High-intensity interval exercise in chronic heart failure: protocol optimization

Short-duration aerobic high-intensity intervals versus moderate exercise training intensity in patients with peripheral artery disease: study protocol for a randomised controlled trial (the Angiof-HIIT Study)

INTRODUCTION

Supervised exercise training is among the first-line therapies for patients with peripheral artery disease (PAD). Current recommendations for exercise include guidance focusing on claudication pain, programme and session duration, and frequency. However, no guidance is offered regarding exercise training intensity. This study aims to compare the effects of 12-week-long supervised walking exercise training (high-intensity interval training (HIIT) vs moderate-intensity exercise (MOD)) in patients with chronic symptomatic PAD.

METHODS AND ANALYSIS

This study is a monocentric, interventional, non-blinded randomised controlled trial. 60 patients (30 in each group) will be randomly allocated (by using the random permuted blocks) to 12 weeks (three times a week) of HIIT or MOD. For HIIT, exercise sessions will consist of alternating brief high-intensity (≥85% of the peak heart rate (HRpeak)) periods (≤60 s) of work with periods of passive rest. Patients will be asked to complete 1 and then 2 sets of 5-7 (progressing to 10-15×60 s) walking intervals. For the MOD group, exercise training sessions will consist of an alternation of periods of work performed at moderate intensity (≤76% HRpeak) and periods of passive rest. Interventions will be matched by training load. The primary outcome will be the maximal walking distance. Secondary outcomes will include functional performance, functional capacity, heath-related quality of life, self-perceived walking abilities, physical activity and haemodynamic parameters.

ETHICS AND DISSEMINATION

The Angiof-HIIT Study was approved by the Human Research Ethics Committee of the Canton de Vaud (study number: 2022-01752). Written consent is mandatory prior to enrolment and randomisation. The results will be disseminated via national and international scientific meetings, scientific peer-reviewed journals and social media.

TRIAL REGISTRATION NUMBER

NCT05612945.

Physiological and psychological outcomes of high intensity interval training in patients with heart failure compared to moderate continuous training and usual care: A systematic review with meta analysis

BACKGROUND

An important component of secondary prevention of CVD (including HF) is comprehensive cardiac rehab, including exercise. Novel, individualised approaches are needed to increase uptake and adherence to exercise programmes, one area offering potential is HIIT. HIIT has been shown to be both safe and effective for improving cardiovascular fitness in both coronary artery disease and HF patients.

OBJECTIVES

To provide a current and up to date evaluation of the physiological and psychological outcomes of HIIT in patients with HF compared to MCT and UC. Secondly to perform sub-group analyses comparing short and long HIIT protocols.

METHODS

A systematic review and meta-analysis of randomised controlled trials was undertaken. Medline, Embase, Scopus, CINAHL and SportDISCUS were searched up to July 2022. Trials were included if they carried out a HIIT intervention (defined at intensity ≥ 80% peak HR or ≥ 80% VO2peak) in HF patients (HFpEF or HFrEF) for at least 6 weeks. Comparator group was UC or MCT.

RESULTS

HIIT was shown to be superior to MCT and UC for improving VO2peak (HIIT mean improvement 3.1 mL.kg-1min-1). HITT was superior to MCT and UC for improving LVEF (HIIT mean improvement 5.7%). HIIT was superior to MCT and UC for improving HRQoL, using the MLHFQ (HIIT mean point change of -12.8). Subgroup analysis showed no difference between long and short HIIT.

CONCLUSION

HIIT improves VO2peak, LVEF and HRQoL in patients with HF, the improvements seen in VO2peak and LVEF are superior in HIIT compared to MCT and UC.

Moderate continuous- and high-intensity interval training elicit comparable cardiovascular effect among middle-aged men regardless of recovery mode

To assess the effect of active and passive intra-interval recovery modes in time-efficient high-intensity interval training (HIT) on cardiorespiratory fitness, autonomic function, and endothelial function in sedentary middle-aged men.Participants (n = 62; age: 49.5 ± 5.8 y; BMI: 29.7 ± 3.7 kg·m^-2) completed the assessments of cardiorespiratory fitness, flow-mediated dilation (FMD) and heart rate variability before being randomly allocated to control (CON; n = 14), moderate intensity continuous training (MICT; n = 15), HIT with passive (P-HIT; n-15), or active recovery (A-HIT; n = 15). Participants performed thrice weekly exercise sessions for 12 weeks. MICT completed 50-60 min of continuous cycling at 60-70% heart rate (HR) maximum. HIT completed 30-s work intervals (∼85% HR) interspaced with 2.5 min of active or passive recovery.All exercise modalities increased oxygen uptake (V̇O₂) (MD: ≥ 3.1 ml·kg^-1·min^-1, 95%CI: 1.5-4.7 ml·kg^-1·min^-1; P < 0.001), power output (MD: ≥ 26 W, 95%CI: 15-37 W; P < 0.001) and cycle duration (MD: ≥ 62 s, 95%CI: 36-88 s; P < 0.001) at 85% HRM. Significant pre-to-post differences were observed among all exercise groups for FMD (MD: ≥ 3.4%, 95%CI: 0.3-6.5%; P < 0.05), while MICT and P-HIT significantly increased the standard deviation of all NN intervals (SDNN) pre-to-post intervention (MD: ≥ 7 ms, 2-13 ms; P ≤ 0.05).Time-efficient HIT elicits significant improvements in cardiorespiratory fitness, FMD and autonomic modulation following a thrice weekly 12-week exercise intervention among sedentary middle-aged men. Active recovery between successive high-intensity intervals provided no additional benefit among this deconditioned cohort.

