Improving Health Outcomes in Coronary Artery Disease Patients with Short-Term Protocols of High-Intensity Interval Training and Moderate-Intensity Continuous Training: A Community-Based Randomized Controlled Trial

Studies have shown that the higher the aerobic capacity, the lower the risk of cardiovascular mortality and morbidity. In the case of cardiac patients, high-intensity interval training (HIIT) seems to be more effective than moderate-intensity continuous training (MICT) in improving aerobic capacity. The aim of this study was to investigate the effects of two community-based exercise programs using two short-term protocols (HIIT and MICT) on physical fitness and physical activity (PA) levels in coronary artery disease (CAD) patients. Methods. In this randomized controlled trial, body composition, aerobic capacity, muscle strength, and daily PA levels were assessed before and after 6 weeks of intervention in 69 patients diagnosed with CAD. All patients were randomly (1 : 1 : 1) assigned to two exercise groups (HIIT or MICT) or a control group (no exercise). Both training programs consisted of 6 weeks of supervised treadmill exercise, three sessions per week. MICT targeted ≈70-75% of peak heart rate (HR), while HIIT aimed for ≈85-95% of peak HR. The control group only followed the medical recommendations. Results. Community-based exercise programs showed more positive effects on physical fitness variables and physical activity levels compared to control. HIIT could significantly improve waist circumference, body fat mass, VO2peak, sedentary behavior, and moderate-to-vigorous PA compared to MICT. Moreover, the control group showed poorer results. Conclusion. HIIT can improve health outcomes more positively than MICT and control. These findings indicate that HIIT may be an alternative and effective training method in community-based exercise programs for CAD patients. This trial is registered with NCT03538119.

Effects of Time-Efficient Occupational Exercise on Cardiorespiratory Fitness in Firefighters

OBJECTIVE

For a cohort of operational firefighters, we assessed the effects of workplace-based high-intensity interval training (HIIT) on cardiorespiratory fitness.

METHODS

Fifteen firefighters performed HIIT or moderate-intensity continuous training for 4 weeks. Outcomes were peak oxygen uptake, time trial performance, and affective (pleasure/displeasure) responses to exercise.

RESULTS

There was an increase in peak oxygen uptake for both conditions, although this did not reach statistical significance ( P = 0.06, η2 = 0.26) and time trial performance improved for both groups (2%, P < 0.01, η2 = 0.51). Affective responses were more favorable for HIIT, but both conditions avoided excessive sensations of displeasure.

CONCLUSION

Results suggest that workplace-based HIIT improved fitness and performance to a similar magnitude to moderate-intensity continuous training while avoiding overly negative affective responses and could improve occupational health of firefighters, despite reduced time commitment.

A Perspective on High-Intensity Interval Training for Performance and Health

Interval training is a simple concept that refers to repeated bouts of relatively hard work interspersed with recovery periods of easier work or rest. The method has been used by high-level athletes for over a century to improve performance in endurance-type sports and events such as middle- and long-distance running. The concept of interval training to improve health, including in a rehabilitative context or when practiced by individuals who are relatively inactive or deconditioned, has also been advanced for decades. An important issue that affects the interpretation and application of interval training is the lack of standardized terminology. This particularly relates to the classification of intensity. There is no common definition of the term "high-intensity interval training" (HIIT) despite its widespread use. We contend that in a performance context, HIIT can be characterized as intermittent exercise bouts performed above the heavy-intensity domain. This categorization of HIIT is primarily encompassed by the severe-intensity domain. It is demarcated by indicators that principally include the critical power or critical speed, or other indices, including the second lactate threshold, maximal lactate steady state, or lactate turnpoint. In a health context, we contend that HIIT can be characterized as intermittent exercise bouts performed above moderate intensity. This categorization of HIIT is primarily encompassed by the classification of vigorous intensity. It is demarcated by various indicators related to perceived exertion, oxygen uptake, or heart rate as defined in authoritative public health and exercise prescription guidelines. A particularly intense variant of HIIT commonly termed "sprint interval training" can be distinguished as repeated bouts performed with near-maximal to "all out" effort. This characterization coincides with the highest intensity classification identified in training zone models or exercise prescription guidelines, including the extreme-intensity domain, anaerobic speed reserve, or near-maximal to maximal intensity classification. HIIT is considered an essential training component for the enhancement of athletic performance, but the optimal intensity distribution and specific HIIT prescription for endurance athletes is unclear. HIIT is also a viable method to improve cardiorespiratory fitness and other health-related indices in people who are insufficiently active, including those with cardiometabolic diseases. Research is needed to clarify responses to different HIIT strategies using robust study designs that employ best practices. We offer a perspective on the topic of HIIT for performance and health, including a conceptual framework that builds on the work of others and outlines how the method can be defined and operationalized within each context.

The effect of chronic high-intensity interval training programs on glycaemic control, aerobic resistance, and body composition in type 2 diabetic patients: a meta-analysis

BACKGROUND

Type 2 diabetes is an increasing health problem worldwide. HIIT has been proposed as an exercise alternative to be part of integral type 2 diabetes treatment.

OBJECTIVE

The aim of this meta-analysis was to determine the effect of different types of chronic HIIT on glycaemic control, aerobic resistance, and body composition in individuals above 18 years with T2D.

DESIGN

This meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement and was registered with PROSPERO on November 21st, 2021.

DATA SOURCES

A systematic literature search of the following databases: EbscoHost (Academic Search Ultimate, Fuente Académica Plus, MEDline and SportDiscus), Web of Science, PubMed, and EMBASE between April of 2021 and April of 2023 was conducted.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Eligibility criteria included (1) participants aged ≥ 18 years with a diagnosis of type 2 diabetes, (2) an HIIT protocol with detailed description, (3) control group and/or continuous aerobic training comparison group, (4) report of pre-test and post-test values for at least one of the studied variables (from glycaemic control, aerobic resistance, and/or body composition), and (5) experimental or quasi-experimental intervention design.

