Left ventricular mechanical, cardiac autonomic and metabolic responses to a single session of high intensity interval training

PURPOSE

High-intensity interval training (HIIT) produces significant health benefits. However, the acute physiological responses to HIIT are poorly understood. Therefore, we aimed to measure the acute cardiac autonomic, haemodynamic, metabolic and left ventricular mechanical responses to a single HIIT session.

METHODS

Fifty young, healthy participants completed a single HIIT session, comprising of three 30-s maximal exercise intervals on a cycle ergometer, interspersed with 2-min active recovery. Cardiac autonomics, haemodynamics and metabolic variables were measured pre-, during and post-HIIT. Conventional and speckle tracking echocardiography was used to record standard and tissue Doppler measures of left ventricular (LV) structure, function and mechanics pre- and post-HIIT.

RESULTS

Following a single HIIT session, there was significant post-exercise systolic hypotension (126 ± 13 to 111 ± 10 mmHg, p < 0.05), parallel to a significant reduction in total peripheral resistance (1640 ± 365 to 639 ± 177 dyne⋅s⋅cm⁵, p < 0.001) and significant increases in baroreceptor reflex sensitivity and baroreceptor effectiveness index (9.2 ± 11 to 24.8 ± 16.7 ms⋅mmHg^-1 and 41.8 ± 28 to 68.8 ± 16.2, respectively) during recovery compared to baseline. There was also a significant increase in the low- to high-frequency heart rate variability ratio in recovery (0.7 ± 0.48 to 1.7 ± 1, p < 0.001) and significant improvements in left ventricular global longitudinal strain (- 18.3 ± 1.2% to - 29.2 ± 2.3%, p < 0.001), and myocardial twist mechanics (1.27 ± 0.72 to 1.98 ± 0.72°·cm^-1, p = 0.028) post-HIIT compared to baseline.

CONCLUSION

A single HIIT session is associated with acute improvements in autonomic modulation, haemodynamic cardiovascular control and left ventricular function, structure and mechanics. The acute responses to HIIT provide crucial mechanistic information, which may have significant acute and chronic clinical implications.

A single session of low-volume high-intensity interval and moderate-intensity continuous exercise elicits a transient reduction in ghrelin levels, but not in post-exercise energy intake in obese men

OBJECTIVE

This study investigated the acute effects of high-intensity interval (HIIE) and moderate-intensity continuous (MICE) exercise on ghrelin levels in obese men.

METHODS

A total of 10 obese men (age 27.6 ± 1.8 years, body mass index 35.4 ± 4.5 kg/m2, body fat 39.9 ± 2.1%) performed two exercise sessions in a randomized order: HIIE (10 × 1 min intervals at 90% of the maximal heart rate [HRmax] interspersed by 1 min of active recovery) and MICE (20 min at 70% of the HRmax). Ghrelin levels were assessed pre-, post- and 1h post-exercise, and energy intake was assessed 1h post-exercise through an ad libitum meal.

RESULTS

HIIE and MICE showed a trend to decrease ghrelin levels immediately post-exercise (-14.1 ± 21.6% and -9.6 ± 23.8%, respectively, p = 0.07) and decreased 1h post-exercise (-12.7 ± 31.8% and -13.8 ± 21.7%, respectively, p < 0.05). No changes were observed for post-exercise energy intake (p > 0.05). There was a positive correlation between the change in ghrelin levels and post-exercise energy intake only for HIIE (r = 0.63, p = 0.05).

CONCLUSION

In summary, a single session of HIIE and MICE elicits a reduction on ghrelin levels without changing post-exercise energy intake in obese men.

High-intensity interval training effects in cardiorespiratory fitness of lung cancer survivors: a systematic review and meta-analysis

PURPOSE

To assess the exercise intervention focused on high-intensity interval training (HIIT) in lung cancer survivors.

DESIGN

We performed a literature search using PubMed, Web of Science, and Science Direct (last search March 2021). Quality assessment and risk of bias were assessed using the Downs and Black scale and the Cochrane tool.

PARTICIPANTS

A total of 305 patients of 8 studies were assessed, with their mean age ranging from 61 ± 6.3 to 66 ± 10 years in the exercise group and from 58.5 ± 8.2 to 68 ± 9 years in the control group.

METHODS

A systematic review and meta-analysis of randomized controlled trials and pilot randomized controlled trials was performed. We included controlled trials testing the effect of HIIT in lung cancer survivors versus the usual care provided to these patients. The data were pooled and a meta-analysis was completed for cardiorespiratory fitness (VO_2peak).

RESULTS

We selected 8 studies, which included 305 patients with lung cancer: 6 studies were performed around surgical moment, one study during radiotherapy's treatment, and other during target therapy. After pooling the data, exercise capacity was included in the analysis. Results showed significant differences in favour to HIIT when compared to usual care in cardiorespiratory fitness (standard mean difference = 2.62; 95% confidence interval = 1.55, 3.68; p < 0.00001).

CONCLUSIONS AND IMPLICATIONS

The findings indicated a beneficial effect of HIIT for improving cardiorespiratory fitness in lung cancer patients in early stages around oncological treatment moment. Nevertheless, this review has several limitations, the total number of studies was low, and the stage and subtype of lung cancer patients were heterogeneous that means that the conclusions of this review should be taken with caution. Review registration: PROSPERO Identifier: CRD42021231229.

Efficacy of high-intensity interval- or continuous aerobic-training on insulin resistance and muscle function in adults with metabolic syndrome: a clinical trial

PURPOSE

We carried out a randomized, clinical trial in adults of both sexes with metabolic syndrome (MS) to assess the efficacy of high-intensity, low-volume interval training (HIIT) compared to moderate-intensity continuous training (MICT) on insulin resistance (IR), muscle mass, muscle activation, and serum musclin.

METHODS

Fasting glycemia, insulinemia, and glycated haemoglobin were determined by conventional methods, IR by Homeostatic model assessment (HOMA), lean mass by Dual-Energy X-ray Absorptiometry, muscle activation through carnosine by Proton Magnetic Resonance Spectroscopy, and musclin by Enzyme-Linked ImmunoSorbent Assay before and after a supervised, three-times/week, 12-week treadmill programme. HIIT (n = 29) consisted of six intervals with one-minute, high-intensity phases at 90% of peak oxygen consumption (VO_2peak). MICT (n = 31) trained at 60% of VO_2peak for 30 min.

RESULTS

Patients had a mean age of 50.8 ± 6.0 years, body mass index of 30.6 ± 4.0 kg/m², and VO_2peak of 29.0 ± 6.3 mL.kg^-1.min^-1. Compared to MICT, HIIT was not superior at reducing Ln HOMA-IR (adjusted mean difference: 0.083 [95%CI - 0.092 to 0.257]), carnosine or musclin or at increasing thigh lean mass. HIIT increased carnosine by 0.66 mmol/kg.ww (95% CI 0.08-1.24) after intervention. Both interventions reduced IR, body fat percentage and increased total lean mass/height² and VO_2peak. Musclin showed a non-significant reduction with a small effect size after both interventions.

CONCLUSION

Compared to MICT, HIIT is not superior at reducing IR, carnosine or musclin or at increasing skeletal muscle mass in adults with MS. Both training types improved IR, muscle mass and body composition. NCT03087721, March 22nd, 2017.

TRIAL REGISTRATION NUMBER

NCT03087721. Registered March 22nd, 2017.

Short-term community-based exercise programs in low-income older women: Does exercise intensity and modality matters?

Our aim was to evaluate the effect of community-based exercise program (CBEP) intensity and modality on anthropometric, hemodynamic, and functional capacity parameters in low-income older women. Forty insufficiently active older women (68.2 ± 7.9 years) were randomly assigned to perform 12 weeks of twice-weekly high-intensity interval training combined with resistance training (HIIT+RT/n = 12), moderate-intensity continuous training combined with resistance training (MICT+RT/n = 13), or resistance training alone (RT/n = 15). Anthropometric (body mass index and waist circumference), hemodynamic (blood pressure and heart rate), and functional capacity variables (flexibility, upper and lower limb muscle strength, and mobility) were assessed before and after training programs. Waist circumference reduced similarly after all CBEP (~3 to ~4 cm; P < 0.05). Tendency toward reduction in diastolic blood pressure (~4 mm Hg; P = 0.073), and improvements in flexibility (14.5%, P = 0.011) and handgrip strength (15.8%; P = 0.02) were found only in HIIT+RT. Indeed, only RT was effective to improve five-time sit to stand (14.1%; P = 0.013). No significant difference between groups was found during follow-up in any variable. The results of present study suggest that low-income older women may improve anthropometric, hemodynamic and functional capacity variables by participating in twice-weekly short-term (i.e.: 12 weeks) CBEP. However, the CBEP-effects on hemodynamic and functional capacity appears to be affected by exercise intensity (only HIIT+RT tended toward improving diastolic BP) and modality (only RT improved significantly five-time sit to stand), respectively.

Six weeks of high-intensity interval training enhances contractile activity induced vascular reactivity and skeletal muscle perfusion in older adults

Impairments in muscle microvascular function are associated with the pathogenesis of sarcopenia and cardiovascular disease. High-intensity interval training (HIIT) is an intervention by which a myriad of beneficial skeletal muscle/cardiovascular adaptations have been reported across age, including capillarisation and improved endothelial function. Herein, we hypothesised that HIIT would enhance muscle microvascular blood flow and vascular reactivity to acute contractile activity in older adults, reflecting HIIT-induced vascular remodelling. In a randomised controlled-trial, twenty-five healthy older adults aged 65–85 years (mean BMI 27.0) were randomised to 6-week HIIT or a no-intervention control period of an equal duration. Measures of microvascular responses to a single bout of muscle contractions (i.e. knee extensions) were made in the m. vastus lateralis using contrast-enhanced ultrasound during a continuous intravenous infusion of Sonovue™ contrast agent, before and after the intervention period, with concomitant assessments of cardiorespiratory fitness and resting blood pressure. HIIT led to improvements in anaerobic threshold (13.2 ± 3.4 vs. 15.3 ± 3.8 ml/kg/min, P < 0.001), dynamic exercise capacity (145 ± 60 vs. 159 ± 59 W, P < 0.001) and resting (systolic) blood pressure (142 ± 15 vs. 133 ± 11 mmHg, P < 0.01). Notably, HIIT elicited significant increases in microvascular blood flow responses to acute contractile activity (1.8 ± 0.63 vs. 2.3 ± 0.8 (arbitrary contrast units (AU), P < 0.01)), with no change in any of these parameters observed in the control group. Six weeks HIIT improves skeletal muscle microvascular responsiveness to acute contractile activity in the form of active hyperaemia-induced by a single bout of resistance exercise. These findings likely reflect reports of enhanced large vessel distensibility, improved endothelial function, and muscle capillarisation following HIIT. Moreover, our findings illustrate that HIIT may be effective in mitigating deleterious alterations in muscle microvascular mediated aspects of sarcopenia.