Effects of exercise training in hypoxia versus normoxia on fat-reducing in overweight and/or obese adults: A systematic review and meta-analysis of randomized clinical trials

Objective: Fat loss theory under various oxygen conditions has been disputed, and relevant systematic review studies are limited. This study is a systematic review and meta-analysis to assess whether hypoxic exercise training (HET) leads to superior fat-reducing compared with normoxic exercise training (NET).

Methods: We searched PubMed, Web of Science, CNKI, ProQuest, Google Scholar, Cochrane Library, and EBSCOhost from inception to June 2022 for articles comparing the effects of hypoxic and normoxic exercise on body composition indicators, glycometabolism, and lipometabolism indicators in obese and overweight adults. Only randomized controlled trials (RCTs) were included. The effect sizes were expressed as standardized mean difference (SMD) and 95% confidence intervals (CI). Between-study heterogeneity was examined using the I² test and evaluated publication bias via Egger’s regression test. The risk of bias assessment was performed for each included trial using Cochrane Evaluation Tool second generation. The meta-analysis was performed by using R 4.1.3 and RevMan 5.3 analytic tools.

Results: A total of 19 RCTs with 444 subjects were analyzed according to the inclusion and exclusion criteria. Among them, there were 14 English literature and five Chinese literature. No significant difference in body composition (SMD -0.10, 95% CI -0.20 to -0.01), glycometabolism and lipid metabolism (SMD -0.01, 95% CI -0.13 to -0.10) has been observed when comparing the HET and NET groups. We only found low heterogeneity among trials assessing glycometabolism and lipometabolism (I² = 20%, p = 0.09), and no publication bias was detected.

Conclusion: The effects of HET and NET on fat loss in overweight or obese people are the same. The application and promotion of HET for fat reduction need further exploration.

Acute Effects of High-Intensity Interval Training on Diabetes Mellitus: A Systematic Review

This study evaluated the scientific evidence on the acute effects of high-intensity interval training (HIIT) on biochemical, cardiovascular, and metabolic parameters in patients with diabetes mellitus. The research took place using two databases (PubMed and Google Scholar) with eligible studies conducted between 2010 and 2020, using the following keywords: (1) high-intensity training/exercise; (2) interval training/exercise; (3) HIIT/exercise; AND “diabetes”. Data extraction was then performed on the eligible studies through content analysis using the categories: author and year of publication; sample characteristics; methods and data collected; intervention protocol; and results found. Methodological quality was assessed using the PEDro scale. Fourteen studies were included, evaluating 168 people with diabetes (122/46 type 2/1) and 42 normoglycemic individuals, which evaluated markers such as capillary and fasting blood glucose, 24-h blood glucose profile, postprandial blood glucose, incidence, and prevalence of hyperglycemia, vascular function and pressure response and control of inflammatory markers. Physical exercise was found to have several acute beneficial effects on the health of the diabetic population, such as reduced capillary and postprandial blood glucose, blood glucose profile, and blood pressure. Moreover, HIIT seems to be a safe and effective alternative in glycemic control and associated factors, superior to continuous moderate-intensity training.

Optimizing sprint interval exercise for post-exercise hypotension: A randomized crossover trial

This study aimed to examine the effects of manipulating the rest intervals during sprint interval training (SIT) on post-exercise hypotension and within-session oxygen consumption.Thirty healthy, trained adults (aged 30.9 ± 8.7 years; 14 males, 16 females; BMI 22.1 ± 2.3 kg/m²; VO₂max 50.7 ± 7.8 ml/kg/min) completed two different SIT protocols (4x 30-seconds all-out cycling sprints) with a one-week washout period. Sprint bouts were separated by either 1 (R1) or 3 (R3) minutes of active recovery. Both before and throughout the 45 minutes after the training, peripheral systolic (pSBP) and diastolic (pDBP) blood pressure, central systolic (cSBP) and diastolic (cDBP) blood pressure, aortic pulse wave velocity (aPWV), stroke volume (SV), and heart rate (HR) were assessed. Throughout the SIT protocols, oxygen consumption (VO₂) was monitored.There were no significant differences in time spent at 75%, 85%, 95%, and 100% of maximal VO₂ between R1 and R3. After R3, there was a significant reduction in pSBP, pDBP, cSBP, cDBP, and aPWV. After R1, there were no changes in the respective parameters. There were significant interaction effects in pSBD (p<0.001), pDBP (p<0.001), cSBP (p<0.001), cDBP (p=0.001), and aPWV (p=0.033). HR significantly increased after both conditions. Only R1 resulted in a significant reduction in SV.Longer resting intervals during SIT bouts seem to result in more substantial post-exercise hypotension effects. Time spent at a high percentage of maximal VO₂ was not affected by rest interval manipulation.

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.

Feasibility and safety of high-intensity interval training for the rehabilitation of geriatric inpatients (HIITERGY) a pilot randomized study

BACKGROUND

High-intensity interval training (HIIT) has been shown to be more effective than moderate-intensity continuous training (MICT) for the physical rehabilitation. However, data on its suitability for older hospitalized patients is scarce.

METHODS

Randomized controlled trial in a hospital setting. Inclusion of 100 patients, ≥65 years old, hospitalized for rehabilitation after an acute medical condition, in a two-week rehabilitation program of either four HIIT or three MICT sessions per week. Completion was defined as participation in all but two planned sessions accomplishing ≥50% of each session. We assessed: upper-limb muscle strength (handgrip isometric strength test), lower-limb muscle strength (quadriceps and ankle flexion and extension tests); gait speed and spatio-temporal parameters (instrumented walkway), and exercise capacity (6-min walk test). All adverse events were recorded as safety endpoints.

RESULTS

An intention-to-treat analysis showed a 44% completion rate for the HIIT group (95% CI, 30-59) and 77% for MICT (95% CI, 55-82). A modified intention-to-treat analysis restricted to patients who participated in ≥1 session showed an 88% completion rate in the HIIT group (95%CI, 69-97) and an 80% completion rate in MICT (95%CI, 65-90). The exercises most frequently undertaken were the pedal exerciser (54%) and the NuStep (32%). There were no significant differences in the various measures. No serious adverse events occurred.