ANALYSES

Meta-analysis was made by a pre-post-test between-group analysis following the inverse variance heterogeneity model for each variable, and then, a subgroup analysis by type of HIIT was conducted.

RESULTS

Of the 2817 records obtained, 180 records were included for meta-analysis. Significant improvements were found in the most part of the variables when HIIT was compared to control group, while fat-free mass kept without changes. HIIT vs. continuous aerobic training results showed and advantage in favor of HIIT for fasting blood glycemia. Subgroup analysis refers a possible advantage of SI-HIIT and SIT-HIIT in the improvement of fasting glycemia and SIT-HIIT advantage in HOMA 1-IR decrease.

CONCLUSIONS

HIIT improves glycaemic control, aerobic resistance, and % fat and waist circumference, and kept fat-free mass unchanged in individuals with T2D. SI-HIIT and SIT-HIIT could be better than the other types of HIIT. HIIT benefit is similar to continuous aerobic training except for fasting blood glycemia.

Intervention Design of High-Intensity Interval Training in Individuals With Spinal Cord Injury: Narrative Review and Future Perspectives

Background

Individuals with spinal cord injury (SCI) have lower levels of physical activity compared to the nondisabled population. Exercise guidelines recommend moderate or vigorous exercise to improve cardiovascular health and reduce cardiometabolic risk factors in persons with SCI. High-intensity interval training (HIIT) is a popular exercise choice and encompasses brief periods of vigorous exercise paired with intermittent periods of recovery.

Objectives

This review describes the available literature on HIIT for individuals with SCI, including differences in protocol design and suggested areas of further investigation.

Methods

Our institution's library system performed the comprehensive search. The primary keywords and phrases used to search included spinal cord injury, high-intensity interval training, tetraplegia, paraplegia, and several other related terms.

Results

Initially 62 records were screened, and 36 were deemed outside the scope of this review. Twenty-six studies published between 2001 and 2021 fulfilled the eligibility criteria and were divided among two researchers for review and analysis. All records required persons with SCI and a standardized HIIT intervention. Study design varied widely with respect to mode of exercise, prescribed intensity, duration of performance intervals, and session duration. This variability necessitates further investigation into the specifics of a HIIT prescription and the associated outcomes for persons with SCI.

Conclusion

Standardization of HIIT protocols may lead to more robust conclusions regarding its effects on cardiorespiratory fitness as well as mitigation of cardiometabolic risk factors. Meta-analyses will eventually be needed on proper dosing and session parameters to improve cardiorespiratory fitness and cardiometabolic risk factors.

Effects of plyometric- and cycle-based high-intensity interval training on body composition, aerobic capacity, and muscle function in young females: a field-based group fitness assessment

High-intensity interval training (HIIT) is an effective alternative to moderate intensity continuous training for improvements in body composition and aerobic capacity; however, there is little work comparing different modalities of HIIT. The purpose of this study was to compare the effects of plyometric- (PLYO) and cycle-oriented (CYC) HIIT on body composition, aerobic capacity, and skeletal muscle size, quality, and function in recreationally trained females. Young (21.7 ± 3.1 yrs), recreationally active females were quasi-randomized (1:1 ratio) to 8 weeks of twice weekly PLYO (n = 15) or CYC (n = 15) HIIT. Body composition (four-compartment model), VO2peak, countermovement jump performance, muscle size, and echo intensity (muscle quality), as well as strength and power of the knee extensors and plantar flexors were measured before and after training. Both groups showed a similar decrease in body fat percentage (p < 0.001;η p 2   = 0.409) and echo intensity (p < 0.001;η p 2 = 0.558), and an increase in fat-free mass (p < 0.001;η p 2   = 0.367) and VO2peak (p = 0.001;η p 2 = 0.318). Muscle size was unaffected (p > 0.05), whereas peak torque was reduced similarly in both groups (p = 0.017;η p 2 = 0.188) and rapid torque capacity was diminished only for the knee extensors after CYC (p = 0.022; d = -0.67). These results suggest that PLYO and CYC HIIT are similarly effective for improving body composition, aerobic capacity, and muscle quality, whereas muscle function may express moderate decrements in recreationally active females. ClinicalTrials.gov (NCT05821504).

A Cardiopulmonary Exercise Testing for Prescribing High-Intensity Interval Training Sessions with Elastic Resistance

This study aims to analyze the agreement of cardiopulmonary variables between a cardiopulmonary exercise test with elastic resistance (CPxEL) and high-intensity interval exercise with elastic resistance (EL-HIIE).

METHODS

Twenty-two physically independent participants were recruited. Visit one consisted of conducting a health survey and anthropometric assessment. On visit two, the participants performed CPxEL. After seven days, on visit three, the participants performed EL-HIIE. The CPxEL was carried out on a rubber mat demarcated by lines representing eight stages. The test consisted of alternating back and forth steps against elastic resistance. The increments were performed at a rate of one stage per minute, following a cadence controlled by a metronome calibrated by beats per minute (bpm). The EL-HIIE was performed at the stage corresponding to an intensity of ~85% VO2max, as determined by CPxEL. The EL-HIIE consisted of 10 × 1 min (work):1 min (passive rest), with a cadence of 200 bpm. Cardiopulmonary parameters, heart rate (HR), and oxygen consumption (VO2) were measured during exercise. Bland-Altman was applied to analyze the agreement between the HR and VO2 found in EL-HIIE and the values prescribed by CPxEL (~85-90% VO2max).