Effects of Three Different Exercise Strategies for Optimizing Aerobic Capacity and Skeletal Muscle Performance in Older Adults: A Pilot Study

This Brief Report describes a pilot study of the effect of 12 weeks of stationary bicycle high-intensity interval training, stationary bicycle moderate-intensity continuous training, and resistance training on cardiorespiratory, muscular, and physical function measures in insufficiently-active older adults (N=14; 66.4±3.9 years; 3 male, 11 female). After baseline testing, participants were randomly assigned to one of the exercise groups. High-intensity interval training and moderate-intensity continuous training had small-to-large effect sizes on cardiorespiratory/endurance and physical function measures, but very small effect sizes on muscular measures. Resistance training had small-to-large effect sizes on cardiorespiratory, muscular, and physical function measures. This pilot study should be interpreted cautiously, but findings suggest that resistance exercise may be the most effective of the three studied exercise strategies for older adults as it can induce beneficial adaptations across multiple domains. These effect sizes can be used to determine optimal sample sizes for future investigations.

Cognitive effectiveness of high-intensity interval training for individuals with methamphetamine dependence: a study protocol for randomised controlled trial

INTRODUCTION

Cognitive deficit is a common syndrome of methamphetamine (MA) dependence. It is related to decision-making, control ability, and social functioning. High-intensity interval training (HIIT) is a training technique that requires people to work out at full intensity during a short period. Many studies have already shown the potential effects of HIIT on cognitive functions. The purpose of this trial is to evaluate the cognitive effects of HIIT on individuals with MA dependence.

METHODS AND ANALYSIS

A total of 240 individuals with MA dependence will be randomly assigned to the HIIT group, moderate-intensity continuous training (MICT) group and control (CON) group. HIIT will consist of a 24-min HIIT exercise on a treadmill. MICT will consist of a 1-h body-mind exercise. CON will be their traditional intervention. The experimental period will be 12 months with 3 interventions weekly for the first 6 months and follow-up for the next 6 months. All subjects will be given cognitive tests at baseline, after intervention and at follow-up. Cognitive performances will be compared by a mixed-model analysis for repeated measures.

DISCUSSION

HIIT training may reduce illicit drug cravings amongst individuals with MA dependence; hence, HIIT may have a good effect on the cognitive functions, such as memory and executive function, of individuals with MA dependence.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000032492 . Registered on April 30, 2020 ( http://www.chictr.org.cn/edit.aspx?pid=52127&htm=4 ).

Brain function during central fatigue induced by intermittent high-intensity cycling

BACKGROUND

The central governor model putatively explains the mechanism of endurance exercise-induced central fatigue, however high-intensity exercise-induced central fatigue strategies have not been investigated yet. This study aimed to examine how central fatigue affects neural response alterations, as measured by electroencephalographic (EEG) recordings, in intermittent high-intensity cycling.

METHODS

Neural responses were assessed by measuring the alteration of brainwaves based on spectral energy band estimates during an intermittent, high-intensity, 60-min exercise bout on a cycle ergometer. The cycle ergometer incline was changed every 10 min in an intermittent pattern (10-20-5-20-5-10°). EEG was used to analyze altering brain function. Heart rate (HR), blood lactate (BL), and rating of perceived exertion (RPE) were measured after the participants completed each change in incline.

RESULTS

The results showed that HR, BL, and RPE increased at an incline of 20° in comparison to a 5° incline. The spectral power of EEG was significantly increased (P ˂ 0.01) in the alpha and beta frequency ranges with a change in inclines between 5 and 20°. The spectral power of the EEG was significantly increased (P ˂ 0.01) over the whole frequency range from rest (theta + 251%, alpha + 165%, beta + 145%).

CONCLUSION

Higher, relative intensities (10 and 20°) increased brain function, regardless of fatigue occurrence. HIIT (high-intensity interval training) led to an alteration in the neural response. Further work investigating the usefulness of HIIT to improve brain function is warranted.

The effect of morning vs evening exercise training on glycaemic control and serum metabolites in overweight/obese men: a randomised trial

AIMS/HYPOTHESIS

We determined whether the time of day of exercise training (morning vs evening) would modulate the effects of consumption of a high-fat diet (HFD) on glycaemic control, whole-body health markers and serum metabolomics.

METHODS

In this three-armed parallel-group randomised trial undertaken at a university in Melbourne, Australia, overweight/obese men consumed an HFD (65% of energy from fat) for 11 consecutive days. Participants were recruited via social media and community advertisements. Eligibility criteria for participation were male sex, age 30-45 years, BMI 27.0-35.0 kg/m² and sedentary lifestyle. The main exclusion criteria were known CVD or type 2 diabetes, taking prescription medications, and shift-work. After 5 days, participants were allocated using a computer random generator to either exercise in the morning (06:30 hours), exercise in the evening (18:30 hours) or no exercise for the subsequent 5 days. Participants and researchers were not blinded to group assignment. Changes in serum metabolites, circulating lipids, cardiorespiratory fitness, BP, and glycaemic control (from continuous glucose monitoring) were compared between groups.

RESULTS

Twenty-five participants were randomised (morning exercise n = 9; evening exercise n = 8; no exercise n = 8) and 24 participants completed the study and were included in analyses (n = 8 per group). Five days of HFD induced marked perturbations in serum metabolites related to lipid and amino acid metabolism. Exercise training had a smaller impact than the HFD on changes in circulating metabolites, and only exercise undertaken in the evening was able to partly reverse some of the HFD-induced changes in metabolomic profiles. Twenty-four-hour glucose concentrations were lower after 5 days of HFD compared with the participants' habitual diet (5.3 ± 0.4 vs 5.6 ± 0.4 mmol/l, p = 0.001). There were no significant changes in 24 h glucose concentrations for either exercise group but lower nocturnal glucose levels were observed in participants who trained in the evening, compared with when they consumed the HFD alone (4.9 ± 0.4 vs 5.3 ± 0.3 mmol/l, p = 0.04). Compared with the no-exercise group, peak oxygen uptake improved after both morning (estimated effect 1.3 ml min^-1 kg^-1 [95% CI 0.5, 2.0], p = 0.003) and evening exercise (estimated effect 1.4 ml min^-1 kg^-1 [95% CI 0.6, 2.2], p = 0.001). Fasting blood glucose, insulin, cholesterol, triacylglycerol and LDL-cholesterol concentrations decreased only in participants allocated to evening exercise training. There were no unintended or adverse effects.

CONCLUSIONS/INTERPRETATION

A short-term HFD in overweight/obese men induced substantial alterations in lipid- and amino acid-related serum metabolites. Improvements in cardiorespiratory fitness were similar regardless of the time of day of exercise training. However, improvements in glycaemic control and partial reversal of HFD-induced changes in metabolic profiles were only observed when participants exercise trained in the evening.

TRIAL REGISTRATION

anzctr.org.au registration no. ACTRN12617000304336.

FUNDING

This study was funded by the Novo Nordisk Foundation (NNF14OC0011493).

Low-volume walking HIIT: Efficient strategy to improve physical capacity and reduce the risk of cardiovascular disease in older women with type 2 diabetes

BACKGROUND AND AIMS

To compare the effect of a low-volume walking high-intensity interval training (HIIT) to moderate-intensity continuous training (MICT) on risk of cardiovascular diseases and physical capacity in older women with type 2 diabetes (T2D).

METHODS

Thirty inactive older women with T2D were randomized into either HIIT (75 min/week) or MICT (150 min/week). Cardiovascular risk profile (lipid profile; waist circumference and fat mass; resting, post-exercise and ambulatory blood pressure [BP]; VO₂ peak; UKPDS score; ABC's) and physical capacity were assessed before and after a 12-week intervention.

RESULTS

While resting systolic and diastolic BP (all p ≤ 0.01) were reduced, ambulatory BP (p ≥ 0.49) and lipid profile (p ≥ 0.40) remained unchanged after the intervention. Although VO₂ peak increased to a similar extent in both groups (p = 0.015), the distance covered during the 6MWT (p = 0.01) and grip strength (p = 0.02) increased to a greater extend in HIIT. The UKPDS risk score decreased in both groups after the intervention (p = 0.03) and 31% of the participants reached the ABC's compared to 24% at baseline.

CONCLUSION

Low-volume walking HIIT is an efficient exercise intervention for older women with T2D as it improved some CVD risk factors and physical capacity. Nevertheless, neither low-volume HIIT nor MICT is sufficient to affect ambulatory blood pressure in T2D patients.

High-Intensity Interval Training in Older Adults: a Scoping Review

High-intensity interval training (HIIT) is an increasingly popular form of aerobic exercise which includes bouts of high-intensity exercise interspersed with periods of rest. The health benefits, risks, and optimal design of HIIT are still unclear. Further, most research on HIIT has been done in young and middle-aged adults, and as such, the tolerability and effects in senior populations are less well-known. The purpose of this scoping review was to characterize HIIT research that has been done in older adults including protocols, feasibility, and safety and to identify gaps in the current knowledge. Five databases were searched with variations of the terms, "high-intensity interval training" and "older adults" for experimental or quasi-experimental studies published in or after 2009. Studies were included if they had a treatment group with a mean age of 65 years or older who did HIIT, exclusively. Of 4644 papers identified, 69 met the inclusion criteria. The average duration of training was 7.9 (7.0) weeks (mean [SD]) and protocols ranged widely. The average sample size was 47.0 (65.2) subjects (mean [SD]). Healthy populations were the most studied group (n = 30), followed by subjects with cardiovascular (n = 12) or cardiac disease (n = 9), metabolic dysfunction (n = 8), and others (n = 10). The most common primary outcomes included changes in cardiorespiratory fitness (such as VO2peak) as well as feasibility and safety of the protocols as measured by the number of participant dropouts, adverse events, and compliance rate. HIIT protocols were diverse but were generally well-tolerated and may confer many health advantages to older adults. Larger studies and more research in clinical populations most representative of older adults are needed to further evaluate the clinical effects of HIIT in these groups.