CONCLUSION

A HIIT rehabilitation program for this population was feasible, safe and had a high adherence rate.

TRIAL REGISTRATION NUMBER

Clinicatrials.gov ID: NCT02318459. Trial registration date: November 7th, 2014. Retrospectively registered. This study adheres to the CONSORT guidelines.

High-intensity interval training irrespective of its intensity improves markers of blood fluidity in hypertensive patients

Aim: The present study examined and compared the effects of two different HIIT (High-intensity interval training) protocols on markers of blood fluidity in hypertensive patients.Methods: Thirty hypertensive (stage 1, systolic BP >140 and diastolic BP>90 mmHg) patients (age, 47.96 ± 3.20 yrs), were randomly allocated to short-duration HIIT (SDHIIT, n = 10), long-duration HIIT (LDHIIT, n = 10), and control (n = 10) groups. After 2 weeks of continuous mild training, patients in SDHIIT group performed 8 weeks of HIIT included 27 min HIIT that encompassed 27 repetitions of 30 s activity at 80%-100% of VO₂peak interspersed by 30 s passive/active (10%-20% of VO₂peak) recovery, while, patients in LDHIIT group performed 8 weeks of HIIT (32 min per session) included 4 repetitions of 4 min activity at 75%-90% of VO₂peak interspersed by 4 min passive/active (15%-30% of VO₂peak) recovery. Two blood samples were taken before and after training and were analyzed for hemorheological variables.Results: Significant (P < .05) reductions in systolic blood pressure (SBP), blood and plasma viscosity, fibrinogen concentration and red blood cell (RBC) aggregation (8-12%) were found following two training protocols (P < .05), though, the differences between adaptations were not statistically significant (P > .05). In addition, HIIT protocols increased RBC deformability significantly (P < .05), with no significant differences being observed between two protocols.Conclusion: It is concluded that HIIT training reduces SBP and markers of blood fluidity in patients with stage 1 hypertension irrespective of the HIIT intensity and duration. Therefore, this type of exercise training could be prescribed for improving the blood fluidity markers in hypertensive patients.

Interval exercise induces milder respiratory responses compared to continuous exercise

The purpose of this study was to explore the respiratory response of acute interval and continuous exercise (CE) of low and high intensity. Fourteen recreational athletes (7 men and 7 women; VO₂max = 35.7 ± 6.1 mlkg^-1min^-1) performed a bout of continuous and a bout of interval exercise (IE) both consisted of 5-min cycling at low intensity [80% of the power output (W) of the predetermined gas exchange threshold (GET) (80%W_GET)] and 5-min cycling at high intensity {W_GET plus the work rate corresponding to 50% of the difference between peak power output (PPO) at oxygen uptake (VO₂max) test and the W_GET [W_GET + 0.50 Δ(PPO - W_GET)]}. CE compared to IE induced significant higher heart rate and ventilation as well as significant higher levels of mouth occlusion pressure for 0.1 s (P_0.1) (P < 0.05) during low and high intensities. Our results indicate that CE stimulates respiration more than IE when the exercise is performed at the same relative intensity.

High intensity interval training improves diabetic cardiomyopathy via miR-1 dependent suppression of cardiomyocyte apoptosis in diabetic rats

Purpose

Diabetes and its complications such as diabetic cardiomyopathy still account for significant morbidity and mortality. High-quality evidence was shown the importance of exercise in controlling diabetes complications, but the molecular mechanism on diabetic cardiomyopathy is not yet fully understood. This study aimed to compare and investigate the effect of high intensity interval training (HIIT) and continuous endurance training (CET) on the signaling pathway of diabetic cardiomyopathy.

Methods

Hence, 21 Wistar rats with an average weight of 260 ± 10 g, after induction of diabetes (STZ 50 mg/kg BW) were randomly divided into three groups (control, CET and HIIT; n = 7). Training programs were conducted 5 days a week for 5 weeks. CET program was defined as running at 60% vVO₂max for 30 min in each session and the HIIT program was defined as running at 85-90% vVO₂max for 3 min followed by 1 min recovery (30-35% vVO₂max), that was repeated four times in each session. The cardiac performance was analyzed via determination of end systolic and diastolic dimensions and the ejection fraction by echocardiography. To elucidate the responsible molecular mechanism of miR-1, IGF-1 and IGF-1R mRNA and apoptosis marker protein expression were investigated.

Results

Both training programs specifically HIIT, significantly reduced the blood glucose, enhanced heart performance, reduced miR-1 expression, induced IGF-1 and IGF-1R expression and reduced apoptotic protein expression.

Conclusion

We showed that HIIT is more effective than CET for reduction of diabetic cardiomyopathy as a complication of diabetes in animal models through suppressing miR-1 and its downstream apoptosis pathway.

Beta-Blocker Type Effect on Substrate Oxidation during HIIE in Heart Failure Patients: Pilot Data

The effect of third and second-generation type of beta-blocker on substrate oxidation especially during high-intensity exercises are scarce.

The objective of the study is to explore differences of beta-blocker regimens (vasodilating vs. non-vasodilating beta-blockers) for substrate oxidation during in high-intensity intermittent exercise (HIIE) in chronic heart failure and reduced ejection fraction (HFrEF).

Eighteen CHF males (58.8 ± 9 years), 8 under use of β1 specific beta-blockers+alfa 1-blocker and 10 using β1 non-specific beta-blockers, were randomly assigned to 4 different HIIE, in a cross-over design. The 4 protocols were: 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 PPO; B and D). Energy expenditure (EE; kcal/min), quantitative carbohydrate (CHO) and lipid oxidation (g/min) and qualitative (%) contribution were calculated. Two-way ANOVA and Bonferroni post-hoc test were used (p-value ≤ 0.05) to compare CHO and lipid oxidation at rest and at 10min.