RESULTS

The HRpeak and VO2peak in the EL-HIIE showed good agreement with the VO2CPxEL and HRCPxEL values, showing an average difference of (-1.7 mL·kg-1·min-1) and (0.3 bpm).

CONCLUSIONS

The results of the present study demonstrate the agreement of cardiopulmonary variables between the CPxEL and the EL-HIIE. Therefore, for a more specific prescription of EL-HIIE intensity, CPxEL can be used.

Rates of compliance and adherence to high-intensity interval training: a systematic review and Meta-analyses

BACKGROUND

To determine rates of compliance (i.e., supervised intervention attendance) and adherence (i.e., unsupervised physical activity completion) to high-intensity interval training (HIIT) among insufficiently active adults and adults with a medical condition, and determine whether compliance and adherence rates were different between HIIT and moderate-intensity continuous training (MICT).

METHODS

Articles on adults in a HIIT intervention and who were either insufficiently active or had a medical condition were included. MEDLINE, EMBASE, PsychINFO, SPORTDiscus, CINAHL, and Web of Science were searched. Article screening and data extraction were completed by two independent reviewers. Risk of bias was assessed using RoB 2.0 or ROBINS-I. Meta-analyses were conducted to discern differences in compliance and adherence between HIIT vs. MICT. Sensitivity analyses, publication bias, sub-group analyses, and quality appraisal were conducted for each meta-analysis.

RESULTS

One hundred eighty-eight unique studies were included (n = 8928 participants). Compliance to HIIT interventions averaged 89.4% (SD:11.8%), while adherence to HIIT averaged 63% (SD: 21.1%). Compliance and adherence to MICT averaged 92.5% (SD:10.6%) and 68.2% (SD:16.2%), respectively. Based on 65 studies included in the meta-analysis, compliance rates were not different between supervised HIIT and MICT interventions [Hedge's g = 0.015 (95%CI: - 0.088-0.118), p = .78]. Results were robust and low risk of publication bias was detected. No differences were detected based on sub-group analyses comparing medical conditions or risk of bias of studies. Quality of the evidence was rated as moderate over concerns in the directness of the evidence. Based on 10 studies, adherence rates were not different between unsupervised HIIT and MICT interventions [Hedge's g = - 0.313 (95%CI: - 0.681-0.056), p = .096]. Sub-group analysis points to differences in adherence rates dependent on the method of outcome measurement. Adherence results should be interpreted with caution due to very low quality of evidence.

CONCLUSIONS

Compliance to HIIT and MICT was high among insufficiently active adults and adults with a medical condition. Adherence to HIIT and MICT was relatively moderate, although there was high heterogeneity and very low quality of evidence. Further research should take into consideration exercise protocols employed, methods of outcome measurement, and measurement timepoints.

REGISTRATION

This review was registered in the PROSPERO database and given the identifier CRD42019103313.

Exercise-Induced Muscle Damage after a High-Intensity Interval Exercise Session: Systematic Review

High-intensity interval training (HIIT) is considered an effective method to improve fitness and health indicators, but its high-intensity exercises and the mechanical and metabolic stress generated during the session can lead to the occurrence of exercise-induced muscle damage. Therefore, this study aimed to describe, by means of a systematic review, the effects of a single HIIT session on exercise-induced muscle damage. A total of 43 studies were found in the Medline/PubMed Science Direct/Embase/Scielo/CINAHL/LILACS databases; however, after applying the exclusion criteria, only 15 articles were considered eligible for this review. The total sample was 315 participants. Among them, 77.2% were men, 13.3% were women and 9.5 uninformed. Their age ranged from 20.1 ± 2 to 47.8 ± 7.5 years. HIIT protocols included running with ergometers (n = 6), CrossFit-specific exercises (n = 2), running without ergometers (n = 3), swimming (n = 1), the Wingate test on stationary bicycles (n = 2), and cycling (n = 1). The most applied intensity controls were %vVO2max, "all out", MV, MAV, Vmax, and HRreserve%. The most used markers to evaluate muscle damage were creatine kinase, myoglobin, and lactate dehydrogenase. The time for muscle damage assessment ranged from immediately post exercise to seven days. HIIT protocols were able to promote changes in markers of exercise-induced muscle damage, evidenced by increases in CK, Mb, LDH, AST, ALT, pain, and muscle circumference observed mainly immediately and 24 h after the HIIT session.

Serum metabolomic adaptations following a 12-week high-intensity interval training combined to citrulline supplementation in obese older adults

Physical activity and nutrition play important roles in preventing adverse health outcomes that accompany aging. It has been shown that high-intensity interval training (HIIT) combined with citrulline (CIT) supplementation can improve physical and functional capacities. The aim of this study was to evaluate serum metabolites following a 12-week HIIT combined or not with CIT in obese older adults, and to correlate the metabolic changes with clinico-biological parameters changes. Eighty-six obese older adults completed a 12-week HIIT program combined with a 10 g daily supplementation of either CIT or placebo (PLA) during a double-blinded randomized interventional trial. Only participants with blood samples at T0 (before the intervention) and/or T12 (after the intervention) were included in our sub-analysis (HIIT-PLA-T0: n = 44 and HIIT-PLA-T12: n = 28; HIIT-CIT-T0: n = 39 and HIIT-CIT-T12: n = 42). Serum samples were analyzed by different liquid or gas phase chromatography methods coupled to mass spectrometry. Among the identified metabolites, 44 changed significantly following the 12-week intervention (Time effect), and 10 of them were more affected when HIIT was combined with CIT (Time × Supp effect). Arginine increased significantly due to the 12-week intervention. Correlation analyses demonstrated that decreased triglyceride (TG) (16:1/18:1/16:0) and aspartic acid significantly correlated with a reduction of adiposity-related parameters (fat mass, leg lean mass, leptin, total triglycerides and low-density lipoprotein). Arginine, TG (16:1/18:1/16:0) and aspartic acid might constitute biomarkers of cardiometabolic health and adiposity. Further studies are needed to confirm these associations and understand the underlying mechanisms.Highlights A 12-week intervention involving high-intensity interval training (HIIT) with or without citrulline (CIT) supplementation induced adaptations in the serum metabolome of obese older adults through significant changes in 44 metabolites.Changes in 23 metabolites were observed when a CIT supplementation was administered along with a 12-week HIIT intervention.TG (16:1/18:1/16:0) correlated with several adiposity parameters including leptin, triglycerides, legs lean mass.Aspartic acid correlated with several adiposity parameters including leptin, LDL cholesterol as well as android, arms and trunk fat mass.

