NEW & NOTEWORTHY This study demonstrates, for the first time, the contribution of aerobic exercise training (AET) in decreasing muscle NADPH oxidase activity associated with reduced reactive oxygen species production and systemic inflammation, which diminish NF-κB overactivation, p38 phosphorylation, and ubiquitin proteasome system hyperactivity. These molecular changes counteract plantaris atrophy in trained myocardial infarction-induced heart failure rats. Our data provide new evidence into how AET may regulate protein degradation and thus prevent skeletal muscle atrophy.

Supervised exercise training versus usual care in ambulatory patients with left ventricular assist devices: A systematic review

Implantation of left ventricular assist devices (LVAD) has increased because of improved safety profile and limited availability of heart transplantation. Although supervised exercise training (ET) programs are known to improve exercise capacity and quality of life (QoL) in heart failure (HF) patients, similar data is inconclusive in LVAD patients. Thus, we performed a systematic review on studies that incorporated supervised ET and measured peak oxygen uptake in LVAD patients. A total of 150 patients in exercise and 55 patients in control groups were included from 8 studies selected from our predefined criteria. Our systematic review suggests supervised ET has an inconsistent effect on exercise capacity and QoL when compared to control groups undergoing usual care. A quantitative sub-analysis was performed with 4 studies that provided enough data to compare peak oxygen uptake and QoL at baseline and at follow-up. After at least 6 weeks of training, LVAD patients undergoing supervised ET demonstrated significant improvement in exercise capacity (standardized mean difference [SMD] = 0.735, 95% Confidence Interval-[CI], 0.31-1.15 units of the standard deviation, P = 0.001) and QoL scores (SMD = 1.58, 95% CI 0.97-2.20 units of the standard deviation, P <0.001) when compared to the usual care group, with no serious adverse events with exercise. These results suggest that supervised ET is safe and can improve patient outcomes in LVAD patients when compared to the usual care.

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.

Exercise as medicine - evidence for prescribing exercise as therapy in 26 different chronic diseases

This review provides the reader with the up-to-date evidence-based basis for prescribing exercise as medicine in the treatment of 26 different diseases: psychiatric diseases (depression, anxiety, stress, schizophrenia); neurological diseases (dementia, Parkinson's disease, multiple sclerosis); metabolic diseases (obesity, hyperlipidemia, metabolic syndrome, polycystic ovarian syndrome, type 2 diabetes, type 1 diabetes); cardiovascular diseases (hypertension, coronary heart disease, heart failure, cerebral apoplexy, and claudication intermittent); pulmonary diseases (chronic obstructive pulmonary disease, asthma, cystic fibrosis); musculo-skeletal disorders (osteoarthritis, osteoporosis, back pain, rheumatoid arthritis); and cancer. The effect of exercise therapy on disease pathogenesis and symptoms are given and the possible mechanisms of action are discussed. We have interpreted the scientific literature and for each disease, we provide the reader with our best advice regarding the optimal type and dose for prescription of exercise.

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.

The Effect of Cardiac Rehabilitation Exercise Training on Cardiopulmonary Function in Ischemic Cardiomyopathy With Reduced Left Ventricular Ejection Fraction

OBJECTIVE

To observe the effect and safety of cardiac rehabilitation (CR) exercise in ischemic cardiomyopathy and to compare the results between patients with preserved left ventricular ejection fraction (LVEF) and reduced LVEF.

METHODS

Patients with ischemic cardiomyopathy with LVEF <50% were included as subjects. The patients were classified into the preserved LVEF (pLVEF; LVEF 41%-49%) group and the reduced LVEF (rLVEF; LVEF ≤40%) group. Patients underwent hourly aerobic exercise training sessions with an intensity of 60%-85% of heart rate reserve, three times a week for 6 weeks. Graded exercise test and transthoracic echocardiogram were performed in all study patients before and after completion of the CR exercise program.

RESULTS

After completion of the CR exercise program, both groups (pLVEF, n=30; rLVEF, n=18) showed significant increases in LVEF and VO2max. In the pLVEF group, LVEF and VO2max increased from 45.1%±4.8% to 52.5%±9.6% (p<0.001) and from 24.1±6.3 to 28.1±8.8 mL/kg/min (p=0.002), respectively. In the rLVEF group, LVEF and VO2max increased from 29.7%±7.7% to 37.6%±10.3% (p<0.001) and from 17.6±4.7 to 21.2±5.1 mL/kg/min (p<0.001), respectively. Both groups completed their exercise program safely.