Total exercise time or EE did not show differences for beta-blocker use. The type of beta-blocker use showed impact in CHO (%) and lipid (g/min and %) for rest and 10 min, but absolute contribution of CHO (g/min) was different just at 10min (Interaction p = 0.029). Higher CHO oxidation was found in vasodilating beta-blockers when comparing to non-vasodilating.

According to our pilot data, there is an effect of beta-blocker type on substrate oxidation during HIIE, but no influence on EE or exercise total time in HFrEF patients.

The Effectiveness of Progressive Aerobic Interval Training in Cardiac Rehabilitation

INTRODUCTION

Aerobic interval training (AIT) has recently emerged as a more effective strategy than moderate-intensity continuous exercise (MICE) for improving peak oxygen consumption (V˙O2peak) in coronary artery disease (CAD) patients. The primary purpose of this retrospective study was to describe the change in V˙O2peak, and cardiovascular (CV) risk profile characteristics (secondary outcomes) after progressive AIT practiced in the largest, outpatient cardiac rehabilitation (CR) program in North America compared with usual care CR involving MICE.

METHODS

Electronic database records were retrieved from consecutively enrolled patients with CAD who attended the Toronto Rehabilitation Institute, between January 1, 2005, and December 31, 2015. Patients were then separated into two, age and sex propensity score-matched groups: 772 patients were prescribed 26 wk of MICE (60%-80% of V˙O2peak, five times per week) as per usual care CR (56.0 ± 9.2 yr; 12% female/88% male; V˙O2peak: 20.8 ± 5.9 mL·kg·min), and 772 patients were prescribed 26 wk of progressive walk/jog intervals (15 min·mile walking pace, 12 min·mile jogging pace, five times per week) (55.9 ± 9.3 yr; 12% female/88% male; V˙O2peak: 24.8 ± 5.7 mL·kg ·min). Treatment effect analysis of AIT on V˙O2peak and CV risk profile characteristics was performed using multiple regression with baseline values as covariates.

RESULTS

Treatment effect analysis revealed a 3.84-mL·kg·min superior improvement in V˙O2peak in the AIT group compared to usual care MICE group (P < 0.001). Furthermore, AIT significantly improved BMI, triglycerides, hip and abdominal girth, and depression score compared with MICE (P < 0.023 for all).

CONCLUSIONS

Progressive AIT performed in a standard, outpatient CR program appears to be superior to usual care MICE for improving V˙O2peak, CV risk profile characteristics, and depression score in stable CAD patients. These findings may have important implications for exercise training guidelines in the rehabilitation setting, and in future studies.

Investigating the effectiveness and feasibility of exercise on microvascular reactivity and quality of life in systemic sclerosis patients: study protocol for a feasibility study

Background

Raynaud’s phenomenon is one of the first clinical manifestations observed in systemic sclerosis (SSc). This microvasculature disorder affects mostly the digits in over 95% of SSc patients, significantly affecting their health-related quality of life (HRQoL) and incurring higher hospital admissions and other healthcare costs. Exercise is known to improve both micro- and macrovascular function – aerobic exercise and resistance training, separately or combined, have been demonstrated to lead to significant vasculo-physiological improvements in conditions that present vasculopathy. However, the effects of a combined exercise programme on microcirculation in SSc patients has yet to be investigated. Therefore, the purpose of this study is to assess the effects of high-intensity interval training (HIIT) combined with circuit resistance training on the microvascular function in the digital area of SSc patients.

Methods

This will be a randomised controlled, feasibility trial with two arms, wherein 30 patients with SSc in receipt of medical treatment will be randomly assigned to usual care (medical treatment) or to a 12-week supervised exercise programme. Patients in the exercise group will undertake two, 45-min sessions each week consisting of 30 min HIIT (30 s 100% peak power output/30 s passive recovery) on the arm crank ergometer and 15 min of upper body circuit resistance training. Patients will be assessed before as well as at 3 and 6 months following randomisation. Primary outcomes of the study will be recruitment and retention rate, intervention acceptability and adherence to the exercise programme. Secondary outcomes include the digital area cutaneous microvascular function (laser Doppler fluximetry combined with iontophoresis), physical fitness, functional ability, upper back transcutaneous oxygen tension, body composition and quality of life (EQ-5D-5L). Selected interviews with a subsample of patients will be undertaken to explore their experiences of having Raynaud’s phenomenon and the acceptability of the exercise intervention and study procedures.

Discussion

Data from this study will be used to identify the feasibility of a combined exercise programme to be implemented in SSc patients, the acceptability of the intervention and the study design, and to determine the effects of exercise on the microvasculature. Overall, this study will provide sufficient data to inform and support a full multicentre clinical trial.

Trial registration

ClinicalTrials.gov (NCT number): NCT03058887, February 23, 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2980-1) contains supplementary material, which is available to authorized users.

[Exercise Training and Physical Activity in Patients with Heart Failure]

Exercise Training and Physical Activity in Patients with Heart Failure Abstract. Heart failure is a clinical syndrome with different etiologies and phenotypes. For all forms, supervised exercise training and individual physical activity are class IA recommendations in current guidelines. Exercise training can start in the hospital, immediately after stabilization of acute heart failure (phase I). After discharge, it can continue in a stationary or ambulatory prevention and rehabilitation program (phase II). Typical components are endurance, resistance and respiratory training. Health insurances cover costs for three to six months. Patients with implantable cardioverter defibrillators or left ventricular assist devices may train in experienced centers. Besides muscular reconditioning, a major goal of phase II is to increase health literacy to improve long-term adherence to physical activity. In phase III, heart groups offer support.

