Should high-intensity-aerobic interval training become the clinical standard in heart failure?

Role of exercise therapy and cardiac rehabilitation in heart failure

Heart failure (HF) is a common cause of hospitalization and death, and the hallmark symptoms of HF, including dyspnea, fatigue, and exercise intolerance, contribute to poor patient quality of life (QoL). Cardiac rehabilitation (CR) is a comprehensive disease management program incorporating exercise training, cardiovascular risk factor management, and psychosocial support. CR has been demonstrated to effectively improve patient functional status and QoL among patients with HF. However, CR participation among patients with HF is poor. This review details the mechanisms of dyspnea and exercise intolerance among patients with HF, the physiologic and clinical improvements observed with CR, and the key components of a CR program for patients with HF. Furthermore, unmet needs and future strategies to improve patient participation and engagement in CR for HF are reviewed.

Medical Rehabilitation of Patients with Post-COVID-19 Syndrome-A Comparison of Aerobic Interval and Continuous Training

INTRODUCTION

Post-COVID-19 syndrome (PCS) is a multisystemic disorder marked by impaired physical performance as one lead symptom. Since it has been suggested that endurance training as part of medical rehabilitation may be effective in improving physical performance capacity in PCS, this study aimed to compare different modes of aerobic endurance training.

METHODS

A total of 110 PCS patients (49.3 ± 11.8 years; 38% women; time after infection = 260.2 ± 127.5 days) underwent detailed clinical screening including symptom-limited cardiopulmonary exercise testing at admission and after 4-6 weeks of inpatient medical rehabilitation. Questionnaires were used to assess disease perception. Patients performed controlled isocaloric cycle ergometer training (3-5 sessions/week; 18 min) as either continuous training (CT) at 50% of maximal workload or as interval training (IT; load = 60%, relief = 30%). Outcomes of PCS patients were compared to coronary artery disease patients (CAD; n = 96) to evaluate overall training effectiveness.

RESULTS

Training participation was comparable between the groups, with no indication of training-specific exercise-induced fatigue. Overall, PCS patients improved significantly by a mean of 6.8 ± 12.1% for W at VT1; 3.1 ± 10.0% for VO2 at VT1; 5.5 ± 14.7% for O2 pulse at VT1; 7.5 ± 15.0% for W at VO2peak; 2.7 ± 11.0% for VO2peak and 4.6 ± 12.4% for O2 pulse at VO2peak (all p < 0.05) with no significant differences between groups (p > 0.05). Both groups showed reduced levels of fatigue, anxiety, and depression as well as improved quality of life and wellbeing (all p < 0.05). Compared to guideline-based cardiac rehabilitation, PCS patients showed a similar improvement in workload and oxygen uptake compared to CAD patients.

CONCLUSION

PCS patients benefit from aerobic endurance training performed as moderate continuous or interval training as part of a medical rehabilitation program in terms of improved physical exercise capacity and disease perception. The results for PCS patients are comparable to the guideline-based rehabilitation of CAD patients.

Comparison of high-intensity interval training versus moderate-intensity continuous training in pulmonary rehabilitation for interstitial lung disease: a randomised controlled pilot feasibility trial

OBJECTIVES

This study aimed to investigate the feasibility and efficacy of high-intensity interval training (HIIT) compared with moderate-intensity continuous training (MICT) in pulmonary rehabilitation (PR) for people with interstitial lung disease (ILD).

DESIGN

Single-centre, randomised controlled feasibility, pilot trial.

SETTING

Patients were recruited from the chest clinic of a tertiary ILD centre and attended circuit-based PR in the hospital's gym, followed by a personalised 6-month community programme.

PARTICIPANTS

58 patients, stratified per ILD type, were randomised into two groups: 33 to HIIT (18 males:15 females) (mean age (SD): 70.2 (11.4) years) and 25 to the MICT exercise mode (14 males:11 females) (mean age (SD): 69.8 (10.8) years).

INTERVENTIONS

8-week, twice weekly, circuit-based PR programme of exercise and education, followed by a personalised 6-month community exercise programme.

OUTCOME MEASURES

Feasibility outcomes included staff-to-patient ratio and dropout rates per group. Primary outcome was the 6 min walk distance (6MWD). Secondary outcomes included the sniff nasal pressure, mouth inspiratory and expiratory pressures, handgrip and quadriceps strength and health status. Random-effects models were used to evaluate average variation in outcomes through time across the two groups.

RESULTS

The 6MWD peaked earlier with HIIT compared with MICT (at 4 months vs 5 months) but values were lower at peak (mean (95% CI): 26.3 m (3.5 to 49.1) vs 51.6 m (29.2 to 73.9)) and declined faster at 6 months post-PR. Secondary outcomes showed similar faster but smaller improvements with HIIT over MICT and more consistent maintenance 6 months post-PR with MICT than HIIT.

CONCLUSIONS

HIIT is feasible in circuit-based ILD PR programmes and provides quick improvements but requires closer supervision of training and resources than MICT and benefits may be less well sustained. This would make it a less attractive option for clinical PR programmes. A definitive, multicentre randomised controlled trial is required to address the role of HIIT in ILD.

TRIAL REGISTRATION NUMBER

ISRCTN55846300.

Exercise interventions for patients with type 1 diabetes mellitus: A narrative review with practical recommendations

Type 1 diabetes mellitus (T1DM) is a chronic endocrine disease that results from autoimmune destruction of pancreatic insulin-producing β cells, which can lead to microvascular (e.g., retinopathy, neuropathy, and nephropathy) and macro-vascular complications (e.g., coronary arterial disease, peripheral artery disease, stroke, and heart failure) as a consequence of chronic hyperglycemia. Despite the widely available and compelling evidence that regular exercise is an efficient strategy to prevent cardiovascular disease and to improve functional capacity and psychological well-being in people with T1DM, over 60% of individuals with T1DM do not exercise regularly. It is, therefore, crucial to devise approaches to motivate patients with T1DM to exercise, to adhere to a training program, and to inform them of its specific characteristics (e.g., exercise mode, intensity, volume, and frequency). Moreover, given the metabolic alterations that occur during acute bouts of exercise in T1DM patients, exercise prescription in this population should be carefully analyzed to maximize its benefits and to reduce its potential risks.

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02792-6.