Aerobic high-intensity intervals improve V̇O2max more than supramaximal sprint intervals in females, similar to males

INTRODUCTION

Maximal oxygen uptake (V̇O2max ) is a pivotal factor for aerobic endurance performance. Recently, aerobic high-intensity interval training (HIIT) was documented to be superior to sprint interval training (SIT) in improving V̇O2max in well-trained males. However, as mounting evidence suggests that physiological responses to training are sex-dependent, examining the effects of HIIT versus SIT on V̇O2max , anaerobic capacity, and endurance performance in females is warranted.

METHODS

We randomized 81 aerobically well-trained females (22 ± 2 years, 51.8 ± 3.6 mL∙kg-1 ∙min-1 V̇O2max ), training three times weekly for 8 weeks, to well-established protocols: (1) HIIT 4 × 4 min at ~95% of maximal aerobic speed (MAS), with 3 min active recovery (2) SIT 8 × 20 s at ~150% of MAS, with 10 s passive recovery (3) SIT 10 × 30 s at ~175% of MAS, with 3.5 min active recovery.

RESULTS

Only HIIT 4 × 4 min increased V̇O2max (7.3 ± 3.1%), different from both SIT groups (all p < 0.001). Anaerobic capacity (maximal accumulated oxygen deficit) increased following SIT 8 × 20 s (6.5 ± 10.5%, p < 0.05), SIT 10 × 30 s (14.4 ± 13.7%, p < 0.05; different from HIIT 4 × 4 min, p < 0.05). SIT 10 × 30 s resulted in eight training-induced injuries, different from no injuries following HIIT 4 × 4 min and SIT 8 × 20 s (p < 0.001). All groups improved long-distance (3000-meter) and sprint (300-meter) running performance (all p < 0.001). SIT protocols improved sprint performance more than HIIT 4 × 4 min (p < 0.05). Compared to previous male results, no increase in V̇O2max following SIT 8 × 20 s (p < 0.01), and a higher injury rate for SIT 10 × 30 s (p < 0.001), were evident.

CONCLUSIONS

In aerobically well-trained women, HIIT is superior to SIT in increasing V̇O2max while all-out treadmill running SIT is potentially more harmful.

Resistance exercise training augments the immunomodulatory adaptations to aerobic high-intensity interval training

To compare the effectiveness of different types of high-intensity interval training (HIIT) on meta-inflammation during obesity, TLR4 pathway activities were assessed following a 10-week randomized trial. 30 young females with overweight and obesity were randomly allocated to aerobic HIIT (HIIT/AE) or resistance exercise in HIIT (HIIT/RE) and performed a 28-minute (4 × 4 min) in each session. During each interval, the HIIT/AE performed four minutes of all-extremity cycling, whereas the HIIT/RE completed four minutes of combined resistance exercises and all-extremity cycling. The TLR4 pathway gene expression was measured for the TLR4 receptor, downstream adaptors (TIR domain-containing adaptor-inducing interferon-β (TRIF) and myeloid differentiation factor (MYD) 88), transcriptional factors (nuclear factor kappa B (NF-κB), and interferon regulatory factor (IRF) 3), and its negative regulator (tumor necrosis factor (TNF) a-induced protein 3 (TNFAIP3)). The serum levels of TNFα, interferon (IFN) γ, interleukin (IL)-10, and adiponectin were measured. We found that TLR4 (HIIT/RE: 0.6 ± 0.43 vs. HIIT/AE: 1.24 ± 0.82, p = 0.02), TRIF (HIIT/RE: 0.51 ± 0.4 vs. HIIT/AE: 3.56 ± 0.52, p = 0.001), and IRF3 (HIIT/RE: 0.49 ± 0.42 vs. HIIT/AE: 0.6 ± 0.89; p = 0.04) levels were significantly downregulated in HIIT/RE compared to the HIIT/AE, with a significant reduction in serum levels of TNFα (pg/ml) (HIIT/RE: 22.5 ± 11.3 to 6.3 ± 5.3 vs. HIIT/AE: 19.16 ± 20.8 to 13.48 ± 21.7, p = 0.04) and IFNγ (pg/ml) (HIIT/RE: 43.5 ± 20.6 to 37.5 ± 4.3 vs. HIIT/AE: 37.6 ± 5.6 to 68.1 ± 22.5, p = 0.03). Adiponectin and IL-10 levels did not significantly differ between the two groups. Thus, resistance exercise training augments the immunomodulatory adaptations to HIIT and should be prescribed to people at risk of cardiometabolic disease.Highlights HIIT in combination with resistance exercise looks more effective than HIIT alone to target TLR4-mediated inflammation in individuals with overweight and obesity.HIIT/RE induces a different effect on two downstream cascades of TLR4, leading to a greater overall reduction of TRIF-dependent pathway activities compared to MYD88.Both HIIT protocols show comparable effects on the negative regulatory protein TNFAIP3 gene expression.