Acute effects of high-intensity interval training and moderate-intensity continuous exercise on BDNF and irisin levels and neurocognitive performance in late middle-aged and older adults

The purposes of the present study were (1) to explore and compare the acute effects of high-intensity interval training (HIIT) and moderate-intensity continuous exercise (MICE) on neurocognitive performance and molecular biomarkers in late middle-aged and older adults, and (2) to examine the relationships of HIIT/MICE exercise-induced neurocognitive changes with changes in circulating irisin and BDNF levels elicited by different acute exercise modes. Using a within-subject design, twenty-one participants completed an acute bout of 30 min of HIIT, MICE, or a non-exercise-intervention (REST) session in a counterbalanced order. The neuropsychological [i.e., accuracy rate (AR) and reaction time (RT)] and neurophysiological [i.e., event-related potential (ERP) P3 latency and amplitude] indices were simultaneously measured when the participants performed a working memory task at baseline and after an intervention mode. Blood samples were also taken before and after the intervention mode. The results showed that, although ARs were significantly increased only via the MICE intervention mode, the acute HIIT and MICE interventions improved RT performance and increased ERP P3 amplitudes in the late middle-aged and older adults under consideration. Serum BDNF levels were significantly increased with the acute HIIT and MICE interventions, and significant irisin level increases were only observed following the HIIT intervention. However, changes in the levels of Irisin and BDNF pre- and post-intervention were not correlated with changes in neurocognitive performance, with the exception of the correlation between the changes in irisin levels and RTs with acute exercise in the MICE intervention mode. The present findings suggested similar beneficial effects on neurocognitive performance (i.e., RTs and ERP P3 amplitudes) and peripheral BDNF levels following MICE and HIIT interventions in the middle-aged and older adults. In terms of ARs and irisin, the two acute exercise modes appear to induce divergent effects. Irisin may play a potential facilitating role in the neuropsychological (e.g., RT) performance of working memory in such a group. However, the mechanisms remain to be determined.

The effects of high-intensity interval training, Nordic walking and moderate-to-vigorous intensity continuous training on functional capacity, depression and quality of life in patients with coronary artery disease enrolled in cardiac rehabilitation: A randomized controlled trial (CRX study)

BACKGROUND

Coronary artery disease (CAD) patients undergoing revascularization procedures often experience ongoing, diminished functional capacity, high rates of depression and markedly low quality of life (QoL). In CAD patients, studies have demonstrated that high-intensity interval training (HIIT) is superior to traditional moderate-to-vigorous intensity continuous training (MICT) for improving functional capacity, whereas no differences between Nordic walking (NW) and MICT have been observed. Mental health is equally as important as physical health, yet few studies have examined the impact of HIIT and NW on depression and QoL. The purpose of this randomized controlled trial (RCT) was to compare the effects of 12 weeks of HIIT, NW and MICT on functional capacity in CAD patients. The effects on depression severity, brain-derived neurotrophic factor (BDNF) and QoL were also examined.

METHODS

CAD patients who underwent coronary revascularization procedures were randomly assigned to: (1) HIIT (4 × 4-min of high-intensity work periods at 85%-95% peak heart rate [HR]), (2) NW (resting HR [RHR] + 20-40 bpm), or (3) MICT (RHR + 20-40 bpm) twice weekly for 12 weeks. Functional capacity (six-min walk test [6MWT]), depression (Beck Depression Inventory-II [BDI-II]), BDNF (from a blood sample), and general (Short-Form 36 [SF-36]) and disease-specific (HeartQoL) QoL were measured at baseline and follow-up. Linear mixed-effects models for repeated measures were used to test the effects of time, group and time × group interactions.

RESULTS

N = 135 CAD patients (aged 61 ± 7 years; male: 85%) participated. A significant time × group interaction (p = 0.042) showed greater increases in 6MWT distance (m) for NW (77.2 ± 60.9) than HIIT (51.4 ± 47.8) and MICT (48.3 ± 47.3). BDI-II significantly improved (HIIT: -1.4 ± 3.7, NW: -1.6 ± 4.0, MICT: -2.3 ± 6.0 points, main effect of time: p < 0.001) whereas BDNF concentrations did not change (HIIT: -2.5 ± 9.6, NW: -0.4 ± 7.7, MICT: -1.2 ± 6.4 ng/mL, main effect of time: p > 0.05). Significant improvements in SF-36 and HeartQoL values were observed (main effects of time: p < 0.05). HIIT, NW and MICT participants attended 17.7 ± 7.5, 18.3 ± 8.0 and 16.1 ± 7.3 of the 24 exercise sessions, respectively (p = 0.387).

CONCLUSIONS

All exercise programmes (HIIT, NW, MICT) were well attended, safe and beneficial in improving physical and mental health for CAD patients. NW was, however, statistically and clinically superior in increasing functional capacity, a predictor of future cardiovascular events.

Effects of two water-based exercise programs on body weight and blood lipid parameters in elderly obese males with a sedentary lifestyle

BACKGROUND AND AIMS

The consequences of exercise on atherogenic features are inconsistent. This study was aimed to examine the impacts of two water-based exercise programs (interval vs. continuous) without dietary intervention on body weight and blood lipid parameters, and its potential interactive effects and the activity of cholesteryl ester transfer protein (CETP) in obese older men with a sedentary lifestyle.

METHODS

Sixty-two sedentary older men, who came to consult on weight loss to the Helal Ferdows Sports Complex, Iran, in 2018, volunteered for participation in this quasi-experimental study. Participants derived from a convenience sample were assigned at random into two aquatic exercise programs: Continuous training (CT) with moderate to vigorous-intensity and interval training (IT) with high-intensity. Both programs continued three months, three times a week, for 60-min each time. Comparing groups and times (pre- and post-intervention) was carried out using the Wilcoxon Nonparametric Test. The following assessments were completed pre- and post-intervention: body weight, body mass index (BMI), CETP activity, and blood lipid parameters.

RESULTS

No significant differences were observed when comparing the variables investigated within and between the groups' pre- and post-intervention (P ˃ 0.05), except for body weight and BMI in the CT after the intervention (respectively, 0.6 kg, P = 0.04; 0.4 kg m^-2, P = 0.03).

CONCLUSIONS

Both water-based exercise programs, without interference in nutrition, do not reveal a significant improvement in atherogenic features. The CT program detected modest but significant influences on body weight and BMI of obese older men with a sedentary lifestyle.

Electrically induced cycling and nutritional counseling for counteracting obesity after spinal cord injury: A pilot study

Objective: The purpose of this pilot study was to determine the preliminary efficacy of interval functional electrical stimulation (FES) cycling combined with nutritional counseling in obese adults with SCI.Setting: Community-based individuals with chronic SCI.Participants: Ten participants with chronic SCI.Interventions: Participants were divided into 2 groups (1) FES cycling and nutritional counseling (FES & Nutri) and (2) nutritional counseling only (Nutri Only). The FES & Nutri group performed high intensity interval FES cycling for 30 min 3 times per week for 8 weeks and received nutritional counseling for 30 min once per week for 8 weeks. The Nutri Only group received the nutritional counseling only.Outcome Measures: Body composition (fat mass, lean mass, body fat percentage), blood glucose levels.Results: Participants in the FES & Nutri group had a statistically significant greater decrease in body fat percentage (M = -1.14) compared to those in the Nutri Only group (M = +0.28) and gained more lean mass in their legs (M = +0.66 kg) compared to the Nutri Only group (M = -1.05 kg).Discussion/Conclusion: The statistically significant decrease in body fat percentage for the FES & Nutri group provides evidence that further study is merited. Future studies should include larger numbers of participants and the possible introduction of a preliminary strengthening program before initiating interval FES cycling. In addition, an increase in exercise volume and a greater role for nutritional counseling should be considered in order to optimize the treatment for obesity.

Upper and lower limb resistance training program versus high-intensity interval training on oxidative stress markers in university athletes

Highly-intensive exercise occurs in reactive oxygen species which leads to cellular damage as a result of increased oxidative stress markers. An appropriate program design incorporating volume, intensity, and types of exercise may produce different effects amid oxidative status in athletes. Therefore, this study aimed to investigate the outcomes of resistance training (RT) and high-intensity interval training (HIIT) on oxidative stress markers, and physical performance in university athlete subjects. The effect of two different protocol types (RT and HIIT) on oxidative stress and antioxidant status were also compared. Seventy-two university athletes, were recruited and divided into control, RT, and HIIT groups (n=22/group). The RT group were undertaken a resistance exercise training program of the upper and lower body. The HIIT group performed their exercise training on a cycle ergometer. The training program was 30 min/day, 3 days/wk, continuously over 8 weeks. We observed that long-term RT and HIIT improved blood glutathione and glutathione disulfide redox ratio in all athletes. The results demonstrated that only RT training significantly decreased plasma malondialdehyde. Another finding was that RT and HIIT resulted in similar elicitation of physical performance in the post-compared with pretraining exercise. This study revealed that RT and HIIT programs improved antioxidants and physical performance in university sports athletes. However, oxidative markers were only improved following the RT program. This study suggests that RT program is superior to HIIT in improving oxidative stress markers in sport athletes.

High-Intensity Interval and Resistance Training Improve Health Outcomes in Older Adults With Coronary Disease

OBJECTIVE

Both high-intensity interval training (HIIT) and resistance exercises (R) are used in cardiac rehabilitation in patients with coronary artery disease (CAD). However, the combined effect of an HIIT + R exercise program in older adults with CAD is not well investigated. The study's purpose was to assess the changes in anthropometric parameters, physical activity, functional capacity, physiological parameters, and quality of life (QoL) in this population following a combined HIIT + R program.

DESIGN

The study was a 2-group (n = 45 each) randomized controlled single-blinded trial.

SETTING AND PARTICIPANTS

The study was done at a treatment clinic of a tertiary hospital. The mean age of participants was 69.23 ± 4.9 years. The HIIT + R group performed 8 sessions (1/wk) of HIIT + R training. The 30 minutes of the active exercise phase consisted of ten 3-minute bouts. Each bout comprised of 1 minute of high-intensity treadmill walking at 85% to 90% maximum heart rate (MHR), followed by a low-intensity walking at 60%-70% MHR, followed by low-to moderate-intensity resistance training. The Usual Care group underwent conventional medical treatment.

MEASURES

Anthropometric measurements [weight, body mass index (BMI), waist circumference, body fat percentage, lean body mass], physical activity (International Physical Activity Questionnaire), functional capacity (Incremental Shuttle Walking Test), physiologic measurements (blood pressure, heart rate), and QoL (36-Item Short Form Health Survey) were measured pre- and postintervention.

RESULTS

Significant group and time interaction were found for the participants in the HIIT + R Group for BMI (P = .001), body fat percentage (P = .001), waist circumference (P < .001), physical activity (P < .001), functional capacity (P < .001), and QoL (P = .001) compared with the UC Group. Significant improvement in systolic blood pressure (P = .001) was seen in the HIIT + R group.

CONCLUSIONS AND IMPLICATIONS

A combined HIIT + R training protocol in older adults with CAD can be useful in producing desired health outcomes. Further evaluation of longer duration exercise programs with more frequent dosing needs to be evaluated for their benefits and sustainability.

Long-term high-intensity interval training increases serum neurotrophic factors in elderly overweight and obese Chinese adults

PURPOSE

To compare the effects of 12-week high-intensity interval training (HIIT) and vigorous-intensity continuous training (VICT) on cognitive function, physical fitness, VO₂max, serum neurotransmitters and neurotrophic factors in overweight and obese elderly individuals.

METHODS

Twenty-nine physically inactive older adults (18 males and 11 females) with a mean age of 64.8 ± 3.9 years were randomly divided into a control group (CON, n = 9), an HIIT group (4 × 3 min at 90% VO₂max interspersed with 3 min at 60% VO₂max, n = 10) and a VICT group (25 min at 70% VO₂max, n = 10) and submitted to 12 weeks of training. Cognitive function questionnaires, physical fitness, VO₂max, serum neurotransmitters and neurotrophic factors were determined at baseline and post training.