Effect of Age and Acute-Moderate Intensity Exercise on Biomarkers of Renal Health and Filtration

Aerobic exercise elicits a multitude of physiological improvements in both healthy and diseased populations. However, acute changes in renal health and filtration with aerobic exercise remain difficult to quantify by traditional biomarkers to estimate glomerular filtration rate (eGFR). This study aimed to determine if an acute bout of moderate-intensity aerobic exercise transiently improves non-traditional biomarkers when compared to traditional biomarkers of renal health and filtration in individuals without cardiometabolic diseases. Thirty-nine participants (n = 18 men; n = 21 women; age 32.5 + 12.6 yr; height 171.1 + 11.4 cm; weight 78.7 + 15.6 kg; BMI 27.1 + 5.8) completed a single bout of moderate-intensity (50-60% HRR) aerobic exercise. Blood and urine samples were collected and compared before and post-exercise. Serum creatinine, urine epidermal growth factor (uEGF), uEGF/urine creatinine ratio (uEGFR), and cystatin C (CyC) were measured. In addition, eGFR-MDRD and the CKD-epidemiology equations were used to analyze renal clearance. Relative to pre-exercise measures: serum creatinine (p = 0.26), uEGF (p = 0.35), and uEGFR (p = 0.09) remained unchanged, whereas cystatin C (p = 0.00) significantly increased post-exercise. CyC eGFR was the only estimator of renal filtration to significantly change (p = 0.04). In conclusion, CyC is the only biomarker of renal health and filtration to significantly increase after aerobic exercise. Further investigation focused on sampling time and exercise-intensity is needed to solidify the current understanding of renal health and filtration.

Effects of High-Intensity Interval vs. Moderate-Intensity Continuous Training on Cardiac Rehabilitation in Patients With Cardiovascular Disease: A Systematic Review and Meta-Analysis

Background

Studies have shown that high-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) for increasing peak oxygen uptake (VO_2peak) and reducing cardiovascular disease (CVD) and mortality. To our knowledge, previously published systematic reviews have neither compared different HIIT models with MICT nor investigated intervention frequencies of HIIT vs. MICT for purposes of improving cardiorespiratory fitness in patients with CVD.

Objective

The purpose of this meta-analysis was to compare the effects of different training models, intervention frequencies and weeks of HIIT vs. MICT on changes in cardiorespiratory fitness during cardiac rehabilitation (CR).

Methods

A systematic search was carried out for research articles on randomized controlled trials (RCTs) indexed in the PubMed, Cochrane Library, Web of Science, Embase and Scopus databases for the period up to December 2021. We searched for RCTs that compared the effect of HIIT vs. MICT on cardiorespiratory fitness in patients with CVD.

Results

Twenty-two studies with 949 participants (HIIT: 476, MICT: 473) met the inclusion criteria. Sensitivity analysis revealed that HIIT increased VO_2peak more than MICT (MD = 1.35). In the training models and durations, there was a greater increase in VO_2peak with medium-interval HIIT (MD = 4.02) and more than 12 weeks duration (MD = 2.35) than with MICT. There were significant improvements in VO_2peak with a HIIT frequency of 3 times/week (MD = 1.28). Overall, one minor cardiovascular and four non-cardiovascular adverse events were reported in the HIIT group, while six non-cardiovascular adverse events were reported in the MICT group.

Conclusion

HIIT is safe and appears to be more effective than MICT for improving cardiorespiratory fitness in patients with CVD. Medium-interval HIIT 3 times/week for more than 12 weeks resulted in the largest improvement in cardiorespiratory fitness during CR.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021245810, identifier: CRD42021245810.

Effects of resistance training on baroreflex sensitivity function in healthy males

[Purpose] This experimental study examined the effects of resistance exercises with three intensities on baroreflex sensitivity (BRS) in healthy males. [Participants and Methods] This study enrolled 27 sedentary healthy males with the following demographic characteristics: mean age, 19.9 years; body mass, 63.4 kg; height, 171.7 cm; and body mass index, 21.5 kg/m². The participants performed 20 alternating knee extensions while sitting, and each excursion comprised 5-seconds contraction and rest periods with 20%, 50% and 80% loads of one repetition maximum. The main outcome measures examined in this study were autonomic nerve activities and BRS during the low-intensity resistance exercise utilizing cardiographic and hemodynamic impedance parameters for cardiac function. While measuring the spectral powers of high-frequency (HF) and low frequency (LF) regions, a continuous RR series of the heart rate was calculated. Moreover, the LF/HF ratio of the RR interval variability power and the HF normalized unit (HFnu) were calculated as parameters for sympathetic and parasympathetic nerve activities. [Results] After the low-intensity resistance training, a significant decrease in the LF/HF ratio associated with significant increases in HFnu and BRS were observed. [Conclusion] Low-intensity resistance training may enhance BRS function in healthy males.

Effect of High-Intensity Interval Training on Physical Health in Coronary Artery Disease Patients: A Meta-Analysis of Randomized Controlled Trials

The effects of exercise-based cardiac rehabilitation (CR) on physical health in coronary artery disease (CAD) patients has long been established, while the optimal exercise mode remains to be determined. This meta-analysis compared the efficacy of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) in CAD patients. Databases were searched up to December 2020. Twenty-five studies with 1272 participants were analyzed. The results showed that both HIIT and MICT induced significant VO_2peak improvement with a 4.52 mL/kg/min (p < 0.01) and 2.36 mL/kg/min (p < 0.01), respectively. Additionally, a larger improvement of VO_2peak (1.92 mL/kg/min, p < 0.01) was observed in HIIT over MICT. HIIT with medium and long intervals, higher work/rest ratio induced larger VO_2peak improvement than the compared subgroup. Interestingly, non-isocaloric exercise protocols induced larger VO_2peak improvement compared with isocaloric protocols. In addition, both HIIT and MICT significantly increased anaerobic threshold and peak power with HIIT superior to MICT. No significant different changes were observed in blood pressure after HIIT or MICT intervention, however when HIIT was compared with MICT, MICT seems superior to HIIT in reducing systolic blood pressure (−3.61 mmHg, p < 0.01) and diastolic blood pressure (−2.37 mmHg, p < 0.01). Although, HIIT and MICT induced significant improvement of most other parameters, like HR_rest, HR_peak, left ventricular ejection fraction (LVEF), quality of life (QoL), no significant differences were noted between groups. This meta-analysis suggested that HIIT is superior to MICT in increasing VO_2peak, anaerobic threshold, peak power in CAD patients. Additionally, the efficacy of HIIT over MICT in improving VO_2peaks was influenced by HIIT intervals, work/rest ratio and total caloric consumption. Both HIIT and MICT did not significantly influence resting BP, however, MICT seemed to be more effective in reducing BP than HIIT. HIIT and MICT equally significantly influenced HR_rest, HR_peak, HRR1min, OUES, LVEF%, QoL.

