Comparison of left ventricular function during interval versus steady-state exercise training in patients with chronic congestive heart failure

Global trends and frontiers in research on exercise training for heart failure: a bibliometric analysis from 2002 to 2022

Background

Heart failure is a common cardiovascular disease that imposes a heavy clinical and economic burden worldwide. Previous research and guidelines have supported exercise training as a safe, effective, and cost-efficient treatment to intervene in heart failure. The aim of this study was to analyze the global published literature in the field of exercise training for heart failure from 2002 to 2022, and to identify hot spots and frontiers within this research field.

Methods

Bibliometric information on literature on the topic of exercise training for heart failure published between 2002 and 2022 was searched and collected in the Web of Science Core Collection. CiteSpace 6.1.R6 (Basic) and VOSviewer (1.6.18) were applied to perform bibliometric and knowledge mapping visualization analyses.

Results

A total of 2017 documents were retrieved, with an upward-stable trend in the field of exercise training for heart failure. The US authors were in the first place with 667 documents (33.07%), followed by Brazilian authors (248, 12.30%) and Italian authors (182, 9.02%). The Universidade de São Paulo in Brazil was the institution with the highest number of publications (130, 6.45%). The top 5 active authors were all from the USA, with Christopher Michael O'Connor and William Erle Kraus publishing the most documents (51, 2.53%). The International Journal of Cardiology (83, 4.12%) and the Journal of Applied Physiology (78, 3.87%) were the two most popular journals, while Cardiac Cardiovascular Systems (983, 48.74%) and Physiology (299, 14.82%) were the two most popular categories. Based on the results of keyword co-occurrence network and co-cited reference network, the hot spots and frontiers of research in the field of exercise training for heart failure were high-intensity interval training, behaviour therapy, heart failure with preserved ejection fraction, and systematic reviews.

Conclusion

The field of exercise training for heart failure has experienced two decades of steady and rapid development, and the findings of this bibliometric analysis provide ideas and references for relevant stakeholders such as subsequent researchers for further exploration.

High Intensity Interval Training Leads to Similar Inflammatory Activation as Seen With Traditional Training in Chronic Heart Failure

BACKGROUND

Inflammatory activation has been associated with the severity and progression of chronic heart failure (CHF). Although cardiac rehabilitation is an important therapy, acute bouts of exercise may lead to increases in pro-inflammatory cytokines with exercise intensity mediating these changes.

OBJECTIVE

To evaluate the acute inflammatory response in patients living with CHF during a randomized trial following Steady State (SS) or High Intensity Interval (HIIT) training.

METHODS

Patients living with CHF (n = 14) were stratified (for body mass and aerobic power) and randomized into SS and HIIT cycle exercise. The HIIT exercise training involved 2 min work:recovery phases at 90:40% heart rate reserve. The SS exercise training involved continuous exercise at 65% of heart rate reserve (matched total work). Acute inflammatory markers were evaluated (via ELISA) at baseline, immediately following the bout, and at 6, 24, and 48 h post-exercise.

RESULTS

There was limited differences in the changes in inflammatory biomarkers across time between the HIIT and SS groups. Both groups experienced a significant (p < 0.05) change in Interleukin-6 immediately post-exercise.

CONCLUSIONS

A single bout of HIIT or SS does not result in excessive inflammatory activation in CHF patients. Acute HIIT and SS result in similar changes in inflammatory markers. These findings have important implications for exercise training and rehabilitation programs in persons living with CHF.

Acute Cardiorespiratory Responses to Different Exercise Modalities in Chronic Heart Failure Patients-A Pilot Study

The purpose of this study was to compare the acute cardiorespiratory responses and time spent above different %VO_2peak intensities between three "iso-work" protocols: (a) a high intensity interval training protocol (HIIT), (b) a higher intensity continuous protocol (CON₇₀) and (c) a lower intensity continuous protocol (CON₅₀) in patients with chronic heart failure (CHF). Ten male CHF patients (aged 55.1 ± 16.2 years) performed in separate days a single session of a HIIT protocol consisted of 4 sets × 4 min cycling at 80% VO_2peak with 3 min of recovery at 50% VO_2peak, a CON₇₀ protocol corresponding to 70% VO_2peak and a CON₅₀ protocol corresponding to 50% VO_2peak. Cardiopulmonary data were collected by an online gas analysis system. The HIIT and CON₇₀ elicited higher cardiorespiratory responses compared to CON₅₀ with no differences between them (p > 0.05). In HIIT and CON₇₀, patients exercised longer at >80% and >90% VO_2peak. The completion rate was 100% for the three protocols. Not any adverse events were observed in either protocol. Both HIIT and CON₇₀ elicited a stronger physiological stimulus and required shorter time than CON₅₀. Both HIIT and CON₇₀ also induced comparable hemodynamic responses and ventilatory demand.