The effects of upper and lower limb exercise on the microvascular reactivity in limited cutaneous systemic sclerosis patients

BACKGROUND

Aerobic exercise in general and high-intensity interval training (HIIT) specifically is known to improve vascular function in a range of clinical conditions. HIIT in particular has demonstrated improvements in clinical outcomes, in conditions that have a strong macroangiopathic component. Nevertheless, the effect of HIIT on microcirculation in systemic sclerosis (SSc) patients is yet to be investigated. Therefore, the purpose of the study was to compare the effects of two HIIT protocols (cycle and arm cranking) on the microcirculation of the digital area in SSc patients.

METHODS

Thirty-four limited cutaneous SSc patients (65.3 ± 11.6 years old) were randomly allocated in three groups (cycling, arm cranking and control group). The exercise groups underwent a 12- week exercise program twice per week. All patients performed the baseline and post-exercise intervention measurements where physical fitness, functional ability, transcutaneous oxygen tension (ΔTcpO2), body composition and quality of life were assessed. Endothelial-dependent as well as -independent vasodilation were assessed in the middle and index fingers using LDF and incremental doses of acetylcholine (ACh) and sodium nitroprusside (SNP). Cutaneous flux data were expressed as cutaneous vascular conductance (CVC).

RESULTS

Peak oxygen uptake increased in both exercise groups (p < 0.01, d = 1.36). ΔTcpO2 demonstrated an increase in the arm-cranking group only, with a large effect, but not found statistically significant,(p = 0.59, d = 0.93). Endothelial-dependent vasodilation improvement was greater in the arm-cranking (p < 0.05, d = 1.07) in comparison to other groups. Both exercise groups improved life satisfaction (p < 0.001) as well as reduced discomfort and pain due to Raynaud's phenomenon (p < 0.05). Arm cranking seems to be the preferred mode of exercise for study participants as compared to cycling (p < 0.05). No changes were observed in the body composition or the functional ability in both exercise groups.

CONCLUSIONS

Our results suggest that arm cranking has the potential to improve the microvascular endothelial function in SSc patients. Also notably, our recommended training dose (e.g., a 12-week HIIT program, twice per week), appeared to be sufficient and tolerable for this population. Future research should focus on exploring the feasibility of a combined exercise such as aerobic and resistance training by assessing individual's experience and the quality of life in SSc patients.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT number): NCT03058887 , February 23, 2017.

Effects of high-intensity interval versus continuous exercise training on post-exercise heart rate recovery in coronary heart-disease patients

BACKGROUND

Heart rate recovery (HRR) has been considered a prognostic and mortality indicator in both healthy and coronary patients. Physical exercise prescription has shown improvements in VO₂peak and HRR, but most of the studies have been carried out applying continuous training at a moderate intensity, being very limited the use of protocols of high intensity interval training in coronary patients. We aimed to compare the effects of a moderate continuous training (MCT) versus a high intensity interval training (HIIT) programme on VO₂peak and HRR.

METHODS

Seventy three coronary patients were assigned to either HIIT or MCT groups for 8weeks. Incremental exercise tests in a cycloergometer were performed to obtain VO₂peak data and heart rate was monitored during and after the exercise test to obtain heart rate recovery data.

RESULTS

Both exercise programmes significantly increase VO₂peak with a higher increase in the HIIT group (HIIT: 4.5±4.46ml/kg/min vs MCT: 2.46±3.57ml/kg/min; p=0.039). High intensity interval training resulted in a significantly increase in HRR at the first and second minute of the recovery phase (15,44±7,04 vs 21,22±6,62, p<0,0001 and 23,73±9,64 vs 31,52±8,02, p<0,0001, respectively).

CONCLUSIONS

The results of our research show that the application of HIIT to patients with chronic ischemic heart disease of low risk resulted in an improvement in VO₂peak, and also improvements in post-exercise heart-rate recovery, compared with continuous training.

Effect of High-Intensity Interval Versus Continuous Exercise Training on Functional Capacity and Quality of Life in Patients With Coronary Artery Disease: A RANDOMIZED CLINICAL TRIAL

PURPOSE

There is strong evidence that exercise training has beneficial health effects in patients with cardiovascular disease. Most studies have focused on moderate continuous training (MCT); however, a body of evidence has begun to emerge demonstrating that high-intensity interval training (HIIT) has significantly better results in terms of morbidity and mortality. The aim of this study was to compare the effects of MCT versus HIIT on functional capacity and quality of life and to assess safety.

METHODS

Seventy-two patients with ischemic heart disease were assigned to either HIIT or MCT for 8 weeks. We analyzed cardiopulmonary exercise test data, quality of life, and adverse events.

RESULTS

High-intensity interval training resulted in a significantly greater increase in (Equation is included in full-text article.)O2peak (4.5 ± 4.7 mL·kg·min) compared with MCT (2.5 ± 3.6 mL·kg·min) (P < .05). The aerobic threshold (VT1) increased by 21% in HIIT and 14% in MCT. Furthermore, there was a significant (P < .05) increase in the distance covered in the 6-minute walk distance test in the HIIT group (49.6 ± 6.3 m) when compared with the MCT group (29.6 ± 12.0 m). Both training protocols improved quality of life. No adverse events were reported in either of the groups.

CONCLUSIONS

On the basis of the results of this study, HIIT should be considered for use in cardiac rehabilitation as it resulted in a greater increase in functional capacity compared with MCT. We also observed greater improvement in quality of life without any increase in cardiovascular risk.

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.