RESULTS

Twelve weeks of HIIT and VICT improved the VO₂max (4.19 ± 2.21 and 1.84 ± 1.63 mL/kg/min, respectively, p = 0.005), sit-and-reach distance (8.7 ± 3.0 and 7.8 ± 3.8 cm, p = 0.033), choice reaction time (- 0.115 ± 0.15 and - 0.09 ± 0.15 s, p = 0.004) and one-leg stand time (4.4 ± 3.4 and 4.2 ± 4.0 s, p < 0.001) of the elderly participants. The serum concentrations of brain-derived neurotrophic factor (375.5 ± 247.9 and 227.0 ± 137.1 pg/ml, p = 0.006), nerve growth factor (33.9 ± 16.7 and 23.3 ± 14.5 pg/ml, p = 0.037), neurotrophin-3 (24.2 ± 9.33 and 16.3 ± 5.91 pg/ml, p = 0.006) and neurotrophin-4 (10.4 ± 3.8 and 7.8 ± 5.0 pg/ml, p = 0.029) increased significantly in the HIIT and VICT groups after training. In addition, compared to VICT, HIIT significantly increased VO₂max and the serum neurotrophin-3 concentration. Serum concentrations of the neurotransmitters acetylcholine, dopamine and serotonin trended upward with training. No significant change was observed in the cognitive function questionnaire scores (p > 0.05).

CONCLUSION

HIIT is suitable for elderly adults and is more effective than VICT for improving VO₂max and serum neurotrophin-3 concentrations.

CHINESE CLINICAL TRIAL REGISTRY NUMBER

No. ChiCTR1900022315, date of registration: 4 April 2019.

Preoperative high intensity interval training for oncological resections: A systematic review and meta-analysis

Exercise prehabilitation prior to major surgery targets a reduction in postoperative complications through improved conditioning and respiratory function. However its effectiveness in cancer surgery is unclear. The objective of this review was to determine if preoperative high-intensity interval training (HIIT) improves preoperative fitness in patients scheduled for oncologic resection, and whether postoperative complications are impacted. METHODS: CINAHL, AMED, PEDro, EMBASE, The Cochrane Library and PubMed/MEDLINE were searched until April 2021 using predefined search strategy and accompanied by manual forward and backwards citation review. Screening of titles, abstracts, full-texts, data extraction, risk of bias assessment and methodologic quality was performed independently by two reviewers. Mean difference (MD) with 95% confidence intervals (CI) was compared and heterogeneity assessed using Chi Squared Test and I² statistic. Six randomised controlled trials (RCTs) were included in the systematic review. Interventions prescribed bouts of high-intensity exercise [80-115% peak work rate (WRp)] interspaced with low-intensity (rest-50% WRp) exercise. The meta-analysis included five RCTs reporting peak oxygen consumption (VO_2peak). Preoperative HIIT did not result in significantly higher VO_2peak in comparison to usual care or moderate intensity exercise (MD 0.83, 95%CI-0.51-2.17) kg/ml/min, p = 0.12). Studies were insufficiently powered with respect to postoperative complications, but there is no evidence of significant impact. No adverse events occurred and high adherence rates were reported. Results of this systematic review and meta-analysis demonstrate there is insufficient evidence to support HIIT as a method of improving preoperative fitness prior to oncologic resection. Further work is needed to determine if specific HIIT parameters can be adapted to improve efficacy over short time-frames.

Effects of High-Intensity Interval Training After Stroke (The HIIT Stroke Study) on Physical and Cognitive Function: A Multicenter Randomized Controlled Trial

OBJECTIVE

To assess the effects of high-intensity interval training (HIIT) on physical, mental, and cognitive functioning after stroke.

DESIGN

The HIIT Stroke Study was a single-blind, multicenter, parallel-group randomized controlled trial.

SETTING

Specialized rehabilitation units at 3 Norwegian hospitals.

PARTICIPANTS

Adult stroke survivors (N=70) 3 months to 5 years after a first-ever stroke. Mean age was 57.6±9.2 years and 58.7±9.2 years in the intervention and control groups, respectively.

INTERVENTIONS

Participants were randomized to standard care in combination with 4×4 minutes of treadmill HIIT at 85%-95% of peak heart rate or standard care only.

OUTCOMES

Outcomes were measured using physical, mental, and cognitive tests and the FIM and Stroke Impact Scale. Linear mixed models were used to analyze differences between groups at posttest and 12-month follow-up.

RESULTS

The intervention group showed a significant treatment effect (95% confidence interval [CI]) from baseline to posttest on a 6-minute walk test of 28.3 (CI, 2.80-53.77) meters (P=.030); Berg Balance Scale 1.27 (CI, 0.17-2.28) points (P=.025); and Trail Making Test Part B (TMT-B; -24.16 [CI, -46.35 to -1.98] s, P=.033). The intervention group showed significantly greater improvement on TMT-B at the 12-month follow-up (25.44 [CI, -49.01 to -1.87] s, P=.035). The control group showed significantly greater improvement in total Functional Independence Measure score with a treatment effect of -2.37 (CI, -4.30 to -0.44) points (P=.016) at 12-month follow-up. No significant differences were identified between groups on other outcomes at any time point.

CONCLUSIONS

HIIT combined with standard care improved walking distance, balance, and executive function immediately after the intervention compared with standard care only. However, only TMT-B remained significant at the 12-month follow-up.

The effects of spirulina under high-intensity interval training on levels of nesfatin-1, omentin-1, and lipid profiles in overweight and obese females: A randomized, controlled, single-blind trial

BACKGROUND

We investigated the effects of spirulina under high-intensity interval training (HIIT) on levels of nesfatin-1, omentin-1, and lipid profiles in overweight and obese females.

MATERIALS AND METHODS

This is a randomized, quasi-experimental controlled, single-blind with a pre- and post-test design, in which twenty overweight and obese women (body mass index = 29.32 ± 3.01 kg/m², age = 21.55 ± 1.76 years), were randomly divided into the following groups: HIIT + spirulina (n = 10) and HIIT + placebo (n = 10). Running anaerobic sprint test was used for HIIT protocol consisting of six intervals at 35 m maximal speed runs, with a rest of 10 s in each trial (3 times/week, 4 weeks). HIIT + spirulina group received 500 mg of the spirulina pills twice daily for 4 weeks and the second group took placebo.

RESULTS

There was a significant increase in serum levels of nesfatin-1 in HIIT + spirulina (P < 0.0001) but not in HIIT + placebo (P = 0.61) group. Furthermore, results indicated a significant difference between two groups with respect to serum levels of nesfatin-1 (P = 0.04). Serum levels of omentin-1 significantly increased in both groups (P < 0.05). However, there was no significant difference between two groups (P = 0.49). In addition, results showed no significant inter- and intra-group differences in total cholesterol levels, triglycerides, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol between groups (P > 0.05).

CONCLUSION

The spirulina under HIIT increased levels of nesfatin-1 and omentin-1 with no effects on the levels of lipid profiles in overweight and obese females.

Effect of high-intensity interval training on patient-reported outcomes and physical function in women with breast cancer receiving anthracycline-based chemotherapy

PURPOSE

The purpose of this study was to determine the effects of an 8-week HIIT intervention on patient-reported outcomes and physical function in breast cancer patients undergoing anthracycline-based chemotherapy.

METHODS

Thirty breast cancer patients were recruited prior to initiating treatment and randomized into the HIIT group (n = 15) or control (CON) group (n = 15). The HIIT group attended HIIT sessions three days per week for eight weeks. The CON group was asked to maintain their current level of physical activity. Patient-reported outcomes were assessed by the Functional Assessment of Cancer Therapy-Breast Cancer (FACT-B), Multidimensional Fatigue Inventory with 20 questions (MFI-20), and the 15-item Five-Facet Mindfulness Questionnaire (FFMQ-15). Physical function was assessed using the timed up and go (TUG), 30-s sit-to-stand (30STS), Margaria-Kalamen stair climb test, and 6-min walk test (6MWT). Repeated measures ANCOVA and paired t-tests were performed to assess group differences.

RESULTS

All patients completed the 8-week study with 82.3% adherence to the intervention among the HIIT group. Post-intervention, significant improvements were found for the Margaria-Kalamen stair climb test (- 3.39%; P = 0.013) and 6MWT (+ 11.6%; P = 0.008) in the HIIT group compared to baseline and CON group. No changes in patient-reported outcomes, TUG, and 30STS were observed following the 8-week study period in both groups (P  > 0.05).

CONCLUSIONS

HIIT may be an effective strategy to improve physical function and possibly maintain QOL in breast cancer patients undergoing the anthracycline-based chemotherapy.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02454777.

Impact of high-intensity interval training on cardiorespiratory fitness, body composition, physical fitness, and metabolic parameters in older adults: A meta-analysis of randomized controlled trials

High-intensity interval training (HIIT) can effectively increase peak oxygen consumption, body composition, physical fitness, and health-related characteristics of adults; however, its impact in the older population remains highly debated. This review and meta-analysis aimed to evaluate the effects of high-intensity interval training on cardiorespiratory fitness, body composition, physical fitness, and health-related outcomes in older adults. Four electronic databases (PubMed, Scopus, Medline, and Web of Science) were searched (until July 2020) for randomized trials comparing the effect of HIIT on physical fitness, metabolic parameters, and cardiorespiratory fitness in older adults. The Cochrane risk of bias assessment tool was used to evaluate the methodological quality of the included studies; Stata 14.0 software was used for statistical analysis. HIIT significantly improved the maximum rate of oxygen consumption (VO_2peak) as compared to a moderate-intensity continuous training (MICT) protocol (HIIT vs. MICT: weighted mean difference = 1.74, 95% confidence interval: 0.80-2.69, p < 0.001). Additional subgroup analyses determined that training periods >12 weeks, training frequencies of 2 sessions/week, session lengths of 40 min, 6 sets and repetitions, training times per repetition of >60 s, and rest times of <90 s were more effective for VO_2peak. This systematic review and meta-analysis showed that HIIT induces favorable adaptions in cardiorespiratory fitness, physical fitness, muscle power, cardiac contractile function, mitochondrial citrate synthase activity, and reduced blood triglyceride and glucose levels in older individuals, which may help to maintain aerobic fitness and slow down the process of sarcopenia.

Comparison of Effect of High-Intensity Interval Training and Aerobic Training on Respiratory Volumes in Female Students

Background

Sedentary lifestyle can cause the deterioration of respiratory indices. The interventions, such as physical activity programs, might prevent such deterioration. This study aimed to compare the effect of high-intensity interval training (HIIT) and aerobic training on the respiratory volumes in female students.