Functional Translation of Exercise Responses from Exercise Testing to Exercise Training: The Test of a Model

Exercise prescription based on exercise test results is complicated by the need to downregulate the absolute training intensity to account for cardiovascular drift in order to achieve a desired internal training load. We tested a recently developed generalized model to perform this downregulation using metabolic equivalents (METs) during exercise testing and training. A total of 20 healthy volunteers performed an exercise test to define the METs at 60, 70, and 80% of the heart rate (HR) reserve and then performed randomly ordered 30 min training bouts at absolute intensities predicted by the model to achieve these levels of training intensity. The training HR at 60 and 70% HR reserve, but not 80%, was significantly less than predicted from the exercise test, although the differences were small. None of the ratings of perceived exertion (RPE) values during training were significantly different than predicted. There was a strong overall correlation between predicted and observed HR (r = 0.88) and RPE (r = 0.52), with 92% of HR values within ±10 bpm and 74% of RPE values within ±1 au. We conclude that the generalized functional translation model is generally adequate to allow the generation of early absolute training loads that lead to desired internal training loads.

Evidence-Based Effects of High-Intensity Interval Training on Exercise Capacity and Health: A Review with Historical Perspective

Engaging in regular exercise results in a range of physiological adaptations offering benefits for exercise capacity and health, independent of age, gender or the presence of chronic diseases. Accumulating evidence shows that lack of time is a major impediment to exercise, causing physical inactivity worldwide. This issue has resulted in momentum for interval training models known to elicit higher enjoyment and induce adaptations similar to or greater than moderate-intensity continuous training, despite a lower total exercise volume. Although there is no universal definition, high-intensity interval exercise is characterized by repeated short bursts of intense activity, performed with a "near maximal" or "all-out" effort corresponding to ≥90% of maximal oxygen uptake or >75% of maximal power, with periods of rest or low-intensity exercise. Research has indicated that high-intensity interval training induces numerous physiological adaptations that improve exercise capacity (maximal oxygen uptake, aerobic endurance, anaerobic capacity etc.) and metabolic health in both clinical and healthy (athletes, active and inactive individuals without any apparent disease or disorder) populations. In this paper, a brief history of high-intensity interval training is presented, based on the novel findings of some selected studies on exercise capacity and health, starting from the early 1920s to date. Further, an overview of the mechanisms underlying the physiological adaptations in response to high-intensity interval training is provided.

High-intensity interval training for heart failure with preserved ejection fraction: A protocol for systematic review and meta-analysis

BACKGROUND

The benefits of high-intensity interval training (HIIT) are well-known, there is insufficient evidence about the effects of HIIT on heart failure with preserved ejection fraction (HFpEF).

METHOD

Multiple databases include MEDLINE, PubMed, EMBASE, CINAHL, Web of Science, PEDro, Cochrane Library, and Google Scholar are used to search for randomized controlled trials investigating the effects of HIIT on HFpEF. All related articles published with the English language with no time limitation will be included. Two reviews independently conducted the selection, data extraction, and quality assessment. The primary outcome is exercise capacity. The secondary outcomes include quality of life (QoL), blood pressure (BP), ventricular function, and left ventricular diastolic function, symptom improvement, endothelial function, and arterial stiffness. Data analysis is performed with Review Manager Software (Version 5.3).

RESULT

This systematic review and meta-analysis aim to evaluate the efficacy of HIIT on HFpEF, its outcome will provide reliable evidence for future studies.

CONCLUSION

The findings of this study will be published in a related peer-reviewed journal.

REGISTRATION NUMBER

INPLASY202050097.

