High-intensity Interval Training Protocols Research Articles

High-intensity interval training mitigates the progression of periodontitis and improves behavioural aspects in rats.

To investigate the effects of high-intensity interval training (HIIT) on periodontitis (PD) progression and behavioural outcomes. Forty-eight Wistar rats were divided into four groups: non-trained (NT); non-trained with PD; HIIT with PD; and HIIT. The HIIT protocol, involving daily treadmill sessions, spanned 8 weeks, with PD induced by ligature after the 6th week. Behavioural tests were conducted to assess anxiety and memory. Post euthanasia, we evaluated the systemic inflammatory profile and oxidative stress markers in the hippocampus and amygdala. A morphological evaluation and elemental composition analysis of the mandibular alveolar bone were performed. PD exacerbated alveolar bone level, bone surface damage and alterations in calcium and phosphorus percentages on the bone surface (p < .05), while HIIT attenuated these changes (p < .05). HIIT improved systemic inflammatory markers altered by PD (tumour necrosis factor [TNF]-α, interleukin [IL]-10, TNF-α/IL-10 and IL-1β/IL-10 ratios, p < .05). PD animals exhibited lower total antioxidant capacity and levels of thiobarbituric acid reactive substances in the amygdala and hippocampus, respectively (p < .05). HIIT maintained these parameters at levels similar to those in NT animals. HIIT improved anxiety and memory outcomes altered by PD (p < .05). HIIT attenuates systemic inflammation, anxiety and memory outcomes promoted by PD.

Exercise enhances hepatic mitochondrial structure and function while preventing endoplasmic reticulum stress and metabolic dysfunction-associated steatotic liver disease in mice fed a high-fat diet

Metabolic dysfunction-associated steatotic liver disease (MASLD) has attracted increasing attention from the scientific community because of its severe but silent progression and the lack of specific treatment. Glucolipotoxicity triggers endoplasmic reticulum (ER) stress with decreased beta-oxidation and enhanced lipogenesis, promoting the onset of MASLD, whereas regular physical exercise can prevent MASLD by preserving ER and mitochondrial function. Thus, the hypothesis of this study was that high-intensity interval training (HIIT) could prevent the development of MASLD in high-fat (HF)-fed C57BL/6J mice by maintaining insulin sensitivity, preventing ER stress, and promoting beta-oxidation. Forty male C57BL/6J mice (3 months old) comprised 4 experimental groups: the control (C) diet group, the C diet + HIIT (C-HIIT) group, the HF diet group, and the HF diet + HIIT (HF-HIIT) group. HIIT sessions lasted 12 minutes and were performed 3 times weekly by trained mice. The diet and exercise protocols lasted for 10 weeks. The HIIT protocol prevented weight gain and maintained insulin sensitivity in the HF-HIIT group. A chronic HF diet increased ER stress-related gene and protein expression, but HIIT helped to maintain ER homeostasis, preserve mitochondrial ultrastructure, and maximize beta-oxidation. The increased sirtuin-1/peroxisome proliferator-activated receptor-gamma coactivator 1-alpha expression implies that HIIT enhanced mitochondrial biogenesis and yielded adequate mitochondrial dynamics. High hepatic fibronectin type III domain containing 5/irisin agreed with the antilipogenic and anti-inflammatory effects observed in the HF-HIIT group, reinforcing the antisteatotic effects of HIIT. Thus, we confirmed that practicing HIIT 3 times per week maintained insulin sensitivity, prevented ER stress, and enhanced hepatic beta-oxidation, impeding MASLD development in this mouse model even when consuming high energy intake from saturated fatty acids.

Increase of VO2 max After 8 Weeks Tuja Shuttle Run Exercise for Athletes in the 14-17 Year Age Group