Physical Inactivity: A Modifiable Risk Factor for Morbidity and Mortality in Kidney Transplantation

In patients with chronic kidney disease, sedentary behavior is widely recognized as a significant risk factor for cardiovascular disease, diabetes, obesity, osteoporosis, cancer, and depression. Nevertheless, the real impact of physical inactivity on the health of kidney transplant (KT) recipients remains uncertain. Over the last decade, there has been a renewed interest in exploring the effects of regular physical exercise on transplant-related outcomes. There is now mounting evidence that physical activity may reduce the burden of cardiovascular risk factors, preserve allograft function, minimize immunosuppression requirement, and ameliorate the quality of life of KT recipients. Many positive feedbacks can be detected in the early stages of the interventions and with a minimal exercise load. Despite these encouraging results, the perceived role of physical activity in the management of KT candidates and recipients is often underrated. The majority of trials on exercise training are small, relatively short, and focused on surrogate outcomes. While waiting for larger studies with longer follow-up, these statistical limitations should not discourage patients and doctors from initiating exercise and progressively increasing intensity and duration. This narrative review summarizes current knowledge about the deleterious effects of physical inactivity after KT. The benefits of regular physical exercise are also outlined.

Sacubitril/valsartan versus enalapril on exercise capacity in patients with heart failure with reduced ejection fraction: A randomized, double-blind, active-controlled study

Sacubitril/valsartan reduces mortality in patients with heart failure with reduced ejection fraction (HFrEF) when compared with enalapril. However, it is unknown the effect of both treatments on exercise capacity. We compared sacubitril/valsartan versus enalapril in patients with HFrEF based on peak oxygen consumption (VO₂) and 6-minute walk test (6-MWT).

METHODS

We included 52 participants with HFrEF with a left ventricular ejection fraction <40% to receive either sacubitril/valsartan (target dose of 400 mg daily) or enalapril (target dose of 40 mg daily). Peak VO₂ was measured by using cardiopulmonary exercise testing. Six-minute walk test was also performed.

RESULTS

At 12 weeks, the sacubitril/valsartan (mean dose 382.6 ± 57.6 mg daily) group had increased peak VO₂ of 13.1% (19.35 ± 0.99 to 21.89 ± 1.04 mL/kg/min) and enalapril (mean dose 34.4 ± 9.2 mg daily) 5.6% (18.58 ± 1.19 to 19.62 ± 1.25 mL/kg/min). However, no difference was found between groups (P = .332 interaction). At 24 weeks, peak VO₂ increased 13.5% (19.35 ± 0.99 to 21.96 ± 0.98 mL/kg/min) and 12.0% (18.58 ± 1.19 to 20.82 ± 1.18 mL/kg/min) in sacubitril/valsartan (mean dose 400 ± 0 mg daily) and enalapril (mean dose 32.7 ± 11.0 mg daily), respectively. However, no differences were found between groups (P= .332 interaction). At 12 weeks, 6-MWT increased in both groups (sacubitril/valsartan: 459 ± 18 to 488 ± 17 meters [6.3%] and enalapril: 443 ± 22 to 477 ± 21 meters [7.7%]). At 24 weeks, sacubitril/valsartan increased 18.3% from baseline (543 ± 26 meters) and enalapril decreased slightly to 6.8% (473 ± 31 meters), but no differences existed between groups (P= .257 interaction).

CONCLUSIONS

Compared to enalapril, sacubitril/valsartan did not substantially improve peak VO₂ or 6-MWT after 12 or 24 weeks in participants with HFrEF. (NEPRIExTol-HF Trial, ClinicalTrials.gov number, NCT03190304).

Exercise-Based Cardiac Rehabilitation Programs in Heart Failure Patients

Exercise training is recommended for patients with heart failure by major societies' guidelines. It improves exercise capacity and quality of life, reduces symptoms of depression, can improve survival, and reduce the risk for hospitalizations. Exercise-based cardiac rehabilitation can be offered with different modalities, such as continuous or interval aerobic training, resistance, and inspiratory muscle training. The intervention must follow an accurate evaluation of the patient's cardiovascular conditions and functional capacity. Despite the multiple benefits of exercise training, there is a lack of adherence to exercise-based programs, due to socioeconomic factors, patients' characteristics, and lack of referral.

Aerobic exercise improves cardiac function in rats with chronic heart failure through inhibition of the long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)

Background

To explore the beneficial effects and underlying mechanisms of aerobic exercise on chronic heart failure (CHF).

Methods

A CHF rat model was induced via left anterior descending coronary artery ligation. Four weeks post-surgery, CHF rats received aerobic exercise training over an 8-week period and cardiac function indexes including xxx were analyzed. To investigate the mechanisms involved in the aerobic exercise-induced benefits on CHF, overexpression of the long non-coding RNA MALAT1 was examined both in vivo and in vitro. Furthermore, the interaction between MALAT1 and the microRNA miR-150-5p and the downstream PI3K/Akt signaling pathway was investigated.

Results

Compared to the control group, the CHF rats showed evidence of left ventricular dysfunction including aggravated cardiac function indexes and lung to body weight ratio. The Masson staining demonstrated a significant degree of blue-stained fibrotic myocardial tissue in CHF rats compared to control rats. Furthermore, the levels of collagen I and collagen II were also markedly increased in CHF rats. Aerobic exercise improved cardiac function and left ventricular remodeling in rats with CHF. There was a significant reduction in the levels of the reactive oxygen species (ROS), inflammatory cytokines including TNF-α, IL-6, and IL-1β, and inflammatory mediums containing the matrix metalloproteinases (MMPs) MMP-2 and MMP-9. Moreover, CHF rats receiving aerobic exercise showed decreased myocardial apoptosis and increased expression of autophagy-related proteins including beclin-1 and LC3B-II. Overexpression of the lncRNA MALAT1 eliminated all the beneficial effects related to aerobic exercise in CHF rats. Subsequent investigations demonstrated that miR-150-5p expression was up-regulated in CHF-Tr rats and down-regulated in CHF-Tr-MALAT1 rats. Furthermore, the downstream PI3K/Akt signaling pathway was re-activated in CHF-Tr-MALAT1 rats. In vitro experiments revealed that overexpression of MALAT1 reduced the miR-150-5p levels, resulting in increased cellular apoptosis and less autophagy. In addition, overexpression of MALAT1 suppressed the downstream PI3K/Akt signaling pathway. Restoring miR-150-5p level with a miR-150-5p mimic decreased the cellular apoptosis and increased autophagy, and the downstream PI3K/Akt signaling pathway was re-activated.