Single-leg cycling increases limb-specific blood flow without concurrent increases in normalised power output when compared with double-leg cycling in healthy middle-aged adults

This study examined the acute performance, cardiovascular and local muscular responses to perceived exertion-based high-intensity interval exercise using either double- or single-leg cycling. Fifteen healthy middle-aged adults completed, on separate occasions, ten 30-s double-leg intervals interspersed with 60 s passive recovery and twenty (ten with each leg) 30-s single-leg intervals interspersed with 60 s passive recovery. Impedance cardiography, blood pressure, muscle oxygenation and total haemoglobin content (near-infrared spectroscopy), oxygen consumption and power output were measured throughout each session. Normalised to the lean mass used during each trial, single-leg cycling resulted in lower power output (single-leg: 8.92 ± 1.74 W kg^-1 and double-leg: 10.41 ± 3.22 W kg^-1; p < 0.05) but greater oxygen consumption (single-leg: 103 ± 11 mL kg^-1 min^-1 and double-leg: 84 ± 21 mL kg^-1 min^-1; p < 0.01) and cardiac output (single-leg: 1407 ± 334 mL kg^-1 min^-1 and double-leg: 850 ± 222 mL kg^-1 min^-1; p < 0.01), compared with double-leg cycling. Mean arterial pressure (double-leg: 108 ± 11 mmHg and single-leg: 102 ± 10 mmHg), change in total haemoglobin content (double-leg: 8.76 ± 10.65 µM cm s^-1 and single-leg: 13.42 ± 4.10 µM cm s^-1) and change in tissue oxygenation index (double-leg: -4.51 ± 3.56% and single-leg: -3.97 ± 3.91%) were not different between double-leg and single-leg cycling. When compared to double-leg cycling, single-leg cycling elicited a higher cardiac output relative to the lean mass, but this did not result in greater power output. The dissociation between blood availability and power output is consistent with an ageing model characterised by a decrease in local oxygen delivery and distribution capability.

Provocative issues in heart disease prevention

In this article, new areas of cardiovascular (CV) prevention and rehabilitation research are discussed: high-intensity interval training (HIIT) and new concepts in nutrition. HIIT consists of brief periods of high-intensity exercise interspersed by periods of low-intensity exercise or rest. The optimal mode according our work (15-second exercise intervals at peak power with passive recovery intervals of the same duration) is associated with longer total exercise time, similar time spent near peak oxygen uptake (VO2 peak) VO2 peak, and lesser perceived exertion relative to other protocols that use longer intervals and active recovery periods. Evidence also suggests that compared with moderate-intensity continuous exercise training, HIIT has superior effects on cardiorespiratory function and on the attenuation of multiple cardiac and peripheral abnormalities. With respect to nutrition, a growing body of evidence suggests that the gut microbiota is influenced by lifestyle choices and might play a pivotal role in modulating CV disease development. For example, recent evidence linking processed (but not unprocessed) meats to increased CV risk pointed to the gut microbial metabolite trimethylamine N-oxide as a potential culprit. In addition, altered gut microbiota could also mediate the proinflammatory and cardiometabolic abnormalities associated with excess added free sugar consumption, and in particular high-fructose corn syrup. Substantially more research is required, however, to fully understand how and which alterations in gut flora can prevent or lead to CV disease and other chronic illnesses. We conclude with thoughts about the appropriate role for HIIT in CV training and future research in the role of gut flora-directed interventions in CV prevention.

High-intensity aerobic interval exercise in chronic heart failure

Aerobic exercise training is strongly recommended in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF) to improve symptoms and quality of life. Moderate-intensity aerobic continuous exercise (MICE) is the best established training modality in HF patients. For about a decade, however, another training modality, high-intensity aerobic interval exercise (HIIE), has aroused considerable interest in cardiac rehabilitation. Originally used by athletes, HIIE consists of repeated bouts of high-intensity exercise interspersed with recovery periods. The rationale for its use is to increase exercise time spent in high-intensity zones, thereby increasing the training stimulus. Several studies have demonstrated that HIIE is more effective than MICE, notably for improving exercise capacity in patients with HF. The aim of the present review is to describe the general principles of HIIE prescription, the acute physiological effects, the longer-term training effects, and finally the future perspectives of HIIE in patients with HF.

Circulating endothelial and progenitor cells: Evidence from acute and long-term exercise effects

Circulating bone-marrow-derived cells, named endothelial progenitor cells (EPCs), are capable of maintaining, generating, and replacing terminally differentiated cells within their own specific tissue as a consequence of physiological cell turnover or tissue damage due to injury. Endothelium maintenance and restoration of normal endothelial cell function is guaranteed by a complex physiological procedure in which EPCs play a significant role. Decreased number of peripheral blood EPCs has been associated with endothelial dysfunction and high cardiovascular risk. In this review, we initially report current knowledge with regard to the role of EPCs in healthy subjects and the clinical value of EPCs in different disease populations such as arterial hypertension, obstructive sleep-apnea syndrome, obesity, diabetes mellitus, peripheral arterial disease, coronary artery disease, pulmonary hypertension, and heart failure. Recent studies have introduced the novel concept that physical activity, either performed as a single exercise session or performed as part of an exercise training program, results in a significant increase of circulating EPCs. In the second part of this review we provide preliminary evidence from recent studies investigating the effects of acute and long-term exercise in healthy subjects and athletes as well as in disease populations.