The quest to enhance athletic performance through increased VO2max levels has led to exploring various training modalities, including the Tuja Shuttle Run, an innovative adaptation of High-Intensity Interval Training (HIIT). This study aims to address these gaps by examining the impact of a tailored HIIT protocol—the Tuja Shuttle Run—on the VO2max of young athletes. A total 50 athletes from KONI Kediri district and Keeltjes Soccer Academy, aged 14-17 years were recruited to be research subjects. The development of HIIT in this research was in the form of the Tuja Shuttle Run. The Tuja Shuttle Run intervention was carried out with a frequency of 3x/week for 8 weeks. Meanwhile, VO2max was gauged using the Multi-Stage 20-m Shuttle Run Fitness Test, a field test valued for its practicality despite debates on its precision relative to laboratory measures. Statistical analysis uses paired sample t-test with a significance level of 5%. Based on the results of the paired sample t-test shows that Sig. 0.000 or p ≤ 0.001, so it can be said that there was a significant difference between the pretest and posttest on the VO2max. Implementing an 8-week Tuja Shuttle Run training program can potentially enhance VO2max in athletes aged 14-17. Based on this research, further studies need to be carried out on the effect of Tuja Shuttle Run training by comparing each sport. Keyword: VO2max Enhancement, Tuja Shuttle Run, High-Intensity Interval Training, Athletic Performance, Youth Athlete Training

Influence of High-Intensity Interval Training on Neuroplasticity Markers in Post-Stroke Patients: Systematic Review.

Background: Exercise has shown beneficial effects on neuronal neuroplasticity; therefore, we want to analyze the influence of high-intensity interval training (HIIT) on neuroplasticity markers in post-stroke patients. Methods: A systematic review of RCTs including studies with stroke participants was conducted using the following databases (PubMed, LILACS, ProQuest, PEDro, Web of Science). Searches lasted till (20/11/2023). Studies that used a HIIT protocol as the main treatment or as a coadjutant treatment whose outcomes were neural plasticity markers were used and compared with other exercise protocols, controls or other kinds of treatment. Studies that included other neurological illnesses, comorbidities that interfere with stroke or patients unable to complete a HIIT protocol were excluded. HIIT protocol, methods to assess intensity, neuroplasticity markers (plasmatic and neurophysiological) and other types of assessments such as cognitive scales were extracted to make a narrative synthesis. Jadad and PEDro scales were used to assess bias. Results: Eight articles were included, one included lacunar stroke (less than 3 weeks) and the rest had chronic stroke. The results found here indicate that HIIT facilitates neuronal recovery in response to an ischemic injury. This type of training increases the plasma concentrations of lactate, BDNF and VEGF, which are neurotrophic and growth factors involved in neuroplasticity. HIIT also positively regulates other neurophysiological measurements that are directly associated with a better outcome in motor learning tasks. Conclusions: We conclude that HIIT improves post-stroke recovery by increasing neuroplasticity markers. However, a limited number of studies have been found indicating that future studies are needed that assess this effect and include the analysis of the number of intervals and their duration in order to maximize this effect.

Effects of microcurrent therapy combined with High-Intensity Interval Training on the reduction of localized abdominal adiposity: a randomized clinical trial

Background: The combination of aerobic exercise and transcutaneous microcurrent application (Microcurrent Electrical Stimulation - MES) was shown to have a positive effect on localized abdominal adiposity(LAA) reduction. However, the effect of the combination of MES and high-intensity interval training (HIIT) is still unknown. Objective: This study aimed to evaluate the effect combination of MES and HIIT on LAA reduction. Methods: 39 sedentary women with LAA, distributed in a Control Group (CG), an Exercise Group (EG), and a Microcurrent plus Exercise Group (MEG) participated in this randomized clinical trial. The CG was not submitted to intervention. The EG was submitted to a HIIT protocol (80% of Heart Rate max in a functional circuit) and MEG was submitted to abdominal transcutaneous application of MES prior to HIIT, 2x/week, during 5 weeks. The outcomes were collected by a blind evaluator and measured in three moments (before the 1st intervention, and after the 5th and 10th intervention), based on body composition parameters, anthropometric data, physical activity level (PAL), body satisfaction, quality of life (QoL), and lumbar functionality. Results: After 10 interventions, MEG showed significant improvement in skinfolds, QoL, and body satisfaction, but no significant difference compared to EG or CG. Regarding PAL, MEG differed significantly in relation to CG, but not in relation to EG. Conclusion: The combination of MES and HIIT in 10 interventions did not show satisfactory results for LAA reduction compared to HIIT, but the increase in PAL and the improvement in lumbar functionality may provide positive effects in the medium-term, although further studies are required.

