The effect of resistance training on left ventricular function and structure of patients with chronic heart failure

Resistance is not futile: a systematic review of the benefits, mechanisms and safety of resistance training in people with heart failure

Exercise offers many physical and health benefits to people with heart failure (CHF), but aerobic training (AT) predominates published literature. Resistance training (RT) provides additional and complementary health benefits to AT in people with CHF; we aimed to elucidate specific health benefits accrued, the mechanism of effect and safety of RT. We conducted a systematic search for RT randomised, controlled trials in people with CHF, up until August 30, 2023. RT offers several benefits including improved physical function (peak VO2 and 6MWD), quality of life, cardiac systolic and diastolic function, endothelial blood vessel function, muscle strength, anti-inflammatory muscle markers, appetite and serious event rates. RT is beneficial and improves peak VO2 and 6MWD, partly restores normal muscle fibre profile and decreases inflammation. In turn this leads to a reduced risk or impact of sarcopenia/cachexia via effect on appetite. The positive impact on quality of life and performance of activities of daily living is related to improved function, which in turn improves prognosis. RT appears to be safe with only one serious event reported and no deaths. Nevertheless, few events reported to date limit robust analysis. RT appears to be safe and offers health benefits to people with CHF. RT modifies the adverse muscle phenotype profile present in people with CHF and it appears safe. Starting slowly with RT and increasing load to 80% of 1 repetition maximum (RM) appears to offer optimal benefit.

Skeletal muscle atrophy, regeneration, and dysfunction in heart failure: Impact of exercise training

This review highlights some established and some more contemporary mechanisms responsible for heart failure (HF)-induced skeletal muscle wasting and weakness. We first describe the effects of HF on the relationship between protein synthesis and degradation rates, which determine muscle mass, the involvement of the satellite cells for continual muscle regeneration, and changes in myofiber calcium homeostasis linked to contractile dysfunction. We then highlight key mechanistic effects of both aerobic and resistance exercise training on skeletal muscle in HF and outline its application as a beneficial treatment. Overall, HF causes multiple impairments related to autophagy, anabolic-catabolic signaling, satellite cell proliferation, and calcium homeostasis, which together promote fiber atrophy, contractile dysfunction, and impaired regeneration. Although both wasting and weakness are partly rescued by aerobic and resistance exercise training in HF, the effects of satellite cell dynamics remain poorly explored.

Cardiopulmonary Exercise Testing, Rehabilitation, and Exercise Training in Postpulmonary Embolism

Long-term exercise intolerance and functional limitations are common after an episode of acute pulmonary embolism (PE), despite 3 to 6 months of anticoagulation. These persistent symptoms are reported in more than half of the patients with acute PE and are referred as "post-PE syndrome." Although these functional limitations can occur from persistent pulmonary vascular occlusion or pulmonary vascular remodeling, significant deconditioning can be a major contributing factor. Herein, the authors review the role of exercise testing to elucidate the mechanisms of exercise limitations to guide next steps in management and exercise training for musculoskeletal deconditioning.

Resistance training in heart failure patients: a systematic review and meta-analysis

Aerobic training (AT) has been the primary mode of exercise training in cardiac rehabilitation. Historically, the reason for the prescription of AT was that it was speculated that although RT may be beneficial for some clinical outcomes, it may have an adverse effect on ventricular structure and function. However, RT has now made its way into current cardiac rehabilitation guidelines, including those directed towards patients with HF, albeit differences exist across institutions and guidelines. A systematic search of PubMed, EMBASE and Cochrane Trials Register on April 30, 2021, was conducted for exercise-based rehabilitation trials in HF. Randomised and controlled trials that reported on resistance training versus usual care or trials that directly compared RT to an AT intervention were included. Resistance training versus controls improves parameters of lower (SMD 0.76 (95%CI 0.26, 1.25, p = 0.003] and upper extremity muscle strength (SMD 0.85 (95%CI 0.35, 1.35), p = 0.0009], both key parameters of physical function throughout the lifespan. Importantly, RT in isolation, versus control, improves VO2peak [MD: 2.64 ml/kg/min (95%CI 1.67, 3.60), p < 0.00001] and 6MWD [MD: 49.94 m (95%CI 34.59, 65.29), p < 0.00001], without any detrimental effect on left ventricular parameters. Resistance training in HF patients is safe and improves parameters of physical function and quality of life. Where people with HF are unable to, or are not inclined to, partake in aerobic activity, RT alone is appropriate to elicit meaningful benefit.