Central hemodynamic responses during acute high-intensity interval exercise and moderate continuous exercise in patients with heart failure

The aim of this study was to compare the acute hemodynamic responses during high-intensity intermittent exercise (HIIE) session compared with moderate-intensity continuous exercise (MICE) session in patients with heart failure and reduced ejection fraction (HFREF). Thirteen patients with HFREF (age, 59 ± 6 years; left ventricular ejection fraction, 27% ± 6%; New York Heart Association class I to III) were randomly assigned to a single session of HIIE (2 × 8 min) corresponding to 30 s at 100% of peak power output (PPO) and 30 s passive recovery intervals or to a MICE (22 min) at 60% of PPO. Gas exchange and central hemodynamic parameters (cardiac bioimpedance) were measured continuously during exercise. Oxygen uptake, stroke volume (SV), cardiac output (CO), and arterio-venous difference (C(a-v)O(2)) were compared. Mean oxygen uptake and ventilation were lower during HIIE vs. MICE. CO, SV, and C(a-v)O(2)) were not different between MICE and HIIE. Optimized HIIE was well tolerated (similar perceived exertion) and no significant ventricular arrhythmias and (or) abnormal blood pressure responses occurred during HIEE session. Compared with MICE, optimized HIIE elicited similar central hemodynamic and C(a-v)O(2) responses in HFREF patients with lower oxygen uptake and ventilation. HIIE may be an efficient exercise training modality in patients with HFREF.

Acute responses to intermittent and continuous exercise in heart failure patients

BACKGROUND

The purpose of this study was to compare cardiopulmonary responses, exercise adherence, tolerance, and safety of optimized high-intensity interval exercise (HIIE) compared with moderate-intensity continuous exercise (MICE) in patients with heart failure and reduced ejection fraction (HFREF).

METHODS

Twenty patients with HFREF (aged 61 ± 9.9 years) were randomly assigned to HIIE corresponding to 2 × 8 minutes of 30-second intervals at 100% of peak power output and 30-second passive recovery intervals and to a 22-minute MICE corresponding to 60% of peak power output. Gas exchange, electrocardiogram, and blood pressure were measured continuously. Cardiac troponin T (cTnT), C-reactive protein (CRP), and brain natriuretic peptide (BNP) were measured before, 20 minutes after, and 24 hours after HIIE and MICE.

RESULTS

Cardiopulmonary responses did not differ between MICE and HIIE. Higher exercise adherence and efficiency were observed on HIIE with a similar perceived exertion and time spent above 90% of peak oxygen consumption compared with MICE. Neither HIIE nor MICE caused any significant arrhythmias or increased CRP, BNP, or cTnT.

CONCLUSIONS

Compared with MICE, HIIE demonstrated a higher exercise adherence and was well tolerated in patients with HFREF, while still providing a high-level physiological stimulus and leaving indices of inflammation (CRP), myocardial dysfunction (BNP), and myocardial necrosis (cTnT) unaffected.

High-intensity interval training in cardiac rehabilitation

High-intensity interval training (HIIT) is frequently used in sports training. The effects on cardiorespiratory and muscle systems have led scientists to consider its application in the field of cardiovascular diseases. The objective of this review is to report the effects and interest of HIIT in patients with coronary artery disease (CAD) and heart failure (HF), as well as in persons with high cardiovascular risk. A non-systematic review of the literature in the MEDLINE database using keywords 'exercise', 'high-intensity interval training', 'interval training', 'coronary artery disease', 'coronary heart disease', 'chronic heart failure' and 'metabolic syndrome' was performed. We selected articles concerning basic science research, physiological research, and randomized or non-randomized interventional clinical trials published in English. To summarize, HIIT appears safe and better tolerated by patients than moderate-intensity continuous exercise (MICE). HIIT gives rise to many short- and long-term central and peripheral adaptations in these populations. In stable and selected patients, it induces substantial clinical improvements, superior to those achieved by MICE, including beneficial effects on several important prognostic factors (peak oxygen uptake, ventricular function, endothelial function), as well as improving quality of life. HIIT appears to be a safe and effective alternative for the rehabilitation of patients with CAD and HF. It may also assist in improving adherence to exercise training. Larger randomized interventional studies are now necessary to improve the indications for this therapy in different populations.