Conclusions

Aerobic exercise improved cardiac function through inhibition of the lncRNA MALAT1 in CHF, and the potential mechanisms may be mediated via the miR-150-5p/PI3K/Akt signaling pathway.

Semisupervised Physical Exercise and Lifestyle Counseling in Cardiometabolic Risk Management in Sedentary Adults: Controlled Randomized Trial (BELLUGAT)

BACKGROUND

The purpose of this study was to evaluate the feasibility and effectiveness of a high-intensity semisupervised exercise program alongside lifestyle counseling as an intervention for managing cardiometabolic risk in sedentary adults.

METHODS

A 40-week 3-arm randomized controlled clinical trial (16-wk intervention and 24-wk follow-up) was used. Seventy-five sedentary adults (34-55 y) with at least 1 cardiometabolic risk factor were randomized into one of the following arms: (1) aerobic interval training (AIT) plus lifestyle counseling (n = 25), (2) low- to moderate-intensity continuous training plus lifestyle counseling (traditional continuous training, TCT) (n = 27), or (3) lifestyle counseling alone (COU) (n = 23). Metabolic syndrome severity scores, accelerometer-based physical activity, and self-reported dietary habits were assessed at baseline, after the intervention, and at follow-up.

RESULTS

AIT was well accepted with high enjoyment scores. All groups showed similar improvements in metabolic syndrome severity scores (standardized effect size = 0.46) and dietary habits (standardized effect size = 0.30). Moderate to vigorous physical activity increased in all study groups, with the number of responders higher in AIT and TCT groups (50%) than in COU group (21%). Both AIT and TCT had a greater impact on sedentary behavior than COU (63.5% vs 30.4% responders).

CONCLUSIONS

AIT appears to be a feasible and effective strategy in sedentary individuals with cardiometabolic risk factors. AIT could be included in intervention programs tackling unhealthy lifestyles.

High-intensity interval training changes the expression of muscle RING-finger protein-1 and muscle atrophy F-box proteins and proteins involved in the mechanistic target of rapamycin pathway and autophagy in rat skeletal muscle

NEW FINDINGS

What is the central question of this study? What are the adaptations of protein synthesis and degradation that occur in skeletal muscle in response to high-intensity interval training (HIIT), and what are the magnitudes of the changes in response to HIIT, compared to moderate-intensity continuous training (MICT), and the mechanisms underlying these changes? What is the main finding and its importance? HIIT is more effective than MICT in altering the expression of muscle RING-finger protein-1 and muscle atrophy F-box, and enhancing the autophagic flux in rat soleus muscle. In addition, HIIT could activate the mechanistic target of rapamycin pathway. These findings suggest that HIIT might be an effective exercise strategy for health promotion in skeletal muscle.

ABSTRACT

This study aimed to investigate the impact of high-intensity interval training (HIIT) on the proteins involved in protein synthesis, the ubiquitin-proteasome system (UPS) and autophagy in skeletal muscle of middle-aged rats. Nine-month-old male Wistar rats (n = 56) were randomly divided into three groups: a control (C) group, a moderate-intensity continuous training (MICT) group and a HIIT group. Rats in the training groups ran on treadmills 5 days per week for 8 weeks. The MICT group ran for 50 min at 60% V ̇ O 2 max , while the HIIT group ran for 3 min at 80% of V ̇ O 2 max six times separated by 3-min periods at 40% V ̇ O 2 max . Aerobic endurance, number of autophagosomes and expression of proteins involved in protein synthesis and degradation in the soleus muscle were measured at three time points: before training, after 4 weeks and after 8 weeks of training. Compared to the C group, HIIT and MICT increased the expression of phosphorylated mechanistic target of rapamycin (mTOR) after 8 weeks (P < 0.05 and P < 0.01, respectively). HIIT increased the expression of muscle RING-finger protein-1 (MuRF-1) after 4 weeks (P < 0.01), and decreased its expression after 8 weeks (P < 0.01). Both HIIT and MICT decreased the expression of muscle atrophy F-box (MAFbx) after 4 weeks (P < 0.05). HIIT improved the expression of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II (P < 0.05), and decreased the P62 content (P < 0.01) after 4 weeks. The LC3II/LC3I ratio was increased after 8 weeks (P < 0.01). This study demonstrated that HIIT could activate the mTOR pathway, alter the expression of MuRF-1 and MAFbx proteins, and enhance autophagic flux in soleus muscle of middle-aged rats.

Interval Endurance and Resistance Training as Part of a Community-Based Secondary Prevention Program for Patients With Diabetes Mellitus and Coronary Artery Disease

PURPOSE

High-intensity interval training (HIIT) has been observed to improve health and fitness in patients with cardiovascular disease. High-intensity interval training may not be appropriate in community-based settings. Moderate-intensity interval training (MIIT) and resistance training (RT) are emerging as effective alternatives to HIIT. These have not been well investigated in a community-based cardiac maintenance program.

METHODS

Patients with coronary artery disease and/or diabetes mellitus participated in clinical examinations and a 6-mo exercise program. Center-based MIIT and home-based moderate continuous intensity exercise were performed for 3-5 d/wk for 30-40 min/session. RT, nutritional counseling, coping, and behavioral change strategies were offered to all patients. Within-group changes in clinical metrics and exercise performance were assessed on a per-protocol basis after 6 mo.