Materials and Methods

In this semi-experimental study, 30 healthy inactive volunteer female students (age: 26.3±4.30 years; height: 1.63±8.36 m; body mass index: 20-28 kg/m²) were divided randomly into two HIIT and aerobic training groups. The aerobic training consisted of three sessions of 50-60 minutes of exercise with an intensity of 70-85% of the maximum heart rate per week for 4 weeks. Additionally, the HIIT program included six repetitions of 4 minutes with an intensity of 90-95% of maximum heart rate for 4 weeks on a treadmill. Spirometry tests were performed to determine lung function before and after the training protocols. The data were analyzed by the independent and dependent t-tests at p < 0.05.

Results

The results showed that aerobic training significantly improved the forced expiratory volume in one second (P=0.045), forced expiratory flow (FEF) within 25-75% (P=0.002), and peak expiratory flow (P=0.003); however, HIIT did not have a significant effect on these indicators. There was no significant difference between the two types of training in any of the indicators except for FEF within 25-75%.

Conclusion

According to the study results, aerobic training might be more effective in the improvement of pulmonary parameters than intense training.

Effect of exercise on endothelial function in heart transplant recipients: systematic review and meta-analysis

Endothelial dysfunction is associated with increased cardiovascular risk and death in heart transplant recipients (HTx). Although the measurement of peripheral endothelial function is considered a significant predictor of cardiovascular events in several populations, few studies have investigated this outcome after therapeutic strategies, including different exercise types, duration, and intensity. This systematic review and meta-analysis aimed to investigate the effects of continuous moderate exercise (CON) or high-intensity interval training (HIIT) to improve endothelial function (EF) in HTx. The search was conducted in Cochrane Central Registry of Controlled Trials (CENTRAL), MEDLINE (via PubMed), Web of Science and Scopus/Elsevier, CINAHL/Ebsco, Physiotherapy Evidence Database (PEDro), LILACS/BIREME, and SciELO databases. Quality of the evidence was assessed using the Grading of Recommendations Assessment Development and Evaluation (GRADE). The search strategy retrieved 5192 titles. A total of four articles met the inclusion criteria and were included for the qualitative analysis. Meta-analysis showed that exercises improved EF ([mean difference-MD] 3.48 95% CI - 0.29 to 7.25, p = 0.007) when compared with the control. However, there was a poor quality of evidence to demonstrate that CON or HIIT is better than usual care to improve EF. Exercise training provides benefits to patients, but the poor quality of evidence does not allow us to state that exercise is related to endothelial function improvement in HTx.

Elevated Lactate by High-Intensity Interval Training Regulates the Hippocampal BDNF Expression and the Mitochondrial Quality Control System

High-intensity interval training (HIIT) is reported to be beneficial to brain-derived neurotrophic factor (BDNF) biosynthesis. A key element in this may be the existence of lactate, the most obvious metabolic product of exercise. In vivo, this study investigated the effects of a 6-week HIIT on the peripheral and central lactate changes, mitochondrial quality control system, mitochondrial function and BDNF expression in mouse hippocampus. In vitro, primary cultured mice hippocampal cells were used to investigate the role and the underlying mechanisms of lactate in promoting mitochondrial function during HIIT. In vivo studies, we firstly reported that HIIT can potentiate mitochondrial function [boost some of the mitochondrial oxidative phosphorylation (OXPHOS) genes expression and ATP production], stimulate BDNF expression in mouse hippocampus along with regulating the mitochondrial quality control system in terms of promoting mitochondrial fusion and biogenesis, and suppressing mitochondrial fission. In parallel to this, the peripheral and central lactate levels elevated immediately after the training. In vitro study, our results revealed that lactate was in charge of regulating mitochondrial quality control system for mitochondrial function and thus may contribute to BDNF expression. In conclusion, our study provided the mitochondrial mechanisms of HIIT enhancing brain function, and that lactate itself can mediate the HIIT effect on mitochondrial quality control system in the hippocampus.

High-intensity interval training and energy management education, compared with moderate continuous training and progressive muscle relaxation, for improving health-related quality of life in persons with multiple sclerosis: study protocol of a randomized controlled superiority trial with six months' follow-up

Background

Persons with multiple sclerosis (PwMS) often have reduced aerobic capacity and report fatigue as the most disabling symptom impacting their health-related quality of life (HRQoL). A multidisciplinary rehabilitation approach is recommended for successful management of symptoms, although there is little supporting evidence. The aim of this study is to evaluate the effect of a multimodal therapy approach, including endurance training and patient education, during a three-week inpatient rehabilitation stay, on HRQoL in PwMS at six months follow-up. Inpatient energy management education (IEME) + high-intensity interval training (HIIT) will be compared with progressive muscle relaxation (PMR) + moderate continuous training (MCT).

Methods

This study has a two-armed single-blind randomized controlled superiority trial design. One hundred six PwMS-related fatigue (relapsing-remitting or chronic progressive phenotypes; Expanded Disability Status Scale (EDSS) ≤ 6.5) will be recruited at the Valens clinic, Switzerland, and randomized into either an experimental (EG) or a control group (CG). EG: participants will perform IEME twice and HIIT three times per week during the three-week rehabilitation stay. IEME is a group-based intervention, lasting for 6.5 h over three weeks. HIIT contains of five 1.5-min high-intensive exercise bouts on a cycle ergometer at 95–100% of peak heart rate (HR_peak), followed by active breaks of unloaded pedalling for 2 min to achieve 60% of HR_peak. CG: participants will perform PMR twice and MCT three times per week during the three-week rehabilitation stay, representing local usual care. PMR consists of six 1-h relaxation group sessions. MCT consists of 24-min continuous cycling at 65% of HR_peak. The primary outcome is HRQoL (Physical and Mental Component Summaries of the Medical Outcome Study 36-item Short Form Health Survey; SF-36), measured at entry to the clinic (baseline, T₀), three weeks after T₀ (T₁) and at four (T₂) and six (T₃) months after T₀. Secondary outcomes comprise cardiorespiratory fitness, inflammatory markers (measured at T₀ and T₁), fatigue, mood, self-efficacy, occupational performance, physical activity (measured at T₀, T₁, T₂ and T₃) and behaviour changes in energy management (measured at T₂ and T₃).

Discussion

This study will provide detailed information on a multimodal therapy approach to further improve rehabilitation for PwMS.

Trial registration

This trial was prospectively registered at ClinicalTrials.gov (NCT04356248; 22 April 2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02084-0.

Acute exercise-induced glycocalyx shedding does not differ between exercise modalities, but is associated with total antioxidative capacity

OBJECTIVES

Regular physical exercise is known to protect endothelial integrity. It has been proposed that acute exercise-induced changes of the (anti-)oxidative system influence early (glycocalyx shedding) and sustained endothelial activation (shedding of endothelial cells, ECs) as well as endothelial-cell repair by circulating hematopoietic stem and progenitor cells (HPCs). However, results are not conclusive and data in trained participants performing different exercise modalities is lacking.

DESIGN

Eighteen healthy, well-trained participants (9 runners, 9 cyclists; age: 29.7 ± 4.2 yrs) performed a strenuous acute exercise session consisting of 4 bouts of 4-min high-intensity with decreasing power profile and 3-min low-intensity in-between.

METHODS

Average power/speed of intense phases was 85% of the peak achieved in a previous incremental test. Before and shortly after exercise, total oxidative and antioxidative capacities (TAC), shedding of syndecan-1, heparan sulfate, hyaluronan, ECs, and circulating HPCs were investigated.

RESULTS

TAC decreased from 1.81 ± 0.42 nmol/L to 1.47 ± 0.23 nmol/L post-exercise (p = 0.010) only in runners. Exercise-induced early and sustained endothelial activation were enhanced post-exercise- syndecan-1: 103.2 ± 63.3 ng/mL to 111.3 ± 71.3 ng/mL, heparan sulfate: from 2637.9 ± 800.1 ng/mL to 3197.1 ± 1416.3 ng/mL, both p < 0.05; hyaluronan: 84.3 ± 21.8 ng/mL to 121.4 ± 29.4 ng/mL, ECs: from 6.6 ± 4.5 cells/μL to 9.5 ± 6.2 cells/μL, both p < 0.01; results were not different between exercise modalities and negatively related to TAC concentrations post-exercise. HPC proportions and self-renewal ability were negatively, while EC concentrations were positively associated with circulating hyaluronan concentrations.

CONCLUSIONS

These results highlight the importance of the antioxidative system to prevent the endothelium from acute exercise-induced vascular injury - independent of exercise modality - in well-trained participants. Endothelial-cell repair is associated with hyluronan signaling, possibly a similar mechanism as in wound repair.

hydrochlorothiazide on blood pressure, cardiovascular health and cognition: Protocol of a non-inferiority trial

BACKGROUND

While the number of people with hypertension (HBP) continues to increase, the therapeutic target for optimal blood pressure (BP) has been revised to a lower level. Studies have suggested that High-Intensity Interval Training (HIIT) could be as efficient as BP-lowering drugs, but no study has compared their efficacy in a randomized trial. The aim of this protocol is to determine if HIIT is as efficient as Hydrochlorothiazide (HCTZ) in lowering 24 h ambulatory BP in prehypertensive older adults. Moreover, the secondary aim is to determine if HIIT is associated with greater cardiovascular and cognitive benefits than HCTZ.

METHODS

This study is an interventional, single-center, non-inferiority trial, with two randomized parallel groups of prehypertensive participants aged 60 years or more. One group will be prescribed daily doses of 12.5 mg of HCTZ for 12 weeks, and the other group will follow thrice-weekly HIIT for 12 weeks. Each group will be composed of 30 participants. The primary outcome is 24 h ambulatory BP. Secondary outcomes are scores on neuropsychological assessments, balance and gait performances, maximal oxygen uptake, peripheral endothelial function, and arterial stiffness. Non-inferiority tests will be performed on the primary outcome, and secondary outcomes will be compared using independent t-tests.

CONCLUSION

This study will determine if HIIT is at least as efficient as HCTZ in lowering BP in prehypertensive older adults. This study will also determine if HIIT provides greater benefits in terms of cardiovascular and cognitive status (NCT04103411).

Differential effects of high-intensity interval training (HIIT) on choriocapillaris perfusion in healthy adults and patients with type 1 diabetes mellitus (T1DM)

PURPOSE

To investigate the effects of a four-week high-intensity interval training (HIIT) on choriocapillaris (CC) perfusion in young healthy adults and type 1 diabetes mellitus (T1DM) patients.

METHODS

Data of two HIIT studies with baseline to follow-up comparison were retrospectively analysed. Twenty healthy participants and twenty T1DM patients without clinical signs of diabetic retinopathy were included. All participants had performed a four-week all-out HIIT protocol with a total of 8 training sessions. Changes in physical fitness were assessed using power output at the individual aerobic lactate threshold (IANT). Optical coherence tomography angiography (OCTA) imaging was performed at baseline and follow-up. CC images were analysed for number, size and total area of flow deficits (FD), mean signal intensity, signal intensity standard deviation and kurtosis of signal intensity distribution.