Acute Responses to High-Intensity Intermittent Exercise in CHD Patients

PURPOSE

although the acute physiological responses to continuous exercise have been well documented in CHD patients, no previous study has examined the responses to high-intensity intermittent exercise in these patients. The purpose of this study was to compare the physiological responses to a high-intensity interval exercise (HIIE) protocol versus a moderate-intensity continuous exercise (MICE) protocol of similar energy expenditure in CHD patients.

METHODS

twenty patients with stable CHD (19 males and 1 female, 62 ± 11 yr) were assigned in random order to a single session of HIIE corresponding to 15-s intervals at 100% of peak power output (PPO) and 15-s passive recovery intervals and, 2 wk later, to an isocaloric MICE corresponding to 70% of PPO.

RESULTS

both protocols were equivalent in terms of energy expenditure. The HIIE protocol resulted in lower mean ventilation (P < 0.001) for a small difference in metabolic demand. All participants preferred the HIIE mainly because the perceived exertion measured by the Borg scale was lower (P < 0.05). No elevation of serum concentration of troponin T was found in all participants at baseline and at 20 min and 24 h after the exercise sessions, thus excluding the presence of any exercise-induced myocardial injury in our patients.

CONCLUSIONS

when considering physiological responses, safety, and perceived exertion, the HIIE protocol seemed to be well tolerated and more efficient in this group of stable CHD patients.

Task-related oxygen uptake and symptoms during activities of daily life in CHF patients and healthy subjects

Patients with chronic heart failure (CHF) have a significantly lower peak aerobic capacity compared to healthy subjects, and, may therefore experience more inconvenience during the performance of domestic activities of daily life (ADLs). To date, the extent to which task-related oxygen uptake, heart rate, ventilation and symptoms during the performance of ADLs in CHF patients is different than in healthy subjects remains uncertain. General demographics, pulmonary function, body composition and peak aerobic capacity were assessed in 23 CHF outpatients and 20 healthy peers. In addition, the metabolic requirement of five simple self-paced domestic ADLs was assessed using a mobile oxycon. Task-related oxygen uptake (ml/min) was similar or lower in CHF patients compared to healthy subjects. In contrast, patients with CHF performing ADLs consumed oxygen at a higher proportion of their peak aerobic capacity than healthy subjects (p < 0.05). For example, getting dressed resulted in a mean task-related oxygen uptake of 49% of peak aerobic capacity, while sweeping the floor resulted in a mean task-related oxygen uptake of 52% of peak aerobic capacity, accompanied by significantly higher Borg symptom scores for dyspnea and fatigue (p < 0.05). Patients with CHF experience use a higher proportion of their peak aerobic capacity, peak ventilation and peak heart rate during the performance of simple self-paced domestic ADL than their healthy peers. These findings represent a necessary step in improving our understanding of improving what troubles patients the most—not being able to do the things that they could when they were healthy.

Systematic review of the effect of aerobic and resistance exercise training on systemic brain natriuretic peptide (BNP) and N-terminal BNP expression in heart failure patients

BACKGROUND

BNP and the N-terminal portion (NT-pro-BNP) have emerged as powerful tools in the diagnosis and prognosis of heart failure on acute presentation. The aim of this work was to systematically review the effect of exercise training on BNP and NT-pro-BNP levels in patients with left ventricular dysfunction.

METHODS

A systematic search was conducted of Medline (Ovid) (1950-July 2008), Embase.com (1974-current), Cochrane Central Register of Controlled Trials, CINAHL (1981-current) and Web of Science (2000-current) to identify randomized controlled trials of aerobic and/or resistance exercise training in heart failure patients that measured BNP and/or pro-BNP. Primary outcome measures were changes in BNP and NT-pro-BNP. Secondary outcomes were changes in functional capacity and energy expenditure, measures of study quality were also recorded.

RESULTS

Nine randomized controlled studies measuring BNP or NT-pro-BNP met our eligibility criteria. Exercise training had a favourable effect on BNP (mean difference -79 pg/ml 95% C.I. -141 to - 17 pg/ml, P=0.01) and NT-pro-BNP (mean difference -621 pg/ml, 95% C.I. -844 to -398 pg/ml, P=<0.00001). Moreover the trials that showed a significant change in NT-pro-BNP all had a weekly exercise energy expenditure of more than 400 Kcal.

CONCLUSION

Data from nine published studies, suggest exercise training has a favorable effect on BNP and NT-pro-BNP in heart failure patients.