Potential Universal Application of High-intensity Interval Training from Athletes and Sports Lovers to Patients

Recently, high-intensity interval training (HIIT) has received much attention as a promising exercise option not only to improve aerobic fitness, but also to prevent and improve lifestyle-related diseases. Epidemiological studies have shown that the exercise volume, as determined by the product of exercise intensity, duration, and frequency, has been shown to be important for improvements in muscle mitochondrial activity and subsequent improvements in aerobic fitness, insulin sensitivity, and metabolic variables. Therefore, continuous moderate-intensity training has been widely recommended. On the other hand, the main contributor of HIIT to improvements in aerobic fitness and metabolic variables is its high-intensity nature, and many recent studies have shown results favoring HIIT when compared with conventional continuous training, despite its shorter exercise duration and smaller exercise volume. In this review, we aim to show the possible universal application of HIIT in a hospital setting, where athletes, sports lovers, and patients have sought medical advice and have the opportunity to undergo detailed evaluations, including an exercise stress test. For athletes, HIIT is mandatory to achieve further improvements in aerobic fitness. For patients, though higher levels of motivation and careful evaluation are required, the time constraints of HIIT are smaller and both aerobic and resistance training can be expected to yield favorable results because of the high-intensity nature of HIIT.

Physiological Responses to High-Intensity Interval Exercise Differing in Interval Duration

We determined the oxygen uptake (V[Combining Dot Above]O2), heart rate (HR), and blood lactate responses to 2 high-intensity interval exercise protocols differing in interval length. On separate days, 14 recreationally active males performed a 4 × 4 (four 4-minute intervals at 90-95% HRpeak, separated by 3-minute recovery at 50 W) and 16 × 1 (sixteen 1-minute intervals at 90-95% HRpeak, separated by 1-minute recovery at 50 W) protocol on a cycle ergometer. The 4 × 4 elicited a higher mean V[Combining Dot Above]O2 (2.44 ± 0.4 vs. 2.36 ± 0.4 L·min) and "peak" V[Combining Dot Above]O2 (90-99% vs. 76-85% V[Combining Dot Above]O2peak) and HR (95-98% HRpeak vs. 81-95% HRpeak) during the high-intensity intervals. Average power maintained was higher for the 16 × 1 (241 ± 45 vs. 204 ± 37 W), and recovery interval V[Combining Dot Above]O2 and HR were higher during the 16 × 1. No differences were observed for blood lactate concentrations at the midpoint (12.1 ± 2.2 vs. 10.8 ± 3.1 mmol·L) and end (10.6 ± 1.5 vs. 10.6 ± 2.4 mmol·L) of the protocols or ratings of perceived exertion (7.0 ± 1.6 vs. 7.0 ± 1.4) and Physical Activity Enjoyment Scale scores (91 ± 15 vs. 93 ± 12). Despite a 4-fold difference in interval duration that produced greater between-interval transitions in V[Combining Dot Above]O2 and HR and slightly higher mean V[Combining Dot Above]O2 during the 4 × 4, mean HR during each protocol was the same, and both protocols were rated similarly for perceived exertion and enjoyment. The major difference was that power output had to be reduced during the 4 × 4 protocol to maintain the desired HR.

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.

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.

Within-session responses to high-intensity interval training in chronic stroke

Poststroke hemiparesis often leads to a vicious cycle of limited activity, deconditioning, and poor cardiovascular health. Accumulating evidence suggests that exercise intensity is a critical factor determining gains in aerobic capacity, cardiovascular protection, and functional recovery after stroke. High-intensity interval training (HIT) is a strategy that augments exercise intensity using bursts of concentrated effort alternated with recovery periods. However, there was previously no stroke-specific evidence to guide HIT protocol selection.

PURPOSE

This study aimed to compare within-session exercise responses among three different HIT protocols for persons with chronic (>6 months after) stroke.

METHODS

Nineteen ambulatory persons with chronic stroke performed three different 1-d HIT sessions in a randomized order, approximately 1 wk apart. HIT involved repeated 30-s bursts of treadmill walking at maximum tolerated speed, alternated with rest periods. The three HIT protocols were different on the basis of the length of the rest periods, as follows: 30 s (P30), 60 s (P60), or 120 s (P120). Exercise tolerance, oxygen uptake (V˙O2), HR, peak treadmill speed, and step count were measured.

RESULTS

P30 achieved the highest mean V˙O2, HR, and step count but with reduced exercise tolerance and lower treadmill speed than P60 or P120 (P30: 70.9% V˙O2peak, 76.1% HR reserve (HRR), 1619 steps, 1.03 m·s(-1); P60: 63.3% V˙O2peak, 63.1% HRR, 1370 steps, 1.13 m·s(-1); P120: 47.5% V˙O2peak, 46.3% HRR, 1091 steps, 1.10 m·s(-1)). P60 achieved treadmill speed and exercise tolerance similar to those in P120, with higher mean V˙O2, HR, and step count.

CONCLUSIONS

For treadmill HIT in chronic stroke, a combination of P30 and P60 may optimize aerobic intensity, treadmill speed, and stepping repetition, potentially leading to greater improvements in aerobic capacity and gait outcomes in future studies.

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.

Forming a consensus opinion on exercise prehabilitation in elderly colorectal cancer patients: a Delphi study

BACKGROUND

There is no consensus amongst colorectal surgeons as to whether preoperative exercise is beneficial in the management of colorectal cancer patients. Research has shown higher rates of postoperative complications in patients who are less fit. Agreement needs to be sought on whether improving fitness via exercise should be a part of preoperative care. The Delphi process is an iterative process designed to refine opinions on a subject, until consensus agreement is reached within an expert group.

METHODS

We performed a Delphi survey with a group of consultant colorectal surgeons. Statements achieving >80% agreement were taken as consensus, those achieving >80% disagreement were removed, and those in between were revised in the following round. The process ended with a group of statements which achieved consensus.