RESULTS

At baseline, CC OCTA revealed a lower and more heterogeneous intensity signal in T1DM eyes (mean intensity signal and standard deviation of signal intensity, p < 0.001). Percent of CC FD area was greater in T1DM eyes (p < 0.001). While T1DM patients showed greater improvement of exercise capacity at IANT than healthy controls (group×time p = 0.0403), CC FD area and standard deviation of intensity increased in healthy controls but not in T1DM patients (group×time p ≤ 0.029). Moreover, linear regression slopes of FD region distribution differed significantly at baseline and follow-up (p = 0.0002) in healthy individuals but not in T1DM patients.

CONCLUSIONS

Effects of regular physical exercise performed as HIIT on CC perfusion were only seen in healthy participants, not in T1DM patients suggesting impaired CC adaptation in T1DM.

The Effects of Very Low Energy Diets and Low Energy Diets with Exercise Training on Skeletal Muscle Mass: A Narrative Review

In recent years, very-low-energy diets (VLEDs) have been recognised as a viable strategy for improving the extent of weight loss and cardio-metabolic outcomes in people who are either overweight or obese. However, concerns exist regarding the reductions in lean body mass (LBM) during VLEDs, particularly in vulnerable demographic groups, such as middle-aged and older adults already prone to developing sarcopenia. Sarcopenia is itself associated with multiple adverse outcomes, including frailty, cardio-metabolic deterioration and increased mortality. Therefore, a number of studies investigating strategies to ameliorate this detrimental effect of VLEDs have attempted to address this concern. This narrative review explores the potential benefits and limitations of exercise and/or protein supplementation for LBM retention during VLEDs based on the available evidence. Current studies suggest that both protein supplementation and exercise training may result in improved LBM retention (and skeletal muscle function) during VLEDs. However, uncertainty remains concerning the interactions between intervention types, based on discordant outcomes reported in the literature and the heterogeneity of exercise modalities in achieving this particular outcome.

Psycho-Physiological Responses to a 4-Month High-Intensity Interval Training-Centered Multidisciplinary Weight-Loss Intervention in Adolescents with Obesity

Background

To evaluate the impact of 4 months of a high-intensity interval training (HIIT)-centered weightmanagement intervention on health-related quality of life (HR-QOL), health perception (HP) and physical selfperception (PSP) in adolescents with obesity.

Methods

Fifty-six adolescents with obesity (28 girls; mean body mass index [BMI], 35±4.89 kg/m²; z-BMI, 2.3±0.3; 11?17 years) followed a multidisciplinary weight-management intervention composed of nutritional counseling, HIIT program, and health-related therapeutic education. Anthropometric parameters, body composition (dual X-ray absorptiometry), and maximal aerobic capacities (maximal oxygen consumption [VO_2peak]) were assessed, and self-reported questionnaires were used to assess HR-QOL (36-item short form survey), HP and PSP at baseline (T0) and post-intervention (T1).

Results

Body weight (92.6±18.9 to 85.9±16.2 kg), BMI (35.0±4.8 to 32.1±4.5 kg/m²), z-BMI (2.3±0.3 to 2.1±0.3) and fat mass percentage (36.0%±9.1% to 30.4%±7.8%) were significantly decreased (P<0.001) between T0 and T1. There was a tendency for VO_2peak to increase from 26.35±5.81 mL/kg/min at T0 to 28.79±6.59 mL/kg/min at T1 (P=0.06). Physical functioning (P=0.002), physical limitation (P=0.048), general health (P<0.001) and bodily pain (P=0.030) were improved at T1. A significant improvement occurred in dimensions of HP such as physical condition (P=0.001), adiposity (P<0.001), alimentation (P<0.001), general health (P=0.038), and perceived general health (P=0.001). In addition, there was an improvement in items of PSP such as self-perceived coordination (P=0.022), endurance (P=0.001) and activity (P=0.001), global self-concept (P=0.015), and appearance (P=0.016). Physical but not mental HR-QOL domains, HP and PSP were associated with weight reduction.

Conclusion

While HIIT favors improved HR-QOL, HP status and PSP in adolescents with obesity, physical but not mental HR-QOL, HP and PSP were associated with weight reduction.

The acute and long-term effects of a cardiac rehabilitation program on endothelial progenitor cells in chronic heart failure patients: Comparing two different exercise training protocols.Int J Cardiol Heart Vasc. 2021;32:100702. [PMID: 33392386 DOI: 10.1016/j.ijcha.2020.100702]

Background

Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure (CHF). Endothelial progenitor cells (EPCs) are also impaired. The purpose of the study was to assess the effect of a cardiac rehabilitation (CR) program on the increase of EPCs at rest and on the acute response after maximal exercise in patients with CHF and investigate whether there were differences between two exercise training protocols and patients of NYHA II and III classes.

Methods

Forty-four patients with stable CHF enrolled in a 36-session CR program and were randomized in one training protocol; either high-intensity interval training (HIIT) or HIIT combined with muscle strength (COM). All patients underwent maximum cardiopulmonary exercise testing (CPET) before and after the CR program and venous blood was drawn before and after each CPET. Five endothelial cellular populations, expressed as cells/10⁶ enucleated cells, were quantified by flow cytometry.

Results

An increase in all endothelial cellular populations at rest was observed after the CR program (p < 0.01). The acute response after maximum exercise increased in 4 out of 5 endothelial cellular populations after rehabilitation. Although there was increase in EPCs at rest and the acute response after rehabilitation in each exercise training group and each NYHA class, there were no differences between HIIT and COM groups or NYHA II and NYHA III classes (p > 0.05).

Conclusions

A 36-session CR program increases the acute response after maximum CPET and stimulates the long-term mobilization of EPCs at rest in patients with CHF. These benefits seem to be similar between HIIT and COM exercise training protocols and between patients of different functional classes.

High-intensity interval training is more effective than continuous training to reduce inflammation markers in female rats with cisplatin nephrotoxicity

AIMS

Cisplatin (CP) is an antineoplastic widely used in the treatment of various solid tumors, however, its clinical application is limited by nephrotoxicity. Here, we compared the impact of preconditioning with high-intensity interval training (HIIT) with continuous training of low (LIT) and moderate (MIT) intensity on innate immunity markers in female rats with CP-induced acute kidney injury.

MATERIALS AND METHODS

The rats were divided into five groups (n = 7): saline control and sedentary (C + S); CP and sedentary (CP + S); CP and LIT (CP + LIT); CP and MIT (CP + MIT) and CP and HIIT (CP + HIIT). The training intensity was determined by a maximum running test. At the end of training, the rats received a single dose of CP (5 mg/kg), and 7 days later they were euthanized. We evaluated renal function parameters (serum creatinine, glomerular filtration rate and proteinuria), renal structure, macrophage tissue infiltration, immunolocalization of nuclear transcription factor kappa B (NF-κB), renal levels of tumor necrosis factor-alpha (TNF-α), interleukin 1β (IL-1β), and interleukin 6 (IL-6), and gene expression of monocyte chemoattractant protein-1 (MCP-1), toll-like receptor 4 (TLR4), and NF-κB in renal tissue.

KEY FINDINGS

Although both MIT and HIIT attenuated the degree of renal injury, only the HIIT prevented changes in renal function. The three training protocols mitigated the increase in expression of all inflammatory markers, however, this effect was more pronounced in HIIT.

SIGNIFICANCE

All training protocols promoted renoprotective actions, but HIIT was more effective in mitigating CP-induced acute kidney injury, in part by modulation of important markers of the innate immune response.

Feasibility and initial efficacy of a high-intensity interval training program using adaptive equipment in persons with multiple sclerosis who have walking disability: study protocol for a single-group, feasibility trial

Background

There is considerable evidence for the efficacy of moderate-intensity continuous exercise benefitting clinically relevant outcomes in persons with multiple sclerosis (MS). However, persons with MS who have walking disability (pwMS-wd) are severely deconditioned and may achieve superior benefits by engaging in high-intensity interval training (HIIT), especially while utilizing adaptive equipment, such as recumbent arm/leg stepping (RSTEP). The proposed study will assess the feasibility of a 12-week, RSTEP HIIT program in pwMS-wd. The secondary aim will examine changes in aerobic fitness, physical activity, ambulation, upper arm function, cognition, fatigue, and depression as clinically relevant efficacy outcomes following the 12-week, RSTEP HIIT intervention.

Methods

The study will recruit 15 pwMS-wd. Feasibility will be measured via process, resource, management, and scientific outcomes throughout the entirety of the research study. The secondary, clinically relevant outcomes will consist of a neurological exam, aerobic capacity, physical activity, ambulation, cognition, upper arm function, fatigue, and depression. Outcomes will be assessed at baseline (T1), midpoint (T2, following 6 weeks), and post-intervention (T3, following 12 weeks). The intervention will involve 12 weeks of supervised, individualized HIIT sessions two to three times per week. The individual HIIT sessions will each involve 10 cycles of 60-s intervals at the wattage associated with 90% VO_2peak followed by 60 s of active recovery intervals at 15 W, totaling 20 min in length plus 5-min warm-up and cool-down periods.

Discussion

The feasibility design of the proposed study will provide experience and preliminary data for advancing towards a proof-of-concept study comparing HIIT to moderate-intensity continuous RSTEP for improving clinically relevant outcomes in a randomized control trial design. The results will be disseminated via manuscripts for publication and a report for distribution among the National Multiple Sclerosis Society.

Trial registration

ClinicalTrials.gov NCT04416243. Retrospectively registered on June 4, 2020

Feasibility of high-intensity interval training in patients with left ventricular assist devices: a pilot study

Aims

Patients with left ventricular assist device (LVAD) suffer from persistent exercise limitation despite improvement of their heart failure syndrome. Exercise training (ET) programmes to improve aerobic capacity have shown modest efficacy. High‐intensity interval training (HIIT), as an alternative to moderate continuous training, has not been systematically tested in this population. We examine the feasibility of a short, personalized HIIT programme in patients with LVAD and describe its effects on aerobic capacity and left ventricular remodelling.

Methods and results

Patients on durable LVAD support were prospectively enrolled in a 15‐session, 5 week HIIT programme. Turndown echocardiogram, Kansas City Cardiomyopathy Questionnaire, and cardiopulmonary exercise test were performed before and after HIIT. Training workloads for each subject were based on pretraining peak cardiopulmonary exercise test work rate (W). Percentage of prescribed training workload completed and adverse events were recorded for each subject. Fifteen subjects were enrolled [10 men, age = 51 (29–71) years, HeartMate II = 12, HeartMate 3 = 3, and time on LVAD = 18 (3–64) months]. Twelve completed post‐training testing. HIIT was well tolerated, and 90% (inter‐quartile range: 78, 99%) of the prescribed workload (W) was completed with no major adverse events. Improvements were seen in aV̇O₂ at ventilatory threshold [7.1 (6.5, 9.1) to 8.5 (7.7, 9.3) mL/kg/min, P = 0.04], work rate at ventilatory threshold [44 (14, 54) to 55 (21, 66) W, P = 0.05], and left ventricular end‐diastolic volume [168 (144, 216) to 159 (124, 212) mL, n = 7, P = 0.02]. HIIT had no effect on maximal oxygen consumption (V̇O_2peak) or Kansas City Cardiomyopathy Questionnaire score.