Resistance Training for Older Adults in Cardiac Rehabilitation

Cardiac rehabilitation plays a key role in the care of older patients after a coronary event. Hospitalizations are prevented and quality of life, exercise capacity, and physical function are improved. Almost 50% of cardiac rehabilitation participants are older adults (>65 years), many of whom are frail or deconditioned. Resistance training, as a component of cardiac rehabilitation, improves muscle strength, endurance, and physical function. The purpose of this review is to describe the effects of resistance training in cardiac rehabilitation for older adults with a particular focus on physical function.

Alterations of the respiratory system in heart failure

The review discusses mechanisms for the development of the pathology of the respiratory system in patients with CHF, such as various types of periodic respiration, pulmonary hypertension due to the pathology of the left chambers of the heart, and remodeling of the respiratory musculature. The role of chemo- and baroreceptors of the carotid zone, as well as the hyperactivation of the respiratory muscle metaboreflex in the development of the pathology of the respiratory system, and the mediated exacerbation of CHF are discussed.

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.

The ‘aerobic/resistance/inspiratory muscle training hypothesis in heart failure’

Evidence from large multicentre exercise intervention trials in heart failure patients, investigating both moderate continuous aerobic training and high intensity interval training, indicates that the ‘crème de la crème’ exercise programme for this population remains to be found. The ‘aerobic/resistance/inspiratory (ARIS) muscle training hypothesis in heart failure’ is introduced, suggesting that combined ARIS muscle training may result in maximal exercise pathophysiological and functional benefits in heart failure patients. The hypothesis is based on the decoding of the ‘skeletal muscle hypothesis in heart failure’ and on revision of experimental evidence to date showing that exercise and functional intolerance in heart failure patients are associated not only with reduced muscle endurance, indication for aerobic training (AT), but also with reduced muscle strength and decreased inspiratory muscle function contributing to weakness, dyspnoea, fatigue and low aerobic capacity, forming the grounds for the addition of both resistance training (RT) and inspiratory muscle training (IMT) to AT. The hypothesis will be tested by comparing all potential exercise combinations, ARIS, AT/RT, AT/IMT, AT, evaluating both functional and cardiac indices in a large sample of heart failure patients of New York Heart Association class II–III and left ventricular ejection fraction ≤35% ad hoc by the multicentre randomized clinical trial, Aerobic Resistance, InSpiratory Training OutcomeS in Heart Failure (ARISTOS-HF trial).

Improvement of exercise tolerance in cardiopulmonary testing with sustained safety after regular training in outpatients with systolic heart failure (NYHA III) and an implantable cardioverter-defibrillator. Prospective 18-month randomized study

INTRODUCTION

The aim of the study was to evaluate the impact of individual training on the level of physical capacity and echocardiographic parameters in patients with systolic heart failure (SHF), NYHA III and an implantable cardioverter-defibrillator (ICD).

MATERIAL AND METHODS

The study included 84 patients with SHF, randomly assigned to one of two groups: with regular training (ICD-Ex) and a control group (ICD-control). The ICD-Ex group participated in a hospital rehabilitation program which after discharge was individually continued for 6 months in an outpatient setting. The ICD-control group participated in a training program during hospitalization, but after discharge did not perform any controlled activities. Prior to discharge, at 6 and 18 months cardiopulmonary exercise testing (CPX), standard echocardiographic examination and the 6-minute walk test (6-MWT) were performed in all patients.

RESULTS

After 18 months in the ICD-Ex group most of the CPX parameters improved significantly (VO₂ peak, ml/kg/min: 13.0 ±4.1 vs. 15.9 ±6.1, p < 0.0017; VCO₂ peak, l/min: 1.14 ±0.34 vs. 1.58 ±0.65, p < 0.0008; Watt: 74.5 ±29.7 vs. 92.6 ±39.1, p < 0.0006; METs 3.72 ±1.81 vs. 4.35 ±1.46, p < 0.0131). In the ICD-control group no significant improvement of any parameter was observed. Left ventricular systolic dimensions remained significantly lower at 18 months only in the ICD-Ex group (49.5 ±11.0 vs. 43.4 ±10.0, p < 0.011). Left ventricular ejection fraction in both groups significantly increased at 6 and 18 months compared to baseline (ICD-Ex: 25.07 ±5.4 vs. 31.4 ±9.2, p < 0.001, vs. 30.9 ±8.9, p < 0.002, ICD-C: 25.1 ±8.3 vs. 29.2 ±7.7, p < 0.012 vs. 30.1 ±9.1, p < 0.005). Distance of the 6-MWT was significantly improved after 6 and 18 months in the ICD-Ex group and was overall longer than in the ICD-control group (491 ±127 vs. 423 ±114 m, p < 0.04).