Training in the aging athlete

The number of healthy older individuals who are active in sports has increased significantly during the past generation. These individuals continue to perform at a high level, although there appears to be a loss in functional capacity that cannot be overcome by training. No accepted theory of aging exists, but older athletes may be limited primarily by the inability to maintain the same volume and intensity of training. Also, older athletes appear to respond more slowly to the same training load than do younger athletes. The principles of training in older athletes are similar to those in young athletes; however, additional days of recovery and cross training may be necessary to prevent orthopedic injuries. Strategies for maintaining exercise intensity, including resistance training, are advisable to prevent sarcopenia and selective loss of type II muscle fibers.

Interval exercise is a path to good health, but how much, how often and for whom?

Interval exercise training has now been examined in a wide variety of individuals, ranging from elite athletes to patients with severe cardiovascular disease. The advantages of interval exercise training programmes in comparison with constant intensity exercise programmes are that they appear to deliver superior improvements in several cardiovascular risk factors, fitness and performance. Depending on the design, some interval exercise programmes result in a range of benefits, even though the time commitment may be dramatically less than more traditional continuous intensity programmes. In the present issue of Clinical Science, a study by Tjønna and co-workers demonstrates that aerobic interval training may also be a powerful tool in combating the increased cardiovascular risk observed in overweight adolescents.

Exercise training for patients with cardiovascular disease

This review surveys effort training, a validated and recommended therapy, in patients with atheromatous cardiovascular disease. This true therapy reduces mortality by 25-35%, reduces clinical manifestations and complications (rhythm problems, thrombosis) and improves physical capacity, reintegration and quality of life. The effects are essentially linked to improved metabolic performance of muscles and reduced endothelial dysfunction, insulin resistance and neurohormonal abnormalities. Training also has an impact on the evolution of major risk factors, especially diabetes and arterial hypertension. The risks are limited as long as the contraindications are respected and the programmes supervised. The indications (stable angina, chronic heart failure, peripheral arterial disease) should be described more precisely by taking into account functional criteria: physical deconditioning, exclusion, compliance, mood swings, and seriousness of risk factors. The training programme should be tailor made and based on evaluation of the patient's adaptation to effort, in terms of frequency, intensity and duration of the exercises. Various types of exercise include overall or segmental physical training; concentric, eccentric, even isokinetic muscle contraction exercises; and proprioceptive rehabilitation. However, knowledge is lacking about the molecular mechanisms of the effects of training, the most effective intensity of effort, and strategies to develop physical activity in this ever-growing population for both primary and secondary prevention.

[Exercise training in cardiac patients: usefulness of the cardiopulmonary exercise test]

Exercise training is currently including in the treatment of coronary arterial disease patients, in patients with left ventricular dysfunction as well as in patients who underwent cardiac transplantation or cardiac surgery. However methods of prescribing exercise-training programs are difficult to determine and must be adapted for each patient Exercise test with gas analysis through the determination of anaerobic threshold may help to understand the physiopathological mechanism related to exercise limitation in these patients. Exercise test may help to precise exercise intensity during cardiac rehabilitation and may assess the benefits on exercise tolerance.

Exercise programmes for patients with chronic heart failure

The safety and efficacy of exercise training in patients with chronic heart failure (CHF) have been reported in a large number of scientific studies, with endurance training representing the most frequently applied training stimulus. Beneath the common continuous method of endurance training, the interval method (short bouts of intense exercise interspersed with pre-scheduled rest intervals), was also applied in some studies. Ergometric testing is a prerequisite for all individualised training prescription and is an appropriate method of efficacy documentation. However, there is a surprisingly large range of exercise intensities being prescribed to patients with CHF. Most of the prescription models refer to maximal ergometric measurements. Submaximal references from lactate and ventilatory curves represent an alternative method in measuring accuracy and efficacy of training. The course of heart rate during submaximal incremental exercise can be reliably used to indicate endurance gains in CHF. Some positive reports exist for carefully executed strength endurance training for patients with CHF and there are convincing arguments for the use of coordination and flexibility exercises; however, substantial scientific evidence is lacking.

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.

Réadaptation physique des patients insuffisants cardiaques chroniques

A BENEFICIAL METHOD: Heart failure combines with peripheral vascular and muscular abnormalities that can be effectively improved by rehabilitation. The data in the literature appears to demonstrate the efficacy and excellent tolerance of such exercise. Regarding functional results and improved quality of life, rehabilitation is as equally efficient as the medical treatment that it completes. It can currently be proposed to the majority of patients exhibiting left ventricular systolic dysfunction and who are are only partially improved with medical treatment alone. MODALITIES: The rehabilitation of heart failure must, optimally, be set-up in ambulatory settings, notably within the context of a health care network. Its modalities remain to be specified in on-going studies and its impact on prognosis has to be determined.