Conclusions

Cardiopulmonary exercise test‐guided HIIT is feasible and can improve submaximal aerobic capacity in stable patients with chronic LVAD support. Further studies are needed on its effects on the myocardium and its potential role in cardiac rehabilitation programmes.

Low-volume high-intensity interval training improves cardiometabolic health, work ability and well-being in severely obese individuals: a randomized-controlled trial sub-study

BACKGROUND

Obesity is associated with impaired health and lower work ability. Increased physical activity is a cornerstone in the treatment of obesity and related risk factors. Recently, high-intensity interval training (HIIT) has emerged as a popular exercise option. However, data regarding the effects on cardiometabolic health, perceived work ability and well-being in severely obese individuals are lacking.

METHODS

Sixty-five obese individuals with sedentary occupation (48.7 ± 9.9 years, BMI: 39.6 ± 7.1 kg/m²) were randomly allocated to an extremely time-efficient HIIT (5 × 1 min at 80-95% maximal heart rate on cycle ergometers, 2×/week for 12 weeks) or an inactive control group (CON). Both groups received nutritional counseling to support weight loss. Primary outcome was maximal oxygen uptake (VO_2max), secondary outcomes were cardiometabolic risk indices, body composition, work ability index (WAI), quality of life (QoL, EQ-5D-5L-questionnaire) and perceived stress (PSQ-questionnaire).

RESULTS

Mean body weight reduction was 5.3 kg [95% confidence interval (95% CI) - 7.3 to - 3.3 kg] in the HIIT group (P < 0.001) and 3.7 kg (95% CI - 5.3 to - 2.1 kg) in CON (P < 0.001), respectively. Only the HIIT group showed significant (P < 0.001) changes in VO_2max [+ 3.5 mL/kg/min (95% CI 2.5 to 4.6 mL/kg/min)], waist circumference [-7.5 cm (95% CI - 9.8 to - 5.1 kg)], mean arterial blood pressure [- 11 mmHg (95% CI - 14 to - 8 mmHg)], WAI [+ 3.0 points (95% CI 1.7 to 4.3 points)] and QoL [+ 10% (95% CI 5 to 16%)]. In CON, none of these parameters improved significantly.

CONCLUSIONS

Low-volume HIIT may induce significant improvements in cardiometabolic health, especially VO_2max, WAI and well-being in obese individuals after only 12 weeks. Our results underpin the wide range of benefits on health and subjective measures through exercise that go well beyond simple weight loss through dietary restriction alone.

TRIAL REGISTRATION

ClinicalTrials.gov Id: NCT03306069. Registered 10 October 2017, https://clinicaltrials.gov/ct2/show/NCT03306069 .

Lessons learned from a pilot randomized clinical trial of home-based exercise prescription before allogeneic hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (alloHCT) is a life-saving technology that can cure otherwise incurable diseases, but imposes significant physiologic stress upon recipients. This stress leads to short-term toxicity and mid- to long-term physical function impairment in some recipients. Exercise interventions have demonstrated preliminary efficacy in preserving physical function in HCT recipients, but the role of these interventions prior to HCT (prehabilitative) is less known. We tested a 5- to 12-week, prehabilitative higher intensity home-based aerobic exercise intervention in a randomized study of alloHCT candidates. Of 113 patients screened, 34 were randomized to control or intervention groups, 16 underwent pre- and post-intervention peak oxygen consumption (VO2peak) testing, and 12 underwent pre- and post-intervention 6-min walk distance (6MWD) testing. No significant differences in VO2peak or 6MWD were seen pre- to post-intervention between intervention and control groups, but final numbers of evaluable participants in each group were too small to draw inferences regarding the efficacy of the intervention. We conclude that the design of our prehabilitative intervention was not feasible in this pilot randomized study, and make recommendations regarding the design of future exercise intervention studies in alloHCT.

High-intensity interval training in the prehabilitation of cancer patients-a systematic review and meta-analysis

PURPOSE

To evaluate the impact of high-intensity interval training (HIIT) on health-related outcome parameters in the prehabilitation of patients diagnosed with cancer.

METHODS

A systematic review and meta-analysis of comparative studies on HIIT in cancer prehabilitation conducted by screening standard databases from their inception to March 30, 2020. Outcomes of interest included cardiorespiratory fitness, feasibility, safety, clinical, and patient-reported outcomes.

RESULTS

Of the 855 identified studies, 8 articles met the inclusion criteria (7 randomized, 1 non-randomized controlled trial) with a total of 896 patients. The study protocols were heterogeneous, but the methodological quality ranged from good to high according to PEDro scale. Meta-analysis revealed a significant improvement of peak oxygen consumption (VO₂peak) achieved with HIIT compared to usual care. Furthermore, HIIT was feasible and safe, showing low risk of adverse events and positive effects on health-related outcomes in prehabilitative settings.

CONCLUSION

In the phase of prehabilitation, HIIT has potential health benefits in patients diagnosed with cancer and is feasible and safe to perform. Nonetheless, larger randomized controlled trials focusing on long-term effects (such as cancer recurrence or survival rates) are missing, to underline the potential relevance of HIIT for cancer patients.

The acute physiological and perceptual effects of recovery interval intensity during cycling-based high-intensity interval training

Purpose

The current study sought to investigate the role of recovery intensity on the physiological and perceptual responses during cycling-based aerobic high-intensity interval training.

Methods

Fourteen well-trained cyclists (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2peak}}}}$$\end{document}V˙O2peak: 62 ± 9 mL kg⁻¹ min⁻¹) completed seven laboratory visits. At visit 1, the participants’ peak oxygen consumption (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2peak}}}}$$\end{document}V˙O2peak) and lactate thresholds were determined. At visits 2–7, participants completed either a 6 × 4 min or 3 × 8 min high-intensity interval training (HIIT) protocol with one of three recovery intensity prescriptions: passive (PA) recovery, active recovery at 80% of lactate threshold (80A) or active recovery at 110% of lactate threshold (110A).

Results

The time spent at > 80%, > 90% and > 95% of maximal minute power during the work intervals was significantly increased with PA recovery, when compared to both 80A and 110A, during both HIIT protocols (all P ≤ 0.001). However, recovery intensity had no effect on the time spent at > 90% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2peak}}}}$$\end{document}V˙O2peak (P = 0.11) or > 95% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2peak}}}}$$\end{document}V˙O2peak (P = 0.50) during the work intervals of both HIIT protocols. Session RPE was significantly higher following the 110A recovery, when compared to the PA and 80A recovery during both HIIT protocols (P < 0.001).

Conclusion

Passive recovery facilitates a higher work interval PO and similar internal stress for a lower sRPE when compared to active recovery and therefore may be the efficacious recovery intensity prescription.

Physiological aspects and energetic contribution in 20s:10s high-intensity interval exercise at different intensities

Background

One of the most popular high-intensity interval exercises is the called “Tabata Protocol”. However, most investigations have limitations in describing the work intensity, and this fact appears to be due to the protocol unfeasibility. Furthermore, the physiological demands and energetic contribution during this kind of exercise remain unclear.

Methods

Eight physically active students (21.8 ± 3.7 years) and eight well-trained cycling athletes (27.8 ± 6.4 years) were enrolled. In the first visit, we collected descriptive data and the peak power output (PPO). On the next three visits, in random order, participants performed interval training with the same time structure (effort:rest 20s:10s) but using different intensities (115%, 130%, and 170% of PPO). We collected the number of sprints, power output, oxygen consumption, blood lactate, and heart rate.

Results

The analysis of variance for multivariate test (number of sprints, power output, blood lactate, peak heart rate and percentage of maximal heart rate) showed significant differences between groups (F = 9.62; p = 0.001) and intensities (F = 384.05; p < 0.001), with no interactions (F = 0.94; p = 0.57). All three energetic contributions and intensities were different between protocols. The higher contribution was aerobic, followed by alactic and lactic. The aerobic contribution was higher at 115%PPO, while the alactic system showed higher contribution at 130%PPO. In conclusion, the aerobic system was predominant in the three exercise protocols, and we observed a higher contribution at lower intensities.

Acute exercise in mice transiently remodels the hepatic lipidome in an intensity-dependent manner

Background

The content of triacylglycerol (TAG) in the liver is known to rapidly increase after a single bout of exercise followed by recovery to sedentary levels. The response of other hepatic lipids, and acyl chain composition of lipid classes, would provide a deeper understanding of the response of hepatic lipid metabolism to acute exercise.

Methods

Female mice performed a single bout of continuous exercise (CE), high-intensity interval exercise (HIIE), or no exercise (CON). The total content of various lipids in the liver, and fatty acids within lipid classes, were measured in tissues collected 3 h after exercise (Day 1) and the day following exercise (Day 2).

Results

The total concentration of TAG rose on Day 1 after exercise (P < 0.05), with a greater elevation in HIIE than CE (P < 0.05), followed by a decline toward CON levels on Day 2. The total concentration of other measured lipid classes was not significantly altered by exercise. However, n-6 polyunsaturated fatty acid relative abundance in diacylglycerol (DAG) was increased by HIIE (P < 0.05). In CON liver, TAG content was positively correlated with DAG and phosphatidylethanolamine (P < 0.05), while these statistical associations were disrupted in exercised mice on Day 1.

Conclusions

The response of lipid metabolism to exercise involves the coordination of metabolism between various tissues, and the lipid metabolism response to acute exercise places a metabolic burden upon the liver. The present findings describe how the liver copes with this metabolic challenge. The flexibility of the TAG pool size in the liver, and other remodeling of the hepatic lipidome, may be fundamental components of the physiological response to intense exercise.

Impact of combined training with different exercise intensities on inflammatory and lipid markers in type 2 diabetes: a secondary analysis from a 1-year randomized controlled trial

Background

Exercise is a well-accepted strategy to improve lipid and inflammatory profile in individuals with type 2 diabetes (T2DM). However, the exercise intensity having the most benefits on lipids and inflammatory markers in patients with T2DM remains unclear. We aimed to analyse the impact of a 1-year combined high-intensity interval training (HIIT) with resistance training (RT), and a moderate continuous training (MCT) with RT on inflammatory and lipid profile in individuals with T2DM.

Methods

Individuals with T2DM (n = 80, aged 59 years) performed a 1-year randomized controlled trial and were randomized into three groups (control, n = 27; HIIT with RT, n = 25; MCT with RT, n = 28). Exercise sessions were supervised with a frequency of 3 days per week. Inflammatory and lipid profiles were measured at baseline and at 1-year follow-up. Changes in inflammatory and lipid markers were assessed using generalized estimating equations.