CONCLUSION

In both groups, patients with ischemic cardiomyopathy who completed a 6-week supervised CR exercise program demonstrated remarkable improvements in cardiopulmonary function. This result implies that neither of the two groups showed higher efficacy in comparison to each other, but we can conclude that CR exercise in the rLVEF group was as effective and safe as that in the pLVEF group.

Effect of exercise training on ventilatory efficiency in patients with heart disease: a review

The analysis of ventilatory efficiency in cardiopulmonary exercise testing has proven useful for assessing the presence and severity of cardiorespiratory diseases. During exercise, efficient pulmonary gas exchange is characterized by uniform matching of lung ventilation with perfusion. By contrast, mismatching is marked by inefficient pulmonary gas exchange, requiring increased ventilation for a given CO2 production. The etiology of increased and inefficient ventilatory response to exercise in heart disease is multifactorial, involving both peripheral and central mechanisms. Exercise training has been recommended as non-pharmacological treatment for patients with different chronic cardiopulmonary diseases. In this respect, previous studies have reported improvements in ventilatory efficiency after aerobic exercise training in patients with heart disease. Against this background, the primary objective of the present review was to discuss the pathophysiological mechanisms involved in abnormal ventilatory response to exercise, with an emphasis on both patients with heart failure syndrome and coronary artery disease. Secondly, special focus was dedicated to the role of aerobic exercise training in improving indices of ventilatory efficiency among these patients, as well as to the underlying mechanisms involved.

Adiponectin resistance in skeletal muscle: pathophysiological implications in chronic heart failure

Skeletal muscle wasting is a common complication of chronic heart failure (CHF) and linked to poor patient prognosis. In recent years, adiponectin was postulated to be centrally involved in CHF-associated metabolic failure and muscle wasting. This review discusses current knowledge on the role of adiponectin in CHF. Particular emphasis will be given to the complex interaction mechanisms and the intracellular pathways underlying adiponectin resistance in skeletal muscle of CHF patients. In this review, we propose that the resistance process is multifactorial, integrating abnormalities emanating from insulin signalling, mitochondrial biogenesis, and ceramide metabolism.

Peripheral reflex feedbacks in chronic heart failure: Is it time for a direct treatment?

Despite repeated attempts to develop a unifying hypothesis that explains the clinical syndrome of heart failure (HF), no single conceptual paradigm for HF has withstood the test of time. The last model that has been developed, the neurohormonal model, has the great virtue of highlighting the role of the heart as an endocrine organ, as well as to shed some light on the key role on HF progression of neurohormones and peripheral organs and tissues beyond the heart itself. However, while survival in clinical trials based on neurohormonal antagonist drugs has improved, HF currently remains a lethal condition. At the borders of the neurohormonal model of HF, a partially unexplored path trough the maze of HF pathophysiology is represented by the feedback systems. There are several evidences, from both animal studies and humans reports, that the deregulation of baro-, ergo- and chemo-reflexes in HF patients elicits autonomic imbalance associated with parasympathetic withdrawal and increased adrenergic drive to the heart, thus fundamentally contributing to the evolution of the disease. Hence, on top of guideline-recommended medical therapy, mainly based on neurohormonal antagonisms, all visceral feedbacks have been recently considered in HF patients as additional potential therapeutic targets.

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.

Cardiac remodeling and physical training post myocardial infarction

After myocardial infarction (MI), the heart undergoes extensive myocardial remodeling through the accumulation of fibrous tissue in both the infarcted and noninfarcted myocardium, which distorts tissue structure, increases tissue stiffness, and accounts for ventricular dysfunction. There is growing clinical consensus that exercise training may beneficially alter the course of post-MI myocardial remodeling and improve cardiac function. This review summarizes the present state of knowledge regarding the effect of post-MI exercise training on infarcted hearts. Due to the degree of difficulty to study a viable human heart at both protein and molecular levels, most of the detailed studies have been performed by using animal models. Although there are some negative reports indicating that post-MI exercise may further cause deterioration of the wounded hearts, a growing body of research from both human and animal experiments demonstrates that post-MI exercise may beneficially alter the course of wound healing and improve cardiac function. Furthermore, the improved function is likely due to exercise training-induced mitigation of renin-angiotensin-aldosterone system, improved balance between matrix metalloproteinase-1 and tissue inhibitor of matrix metalloproteinase-1, favorable myosin heavy chain isoform switch, diminished oxidative stress, enhanced antioxidant capacity, improved mitochondrial calcium handling, and boosted myocardial angiogenesis. Additionally, meta-analyses revealed that exercise-based cardiac rehabilitation has proven to be effective, and remains one of the least expensive therapies for both the prevention and treatment of cardiovascular disease, and prevents re-infarction.