CONCLUSIONS

An individual, 6-month training program, properly controlled in patients with SHF and an implanted ICD, was safe and resulted in a significant improvement of exercise tolerance and capacity and echocardiographic parameters.

The Effect of Exercise Training Intensity on Quality of Life in Heart Failure Patients: A Systematic Review and Meta-Analysis

OBJECTIVES

To establish if exercise training intensity produces different effect sizes for quality of life in heart failure.

BACKGROUND

Exercise intensity is the primary stimulus for physical and mental adaptation.

METHODS

We conducted a MEDLINE search (1985 to February 2016) for exercise-based rehabilitation trials in heart failure using the search terms 'exercise training', 'left ventricular dysfunction', 'peak VO2', 'cardiomyopathy', and 'systolic heart dysfunction'.

RESULTS

Twenty-five studies were included; 4 (16%) comprised high-, 10 (40%) vigorous-, 9 (36%) moderate- and 0 (0%) low-intensity groups; two studies were unclassified. The 25 studies provided a total of 2,385 participants, 1,223 exercising and 1,162 controls (36,056 patient-hours of training). Analyses reported significant improvement in total Minnesota living with heart failure (MLWHF) total score [mean difference (MD) -8.24, 95% CI -11.55 to -4.92, p < 0.00001]. Physical MLWHF scorewas significantly improved in all studies (MD -2.89, 95% CI -4.27 to -1.50, p < 0.00001). MLWHF total score was significantly reduced after high- (MD -13.74, 95% CI -21.34 to -6.14, p = 0.0004) and vigorous-intensity training (MD -8.56, 95% CI -12.77 to -4.35, p < 0.0001) but not moderate-intensity training. A significant improvement in the total MLWHF score was seen after aerobic training (MD -3.87, 95% CI -6.97 to -0.78, p = 0.01), and combined aerobic and resistance training (MD -9.82, 95% CI -15.71 to -3.92, p = 0.001), but not resistance training.

CONCLUSIONS

As exercise training intensity rises, so may the magnitude of improvement in quality of life in exercising patients. Aerobic-only or combined aerobic and resistance training may offer the greatest improvements in quality of life.

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.

Resistance training improves hemodynamic function, collagen deposition and inflammatory profiles: experimental model of heart failure

The role of resistance training on collagen deposition, the inflammatory profile and muscle weakness in heart failure remains unclear. Therefore, this study evaluated the influence of a resistance training program on hemodynamic function, maximum strength gain, collagen deposition and inflammatory profile in chronic heart failure rats. Thirty-two male Wistar rats submitted to myocardial infarction by coronary artery ligation or sham surgery were assigned into four groups: sedentary sham (S-Sham, n = 8); trained sham (T-Sham, n = 8); sedentary chronic heart failure (S-CHF, n = 8) and trained chronic heart failure (T-CHF, n = 8). The maximum strength capacity was evaluated by the one maximum repetition test. Trained groups were submitted to an 8-week resistance training program (4 days/week, 4 sets of 10-12 repetitions/session, at 65% to 75% of one maximum repetition). After 8 weeks of the resistance training program, the T-CHF group showed lower left ventricular end diastolic pressure (P<0.001), higher left ventricular systolic pressure (P<0.05), higher systolic blood pressure (P<0.05), an improvement in the maximal positive derivative of ventricular pressure (P<0.05) and maximal negative derivative of ventricular pressure (P<0.05) when compared to the S-CHF group; no differences were observed when compared to Sham groups. In addition, resistance training was able to reduce myocardial hypertrophy (P<0.05), left ventricular total collagen volume fraction (P<0.01), IL-6 (P<0.05), and TNF-α/IL-10 ratio (P<0.05), as well as increasing IL-10 (P<0.05) in chronic heart failure rats when compared to the S-CHF group. Eight weeks of resistance training promotes an improvement of cardiac function, strength gain, collagen deposition and inflammatory profile in chronic heart failure rats.