Results

After adjusting for sex, age and baseline moderate-to-vigorous physical activity (MVPA), we observed a time-by-group interaction for Interleukin-6 (IL-6) in both the MCT with RT (β = − 0.70, p = 0.034) and HIIT with RT (β = − 0.62, p = 0.049) groups, whereas, only the HIIT with RT group improved total cholesterol (β = − 0.03, p = 0.045) and LDL-C (β = − 0.03, p = 0.034), when compared to control. No effect was observed for C-reactive protein (CRP), cortisol, tumour necrosis factor-α (TNF-α), soluble form of the haptoglobin-hemoglobin receptor CD163 (sCD163), triglycerides and HDL-C in both groups (p > 0.05).

Conclusions

Favorable adaptations on IL-6 were observed in both the HIIT and MCT combined with RT groups following a long-term 1-year exercise intervention in individuals with T2DM. However, only the HIIT with RT prevented further derangement of total cholesterol and LDL-C, when compared to the control group. Therefore, in order to encourage exercise participation and improve inflammatory profile, either exercise protocols may be prescribed, however, HIIT with RT may have further benefits on the lipid profile.

Trial registration Clinicaltrials.gov ID: NCT03144505

A flow resistive inspiratory muscle training mask worn during high-intensity interval training does not improve 5 km running time-trial performance

Purpose

There is little evidence of the ergogenic effect of flow-resistive masks worn during exercise. We compared a flow-resistive face mask (MASK) worn during high-intensity interval training (HIIT) against pressure threshold loading inspiratory muscle training (IMT).

Methods

23 participants (13 males) completed a 5 km time trial and six weeks of HIIT (3 sessions weekly). HIIT (n = 8) consisted of repeated work (2 min) at the speed equivalent to 95% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\text{V}}}$$\end{document}V˙O₂ peak with equal rest. Repetitions were incremental (six in weeks 1, 2 and 6, eight in weeks 3 and 4 and ten in week 5). Participants were allocated to one of three training groups. MASK (n = 8) wore a flow-resistive mask during all sessions. The IMT group (n = 8) completed 2 × 30 breaths daily at 50% maximum inspiratory pressure (P_Imax). A control group (CON, n = 7) completed HIIT only. Following HIIT, participants completed two 5 km time trials, the first matched identically to pre-intervention trial (ISO time), and a self-paced effort.

Results

Time trial performance was improved in all groups (MASK 3.1 ± 1.7%, IMT, 5.7 ± 1.5% and CON 2.6 ± 1.0%, p < 0.05). IMT improved greater than MASK and CON (p = 0.004). Post intervention, P_Imax and diaphragm thickness were improved in IMT only (32% and 9.5%, respectively, p = 0.003 and 0.024).

Conclusion

A flow-resistive mask worn during HIIT provides no benefit to 5 km performance when compared to HIIT only. Supplementing HIIT with IMT improves respiratory muscle strength, morphology and performance greater than HIIT alone.

HIIT is superior than MICT on cardiometabolic health during training and detraining

PURPOSE

This study investigated the cardiometabolic health of overweight/obese untrained individuals in response to 8 weeks of HIIT and MICT using a field approach, and to 4 weeks of training cessation (TC).

METHODS

Twenty-two subjects performed 8 weeks of moderate intensity continuous training (MICT-n = 11) or high-intensity interval training (HIIT-n = 11) (outdoor running), followed by 4 weeks of TC. Cardiorespiratory fitness, body composition, arterial blood pressure, glucose metabolism and blood lipids were measured pre-training (PRE), post-training (POST) and TC.

RESULTS

HIIT improved eight indicators of cardiometabolic health ([Formula: see text], BMI, body fat, visceral fat, systolic blood pressure, total cholesterol, fasting glucose and triglycerides-p  < 0.05) while MICT only three ([Formula: see text], BMI, and visceral fat-p  < 0.05). After 4 weeks of TC, four positive adaptations from HIIT were negatively affected ( [Formula: see text], visceral fat, systolic blood pressure and total cholesterol-p  < 0.05) and three in the MICT group ([Formula: see text], BMI and visceral fat, p  < 0.05).

CONCLUSION

Eight weeks of HIIT performed in a real-world setting promoted a greater number of positive adaptations in cardiometabolic health of individuals with overweight/obese compared to MICT. Most of the positive effects of the HIIT protocol were also found to be longer lasting and maintained after the suspension of high-intensity interval running for 4 weeks. Conversely, all positive effects of MICT protocols were reversed after TC.

Feasibility of a progressive protocol of high-intensity interval training for overweight/obese, sedentary African American women: a retrospective analysis

Background

African American (AA) women have a higher prevalence of obesity and related metabolic dysfunction and lower level of physical activity compared to white counterparts. Determining feasible exercise alternatives for AA women is, therefore, paramount. Time-efficient high-intensity interval training (HIIT) might be particularly suited for AA women who cite time constraints as a frequent barrier to exercise adherence. The purpose of this study was to assess the feasibility of a 14-week progressive HIIT protocol for previously-sedentary overweight/obese AA women.

Methods

Twenty-eight healthy, premenopausal (age, 20-40 yr), sedentary, nondiabetic, overweight/obese AA women volunteered to participate in the randomized controlled clinical trial from which these data were retrospectively analysed. After assessment, participants were randomly allocated to a HIIT group (n = 14) or a no-exercise control group. The HIIT intervention consisted of 24-min sessions performed three times per week for 14 weeks during which work-interval intensity (75 to 90% of heart rate reserve; HRR) and duration (30 to 60 s) and work/recovery ratio (1:7 to 1:3) were progressed in four stages. Feasibility was assessed based on adherence (attrition rate), perceptual response (RPE) and success rate, which was calculated based on the degree to which target intensities for work intervals were achieved/maintained.

Results

Five of 14 participants (35%) in the HIIT group dropped out during the intervention. One-way repeated-measures ANOVA revealed a significant difference across stages for success rate (p = 0.018) with post-hoc analysis indicating a significant difference between stage 1 and the other stages and stage 4 and the other stages. There was no significant difference in RPE across stages (p = 0.057).

Conclusion

Albeit based on a limited number of participants, we found an attrition rate that was higher than what has been reported previously for HIIT (~ 17.6%) when previously-sedentary overweight/obese AA women performed a protocol with work-interval intensity progressed from 75 to 90% HRR during a 14-week intervention. With respect to intensity, the precipitous drop for achievement of the target HR during the fourth stage (weeks 8-14) for those who did complete the protocol implies that it might be advisable to restrict work-interval intensity to < 90% HRR.

Trial registration

ClinicalTrials.gov. (NCT04293367). Registered 03 March 2020 - Retrospectively registered.

Effects of Different Exercise Interventions on Cardiac Function in Rats With Myocardial Infarction

BACKGROUND

High-intensity interval training (HIIT) and aerobic training (AT) both improve cardiac function; however, their effects on cardiac function after myocardial infarction (MI) and the molecular mechanisms are unclear. In this study, HIIT, AT and sedentary (SED) interventions were performed for 4 weeks to compare the effects on cardiac function after MI and explore a more suitable approach for clinical application and the potential mechanisms.

METHODS

Twenty-four (24) male rats were randomly divided into a control group (CON), MI-sedentary group (MI-SED), MI-aerobic training group (MI-AT), and MI-high-intensity interval training group (MI-HIIT). After 4 weeks of intervention the exercise capacity, heart rate (HR), left ventricular end-diastolic diameter (LVEDD), left ventricular end systolic diameter (LVESD), left ventricular ejection fraction (LVEF), AMP-activated protein kinase α1 (AMPKα1), cardiomyocyte morphology, and cardiac mitochondria were assessed.

RESULTS

After intervention: 1) exercise capacity in the MI-AT (49.08±3.141 m; p<0.001) and MI-HIIT (51.70±7.572 m; p<0.001) groups was significantly more increased than the MI-SED group; there was no significant difference between the MI-AT and MI-HIIT group (p=0.33). 2) LVEDD and LVESD in the MI-SED (p<0.01) and MI-HIIT (p<0.01) groups was significantly more increased than the CON group; the MI-AT group showed no significant difference in LVEDD and LVESD compared with the CON group; LVEF in the MI-AT (53.47±7.913%; p=0.03) and MI-HIIT (56.20±7.224%; p=0.006) groups was significantly more increased than the MI-SED group, and there was no statistical difference between the MI-AT and MI-HIIT groups. 3) AMPKα1 expression was significantly increased in the MI-AT (1.15±0.264; p=0.001) and MI-HIIT (1.04±0.238; p=0.003) groups and decreased in the MI-SED group (0.71±0.257; p<0.001) when compared with the CON group. 4) The MI-SED group exhibited sarcoplasmic dissolution and fibrous hyperplasia in the myocardium, cardiac mitochondrial damage and reduced mitochondrial numbers; the MI-HIIT group displayed swollen and vacuolated cardiac mitochondria with disrupted cristae; the MI-AT and MI-HIIT groups had significantly increased cardiac mitochondrial numbers than the MI-SED group; there was no statistical difference between the MI-AT and MI-HIIT groups.

CONCLUSIONS

Aerobic training and HIIT for 4 weeks had similar cardioprotection and were superior to SED intervention. Both AT and HIIT improved cardiac function and exercise capacity by upregulating AMPKα1 expression. However, 4 weeks of intervention resulted in left ventricular dilation and cardiac myocardial mitochondrial injury in the MI-HIIT group.

Technical feasibility of constant-load and high-intensity interval training for cardiopulmonary conditioning using a re-engineered dynamic leg press

Background

Leg-press devices are one of the most widely used training tools for musculoskeletal strengthening of the lower-limbs, and have demonstrated important cardiopulmonary benefits for healthy and patient populations. Further engineering development was done on a dynamic leg-press for work-rate estimation by integrating force and motion sensors, power calculation and a visual feedback system for volitional work-rate control. This study aimed to assess the feasibility of the enhanced dynamic leg press for cardiopulmonary exercise training in constant-load training and high-intensity interval training. Five healthy participants aged 31.0±3.9 years (mean ± standard deviation) performed two cardiopulmonary training sessions: constant-load training and high-intensity interval training. Participants carried out the training sessions at a work rate that corresponds to their first ventilatory threshold for constant-load training, and their second ventilatory threshold for high-intensity interval training.

Results

All participants tolerated both training protocols, and could complete the training sessions with no complications. Substantial cardiopulmonary responses were observed. The difference between mean oxygen uptake and target oxygen uptake was 0.07±0.34 L/min (103 ±17%) during constant-load training, and 0.35±0.66 L/min (113 ±27%) during high-intensity interval training. The difference between mean heart rate and target heart rate was −7±19 bpm (94 ±15%) during constant-load training, and 4.2±16 bpm (103 ±12%) during high-intensity interval training.

Conclusions

The enhanced dynamic leg press was found to be feasible for cardiopulmonary exercise training, and for exercise prescription for different training programmes based on the ventilatory thresholds.