RESULTS

Two hundred ninety-two patients (74%) concluded the 6-mo program. There were no serious adverse events. The peak oxygen uptake and peak workload increased significantly, 21.8 ± 6.1 to 22.8 ± 6.3 mL/kg/min and 128 ± 39 to 138 ± 43 W, respectively (both P < .001). Submaximal exercise performance increased from 68 ± 19 to 73 ± 22 W (P < .001). Glycated hemoglobin decreased from 6.57 ± 0.93% to 6.43 ± 0.12%, (P = .023). Daily injected insulin dosage was reduced from 42 IU (interquartile range: 19.0, 60.0) to 26 IU (interquartile range: 0, 40.3, P < .001).

CONCLUSIONS

MIIT and RT were feasible and effective in a community-based cardiac maintenance program for patients with cardiovascular disease, improving exercise performance, and blood glucose control.

Cardiovascular response of postmenopausal women to 8 weeks of sprint interval training

INTRODUCTION

Menopause is accompanied by decreased aerobic fitness and increased risk of cardiovascular disease. Sprint interval training (SIT) is a time-efficient intervention for improving cardiovascular function and aerobic fitness of young adults.

AIM

To determine the effect of an 8-week SIT program on the cardiovascular function and aerobic fitness of overweight postmenopausal women.

METHOD

Thirty overweight postmenopausal women were randomized into exercise (n = 15) or control (n = 15) groups. The intervention group completed three SIT sessions a week for 8 weeks. Each session consisted of 20 min of 8-s sprints and 12 s of light pedalling. Participants also completed 8 min of light aerobic cycle exercise, before and after the SIT intervention. Cardiovascular function including heart rate, stroke volume (SV), and diastolic filling time (DFT) was assessed before and after the intervention and during 8 min of light aerobic exercise. Estimated maximal oxygen uptake ([Formula: see text]) was also assessed.

RESULTS

Resting SV was increased (p = 0.001) from pre- (77.5 ± 17.0 mL) to post-SIT (81.3 ± 17.0 mL), whereas SV during 8 min of light aerobic exercise was increased (p = 0.000), from pre- (97.8 ± 1.6 mL) to post-test (103.5 ± 17.8 mL). Resting DFT was increased, (p = 0.010), at pre- (333.4 ± 94.4 mL) to post-SIT (357.4 ± 88.2 mL), whereas DFT during 8 min of aerobic exercise was increased, (p = 0.000), from pre- (480.1 ± 99.5 mL) to posttest (527.2 ± 123.0 mL). Predicted [Formula: see text] was increased, (p = 0.016), from pre- (19.5 ± 5.87 mL kg^-1 min^-1) to post-SIT (21.4 ± 7.02 mL kg^-1 min^-1).

CONCLUSION

SIT improved cardiovascular function and aerobic fitness of overweight postmenopausal women after 8 weeks of exercise.

Exercise capacity, physical activity, and morbidity

Muscle weakness and atrophy are key characteristics of the aging adult but can also be found in chronically ill patients with heart failure, cancer, renal failure, and chronic infectious diseases all associated with an accelerated level of muscle dysfunction. Reduced physical activity levels and exercise intolerance increase muscle loss and decrease quality of life in both the aging and heart failure populations. The purpose of this review is to provide an overview of the effects of aging and heart failure on skeletal muscle function and how exercise training can improve long-term outcomes associated with skeletal muscle dysfunction.

Adherence to recommended exercise guidelines in patients with heart failure

Exercise training has been shown to be beneficial in patients with heart failure, and its effectiveness is connected to adherence to the exercise program. Nonetheless, adherence to exercise in these patients remains a concern. Heart failure patients can be considered adherent to an exercise program if they meet 80 % of the recommended dose. We summarize exercise recommendations for patients with heart failure, identify exercise prescription methodologies used in studies that have reported exercise adherence, identify strategies and tools used to improve adherence and examine whether these strategies were developed using a theoretical platform with the primary aim to change behavior and improve adherence to exercise. Factors which may also impact adherence such as exercise setting, intensity and length of participation, gender, race, New York Heart Association functional class and heart failure with preserved and reduced ejection fraction were also investigated. Finally, recommendations for future studies for improving adherence to exercise in patients with heart failure are provided.

Return-to-Play in 2017 and the Role of Shared Decision-Making in Patients with Inherited and Acquired Channelopathies and Cardiomyopathies

OPINION STATEMENT

Shared decision-making is based upon a physician-patient encounter in which there is adequate education using aids if needed, a mutual discussion of how to assist the patient in weighing risks and benefits, and a supportive environment that allows the patient to deliberate on the clinical decision and make their own choice. This decision-making paradigm centers on the principles of autonomy and self-determination. Physical activity is a critical part of healthy lifestyle choices that helps lower risk of cardiovascular disease or the progression of it. Exercise is also a significant contributor to quality of life in many patients in additional to the health benefits. In patients with inherited or acquired cardiovascular disease, exercise may increase risk of electrical and hemodynamic instability. There is a paucity of data to guide physicians and committees that create guidelines regarding athletic and fitness participation in these patients, particularly when the patient wants to participate in those activities that are considered moderate-severe in intensity. As a consequence, the principles of shared decision-making are critical for physicians to use to help patients with cardiovascular disease make the best decision regarding fitness participation that will minimize their risk of new disease or progression of their disease and enhance their quality of life.

High Intensity Interval Training for Maximizing Health Outcomes

Regular physical activity and exercise training are important actions to improve cardiorespiratory fitness and maintain health throughout life. There is solid evidence that exercise is an effective preventative strategy against at least 25 medical conditions, including cardiovascular disease, stroke, hypertension, colon and breast cancer, and type 2 diabetes. Traditionally, endurance exercise training (ET) to improve health related outcomes has consisted of low- to moderate ET intensity. However, a growing body of evidence suggests that higher exercise intensities may be superior to moderate intensity for maximizing health outcomes. The primary objective of this review is to discuss how aerobic high-intensity interval training (HIIT) as compared to moderate continuous training may maximize outcomes, and to provide practical advices for successful clinical and home-based HIIT.

Metabolic risk management, physical exercise and lifestyle counselling in low-active adults: controlled randomized trial (BELLUGAT)

BACKGROUND

The primary aim of this study is to evaluate the effectiveness of different doses (intensity) of supervised exercise training - concomitant with lifestyle counselling - as a primary care intervention tool for the management of metabolic syndrome risk factors in low-active adults with one or more such factors (programme name in Catalan: Bellugat de CAP a peus).