Effect of High-Intensity Interval Training on the Levels of Liver Fat Transporter Proteins (LFAB and CD36) in Rats with Fatty Liver

Background: Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver condition linked to a rise in other metabolic disorders, such as type 2 diabetes and metabolic syndrome. Methods: Thirty 5-week-old rats with an average body weight of 165.4 ± 31.3 g were randomly assigned into two main groups: A sham group (10 rats) and an experimental group (20 rats, including control for fatty liver and exercise + fatty liver subgroups). The high-intensity interval training (HIIT) group underwent a HIIT protocol for 8 weeks, training 5 days per week. The data were analyzed using a dependent t-test and one-way analysis of variance (ANOVA), followed by Bonferroni's post hoc test. Results: Non-alcoholic fatty liver disease significantly increased CD36 and LFABP levels in liver tissue (P = 0.023 and P = 0.001, respectively). Eight weeks of interval training significantly decreased the levels of CD36 and LFABP in liver tissue (P = 0.019 and P = 0.007, respectively). Conclusions: The onset of non-alcoholic fatty liver elevates fatty acid transporter levels in liver tissue. However, eight weeks of HIIT markedly reduces these transporter levels.

A Review of High-Intensity Interval Training in Heart Transplant Recipients: Current Knowledge and Future Perspectives.

This review reports how exercise-based rehabilitation strategies have developed over the past decades, and it specifically focuses on the effectiveness, safety, and implementation of high-intensity interval training (HIIT). It provides an overview of the historical progression, main research findings, and considerations surrounding HIIT as the preferred exercise modality for recipients of heart transplant (HTx). The review includes a timeline of studies spanning from 1976-2023. The 2017 Cochrane systematic review on exercise-based cardiac rehabilitation in recipients of HTx serves as the main knowledge base (≥2015). Additionally, literature searches in PubMed/Medline and ClinicalTrials.gov have been performed, and all reviews and studies reporting the effects of moderate- to high-intensity exercise in recipients of HTx, published in 2015 or later have been screened. High-intensity interval training has gained prominence as an effective exercise intervention for recipients of HTx, demonstrated by an accumulation of performed studies in the past decade, although implementation in clinical practice remains limited. Early restrictions on HIIT in HTx recipients lacked evidence-based support, and recent research challenges these previous restrictions. High-intensity interval training results in greater improvements and benefits compared with moderate-intensity continuous training in the majority of studies. While HIIT is now regarded as generally suitable on a group level, individual assessment is still advised. The impact of HIIT involves reinnervation and central and peripheral adaptations to exercise, with variations in recipent responses, especially between de novo and maintenance recipients, and also between younger and older recipients. Long-term effects and mechanisms behind the HIIT effect warrant further investigation, as well as a focus on optimized HIIT protocols and exercise benefits.

The Effect of Acute Physical Fatigue on Information Processing, Pain Threshold and Muscular Performance

This study explores the multifaceted effects of acute physical fatigue on information processing, pain threshold, and muscular performance. Enrolling 28 recreational athletes, we used a high-intensity interval training (HIIT) protocol to induce fatigue and conducted pre- and post-intervention assessments. Our findings revealed significant physiological and performance adaptations following the HIIT sessions. Key observations included increased heart rate and rate of perceived exertion and an enhancement in horizontal jump performance and isometric hand strength but no significant change in cognitive processing speed. Remarkably, participants demonstrated a notable increase in pain threshold and blood lactate levels post-exercise. These results challenge traditional views of fatigue, indicating not only a physiological but also a psychological resilience to high-intensity stress. This study provides new insights into the complex interplay between physical fatigue, cognitive function, and pain perception, highlighting the comprehensive effects of HIIT on both physiological and psychological dimensions of human performance.