Reasonable expectations: how much aerobic capacity, muscle strength, and quality of life can improve with exercise training in heart failure

In this article, the literature that describes the magnitude of functional and quality of life gains with a traditional moderate-intensity aerobic and resistance training programs is reviewed, and differences between the impact of exercise training in heart failure with preserved ejection fraction versus heart failure with reduced ejection fraction are discussed.

Effect of exercise training on left ventricular remodeling in diabetic patients with diastolic dysfunction: rationale and design

INTRODUCTION

This study will examine the effects of combined aerobic and resistance training on left ventricular remodeling in diabetic patients with diastolic dysfunction. This is the first randomized controlled trial to look for effects of combined strength training and aerobic exercise on myocardial function as well as other clinical, functional, or psychological parameters in diabetic patients with isolated diastolic dysfunction, and will provide important insights into the potential management strategies for heart failure with preserved ejection fraction.

METHODS AND ANALYSIS

This is a prospective, randomized controlled investigator initiated single center trial. Diabetic patients with LV diastolic dysfunction suitable for exercise training intervention will be randomized to three months of a supervised combination of aerobic and strength training exercises, or supervised light stretching (control arm). Pre and post intervention assessment will include stress echocardiography, peak aerobic power with 12-lead ECG, dual-energy X-ray absorptiometry, muscle strength, the capacity to perform activities of daily living (ADLs), and questionnaires to assess self-perceived quality of life and symptoms of depression. The primary endpoint is to compare any change in tissue Doppler-derived LV systolic and early diastolic velocities.

ETHICS AND DISSEMINATION

The current trial protocol has been approved by the Human Research Ethics Committee of Austin Health and the University of Melbourne, Melbourne. The study will be performed in accordance with the Declaration of Helsinki. The investigator, regardless of the outcome, will publish the results of the study.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12610000943044.

Therapeutic interventions for heart failure with preserved ejection fraction: A summary of current evidence

Heart failure with preserved ejection fraction (HFPEF) is common and represents a major challenge in cardiovascular medicine. Most of the current treatment of HFPEF is based on morbidity benefits and symptom reduction. Various pharmacological interventions available for heart failure with reduced ejection fraction have not been supported by clinical studies for HFPEF. Addressing the specific aetiology and aggressive risk factor modification remain the mainstay in the treatment of HFPEF. We present a brief overview of the currently recommended therapeutic options with available evidence.

Cardiac rehabilitation exercise and self-care for chronic heart failure

Chronic heart failure (CHF) is highly prevalent in older individuals and is a major cause of morbidity, mortality, hospitalizations, and disability. Cardiac rehabilitation (CR) exercise training and CHF self-care counseling have each been shown to improve clinical status and clinical outcomes in CHF. Systematic reviews and meta-analyses of CR exercise training alone (without counseling) have demonstrated consistent improvements in CHF symptoms in addition to reductions in cardiac mortality and number of hospitalizations, although individual trials have been less conclusive of the latter 2 findings. The largest single trial, HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training), showed a reduction in the adjusted risk for the combined endpoint of all-cause mortality or hospitalization (hazard ratio: 0.89, 95% confidence interval: 0.81 to 0.99; p = 0.03). Quality of life and mental depression also improved. CHF-related counseling, whether provided in isolation or in combination with CR exercise training, improves clinical outcomes and reduces CHF-related hospitalizations. We review current evidence on the benefits and risks of CR and self-care counseling in patients with CHF, provide recommendations for patient selection for third-party payers, and discuss the role of CR in promoting self-care and behavioral changes.

Role of four-week resistance exercise in preserving the heart against ischaemia-reperfusion-induced injury

Objective

We studied the cardioprotective effect of resistance training against ischaemia–reperfusion-induced injury.

Methods

Forty male rats were divided into trained and sedentary groups (n = 20 for each). The trained rats were exercised at 12 repetitions/set, four sets/day and five days/week for four weeks. Transient regional ischaemia of the left anterior descending coronary artery (40 min) was followed by 80 min of reperfusion.

Results

Baseline developed and diastolic pressures and coronary flow were similar in the two groups. While diastolic pressure increased and developed pressure and coronary flow decreased in both the ischaemic and perfusion periods (as indices of cardiac damage), there were no statistically significant differences between the trained and sedentary groups in these parameters. Resistance training did not significantly change the infarct size and apoptosis rate.