Effects of exercise training on neurovascular control and skeletal myopathy in systolic heart failure

Neurohormonal excitation and dyspnea are the hallmarks of heart failure (HF) and have long been associated with poor prognosis in HF patients. Sympathetic nerve activity (SNA) and ventilatory equivalent of carbon dioxide (VE/VO2) are elevated in moderate HF patients and increased even further in severe HF patients. The increase in SNA in HF patients is present regardless of age, sex, and etiology of systolic dysfunction. Neurohormonal activation is the major mediator of the peripheral vasoconstriction characteristic of HF patients. In addition, reduction in peripheral blood flow increases muscle inflammation, oxidative stress, and protein degradation, which is the essence of the skeletal myopathy and exercise intolerance in HF. Here we discuss the beneficial effects of exercise training on resting SNA in patients with systolic HF and its central and peripheral mechanisms of control. Furthermore, we discuss the exercise-mediated improvement in peripheral vasoconstriction in patients with HF. We will also focus on the effects of exercise training on ventilatory responses. Finally, we review the effects of exercise training on features of the skeletal myopathy in HF. In summary, exercise training plays an important role in HF, working synergistically with pharmacological therapies to ameliorate these abnormalities in clinical practice.

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.

Quantification of skeletal muscle mitochondrial function by 31P magnetic resonance spectroscopy techniques: a quantitative review

Magnetic resonance spectroscopy (MRS) can give information about cellular metabolism in vivo which is difficult to obtain in other ways. In skeletal muscle, non-invasive (31) P MRS measurements of the post-exercise recovery kinetics of pH, [PCr], [Pi] and [ADP] contain valuable information about muscle mitochondrial function and cellular pH homeostasis in vivo, but quantitative interpretation depends on understanding the underlying physiology. Here, by giving examples of the analysis of (31) P MRS recovery data, by some simple computational simulation, and by extensively comparing data from published studies using both (31) P MRS and invasive direct measurements of muscle O2 consumption in a common analytical framework, we consider what can be learnt quantitatively about mitochondrial metabolism in skeletal muscle using MRS-based methodology. We explore some technical and conceptual limitations of current methods, and point out some aspects of the physiology which are still incompletely understood.

The influence of aerobic fitness status on ventilatory efficiency in patients with coronary artery disease

OBJECTIVE

To test the hypotheses that 1) coronary artery disease patients with lower aerobic fitness exhibit a lower ventilatory efficiency and 2) coronary artery disease patients with lower initial aerobic fitness exhibit greater improvements in ventilatory efficiency with aerobic exercise training.

METHOD

A total of 123 patients (61.0±0.7 years) with coronary artery disease were divided according to aerobic fitness status into 3 groups: group 1 (n = 34, peak VO₂<17.5 ml/kg/min), group 2 (n = 67, peak VO₂>17.5 and <24.5 ml/kg/min) and group 3 (n = 22, peak VO₂>24.5 ml/kg/min). All patients performed a cardiorespiratory exercise test on a treadmill. Ventilatory efficiency was determined by the lowest VE/VCO₂ ratio observed. The exercise training program comprised moderate-intensity aerobic exercise performed 3 times per week for 3 months. Clinicaltrials.gov: NCT02106533 RESULTS: Before intervention, group 1 exhibited both lower peak VO2 and lower ventilatory efficiency compared with the other 2 groups (p<0.05). After the exercise training program, group 1 exhibited greater improvements in aerobic fitness and ventilatory efficiency compared with the 2 other groups (group 1: ▵ = -2.5±0.5 units; group 2: ▵ = -0.8±0.3 units; and group 3: ▵ = -1.4±0.6 units, respectively; p<0.05).

CONCLUSIONS

Coronary artery disease patients with lower aerobic fitness status exhibited lower ventilatory efficiency during a graded exercise test. In addition, after 3 months of aerobic exercise training, only the patients with initially lower levels of aerobic fitness exhibited greater improvements in ventilatory efficiency.