RESPOSTAS FISIOLÓGICAS E PSICOAFETIVAS DE ADULTOS TREINADOS EM PROTOCOLOS AGUDOS DE HIIT

ABSTRACT High Intensity Interval Training (HIIT) promotes similar adaptations and in some cases, superior to continuous aerobic training of moderate intensity, even when performed at all-out intensities. In this condition, it tends to have the greatest physiological disturbance and accumulation of metabolites compared to submaximal intensities, being one of the main factors associated with the negative response of pleasure in training. Objective: To verify the relationship between physiological and psychophysiological responses in order to repeat the training of two HIIT protocols of mesm volume load and different periods of work in trained adults of both sexes. Methods: In a randomized experiment, the sample consisted of 9 individuals aged 28±5 years, body mass 69.6±14.2 kg, height 169±0.1cm, BMI 24.1±2.3 kg/m2 and body fat percentage 20.2±7.9% practitioners of structured aerobic physical exercises for at least six months. Two different HIIT protocols were performed on an exercise bike, being (I) protocol 1:0.5, with prescribed intensity (80-90% of MAX HR), (II) protocol 1:2 with prescribed intensity (all-out) with total duration of effort of 20 minutes and interval of at least 48 hours between each session. Heart rate (HR), systemic blood pressure (SBP), subjective perception of exertion (SPE), visual analog scale (VAS), affective response (AR), fun (PACES) and intention to repeat the session were analyzed. The statistical analysis used was ANOVA with Tukey's post-hoc (p&lt;0.05). Results: The analyses of HR, SBP, VAS, PACES and SPE showed no significant difference between the training protocols. The affective response (AR and intention to repeat) showed a decline in the protocol 1:0.5, but without significance (p&gt;0.05). Conclusion: The data allow us to conclude that the 1:2 protocol caused greater physiological disturbances during exertion and presented greater positive affective response and intention to repeat the exercise session, variables that may contribute to adherence to regular physical exercise. Level of Evidence I; Therapeutic studies - Investigation of treatment results.

Spirulina Supplementation with High-Intensity Interval Training Decreases Adipokines Levels and Cardiovascular Risk Factors in Men with Obesity

Adiposity, a state characterized by excessive accumulation of body fat, is closely linked to metabolic complications and the secretion of specific adipokines. This study explores the potential of exercise and Spirulina supplementation to mitigate these complications and modulate adipokine release associated with obesity. The primary objective of this investigation was to examine the impact of a 12-week regimen of high-intensity training combined with Spirulina supplementation on adipokine concentrations and lipid profiles in male individuals with obesity (N = 44). The participants were randomly distributed into four groups, each consisting of 11 participants: a control group (CG), a supplement group (SG), a training group (TG), and a training plus supplement group (TSG). The intervention comprised a 12-week treatment involving Spirulina supplementation (6 g capsule daily), a 12-week high-intensity interval training (HIIT) protocol with three sessions per week, or a combined approach. Following the interventions, metabolic parameters, anthropometric measurements, cardiorespiratory indices, and circulating adipokines [CRP, Sema3C, TNF-α, IL-6, MCP1, IL-8] were assessed within 48 h of the before and final training session. Statistical analyses revealed significant differences across all measures among the groups (p &lt; 0.05). Notably, post hoc analyses indicated substantial disparities between the CG and the three interventional groups regarding body weight (p &lt; 0.05). The combined training and supplementation approach led to noteworthy reductions in low-density lipoprotein (LDL), total cholesterol (TC), and triglyceride (TGL) levels (all p &lt; 0.0001), coupled with an elevation in high-density lipoprotein–cholesterol (HDL-C) levels (p = 0.0001). Furthermore, adipokine levels significantly declined in the three intervention groups relative to the CG (p &lt; 0.05). The findings from this 12-week study demonstrate that Spirulina supplementation in conjunction with high-intensity interval training reduced adipokine levels, improved body weight and BMI, and enhanced lipid profiles. This investigation underscores the potential of Spirulina supplementation and high-intensity interval training as a synergistic strategy to ameliorate obesity-related complications and enhance overall cardiometabolic well-being in obese males.

High-intensity interval training ameliorates spatial and recognition memory impairments, reduces hippocampal TNF-alpha levels, and amyloid-beta peptide load in male hypothyroid rats

Thyroid hormones are critical for healthy brain functions at every stage of life. Hypothyroidism can cause severe cognitive dysfunction in patients who do not receive adequate treatment. Although thyroid hormone replacement alleviates cognitive decline in hypothyroid patients, there are studies showing that there is no complete recovery. The aim of this study was to investigate the effects of high-intensity interval training (HIIT) in hypothyroid rats on spatial and recognition memory, neuroinflammation, amyloid-beta load and compare these effects with T3 replacement. Hypothyroidism was induced and maintained by administration of 6-n-propyl-2-thiouracil (PTU) with their drinking water to 6-weeks-old male Sprague–Dawley rats for 7 weeks. The animals exercised in the treadmill according to the HIIT protocol for four weeks. T3 was injected intraperitoneally daily during the last two weeks of the study. All animals performed in the elevated plus maze test, Morris water maze test, novel object recognition test, and rotarod motor performance test in the last week of the study and then the animals were sacrificed. Amyloid beta (1−42) and TNFα levels were measured in the prefrontal cortex and hippocampus by ELISA. Anxiety-like behaviors did not significantly differ between groups. T3 replacement with or without HIIT increased motor performance in PTU-treated rats. HIIT and/or T3 replacement increased the exercise performance. HIIT and/or T3 replacement alleviated spatial and recognition memory impairments and normalized TNFα and amyloid-beta levels in the hippocampus in hypothyroid rats. In summary, regular physical exercise may have potential benefits in preserving cognitive functions in hypothyroid patients.