Conclusion

We did not see a cardioprotective effect of resistance exercise against ischaemia–reperfusion-induced injury in this study. A precise conclusion about this issue needs more investigations.

The role of exercise training in heart failure

Exercise training in patients with systolic heart failure (HF) is an accepted adjunct to an evidence-based management program. This review describes the pathophysiologic features that are thought to be responsible for the exercise intolerance experienced in the HF patient. Significant research has expanded our appreciation of the interplay of hemodynamic, ventilatory, and skeletal myopathic processes in this common, chronic condition. Randomized, controlled exercise trials designed to measure endothelial function, inflammatory markers, sympathetic neural activation, and skeletal muscle metabolism and structure have further defined the pathophysiology, documented the impact of exercise training on these processes, and confirmed the benefit of this therapy. Consistent with prior clinical research and patient experience are the recently published results of the HF-ACTION (Heart Failure-A Controlled Trial Investigating Outcomes of exercise TraiNing), which demonstrated a modest improvement in exercise capacity, reduction of symptoms, and improved self-reported measures of quality of life without adverse events. Consideration is given in this review to the benefits of variable intensity programs and the addition of resistance exercise to a standard aerobic prescription. Despite increasing validation of the role exercise training plays in the modification of exercise intolerance, challenges remain in its routine therapeutic application, including acceptance and use as an adjunctive intervention in the management of the patient with HF, limited insurance coverage for HF patients in cardiac rehabilitation, tailoring of exercise programs to best address the needs of subgroups of patients, and improved short- and long-term adherence to exercise training and a physically active lifestyle.

Resistance training increases 6-minute walk distance in people with chronic heart failure: a systematic review

QUESTION

Does resistance training, either alone or as an adjunct to aerobic training, improve cardiac function, exercise capacity and quality of life in people with chronic heart failure?

DESIGN

Systematic review with meta-analysis of randomised trials.

PARTICIPANTS

Adults with stable chronic heart failure.

INTERVENTION

Progressive resistance exercise training, alone or as an adjunct to aerobic training.

OUTCOME MEASURES

Cardiac function, exercise capacity and quality of life.

RESULTS

241 participants from eight trials performed 2 to 6 months of moderate-intensity resistance training (50-75% of 1RM). Most programs consisted of 5 to 6 exercises for large limb and trunk muscles with two sets of 8 to 12 repetitions, three times a week. Resistance training significantly increased 6-minute walk distance (WMD 52 m, 95% CI 19 to 85) but not peak oxygen consumption (WMD 1.4 ml/kg/min, 95% CI -0.3 to 3.1). When used as an adjunct to aerobic training, resistance training did not significantly alter left ventricular ejection fraction (WMD -0.5%, 95% CI -4.3 to 3.3), peak oxygen consumption (WMD -0.7 ml/kg/min, 95% CI -2.3 to 1.0), or Minnesota Living with Heart Failure Questionnaire scores (WMD -0.9, 95% CI -5.4 to 3.7), compared with aerobic training alone.

CONCLUSION

Resistance training increased 6-minute walk distance compared to no training, but had no other benefits on cardiac function, exercise capacity, or quality of life if used alone or as an adjunct to aerobic training in people with chronic heart failure. However, further high quality, large scale, randomised trials are needed.

Cardiovascular adaptive responses in rats submitted to moderate resistance training

The present study investigated the effects of 8 week of resistance training (RT) on hemodynamic and ventricular function on cardiac myosin ATPase activity, and on contractility of papillary muscles of rats. Groups: control (CO), electrically stimulated (ES), trained at 60% (TR 60%) and 75% of one repetition maximum (1RM) (TR 75%). Exercise protocol: 5 sets of 12 repetitions at 60 and 75% of 1RM, 5 times per week. The CO and ES groups had similar values for parameters analyzed (P > 0.05). Blood pressure (BP), heart rate (13%), left ventricle systolic pressure (LVSP 13%) decreased and cardiac myosin ATPase activity increased in the TR 75% group (90%, P < 0.05). The contractile performance of papillary muscles increased in trained rats (P < 0.05). Eight weeks of RT was associated with lowering of resting BP, heart rate and LVSP, improvements in contractility of the papillary muscle and an increase of cardiac myosin ATPase activity in rats.