Encouraging exercise in older adults with congestive heart failure

Congestive heart failure (CHF) is a chronic medical problem commonly found in older adults. Management of CHF ideally should combine lifestyle modifications and medication management. Exercise prescriptions and encouraging patients with CHF to exercise can have a significant impact on management of symptoms as well as exacerbation of further disease. The recommended exercise program should ideally incorporate 10 to 15 minutes of warm-up with exercise durations of 20 to 30 minutes and a cool-down period generally repeating the warm up exercises. Exercise should be done at least 3 to 5 days per week and should include a combination of aerobic and resistance exercise. The HEART approach provides a useful guide to help motivate older adults with CHF to exercise regularly. In so doing, older adults with CHF will be helped to improve and maintain cardiac status, decrease the symptoms of CHF, and improve overall quality of life.

Exercise training for patients with heart failure: a systematic review of factors that improve mortality and morbidity

PURPOSE

To determine the efficacy of exercise training and its effects on outcomes in patients with heart failure.

METHODS

MEDLINE, Medscape, and the Cochrane Controlled Trials Registry were searched for trials of exercise training in heart failure patients. Data relating to training protocol, exercise capacity, and outcome measures were extracted and reviewed.

RESULTS

A total of 81 studies were identified: 30 randomized controlled trials, five nonrandomized controlled trials, nine randomized crossover trials, and 37 longitudinal cohort studies. Exercise training was performed in 2387 patients. The average increment in peak oxygen consumption was 17% in 57 studies that measured oxygen consumption directly, 17% in 40 studies of aerobic training, 9% in three studies that only used strength training, 15% in 13 studies of combined aerobic and strength training, and 16% in the one study on inspiratory training. There were no reports of deaths that were directly related to exercise during more than 60,000 patient-hours of exercise training. During the training and follow-up periods of the randomized controlled trials, there were 56 combined (deaths or adverse events) events in the exercise groups and 75 combined events in the control groups (odds ratio [OR] = 0.98; 95% confidence interval [CI]: 0.61 to 1.32; P = 0.60). During this same period, 26 exercising and 41 nonexercising subjects died (OR = 0.71; 95% CI: 0.37 to 1.02; P = 0.06).

CONCLUSION

Exercise training is safe and effective in patients with heart failure. The risk of adverse events may be reduced, but further studies are required to determine whether there is any mortality benefit.

Exercise training as a therapy for chronic heart failure: can older people benefit?

Despite recent advances in pharmacological therapy, chronic heart failure remains a major cause of morbidity and mortality in older people. Studies of exercise training in younger, carefully selected patients with heart failure have shown improvements in symptoms and exercise capacity and in many pathophysiological aspects of heart failure, including skeletal myopathy, ergoreceptor function, heart rate variability, endothelial function, and cytokine expression. Data on mortality and hospitalization are lacking, and effects on everyday activity, depression, and quality of life are unclear. Exercise therapy for patients with heart failure appears to be safe and has the potential to improve function and quality of life in older people with heart failure. To realize these potential benefits, exercise programs that are suitable for older, frail people need to be established and tested in an older, frail, unselected population with comorbidities.

Hemodynamic responses during aerobic and resistance exercise

PURPOSE

Resistance training has become an accepted part of cardiac rehabilitation programs. Because of the potential for a high afterload to have a negative impact on left ventricular function, there has been concern regarding the safety of resistance training for patients with congestive heart failure.

METHODS

This study addressed this concern by studying 12 healthy volunteers, 12 patients with stable coronary artery disease, and 12 patients with stable congestive heart failure during upright cycling at 90% of ventilatory threshold, and during one set of 10 repeated leg presses, shoulder presses, and biceps curls at 60% to 70% of 1-repetition maximum. Left ventricular function was measured by echocardiography.

RESULTS

The pattern of changes in heart rate, blood pressure, left ventricular ejection fraction, wall thickness, and left ventricular internal diameters was similar across all three groups of subjects, although there were large differences in absolute values. Despite elevations in diastolic and mean arterial pressures during resistance exercise, there was no evidence of significant rest-to-exercise deterioration in left ventricular function during leg press (ejection fraction, 60%-59%, 56%-55%, and 38%-37%), shoulder press (66%-65%, 59%-53%, and 38%-35%), or biceps curls (63%-58%, 53%-54%, and 35%-36%), as compared with cycle ergometry (63%-69%, 51%-57%, and 35%-42%) in the healthy control subjects, the patients with coronary artery disease, and the patients with congestive heart failure, respectively.