The Effect of High Intensity Interval Training with High-Fat Diet on Levels of Glutathione Peroxidase and Malondialdehyde in Heart Tissue of Wistar Rats

Introduction: It has been found that a high-fat diet increases the oxidative stress of the heart, which may be effective in the pathogenesis of cardiovascular diseases. The present study aimed to evaluate the effects of a high-fat diet and high-intensity interval training (HIIT) on the levels of glutathione peroxidase (GPX) and malondialdehyde (MDA) in heart tissue of rats. Method: In this experimental study, 21 male Wistar rats within the age range of 12-14 weeks were randomly assigned to three groups, including normal diet (n=7), high-fat diet (n=7), and high-fat diet+HIIT (n=7). Animals in the high-fat diet groups received a high-fat diet for 23 weeks. At the same time, the high-fat diet+HIIT group received a high-fat diet followed by performing the HIIT protocol on the treadmill three times a week in the final eight weeks. At the end of the intervention, the levels of GPX enzyme and MDA in heart tissue were assessed using the enzyme colorimetric method. The data were analyzed by one-way analysis of variance followed by post hoc Tukey test at the significant level of P&lt;0.05. Results: The results demonstrated no significant changes in GPX (P=0.14) and MDA (P=0.214) heart tissue levels in all three groups: normal diet, high-fat diet, and high-fat diet+HIIT. Conclusion: It seems that performing eight weeks of HIIT has no effect on oxidative stress markers in rats with a high-fat diet.

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.

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.

A systematic review and cluster analysis approach of 103 studies of high-intensity interval training on cardiorespiratory fitness.

This study aims to systematically review the systematic reviews and meta-analyses examining the effect of high-intensity interval training (HIIT) protocols on improving cardiorespiratory fitness (CRF) and to characterize the main patterns of HIIT modalities using clustering statistical procedures to examine their potential differences on improving CRF. Finally, we aimed to develop a comprehensive guideline for reporting HIIT protocols. A systematic review was conducted on PubMed and Web of Science from their inception to 31 October 2022 for systematic reviews and meta-analysis aimed at assessing the effect of HIIT on CRF in the entire study population. The Assessment of Multiple Systematic Reviews 2 tool was used to evaluate the risk of bias of each review. Additionally, a principal component analysis testing the data adequacy for the factor solution through the Kaiser-Meyer-Olkin procedure test was conducted. Once the number of factors was identified, in order to identify data patterns according to the main characteristics of the HIIT protocols, a two-step cluster analysis was conducted. Nineteen systematic reviews and/or meta-analyses comprising 103 studies were included. Clustering of systematic reviews and meta-analyses identified three HIIT modalities ('HIIT-normal mixed', 'HIIT-long running', and 'HIIT-short cycling') underlying the interventions across the included studies. Similar effectiveness in increasing CRF among the three HIIT modalities was observed. Subgroup analyses showed no significant differences in CRF by sex, weight status, study design, and baseline physical activity level (P > 0.05), but differences were observed by age group, and exercise intensity indicator was used in the HIIT programmes (P < 0.05). All three HIIT modalities produced significant improvements of CRF, although some modalities showed greater changes for some specific age groups or intensity indicators.

Effects of short-term supervised exercise training on liver fat in adolescents with obesity: a randomized controlled trial.