Effects of the order of endurance and high-intensity interval exercise in combined training on mouse skeletal muscle metabolism

Endurance exercise (EE) mainly improves oxidative capacity, whereas high-intensity interval exercise (HIIE) also improves glycolytic capacity. There is growing evidence that suggests that combining EE with HIIE can lead to improved athletic performance and fitness outcomes compared with either form of exercise alone. This study aimed to elucidate whether the order in which EE and HIIE are performed in combined training affects oxidative metabolism and glycolysis in mouse skeletal muscle. Male ICR mice at 7 wk of age were divided into three groups: control (CON), EE-HIIE, and HIIE-EE. The total training period was 3 wk (3 times/week). Mice performed running on a treadmill as endurance exercise and swimming with a weight load of 10% of body weight as high-intensity interval exercise. EE before HIIE (EE-HIIE) improved running performance in the maximal EE capacity test (all-out test) and partly enhanced the expression levels of molecular signals involved in glycolysis compared with HIIE before EE (HIIE-EE). The order of exercise did not, however, impact the expression of proteins related to mitochondrial dynamics, including those involved in the morphological changes of mitochondria through repeated fusion and fission, as well as oxidative energy metabolism. The findings suggest that the order of exercise has no significant impact on the expression of proteins associated with glycolytic and oxidative energy metabolism. Nevertheless, our results indicate that the order of EE-HIIE may enhance running performance.

Effect of resistance training and high-intensity interval training on metabolic parameters and serum level of Sirtuin1 in postmenopausal women with metabolic syndrome: a randomized controlled trial

BACKGROUND

The present study analyzes the influence of resistance training (RT) and high-intensity interval training (HIIT) on metabolic indices and serum levels of Sirtuin1 (SIRT1) in postmenopausal women who suffer from the metabolic syndrome (MetS).

METHODS

45 postmenopausal women aged 45-65 years with MetS were divided into two intervention groups (RT and HIIT) and one control group, each consisting of 15 people. The RT group performed resistance training for both the upper and lower body, while the HIIT group completed 3 min(min) of high-intensity training at 80-90% of their maximum heart rate (HRmax), followed by moderate walking for 3 min at 55-65% of HRmax. These sessions were conducted for a duration of eight weeks and three times a week, with the samples being collected at the baseline and at the end of the treatment, i.e., week 8.

RESULTS

The results showed that weight, waist circumference, body mass index, fat mass, low-density lipoprotein, triglyceride, cholesterol, fasting blood sugar (FBS), hemoglobin A1c (HbA1C), systolic and diastolic blood pressure decreased, and SIRT1 increased significantly in both training groups. Systolic blood pressure, cholesterol, HbA1C, and FBS decreased more in the HIIT group. Skeletal muscle mass and 1-repetition maximum (1-RM) increased more in the RT group.

CONCLUSIONS

RT and HIIT serve as one of the most effective strategies for therapeutically treating patients with metabolic syndrome.

TRIAL REGISTRATION

IRCT, IRCT20221120056548N1. Registered 23 November 2022 - Retrospectively registered.

Effects of high-intensity interval training on functional performance and maximal oxygen uptake in comparison with moderate intensity continuous training in cancer patients: a systematic review and meta-analysis

INTRODUCTION

High-intensity interval training (HIIT) is an appropriate training modality to improve endurance and therefore contributes to physical performance. This review investigates the effect of HIIT on functional performance in cancer patients. We reviewed the relative peak oxygen uptake (relV̇O2PEAK) and meta-analytical compared HIIT with moderate intensity continuous training (MICT). Furthermore, we took various training parameters under consideration.

METHODS

A systematic literature search was conducted in Scopus, PubMed, and Cochrane Library databases. For the review, we included randomized controlled trials containing HIIT with cancer patients. From this, we filtered interventions with additional MICT for the meta-analysis. Outcomes of interest were various functional performance assessments and V̇O2MAX.

RESULTS

The research yielded 584 records which fit the inclusion criteria, of which 31 studies with n=1555 patients (57.4±8.6 years) could be included in the overall review and 8 studies in the meta-analysis (n=268, 59.11±5.11 years) regarding relV̇O2PEAK. Different functional outcomes were found, of which walking distance (+8.63±6.91% meters in 6-min walk test) and mobility (+2.7cm in sit and reach test) improved significantly due to HIIT. In terms of relV̇O2PEAK, the performance of cancer patients was improved by HIIT (10.68±6.48%) and MICT (7.4±4.29%). HIIT can be favored to increase relV̇O2PEAK (SMD 0.37; 95% CI 0.09-0.65; I2=0%; p=0.009). Effect sizes for relV̇O2PEAK improvements correlate moderately with total training volume (Spearman's ρ=0.49; p=0.03), whereas percentage increases do not (Spearman's ρ=0.24; p=0.14).

CONCLUSION

Functional and physical outcomes were positively altered by different HIIT protocols and forms of implementation, whereas a tendency toward more effectiveness of HIIT vs. MICT was found for relV̇O2PEAK. Future studies should include functional parameters more often, to finally allow a comparison between both training protocols in this regard.