METHODS/DESIGN

Three-arm, randomized controlled clinical trial implemented in the primary care setting, with a duration of 40 weeks (16 weeks intervention and 24-week follow-up). Adults aged 30 to 55 years with metabolic risk factors will be randomized into three intervention groups: 1) aerobic interval training (16 supervised training lessons) plus a healthy lifestyle counselling programme (6 group and 3 individual meetings); 2) low-to-moderate intensity continuous training (16 supervised training lessons) plus the same counselling programme; or 3) the counselling- programme without any supervised physical exercise. The main output variables assessed will be risk factors for metabolic syndrome (waist circumference, blood pressure, and levels of plasma triglycerides, high-density lipoproteins and glucose), systemic inflammation, cardiorespiratory fitness, physical activity and sedentary behaviour, dietary habits, health-related quality of life, self-efficacy and empowerment. Economic factors will also be analysed in order to determine the cost-effectiveness of the programme. These variables will be assessed three times during the study: at baseline, at the end of the intervention, and at follow-up. We estimate to recruit 35 participants per group.

DISCUSSION

The results of this study will provide insight into the immediate and medium-term effects on metabolic risk and lifestyle of a combined approach involving aerobic interval training and a multidisciplinary behavioural intervention. If effective, the proposed intervention would provide both researchers and practitioners in this field with a platform on which to develop similar intervention programmes for tackling the repercussions of an unhealthy lifestyle.

TRIAL REGISTRATION

Clinical trials.gov. NTC02832453 . Registered 6 July 2016 (retrospectively registered).

The future of pleiotropic therapy in heart failure. Lessons from the benefits of exercise training on endothelial function

A novel generation of drugs is introduced in the treatment of heart failure (HF). These drugs, including phosphodiesterase-5 inhibitors, guanylate cyclase stimulators and activators, share the feature that their action is either endothelial-mediated or substitutes for endothelial pathways, in particular the nitric oxide-cyclic guanosine monophosphate pathway, thereby influencing homeostatic balances in virtually each organ system in a pleiotropic fashion. Unfortunately, recent clinical trials with some of these drugs have shown disappointing results, at least in the setting of HF with a preserved ejection fraction. This suggests that their clinical use may require approaches that diverge from traditional pharmacological approaches, the latter often titrated on the effects of drugs on haemodynamic parameters or single biomarkers. In this paper we preconize that HF drugs with an endothelial profile should be applied conform to principles of endothelial physiology and systems pharmacology. This type of drug therapy should be viewed as a systems physio-pharmacological intervention and its clinical use accustomed to systems pharmacological principles, comparable to the systemic endothelial-mediated benefits induced by exercise training in HF. We will review the actions of these drugs and define criteria to which trials with these drugs should comply in order to increase chances of success.

A Practical and Time-Efficient High-Intensity Interval Training Program Modifies Cardio-Metabolic Risk Factors in Adults with Risk Factors for Type II Diabetes

INTRODUCTION

Regular physical activity (PA) can reduce the risk of developing type 2 diabetes, but adherence to time-orientated (150 min week^-1 or more) PA guidelines is very poor. A practical and time-efficient PA regime that was equally efficacious at controlling risk factors for cardio-metabolic disease is one solution to this problem. Herein, we evaluate a new time-efficient and genuinely practical high-intensity interval training (HIT) protocol in men and women with pre-existing risk factors for type 2 diabetes.

MATERIALS AND METHODS

One hundred eighty-nine sedentary women (n = 101) and men (n = 88) with impaired glucose tolerance and/or a body mass index >27 kg m^-2 [mean (range) age: 36 (18-53) years] participated in this multi-center study. Each completed a fully supervised 6-week HIT protocol at work-loads equivalent to ~100 or ~125% [Formula: see text]. Change in [Formula: see text] was used to monitor protocol efficacy, while Actiheart™ monitors were used to determine PA during four, weeklong, periods. Mean arterial (blood) pressure (MAP) and fasting insulin resistance [homeostatic model assessment (HOMA)-IR] represent key health biomarker outcomes.

RESULTS

The higher intensity bouts (~125% [Formula: see text]) used during a 5-by-1 min HIT protocol resulted in a robust increase in [Formula: see text] (136 participants, +10.0%, p < 0.001; large size effect). 5-by-1 HIT reduced MAP (~3%; p < 0.001) and HOMA-IR (~16%; p < 0.01). Physiological responses were similar in men and women while a sizeable proportion of the training-induced changes in [Formula: see text], MAP, and HOMA-IR was retained 3 weeks after cessation of training. The supervised HIT sessions accounted for the entire quantifiable increase in PA, and this equated to 400 metabolic equivalent (MET) min week^-1. Meta-analysis indicated that 5-by-1 HIT matched the efficacy and variability of a time-consuming 30-week PA program on [Formula: see text], MAP, and HOMA-IR.

CONCLUSION

With a total time-commitment of <15 min per session and reliance on a practical ergometer protocol, 5-by-1 HIT offers a new solution to modulate cardio-metabolic risk factors in adults with pre-existing risk factors for type 2 diabetes while approximately meeting the MET min week^-1 PA guidelines. Long-term randomized controlled studies will be required to quantify the ability for 5-by-1 HIT to reduce the incidence of type 2 diabetes, while strategies are required to harmonize the adaptations to exercise across individuals.

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.

Exercise training-induced modification in autonomic nervous system: An update for cardiac patients

Patients with cardiovascular disease show autonomic dysfunction, including sympathetic activation and vagal withdrawal, which leads to fatal events. This review aims to place sympathovagal balance as an essential element to be considered in management for cardiovascular disease patients who benefit from a cardiac rehabilitation program. Many studies showed that exercise training, as non-pharmacologic treatment, plays an important role in enhancing sympathovagal balance and could normalize levels of markers of sympathetic flow measured by microneurography, heart rate variability or plasma catecholamine levels. This alteration positively affects prognosis with cardiovascular disease. In general, cardiac rehabilitation programs include moderate-intensity and continuous aerobic exercise. Other forms of activities such as high-intensity interval training, breathing exercises, relaxation and transcutaneous electrical stimulation can improve sympathovagal balance and should be implemented in cardiac rehabilitation programs. Currently, the exercise training programs in cardiac rehabilitation are individualized to optimize health outcomes. The sports science concept of the heart rate variability (HRV)-vagal index used to manage exercise sessions (for a goal of performance) could be implemented in cardiac rehabilitation to improve cardiovascular fitness and autonomic nervous system function.