CONCLUSIONS

Left ventricular function remains stable during moderate-intensity resistance exercise, even in patients with congestive heart failure, suggesting that this form of exercise therapy can be used safely in rehabilitation programs.

Physical activity and exercise training prescriptions for patients

The dominant outcome from exercise prescription is an increase in various markers of exercise capacity. A very large group of studies have demonstrated that the VO2max is increased in response to exercise performed according to well-accepted principles of exercise prescription. Other markers of exercise capacity, such as the VT, also improve substantially following exercise training. Finally, improvement in exercise capacity is generally related to improved quality of life, particularly in patients with exercise capacity limited by various disease processes. Beyond the specific physiologic gains from training, exercise contributes to a better overall clinical outcome. Although there are few data conclusively demonstrating that exercise independently causes favorable changes in other risk factors, it should be recognized that exercise can contribute indirectly to modulation of other risk factors. Exercise represents positive health advice. Since most of our other recommendations to patients are in the nature of negative advice (e.g., don't smoke, don't eat high-fat foods), and since people are infamous for ignoring negative advice, the value of using a positive recommendation that may indirectly lead the patient to discontinue bad behaviors can hardly be overstated.

Metabolic responses associated with deer hunting

PURPOSE

Deer hunting is a popular recreational activity with a high rate of cardiovascular events. Previous studies have demonstrated large HR responses during deer hunting. This study compared the HR and metabolic costs of maximal treadmill (TM) exercise with those of hiking while deer hunting and while dragging a deer.

METHODS

Healthy male volunteers (N = 16) performed a maximal TM exercise test, a 0.8-km hiking test, and a 0.4-km dragging test over lightly rolling terrain. VO2 was measured by portable spirometry and HR by radiotelemetry.

RESULTS

HR averaged 74.0 +/- 7.0% and 89.1 +/- 4.5% of peak TM HR during the hike and drag, respectively. The peak HR observed during hiking and dragging was 83.2 +/- 6.0% and 94.9 +/- 4.2% of peak TM HR, respectively. VO2 averaged 62.2 +/- 15.8% and achieved a peak of 77.2 +/- 19.0% of TM VO2 while hiking. This corresponded to 86.8 +/- 17.3% and 108.1 +/- 22.3% of ventilatory threshold (VT), respectively. VO2 averaged 72.3 +/- 21.0% and achieved a peak of 91.2 +/- 21.4% of peak TM VO2 while dragging the deer. This corresponded to 101.5 +/- 27.7% and 128.5 +/- 26.8% of VT, respectively. The VO2/HR relationship showed significant (P < 0.05) difference between the dragging test and the TM test with a disproportionately high HR. The VO2/HR relationship between the hiking and TM tests was comparable.

CONCLUSION

In part, the previously described large HR responses and high rate of cardiovascular complications associated with deer hunting may attributable to the elevated metabolic costs of associated activities.

Left ventricular function during interval and steady state exercise

PURPOSE

Interval training (INT) is a commonly used method of exercise training in both athletic and clinical populations. Although we generally understand left ventricular (LV) function during steady state (SS) exercise, there are no data regarding LV function during INT.

METHODS

We studied eight healthy, physically active volunteers during upright cycle ergometry during 15 min of both SS and INT, at the same average power output (90% individual anaerobic threshold), using first pass radionuclide ventriculography. During INT (60s/60s), measures of LV function were made during work (220 W) after 4 and 12 min and during recovery (120 W) after 7 and 15 min. These were compared with the average of four temporally matched measures made during SS (170 W).

RESULTS

During INT, LV ejection fraction increased from rest (67 +/- 6%) to 77 +/- 5, 80 +/- 5, 77 +/- 5 and 79 +/- 4% after 4, 7, 12, and 15 min, respectively. During SS, LV ejection fraction was not significantly different at rest (70 +/- 4%) or during exercise (76 +/- 4, 79 +/- 4, 80 +/- 3, and 81 +/- 3%) after 4, 7, 12, and 15 min, respectively. Other measures of LV function (HR, BP, LV volumes, cardiac output, systemic vascular resistance, peak emptying, and filling rates) were likewise similar during temporally matched measurements during INT and SS.

CONCLUSIONS

Although there were the expected transitions of ejection fraction with work and recovery, the overall hemodynamic picture during INT was very similar to SS. These data suggest that LV function during INT is not substantially different to that during SS.