Moderate intensity continuous versus high intensity interval training: Metabolic responses of slow and fast skeletal muscles in rat

The healthy benefits of regular physical exercise are mainly mediated by the stimulation of oxidative and antioxidant capacities in skeletal muscle. Our understanding of the cellular and molecular responses involved in these processes remain often uncomplete particularly regarding muscle typology. The main aim of the present study was to compare the effects of two types of exercise training protocol: a moderate-intensity continuous training (MICT) and a high-intensity interval training (HIIT) on metabolic processes in two muscles with different typologies: soleus and extensor digitorum longus (EDL). Training effects in male Wistar rats were studied from whole organism level (maximal aerobic speed, morphometric and systemic parameters) to muscle level (transcripts, protein contents and enzymatic activities involved in antioxidant defences, aerobic and anaerobic metabolisms). Wistar rats were randomly divided into three groups: untrained (UNTR), n = 7; MICT, n = 8; and HIIT, n = 8. Rats of the MICT and HIIT groups ran five times a week for six weeks at moderate and high intensity, respectively. HIIT improved more than MICT the endurance performance (a trend to increased maximal aerobic speed, p = 0.07) and oxidative capacities in both muscles, as determined through protein and transcript assays (AMPK-PGC-1α signalling pathway, antioxidant defences, mitochondrial functioning and dynamics). Whatever the training protocol, the genes involved in these processes were largely more significantly upregulated in soleus (slow-twitch fibres) than in EDL (fast-twitch fibres). Solely on the basis of the transcript changes, we conclude that the training protocols tested here lead to specific muscular responses.

Is isoenergetic high-intensity interval exercise superior to moderate-intensity continuous exercise for cardiometabolic risk factors in individuals with type 2 diabetes mellitus? A single-blinded randomized controlled study

The aim of this study was to compare the effect of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) with equal energy expenditure on glycaemic and cardiometabolic risk factors in people with Type 2 Diabetes Mellitus (T2DM) when compared to the control. Sixty-three people with T2DM were randomly assigned to HIIT, MICT, or non-exercising controls. Individuals were trained with HIIT at 90 and 30% of their VO2peak (1:2 min ratio) starting from 8 up to 16 intervals and MICT at 50% of VO2peak, on a cycle ergometer, 3 times/week for 12 weeks under supervision. The primary outcome measure was the change in HbA1c. Aerobic capacity, cardiovascular responses, anthropometric measures, body composition, glycaemic, and cardiometabolic risk factors were measured at the beginning and the end of the 12-week training period. There was no significant difference between HIIT and MICT or when compared to the control for HbA1c, glucose, insulin resistance, blood lipids, cardiovascular responses, anthropometric measures, body composition, and abdominal and visceral fat (padj > 0.05). HIIT and MICT increased VO2peak significantly compared to controls (p < 0.05) but not to each other (p > 0.05). Both HIIT and MICT improved VO2peak and HbA1c after 12 weeks of training compared to their baseline, furthermore, only MICT caused additional improvements in cardiovascular responses, anthropometric measures, and abdominal fat compared to baseline (p < 0.05). As a conclusion, isoenergetic HIIT or MICT did not improve HbA1c. The two protocols were equally efficient for improvement in aerobic capacity but had little effect on other cardiometabolic factors.Trial registration: ClinicalTrials.gov identifier: NCT03682445.HighlightsHIIT and MICT with equal energy expenditure were equally efficient for aerobic capacity compared to controls.Isoenergetic HIIT or MICT were not superior for improving HbA1c.Isoenergetic HIIT and MICT were not superior to each other for anthropometric measures, body composition, and cardiometabolic risk factors.

Neuromuscular and autonomic function is fully recovered within 24 h following a sprint interval training session

BACKGROUND

Recovery is a key factor to promote adaptations and enhance performance. Sprint Interval Training (SIT) is known to be an effective approach to improve overall physical function and health. Although a 2-day rest period is given between SIT sessions, the time-course of recovery after SIT is unknown.

PURPOSE

The aim of this study was to determine whether the neuromuscular and autonomic nervous systems would be impaired 24 and 48 h after an SIT session.

METHODS

Twenty-five healthy subjects performed an 8 × 15 s all-out session on a braked cycle ergometer with 2 min of rest between repetitions. Isometric maximal voluntary contraction (iMVC) and evoked forces to electrical nerve stimulation during iMVC and at rest were used to assess muscle contractile properties and voluntary activation before (Pre), 1 (Post24h), and 2 (Post48h) days after the session. Two maximal 7 s sprints with two different loads were performed at those same time-points to evaluate the maximal theoretical force (F0), velocity (V0) and maximal power (Pmax) production during a dynamic exercise. Additionally, nocturnal heart rate variability (HRV) was assessed the previous and the three subsequent nights to the exercise bout.

RESULTS

No significant impairments were observed for the iMVC or for the force evoked by electrical stimulation 1 day after the session. Similarly, F0, V0, and Pmax were unchanged at Post24h and Post48h. Furthermore, HRV did not reveal any temporal or frequential significant difference the nights following SIT compared to Pre.

CONCLUSION

The results of this study show a full recovery of neuromuscular and autonomic functions a day after an all-out SIT session.

The effect of gradual ovarian failure on dynamic muscle function and the role of high-intensity interval training on mitigating impairments