Comparing exercise training modalities in heart failure: A systematic review and meta-analysis

Exercise training (ET) is suggested to improve exercise capacity, prognosis, quality of life (QOL) and functional modifications of the heart in patients with heart failure (HF). However, it is not clear which modality is best. In order to assess the effectiveness of different ET modalities on prognostic cardiopulmonary exercise test (CPET) parameters, QOL and left ventricular remodeling, a systematic review and meta-analysis was performed. Randomized clinical trials (RCTs) were selected in three databases. The primary outcome data were peak oxygen uptake, ventilation over carbon dioxide slope, oxygen uptake efficiency slope, exercise oscillatory ventilation, rest and peak pulmonary end-tidal CO2. Secondary variables were QOL, left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD). Twenty RCTs (n=811) met the a priori stated inclusion criteria. Studies were categorized into four different groups: "interval training (IT1) versus combined interval and strength training (IT1S)" (n=156), "continuous training (CT1) versus combined continuous and strength training (CT1S)" (n=130), "interval training (IT2) versus continuous training (CT2)" (n=501) and "continuous training (CT3) versus strength training (S3)" (n=24). No significant random effects of exercise modality were revealed assessing the CPET parameters. There was a significant improvement in QOL applying CT1S (P<0.001). Comparing IT2 with CT2, LVEDD and LVEF were significantly improved favoring IT2 (P<0.001). There is some evidence to support that interval training is more effective to improve LVEF and LVEDD. The fact that patients with HF are actively involved in any kind of ET program seems sufficient to improve the prognosis, QOL and anatomic function.

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

INTRODUCTION

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

AREAS COVERED

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

Comparison of Carbohydrate and Lipid Oxidation During Different High-Intensity Interval Exercise in Patients with Chronic Heart Failure

Substrate oxidation was compared during different high-intensity intermittent exercise (HIIE) protocols in patients with heart failure and reduced ejection fraction (HFREF). Eighteen males with HFREF (58.8 ± 9 years) were randomly assigned to 4 different HIIEs: 30 seconds (A and B) or 90 seconds (C and D) at 100% peak power output, with passive (A and C) or active recovery (50% of peak power output; B and D). Each HIIE protocol was separated by 1 week. Substrate oxidation (carbohydrate [CHO] and lipid: in g/min and in %) was calculated with gas exchange analysis. A 2-way analysis of variance and Bonferroni post hoc test were used (P ≤ 0.05) to compare CHO and lipid oxidation during the 4 HIIEs. Protocols with passive recovery (A and C) resulted in significantly lower quantitative CHO oxidation (g/min) (interaction, P < 0.001) compared to modes with active recovery (B and D). Quantitative lipid oxidation (g/min) was significantly lower in protocol C compared to the 3 other HIIE protocols (interaction, P < 0.001). In patients with HFREF, shorter HIIE bouts with passive recovery oxidize less CHO and more lipids (quantitatively) compared to the other HIIE protocols. This might be taken into account the exercise training prescription and might influence muscle metabolism adaptations.

Acute Physiological Responses to Short- and Long-Stage High-Intensity Interval Exercise in Cardiac Rehabilitation: A Pilot Study

Despite described benefits of aerobic high-intensity interval exercise (HIIE), the acute responses during different HIIE modes and associated health risks have only been sparsely discovered in heart disease patients. Therefore, the aim of this study was to investigate the acute responses for physiological parameters, cardiovascular and inflammatory biomarkers, and catecholamines yielded by two different aerobic HIIE protocols compared to continuous exercise (CE) in phase III cardiac rehabilitation. Eight cardiac patients (7 with coronary heart disease, 1 with myocarditis; 7 males, 1 female; age: 63.0 ± 9.4 years; height: 1.74 ± 0.05 m; weight: 83.6 ± 8.7 kg), all but one treated with ß-blocking agents, performed a maximal symptom-limited incremental exercise test (IET) and three different exercise tests matched for mean load (Pmean) and total duration: 1) short HIIE with a peak workload duration (tpeak) of 20 s and a peak workload (Ppeak) equal to the maximum power output (Pmax) from IET; 2) long HIIE with a tpeak of 4 min, Ppeak was corresponding to the power output at 85 % of maximal heart rate (HRmax) from IET; 3) CE with a target workload equal to Pmean of both HIIE modes. Acute metabolic and peak cardiorespiratory responses were significantly higher during long HIIE compared to short HIIE and CE (p < 0.05) except HRpeak which tended to be higher in long HIIE than in short HIIE (p = 0.08). Between short HIIE and CE, no significant difference was found for any parameter. Acute responses of cardiovascular and inflammatory biomarkers and catecholamines didn't show any significant difference between tests (p > 0.05). All health-related variables remained in a normal range in any test except NT-proBNP, which was already elevated at baseline. Despite a high Ppeak particularly in short HIIE, both HIIE modes were as safe and as well tolerated as moderate CE in cardiac patients by using our methodological approach. Key pointsHigh-intensity interval exercise (HIIE) with short peak workload durations (tpeak) induce a lower acute metabolic and peak cardiorespiratory response compared to intervals with long tpeak despite higher peak workload intensities and identical mean load. No significant difference for any physiological parameter was found between short HIIE and CE.Between short HIIE, long HIIE, and CE, no significant difference was found in the increase (or decrease, respectively,) of health related markers such as cardiovascular biomarkers, catecholamines, or inflammatory parameters during exercise.During all exercise modes, all risk markers remained in a normal range except for NT-proBNP which was, however, already elevated at baseline.Short HIIE, long HIIE, and CE were safely performed by patients with CHD or myocarditis in cardiac rehabilitation by using our methodological approach to exercise prescription. This approach included the prescription of exercise intensities with respect to LTP1, LTP2, and Pmax as well as a conscious setting of Pmean at a moderate level (80 % of PLTP2). Importantly, all exercise modes were matched for Pmean and exercise duration in order to enable a comparison of the three protocols.