RESULTS

Thirty-two statements were included in the first round of the survey. After three rounds of the survey, 21 statements were accepted as consensus, six statements were rejected, and seven statements did not reach consensus. It was agreed that exercise training should form part of preoperative care and would be supported by surgeons. That suitable programmes pose significant risk to patients was rejected. There was no consensus reached on the strength of current available evidence or whether it would be possible to deliver exercise programmes.

CONCLUSIONS

This work is the first to produce a set of statements on which expert consensus opinion has been agreed regarding preoperative exercise in colorectal cancer patients. Future work, informed by this study, will design interventions to produce rapid improvements in fitness before surgery.

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 interval exercise improves vagal tone and decreases arrhythmias in chronic heart failure

PURPOSE

Autonomic dysfunction including sympathetic activation and vagal withdrawal has been reported in patients with chronic heart failure (CHF). We tested the hypotheses that high-intensity interval exercise (HIIE) in CHF patients would enhance vagal modulation and thus decrease arrhythmic events.

METHODS

Eighteen CHF patients underwent a baseline assessment (CON) and were then randomized to a single session of HIIE and to an isocaloric moderate-intensity continuous exercise (MICE). We evaluated the HR, HR variability parameters, and arrhythmic events by 24-h Holter ECG recordings after HIIE, MICE, and CON sessions.

RESULTS

We found that HR was significantly decreased after HIIE (68 ± 3 bpm, P < 0.01) when compared with CON and MICE values (71.1 ± 2 and 69 ± 3 bpm, respectively). HIIE led to a significant increase in normalized high-frequency power (35.95% ± 2.83% vs 31.56% ± 1.93% and 24.61% ± 2.62% for CON and MICE, respectively, P < 0.01). Both exercise conditions were associated with an increase in very low frequency power comparative to CON. After HIIE, premature ventricular contractions were significantly decreased (531 ± 338 vs 1007 ± 693 and 1671 ± 1604 for CON and MICE, respectively, P < 0.01). An association was found between the changes in premature ventricular contraction and the changes in low-frequency/high-frequency ratio (r = 0.66, P < 0.01) in patients exposed to HIIE.

CONCLUSION

We demonstrate that a single session of HIIE improves autonomic profile of CHF patients, leading to significant reductions of HR and arrhythmic events in a 24-h posttraining period. Cardioprotective effects of HIIE in CHF patients need to be confirmed in a larger study population and on a long-term basis.

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.

High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: a systematic review and meta-analysis

BACKGROUND/AIM

Cardiorespiratory fitness (CRF) is a strong determinant of morbidity and mortality. In athletes and the general population, it is established that high-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) in improving CRF. This is a systematic review and meta-analysis to quantify the efficacy and safety of HIIT compared to MICT in individuals with chronic cardiometabolic lifestyle diseases.

METHODS

The included studies were required to have a population sample of chronic disease, where poor lifestyle is considered as a main contributor to the disease. The procedural quality of the studies was assessed by use of a modified Physiotherapy Evidence Base Database (PEDro) scale. A meta-analysis compared the mean difference (MD) of preintervention versus postintervention CRF (VO2peak) between HIIT and MICT.

RESULTS

10 studies with 273 patients were included in the meta-analysis. Participants had coronary artery disease, heart failure, hypertension, metabolic syndrome and obesity. There was a significantly higher increase in the VO2peak after HIIT compared to MICT (MD 3.03 mL/kg/min, 95% CI 2.00 to 4.07), equivalent to 9.1%.

CONCLUSIONS

HIIT significantly increases CRF by almost double that of MICT in patients with lifestyle-induced chronic diseases.

The 2013 Canadian Cardiovascular Society Heart Failure Management Guidelines Update: focus on rehabilitation and exercise and surgical coronary revascularization

The 2013 Canadian Cardiovascular Society Heart Failure Management Guidelines Update provides focused discussions on the management recommendations on 2 topics: (1) exercise and rehabilitation; and (2) surgical coronary revascularization in patients with heart failure. First, all patients with stable New York Heart Association class I-III symptoms should be considered for enrollment in a tailored exercise training program, to improve exercise tolerance and quality of life. Second, selected patients with suitable coronary anatomy should be considered for bypass graft surgery. As in previous updates, the topics were chosen in response to stakeholder feedback. The 2013 Update also includes recommendations, values and preferences, and practical tips to assist the clinicians and health care workers manage their patients with heart failure.

Physical Activity and Exercise for Secondary Prevention among Patients with Cardiovascular Disease

Most adults do not achieve the recommended levels of physical activity, including patients with cardiovascular disease (CVD). Furthermore, healthcare providers often do not understand the benefits of physical activity in CVD patients, rather over emphasizing the potential risks related to activity. Recent studies suggest reductions in cardiovascular events including mortality with concomitant improvements in quality of life for many vascular conditions. However gaps in our current knowledge base remain. Recent research on physical activity including use of novel internet based interventions are developing areas of interest have moved to reduce such knowledge gaps.

High-intensity interval training in stroke rehabilitation

After stroke, people with weakness enter a vicious cycle of limited activity and deconditioning that limits functional recovery and exacerbates cardiovascular risk factors. Conventional aerobic exercise improves aerobic capacity, function, and overall cardiometabolic health after stroke. Recently, a new exercise strategy has shown greater effectiveness than conventional aerobic exercise for improving aerobic capacity and other outcomes among healthy adults and people with heart disease. This strategy, called high-intensity interval training (HIT), uses bursts of concentrated effort alternated with recovery periods to maximize exercise intensity. Three poststroke HIT studies have shown preliminary effectiveness for improving functional recovery. However, these studies were varied in approach and the safety of poststroke HIT has received little attention. The objectives of this narrative review are to (1) propose a framework for categorizing HIT protocols; (2) summarize the safety and effectiveness evidence of HIT among healthy adults and people with heart disease and stroke; (3) discuss theoretical mechanisms, protocol selection, and safety considerations for poststroke HIT; and (4) provide directions for future research.