The objective of this study was to quantify the effects of a 4-week, supervised, high-intensity interval training (HIIT) on intrahepatic triglyceride content (IHTG, percentage), cardiorespiratory fitness (CRF), and cardiometabolic markers in adolescents with obesity. A total of 40 adolescents (age 13-18 y, BMI 36.7 ± 5.8 kg/m2 ) at risk for metabolic dysfunction-associated steatotic liver disease (MASLD) based on obesity and elevated Fibroscan measured controlled attenuation parameter (CAP) scores were randomized to HIIT three times a week for 4 weeks (n = 34) or observation (control; n = 6). Liver magnetic resonance imaging proton-density fat-fraction (MRI-PDFF), CAP, oral glucose tolerance test, serum alanine aminotransferase, dual-energy x-ray absorptiometry, and CRF tests were performed before and after intervention. Within- and between-group differences were compared. A total of 13 (38%) and 4 (66%) children had MASLD by MRI-PDFF (IHTG ≥ 5%) in the HIIT and control groups, respectively. The implemented HIIT protocol had no impact on CRF or IHTG (baseline 5.26%, Δ = -0.31 percentage points, 95% CI: -0.77 to 0.15; p = 0.179), but it decreased the 2-h glucose concentration (baseline 116 mg/dL, Δ = -11 mg/dL; 95% CI: -17.6 to -5.5; p < 0.001). When limiting the analysis to participants with MASLD (n = 17), HIIT decreased IHTG (baseline 8.81%, Δ = -1.05 percentage points, 95% CI: -2.08 to -0.01; p = 0.048). Between-group comparisons were not different. The implemented exercise protocol did not reduce IHTG, but it led to modest improvement in markers of cardiometabolic health.

Comparison of Ultra-Short Race Pace and High-Intensity Interval Training in Age Group Competitive Swimmers.

The aim of this study was tο examine the acute responses to an Ultra-Short Race Pace Training (USRPT) and a High-Intensity Interval Training (HIIT), both oriented for the event of 100 m freestyle. Eighteen national-level swimmers (8 boys, 10 girls) aged 13.5 ± 0.1 years, with 8.0 ± 0.5 years of experience participated in the study. All participants completed a USRPT and a HIIT protocol consisting of 2 × 10 × 25 m (USRPT1 & USRPT2) and 5 × 50 m. Significantly higher swimming velocity (SV) were achieved in USRPT compared to HIIT (p < 0.001), while significantly lower distance per stroke (DPS) and stroke index (SI) were obtained (p = 0.007 and p < 0.001). Also, significantly lower blood lactate and glucose (BL & BG) concentrations were found after USRPT (p ≤ 0.001 and p = 0.037). Heart rate (HR) and rate of perceived exertion (RPE) were significantly lower after USRPT than HIIT (p < 0.001 and p = 0.015). According to the results, an USRPT swimming set consisting of 20 × 25 m at a 100 m pace seems to induce more specific responses in kinematic characteristics, biomarkers, HR and RPE compared to a 5 × 50 m HIIT set.

High-intensity interval training improves long-term memory and increases hippocampal antioxidant activity and BDNF levels in ovariectomized Wistar rats

Menopause is the period in which women cease to produce the hormone estrogen, which can trigger physiological, cognitive, and behavioral changes. In this context, alternatives are needed that can reduce the effects provided by menopause, specifically in terms of cognitive and behavioral aspects. High-intensity interval training (HIIT) is an exercise protocol that has shown the potential to improve cognition by promoting an increase in antioxidant defenses and BDNF levels. Therefore, the aim of this study was to evaluate the effects of HIIT on behavior and hippocampal neurochemistry in ovariectomized adult rats. Four groups of rats were divided into: females without ovariectomy surgery and sedentary (SHAM-SED); females with ovariectomy surgery and sedentary (OVX-SED); females without ovariectomy surgery and trained (SHAM-HIIT); females with ovariectomy surgery and trained (OVX-HIIT). After the surgical procedure and the HIIT protocol, the animals underwent anxiety (elevated plus maze and open field) and memory (novel object recognition) tests. Corticosterone was measured in blood and BDNF levels and redox status were evaluated in the hippocampus. The OVX-SED group showed low BDNF levels and antioxidant enzymes, which may be linked to the observed memory impairments. The HIIT protocol (SHAM-HIIT and OVX-HIIT groups) increased the BDNF levels and antioxidant enzymes in the hippocampus, improving the animals' memory. However, HIIT also led to increased plasma corticosterone and anxiety-like behaviors. The ovariectomy procedure induced memory impairment probably due to reductions in hippocampal BDNF levels and redox imbalance. The HIIT protocol demonstrates promising results as an alternative to improve memory in ovariectomized rats.