Rheumatoid arthritis, cardiovascular disease and physical exercise: a systematic review

This systematic review investigates the effectiveness of exercise interventions in improving disease-related characteristics in patients with rheumatoid arthritis (RA). It also provides suggestions for exercise programmes suitable for improving the cardiovascular profile of RA patients and proposes areas for future research in the field. Six databases (Medline, Cochrane Library, CINAHL, Google Scholar, EMBASE and PEDro) were searched to identify publications from 1974 to December 2006 regarding RA and exercise interventions. The quality of the studies included was determined by using the Jadad scale. Initial searches identified 1342 articles from which 40 met the inclusion criteria. No studies were found investigating exercise interventions in relation to cardiovascular disease in RA. There is strong evidence suggesting that exercise from low to high intensity of various modes is effective in improving disease-related characteristics and functional ability in RA patients. Future studies are required to investigate the effects of exercise in improving the cardiovascular status of this patient population.

Effects of resistance training on ventricular function and hypertrophy in a rat model

OBJECTIVE

The purpose of this study was to follow the ventricular function and cardiac hypertrophy in rats undergoing a resistance-training program for a period of 3 months.

DESIGN

Forty animals were divided into two major groups: control (n=16) and resistance trained (n=24). From the resistance-trained group, 12 animals were resistance trained for 1 month and another 12 for 3 months. The resistance-training protocol was performed with 4 sets of 12 repetitions using 65% to 75% of one repetition maximum (maximum lifted weight with the exercise apparatus).

METHODS

Echocardiographic analysis was performed at the beginning of the resistance-training period and at the end of each month. The repetition maximum was measured every 2 weeks. Cardiac hypertrophy was determined by echocardiography, by the absolute weight of the cardiac chambers and by histology of the left ventricle.

RESULTS

Before resistance training, both groups had similar repetition maximums, ranging from 1.8-fold to 2-fold the body weight; however, at the end of the resistance-training period, the repetition maximum of the resistance-trained group was 6-fold greater than the body weight. The left ventricular mass as assessed by echocardiography was 8%, 12% and 16% larger in the resistance-trained group than in the control group in the first, second and third months, respectively. This hypertrophy showed a similar increase in the interventricular septum and in the free posterior wall mass. There was no reduction in the end-diastolic left ventricular internal diameter during the 3-month resistance-training period. Systolic function did not differ between the groups throughout the resistance-training period.

CONCLUSION

Resistance training induces the development of concentric cardiac hypertrophy without ventricular dysfunction or cavity reduction. Although diastolic function was not completely investigated, we cannot exclude the possibility that resistance training results in diastolic dysfunction.

Resistance Exercise Training in Patients with Heart Failure

The utility, safety and physiological adaptations of resistance exercise training in patients with chronic heart failure (CHF) are reviewed and recommendations based on current research are presented. Patients with CHF have a poor clinical status and impaired exercise capacity due to both cardiac limitations and peripheral maladaptations of the skeletal musculature. Because muscle atrophy has been demonstrated to be a hallmark of CHF, the main principle of exercise programmes in such patients is to train the peripheral muscles effectively without producing great cardiovascular stress. For this reason, new modes of training as well as new training methods have been applied. Dynamic resistance training, based on the principles of interval training, has recently been established as a safe and effective mode of exercise in patients with CHF. Patients perform dynamic strength exercises slowly, on specific machines at an intensity usually in the range of 50-60% of one repetition maximum; work phases are of short duration (< or =60 seconds) and should be followed by an adequate recovery period (work/recovery ratio >1 : 2). Patients with a low cardiac reserve can use small free weights (0.5, 1 or 3 kg), elastic bands with 8-10 repetitions, or they can perform resistance exercises in a segmental fashion. Based on recent scientific evidence, the application of specific resistance exercise programmes is safe and induces significant histochemical, metabolic and functional adaptations in skeletal muscles, contributing to the treatment of muscle weakness and specific myopathy occurring in the majority of CHF patients. Increased exercise tolerance and peak oxygen consumption (V-dotO(2peak)), changes in muscle composition, increases in muscle mass, alterations in skeletal muscle metabolism, improvement in muscular strength and endurance have also been reported in the literature after resistance exercise alone or in combination with aerobic exercise. According to new scientific evidence, appropriate dynamic resistance exercise should be recommended as a safe and effective alternative training mode (supplementary to conventional aerobic exercise) in order to counteract peripheral maladaptation and improve muscle strength, which is necessary for recreational and daily living activities, and thus quality of life, of patients with stable, CHF.