Reducing the intensity and volume of interval training diminishes cardiovascular adaptation but not mitochondrial biogenesis in overweight/obese men

OBJECTIVE

The purpose of this research was to determine if the adaptations to high intensity interval training (HIT) are mitigated when both intensity and training volume (i.e. exercise energy expenditure) are reduced.

METHODS

19 overweight/obese, sedentary males (Age: 22.7±3.9 yrs, Body Mass Index: 31.4±2.6 kg/m(2), Waist Circumference: 106.5±6.6 cm) performed 9 sessions of interval training using a 1-min on, 1-min off protocol on a cycle ergometer over three weeks at either 70% (LO) or 100% (HI) peak work rate.

RESULTS

Cytochrome oxidase I protein content, cytochrome oxidase IV protein content, and citrate synthase maximal activity all demonstrated similar increases between groups with a significant effect of training for each. β-hydroxyacyl-CoA dehydrogenase maximal activity tended to increase with training but did not reach statistical significance (p = 0.07). Peroxisome proliferator-activated receptor gamma coactivator-1α and silent mating type information regulator 2 homolog 1 protein contents also increased significantly (p = 0.047), while AMP-activated protein kinase protein content decreased following the intervention (p = 0.019). VO2peak increased by 11.0±7.4% and 27.7±4.4% in the LO and HI groups respectively with significant effects of both training (p<0.001) and interaction (p = 0.027). Exercise performance improved by 8.6±7.6% in the LO group and 14.1±4.3% in the HI group with a significant effect of training and a significant difference in the improvement between groups. There were no differences in perceived enjoyment or self-efficacy between groups despite significantly lower affect scores during training in the HI group.

CONCLUSIONS

While improvements in aerobic capacity and exercise performance were different between groups, changes in oxidative capacity were similar despite reductions in both training intensity and volume.

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

Aerobic exercise training in the heart failure (HF) population is supported by an extensive body of literature. The clinically accepted model for exercise prescription is currently moderate-intensity-aerobic continuous training (MI-ACT). Documented benefits from the literature include improvements in various aspects of physiologic function, aerobic exercise capacity and quality of life while the impact on morbidity and mortality is promising but requires further investigation. Recently, however, a body of evidence has begun to emerge demonstrating high-intensity-aerobic interval training (HI-AIT) can be performed safely with impressive improvements in physiology, functional capacity and quality of life. These initial findings have led some to question the long-standing clinical approach to aerobic exercise training in patients with HF (i.e., MI-ACT), implying it should perhaps be replaced with a HI-AIT model. This is a potentially controversial paradigm shift given the potential increase in adverse event risk associated with exercising at higher intensities, particularly in the HF population where the likelihood of an untoward episode is already at a heightened state relative to the apparently healthy population. The present review therefore addresses key issues related to HI-AIT in the HF population and makes recommendations for future research and current clinical practice.

Exercise: friend or foe?

Physical activity and exercise have been associated with reduced cardiovascular risk, morbidity, and mortality, as well as all-cause mortality, both in the general population and in patients with various forms of cardiovascular disease. Increasing amounts of exercise are associated with incremental reductions in mortality, but considerable benefits have been found even with a low level of exercise. Exercise is beneficial for most individuals, but risks exist. Exercise is associated with reduced long-term morbidity and mortality, but acute exercise can transiently increase the risk of fatal or nonfatal cardiovascular events. Although tragic, these events are very rare, and even to some extent preventable with screening programmes. Low-intensity physical activity is important and beneficial to all individuals, including those with a high risk of adverse cardiovascular events. In individuals who are physically fit and who do not have genetic predisposition to, or signs of, cardiovascular disease, the greater the intensity and amount of exercise, the greater the health benefits. Nevertheless, effective strategies to encourage exercise in the population are lacking. A sustained increase in physical activity is likely to require more than individual advice, and needs to include urban planning and possibly even legislation.

Long-term high-intensity interval training associated with lifestyle modifications improves QT dispersion parameters in metabolic syndrome patients

BACKGROUND

QT dispersion (QTd) is a marker of myocardial electrical instability, and is increased in metabolic syndrome (MetS). Moderate intensity continuous exercise (MICE) training was shown to improve QTd in MetS patients.

OBJECTIVES

To describe long-term effects of MICE and high-intensity interval exercise training (HIIT) on QTd parameters in MetS.

METHODS

Sixty-five MetS patients (53 ± 9 years) were assigned to either a MICE (60% of peak power output [PPO]), or a HIIT program (alternating phases of 15-30 s at 80% of PPO interspersed by passive recovery phases of equal duration), twice weekly during 9 months. Ventricular repolarization indices (QT dispersion=QTd, standard deviation of QT = sdQT, relative dispersion of QT = rdQT, QT corrected dispersion = QTcd), metabolic, anthropometric and exercise parameters were measured before and after the intervention.

RESULTS

No adverse events were noted during exercise. QTd decreased significantly in both groups (51 vs 56 ms in MICE, P < 0.05; 34 vs 38 ms in HIIT, P < 0.05). Changes in QTd were correlated with changes in maximal heart rate (r = -0.69, P < 0.0001) and in heart rate recovery (r = -0.49, P < 0.01) in the HIIT group only. When compared to MICE, HIIT training induced a greater decrease in weight, BMI and waist circumference. Exercise capacity significantly improved by 0.82 and 1.25 METs in MICE and HIIT groups respectively (P < 0.0001). Lipid parameters also improved to the same degree in both groups.

CONCLUSION

In MetS, long-term HIIT and MICE training led to comparable effects on ventricular repolarization indices, and HIIT might be associated with greater improvements in certain cardiometabolic risk factors.

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.