Skeletal muscle contractile function is impaired in menopause and exercise may mitigate this decline. We used the 4-vinylcyclohexene diepoxide (VCD) model of menopause to investigate the effects of gradual ovarian failure on skeletal muscle contractile function and whether high-intensity interval training (HIIT) can mitigate impairments. Sexually mature female CD-1 mice were assigned to one of three groups: control sedentary (n = 5), VCD-sedentary (n = 5), or VCD-training (n = 5). Following ovarian failure (a 4-mo process), the VCD-training group underwent 8 wk of uphill HIIT. Mice were euthanized 8 wk after ovarian failure, representing late menopause. Single fibers from the soleus (SOL) and extensor digitorum longus (EDL) muscles were dissected, chemically permeabilized, and mechanically tested. Single muscle fibers were maximally activated (pCa 4.5), then isotonic load clamps were performed to evaluate force-velocity-power relationships. Absolute force and peak power were 31.0% and 32.2% lower in VCD-sedentary fibers compared with control fibers, respectively, in both SOL and EDL muscles. Despite reductions in absolute force, there were no concomitant increases in contractile velocity to preserve power production. HIIT attenuated force loss in the VCD-training group such that peak force was not different from the control group across muscles and was partially effective at mitigating power loss (21.7% higher peak power in VCD-training compared with VCD-sedentary) but only in fast-type SOL fibers. These findings indicate that ovarian failure impairs dynamic contractile function-likely through a combination of lower force-generating capacity and slower shortening velocity-and that HIIT may be insufficient to completely counteract the deleterious effects of menopause at the cellular level.NEW & NOTEWORTHY We used the VCD model of menopause to investigate the effects of gradual ovarian failure on skeletal muscle contractile function and whether high-intensity interval training (HIIT) can mitigate impairments. Our findings indicate that ovarian failure impairs dynamic contractile function-likely through a combination of lower force-generating capacity and slower shortening velocity-and that HIIT may be insufficient to completely counteract the deleterious effects of menopause at the cellular level.

Mental, physical, and phychophysiological responses to FFP2/N95 face mask during HIIT in active women

Training systems based on high-intensity interval training (HIIT) have experienced great influence in recent years within the context of exercise and sport. This study aims to provide insight on whether the immediate outcomes (e.g., central and peripheral acute responses) may be intensified or attenuated when a HIIT protocol is performed using a FFP2/N95 face mask in active healthy adult women. In other words, it strives to provide new findings relative to the use of face masks as a potential performance enhancing tool. In the current study, the same training session was carried out on two occasions under different conditions (i.e., with FFP2/N95 and without FFP2/N95) in a cross-over experimental design. The following study variables were assessed before and after the HIIT in both sessions: Lactate, cortisol, alpha-amylase, selective attention, countermovement jump (CMJ), and power output. Additionally, central and peripheral Rates of Perceived Exertion (RPE) were assessed before and during the HIIT. This study makes novel contributions to prior research, showing that the use of FFP2/N95 face mask (vs. no mask) yielded higher alpha-amylase, selective attention, and peripheral RPE scores. No significant differences were found for lactate, cortisol, CMJ, and power output. Interestingly, central RPE scores were significantly lower under FFP2/N95 face mask (vs. no mask) condition. The main suggestion in light of these results is that researchers and practitioners should consider potential peripheral and central responses to training stimuli when using FFP2/N95 face masks.

High-Intensity Interval Training and Cardiometabolic Health in the General Population: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

BACKGROUND

High-intensity interval training (HIIT) remains a promising exercise mode in managing cardiometabolic health. Large-scale analyses are necessary to understand its magnitude of effect on important cardiometabolic risk factors and inform guideline recommendations.

OBJECTIVE

We aimed to perform a novel large-scale meta-analysis on the effects of HIIT on cardiometabolic health in the general population.

METHODS

PubMed (MEDLINE), the Cochrane library and Web of Science were systematically searched. Randomised controlled trials (RCTs) published between 1990 and March 2023 were eligible. Research trials reporting the effects of a HIIT intervention on at least one cardiometabolic health parameter with a non-intervention control group were considered.

RESULTS

This meta-analysis included 97 RCTs with a pooled sample size of 3399 participants. HIIT produced significant improvements in 14 clinically relevant cardiometabolic health parameters, including peak aerobic capacity (VO2) [weighted mean difference (WMD): 3.895 ml min-1 kg-1, P < 0.001), left ventricular ejection fraction (WMD: 3.505%, P < 0.001), systolic (WMD: - 3.203 mmHg, P < 0.001) and diastolic (WMD: - 2.409 mmHg, P < 0.001) blood pressure, resting heart rate (WMD: - 3.902 bpm, P < 0.001) and stroke volume (WMD: 9.516 mL, P < 0.001). Body composition also significantly improved through reductions in body mass index (WMD: - 0.565 kg m-2, P < 0.001), waist circumference (WMD: - 2.843 cm, P < 0.001) and percentage body fat (WMD: - 0.972%, P < 0.001). Furthermore, there were significant reductions in fasting insulin (WMD: - 13.684 pmol L-1, P = 0.004), high-sensitivity C-reactive protein (WMD: - 0.445 mg dL-1, P = 0.043), triglycerides (WMD: - 0.090 mmol L-1, P = 0.011) and low-density lipoprotein (WMD: - 0.063 mmol L-1, P = 0.050), concurrent to a significant increase in high-density lipoprotein (WMD: 0.036 mmol L-1, P = 0.046).

CONCLUSION

These results provide further support for HIIT in the clinical management of important cardiometabolic health risk factors, which may have implications for physical activity guideline recommendations.

Making a HIIT: Methods for quantifying intensity in high-intensity interval training in schools and validity of session rating of perceived exertion

Using the data from Making a HIIT, this paper aimed to: 1) investigate the different heart rate (HR) quantification methods reported in school-based high-intensity interval training (HIIT) studies; and 2) assess the criterion validity of session rating of perceived exertion (RPE). During an 8-week HIIT intervention, 213 students (13.1 (0.6) years; 46% female) completed 10-minute HIIT workouts during physical education lessons. In total, 1057 HR and RPE measurements were collected across 68 HIIT workouts. For aim 1, the average and peak HR across all participants and workouts were 79% (8%) and 92% (6%) of HRmax, respectively. The average RPE was 6 (2) points on a 10-point scale. An average of 51% of students in a class had an average HR ≥ 80% for each workout. The between-person variation for peak and average HR were 19% and 30% , respectively. Both average and peak HR decreased by 0.5% each week (p < 0.001). To assess aim 2, a within-participant correlation was calculated for the internal training load produced using HR and RPE data. The correlation was 0.39 (p < 0.001), which suggests utility of using RPE when HR is not a viable option.