Association of Preoperative High-Intensity Interval Training With Cardiorespiratory Fitness and Postoperative Outcomes Among Adults Undergoing Major Surgery

Preoperative high-intensity interval training (HIIT) is associated with improved cardiorespiratory fitness (CRF) and may improve surgical outcomes. To summarize data from studies comparing the association of preoperative HIIT vs standard hospital care with preoperative CRF and postoperative outcomes. Data sources included Medline, Embase, Cochrane Central Register of Controlled Trials Library, and Scopus databases with no language constraints, including abstracts and articles published before May 2023. The databases were searched for randomized clinical trials and prospective cohort studies with HIIT protocols in adult patients undergoing major surgery. Thirty-four of 589 screened studies met initial selection criteria. A meta-analysis was performed according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Data were extracted by multiple independent observers and pooled in a random-effects model. The primary outcome was change in CRF, as measured by either peak oxygen consumption (V̇o2 peak) or 6-Minute Walk Test (6MWT) distance. Secondary outcomes included postoperative complications; hospital length of stay (LOS); and changes in quality of life, anaerobic threshold, and peak power output. Twelve eligible studies including 832 patients were identified. Pooled results indicated several positive associations for HIIT when compared with standard care either on CRF (V̇o2 peak, 6MWT, anaerobic threshold, or peak power output) or postoperative outcomes (complications, LOS, quality of life), although there was significant heterogeneity in study results. In 8 studies including 627 patients, there was moderate-quality evidence of significant improvement in V̇o2 peak (cumulative mean difference, 2.59 mL/kg/min; 95% CI, 1.52-3.65 mL/kg/min; P < .001). In 8 studies including 770 patients, there was moderate-quality evidence of a significant reduction in complications (odds ratio, 0.44; 95% CI, 0.32-0.60; P < .001). There was no evidence that HIIT differed from standard care in hospital LOS (cumulative mean difference, -3.06 days; 95% CI, -6.41 to 0.29 days; P = .07). The analysis showed a high degree of heterogeneity in study outcomes and an overall low risk of bias. The results of this meta-analysis suggest that preoperative HIIT may be beneficial for surgical populations through the improvement of exercise capacity and reduced postoperative complications. These findings support including HIIT in prehabilitation programs before major surgery. The high degree of heterogeneity in both exercise protocols and study results supports the need for further prospective, well-designed studies.

596-P: Exercise Increases Plasma Neuronal Growth Regulator 1 (NEGR1) Concentrations in Human Subjects

Recent studies suggest that exercise-induced circulating factors are critical for the health benefits of exercise. In rodent models, we have identified NEGR1 as a cell adhesion molecule that is essential for remodeling white adipose tissue (WAT) innervation via sympathetic neurite outgrowth, and that NEGR1 is a secreted factor that may be involved inter-tissue communication. In humans, exercise training increases NEGR1 mRNA in subcutaneous WAT, but whether exercise regulates circulating NEGR1 in humans is not known. Here, we investigated the effects of a single bout of maximal exercise and exercise training on plasma NEGR1 in two different cohorts of obese subjects. Acute exercise (single bout until VO2MAX achieved) increased NEGR1 in plasma in all subjects (p&amp;lt;0.05; n=M3/F4). For the training study, obese subjects were randomized to one of three protocols: two different high intensity interval training (HIIT) protocols and one moderate continuous training (MCT) (Table), and blood samples were taken four days after the last training session. 1-HIIT and 4-HIIT similarly increased plasma NEGR1 concentrations, while there was no significant effect of MCT on NEGR1. In conclusion, we identify NEGR1 as a novel exercise-induced circulating factor in human subjects. We hypothesize that NEGR1 plays a role in tissue cross-talk mediating neuronal refinement in several tissues. Disclosure P.Nigro: None. N.P.Carbone: None. C.Bueno junior: None. M.Vamvini: None. L.Simpson: None. G.A.Hansbury: None. M.F.Hirshman: Stock/Shareholder; Abbott, AbbVie Inc., Amgen Inc., Colgate-Palmolive, Eli Lilly and Company, Medtronic. R.J.W.Middelbeek: Research Support; Novo Nordisk. L.Goodyear: None. Funding National Institutes of Health (R01DK099511, R01DK101043, K23DK114550, 5T32DK00726042, F32DK12643201); Joslin Diabetes Center (P30DK36836)