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

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

Design and rationale of the HITTS randomized controlled trial: Effect of High-intensity Interval Training in de novo Heart Transplant Recipients in Scandinavia

There is no consensus on how, when, and at what intensity exercise should be performed and organized after heart transplantation (HTx). Most rehabilitation programs are conducted in HTx centers, which might be impractical and costly. We have recently shown that high-intensity interval training (HIT) is safe, well tolerated, and efficacious in maintenance HTx recipients, but there are no studies among de novo patients, and whether HIT is feasible and superior to moderate training in HTx recipients is unclear. A total of 120 clinically stable HTx recipients older than 18 years will be recruited from 3 Scandinavian HTx centers. Participants are randomized to HIT or moderate training, shortly after surgery. All exercises are supervised in the patients' local communities. Testing at baseline and follow-up includes the following: VO2peak (primary end point), muscle strength, body composition, quality of life, myocardial performance, endothelial function, biomarkers, and progression of cardiac allograft vasculopathy. A subgroup (n = 90) will also be tested at 3-year follow-up to assess long-term effects of exercise. So far, the HIT intervention is well tolerated, without any serious adverse events. We aim to test whether decentralized HIT is feasible, safe, and superior to moderate training, and whether it will lead to significant improvement in exercise capacity and less long-term complications.

Comparison of Different Forms of Exercise Training in Patients With Cardiac Disease: Where Does High-Intensity Interval Training Fit?

In this review, we discuss the most recent forms of exercise training available to patients with cardiac disease and their comparison or their combination (or both) during short- and long-term (phase II and III) cardiac rehabilitation programs. Exercise training modalities to be discussed include inspiratory muscle training (IMT), resistance training (RT), continuous aerobic exercise training (CAET), and high-intensity interval training (HIIT). Particular emphasis is placed on HIIT compared or combined (or both) with other forms such as CAET or RT. For example, IMT combined with CAET was shown to be superior to CAET alone for improving functional capacity, ventilatory function, and quality of life in patients with chronic heart failure. Similarly, RT combined with CAET was shown to optimize benefits with respect to functional capacity, muscle function, and quality of life. Furthermore, in recent years, HIIT has emerged as an alternative or complementary (or both) exercise modality to CAET, providing equivalent if not superior benefits to conventional continuous aerobic training with respect to aerobic fitness, cardiovascular function, quality of life, efficiency, safety, tolerance, and exercise adherence in both short- and long-term training studies. Finally, short-interval HIIT was shown to be useful in the initiation and improvement phases of cardiac rehabilitation, whereas moderate- or longer-interval (or both) HIIT protocols appear to be more appropriate for the improvement and maintenance phases because of their high physiological stimulus. We now propose progressive models of exercise training (phases II-III) for patients with cardiac disease, including a more appropriate application of HIIT based on the scientific literature in the context of a multimodal cardiac rehabilitation program.

Review of High-intensity Interval Training in Cardiac Rehabilitation

For the secondary prevention of cardiovascular disease, comprehensive cardiac rehabilitation is required. This involves optimal medical therapy, education on nutrition and exercise therapy, and smoking cessation. Of these, efficient exercise therapy is a key factor. A highly effective training protocol is therefore warranted, which requires a high rate of compliance. Although moderate-intensity continuous training has been the main training regimen recommended in cardiac rehabilitation guidelines, high-intensity interval training has been reported to be more effective in the clinical and experimental setting from the standpoint of peak oxygen uptake and central and peripheral adaptations. In this review, we illustrate the scientific evidence for high-intensity interval training. We then verify this evidence and discuss its significance and the remaining issues.

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

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

Effects of High-Intensity Interval Training versus Continuous Training on Physical Fitness, Cardiovascular Function and Quality of Life in Heart Failure Patients

Introduction

Physical fitness is an important prognostic factor in heart failure (HF). To improve fitness, different types of exercise have been explored, with recent focus on high-intensity interval training (HIT). We comprehensively compared effects of HIT versus continuous training (CT) in HF patients NYHA II-III on physical fitness, cardiovascular function and structure, and quality of life, and hypothesize that HIT leads to superior improvements compared to CT.

Methods

Twenty HF patients (male:female 19:1, 64±8 yrs, ejection fraction 38±6%) were allocated to 12-weeks of HIT (10*1-minute at 90% maximal workload—alternated by 2.5 minutes at 30% maximal workload) or CT (30 minutes at 60–75% of maximal workload). Before and after intervention, we examined physical fitness (incremental cycling test), cardiac function and structure (echocardiography), vascular function and structure (ultrasound) and quality of life (SF-36, Minnesota living with HF questionnaire (MLHFQ)).

Results

Training improved maximal workload, peak oxygen uptake (VO_2peak) related to the predicted VO_2peak, oxygen uptake at the anaerobic threshold, and maximal oxygen pulse (all P<0.05), whilst no differences were present between HIT and CT (N.S.). We found no major changes in resting cardiovascular function and structure. SF-36 physical function score improved after training (P<0.05), whilst SF-36 total score and MLHFQ did not change after training (N.S.).

Conclusion

Training induced significant improvements in parameters of physical fitness, although no evidence for superiority of HIT over CT was demonstrated. No major effect of training was found on cardiovascular structure and function or quality of life in HF patients NYHA II-III.

Trial Registration

Nederlands Trial Register NTR3671

Exercise and the cardiovascular system: clinical science and cardiovascular outcomes

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

What Doesn't Kill You Makes You Fitter: A Systematic Review of High-Intensity Interval Exercise for Patients with Cardiovascular and Metabolic Diseases

High-intensity interval exercise (HIIE) has gained popularity in recent years for patients with cardiovascular and metabolic diseases. Despite potential benefits, concerns remain about the safety of the acute response (during and/or within 24 hours postexercise) to a single session of HIIE for these cohorts. Therefore, the aim of this study was to perform a systematic review to evaluate the safety of acute HIIE for people with cardiometabolic diseases. Electronic databases were searched for studies published prior to January 2015, which reported the acute responses of patients with cardiometabolic diseases to HIIE (≥80% peak power output or ≥85% peak aerobic power, VO2peak). Eleven studies met the inclusion criteria (n = 156; clinically stable, aged 27-66 years), with 13 adverse responses reported (~8% of individuals). The rate of adverse responses is somewhat higher compared to the previously reported risk during moderate-intensity exercise. Caution must be taken when prescribing HIIE to patients with cardiometabolic disease. Patients who wish to perform HIIE should be clinically stable, have had recent exposure to at least regular moderate-intensity exercise, and have appropriate supervision and monitoring during and after the exercise session.

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.