The Effects of "Physical BEMER® Vascular Therapy" on Work Performed During Repeated Wingate Sprints

Purpose: The purpose of this study was to investigate the effects of Bio-Electro-Magnetic-Energy-Regulation (BEMER) on recovery and performance parameters in anaerobic exercise compared to active and passive recovery. Method: Fifteen recreationally active participants completed four sessions separated by 2-5 days between each session. The first visit involved one Wingate Anaerobic Test (WAnT; 30-s cycling sprint on a Monark ergometer) to familiarize participants with testing procedures. The three subsequent sessions involved four repeated WAnTs. Each sprint was followed by 4 min of either passive recovery (laying supine), active recovery (pedaling at 50 rpm at 20% of sprint workload), or BEMER recovery (laying supine on the BEMER body pad at intensity level "5-Plus."). The same recovery method was used within each testing session, and recovery method order was randomized across participants. Results: There was no difference in peak power, average power, fatigue index, or average work performed between recovery conditions. Active recovery resulted in a statistically significant decrease in ratings of pain intensity (M = -0.767, SD = 0.928) and pain unpleasantness (M = -0.608, SD = 0.915), from the first minute to the fourth minute of recovery, compared to both BEMER (Intensity: M = 0.675, SD = 0.745, Unpleasantness: M = 1.125, SD = 0.862) and passive (Intensity: M = 0.542, SD = 0.774, Unpleasantness: M = 1.018, SD = 0.872) recoveries, where pain ratings increased. Conclusions: Although no recovery method resulted in increased performance, active recovery led to a more comfortable exercise experience while still allowing comparable exercise performance.

Conventional methods to prescribe exercise intensity are ineffective for exhaustive interval training

PURPOSE

To compare methods of relative intensity prescription for their ability to normalise performance (i.e., time to exhaustion), physiological, and perceptual responses to high-intensity interval training (HIIT) between individuals.

METHODS

Sixteen male and two female cyclists (age: 38 ± 11 years, height: 177 ± 7 cm, body mass: 71.6 ± 7.9 kg, maximal oxygen uptake ([Formula: see text]O2max): 54.3 ± 8.9 ml·kg-1 min-1) initially undertook an incremental test to exhaustion, a 3 min all-out test, and a 20 min time-trial to determine prescription benchmarks. Then, four HIIT sessions (4 min on, 2 min off) were each performed to exhaustion at: the work rate associated with the gas exchange threshold ([Formula: see text]GET) plus 70% of the difference between [Formula: see text]GET and the work rate associated with [Formula: see text]O2max; 85% of the maximal work rate of the incremental test (85%[Formula: see text]max); 120% of the mean work rate of the 20 min time-trial (120%TT); and the work rate predicted to expend, in 4 min, 80% of the work capacity above critical power. Acute HIIT responses were modelled with participant as a random effect to provide estimates of inter-individual variability.

RESULTS

For all dependent variables, the magnitude of inter-individual variability was high, and confidence intervals overlapped substantially, indicating that the relative intensity normalisation methods were similarly poor. Inter-individual coefficients of variation for time to exhaustion varied from 44.2% (85%[Formula: see text]max) to 59.1% (120%TT), making it difficult to predict acute HIIT responses for an individual.

CONCLUSION

The present study suggests that the methods of intensity prescription investigated do not normalise acute responses to HIIT between individuals.

Aerobic adaptations following two iso-effort training programs: an intense continuous and a high-intensity interval

The intensity of the training stimulus and the effort exerted (regarded as an index of internal load) to complete an exercise session are driving forces for physiological processes and long-term training adaptations. This study compared the aerobic adaptations following two iso-effort, ratings of perceived exertion (RPE)-based training programs, an intense continuous (CON) and a high-intensity interval (INT). Young adults were assigned to a CON (n = 11) or an INT (n = 13) training group to perform 14 training sessions within 6 weeks. The INT group performed running bouts (9.3 ± 4.4 repetitions) at 90% of peak treadmill velocity (PTV) with bout duration equal to 1/4 of time to exhaustion at this speed (134.2 ± 27.9 s). The CONT group ran (1185.0 ± 487.6 s) at a speed corresponding to -2.5% of critical velocity (CV; 80.1% ± 3.0% of PTV). Training-sessions were executed until RPE attained 17 on the Borg scale. VO2max, PTV, CV, lactate threshold velocity (vLT), and running economy were assessed pre-, mid-, and post-training. Both CONT and INT methods increased (p < 0.05) VO2max (INT: 57.7 ± 8.1-61.41 ± 9.2; CONT: 58.1 ± 7.5-61.1 ± 6.3 mL kg-1 min-1), PTV (INT: 14.6 ± 1.8-15.7 ± 2.1; CONT: 15.0 ± 1.7-15.7 ± 1.8 km h-1), CV (INT: 11.8 ± 1.4-12.8 ± 1.8; CONT: 12.2 ± 1.6-12.9 ± 1.7 km h-1), and vLT (INT: 9.77 ± 1.1-10.8 ± 1.4; CONT: 10.4 ± 1.4-11.0 ± 1.8 km h-1) with no differences (p > 0.05) between them; running economy remained unchanged. The continuous training method, when matched for effort and executed at relatively high intensity at the upper boundaries of the heavy-intensity domain (∼80% of PTV), confers comparable aerobic adaptations to those attained after a high-intensity interval protocol following a short-term training period.