High intensity interval training exercise-induced physiological changes and their potential influence on metabolic syndrome clinical biomarkers: a meta-analysis

High-intensity interval training for cardiometabolic health in adults with metabolic syndrome: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To assess the effectiveness of high-intensity interval training (HIIT) compared with traditional moderate-intensity continuous training (MICT) and/or non-exercise control (CON) for modification of metabolic syndrome (MetS) components and other cardiometabolic health outcomes in individuals with MetS.

DESIGN

Systematic review and meta-analysis DATA SOURCES: Five databases were searched from inception to March 2024.

STUDY APPRAISAL AND SYNTHESIS

Meta-analyses of randomised controlled trials (RCTs) comparing HIIT with MICT/CON were performed for components of MetS (waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), and fasting blood glucose (BG)) and clinically relevant cardiometabolic health parameters. Subgroup moderator analyses were conducted based on the intervention duration and HIIT volume.

RESULTS

Out of 4819 studies, 23 RCTs involving 1374 participants were included (mean age: 46.2-67.0 years, 55% male). HIIT significantly improved WC (weighted mean difference (WMD) -4.12 cm, 95% CI -4.71 to -3.53), SBP (WMD -6.05 mm Hg, 95% CI -8.11 to -4.00), DBP (WMD -3.68 mm Hg, 95% CI -5.70 to -1.65), HDL-C (WMD 0.12 mmol/L, 95% CI 0.04 to 0.20), TG (WMD -0.34 mmol/L, 95% CI -0.41 to -0.27) and BG (WMD -0.35 mmol/L, 95% CI -0.54 to -0.16) compared with CON (all p<0.01). HIIT approaches demonstrated comparable effects to MICT across all parameters. Subgroup analyses suggested that HIIT protocols with low volume (ie, <15 min of high-intensity exercise per session) were not inferior to higher volume protocols for improving MetS components.

CONCLUSION

This review supports HIIT as an efficacious exercise strategy for improving cardiometabolic health in individuals with MetS. Low-volume HIIT appears to be a viable alternative to traditional forms of aerobic exercise.

Efficacy of Interval Training in Improving Body Composition and Adiposity in Apparently Healthy Adults: An Umbrella Review with Meta-Analysis

BACKGROUND

Although the efficacy of interval training for improving body composition has been summarized in an increasing number of systematic reviews in recent years, discrepancies in review findings and conclusions have been observed.

OBJECTIVE

This study aims to synthesize the available evidence on the efficacy of interval training compared with moderate-intensity continuous training (MICT) and nonexercise control (CON) in reducing body adiposity in apparently healthy adults.

METHODS

An umbrella review with meta-analysis was performed. A systematic search was conducted in seven databases (MEDLINE, EMBASE, Cochrane Database, CINAHL, Scopus, SPORTDiscus, and Web of Science) up to October 2023. Systematic reviews with meta-analyses of randomized controlled trials (RCTs) comparing interval training and MICT/CON were included. Literature selection, data extraction, and methodological quality assessment (AMSTAR-2) were conducted independently by two reviewers. Meta-analyses were performed using a random-effects model. Subgroup analyses were conducted based on the type of interval training [high-intensity interval training (HIIT) and sprint interval training (SIT)], intervention duration, body mass index, exercise modality, and volume of HIIT protocols.

RESULTS

Sixteen systematic reviews, including 79 RCTs and 2474 unique participants, met the inclusion criteria. Most systematic reviews had a critically low (n = 6) or low (n = 6) AMSTAR-2 score. Interval training demonstrated significantly greater reductions in total body fat percent (BF%) compared with MICT [weighted mean difference (WMD) of - 0.77%; 95% confidence interval (CI) - 1.12 to - 0.32%] and CON (WMD of - 1.50%; 95% CI - 2.40 to - 0.58%). Significant reductions in fat mass, visceral adipose tissue, subcutaneous abdominal fat, and android abdominal fat were also observed following interval training compared to CON. Subgroup analyses indicated that both HIIT and SIT resulted in superior BF% loss than MICT. These benefits appeared to be more prominent in individuals with overweight/obesity and longer duration interventions (≥ 12 weeks), as well as in protocols using cycling as a modality and low-volume HIIT (i.e., < 15 min of high-intensity exercise per session).

CONCLUSIONS

This novel umbrella review with large-scale meta-analysis provides an updated synthesis of evidence with implications for physical activity guideline recommendations. The findings support interval training as a viable exercise strategy for reducing adiposity in the general population.

Highlighting the effects of high-intensity interval training on the changes associated with hypertrophy, apoptosis, and histological proteins of the heart of old rats with type 2 diabetes

T2DM is known to cause disturbances in glucose homeostasis and negative changes in the heart muscle, while aging and diabetes are recognized risk factors for CVD. Given this, our study aims to investigate a method for controlling and managing CVDs induced by T2DM in elderly populations. To achieve this, we categorized 40 rats into 5 groups, including HAD (n = 8), HA (n = 8), AD (n = 8), AHT (n = 8), and ADT (n = 8). The exercise protocol consisted of eight weeks of HIIT (three sessions per week) performed at 90-95% of maximal speed. Following cardiac tissue extraction, we assessed the levels of IGF-1, PI3K, and AKT proteins using Western blot technique, and analyzed the histopathological variations of the heart tissue using H&E, Sudan Black, and Masson's trichrome tissue staining. The histological findings from our study demonstrated that T2DM had a significant impact on the development of pathological hypertrophy and fibrosis in the heart tissue of elderly individuals. However, HIIT not only effectively controlled pathological hypertrophy and fibrosis, but also induced physiological hypertrophy in the AHT and ADT groups compared to the HA and AD groups. Results from Sudan Black staining indicated that there was an increase in lipid droplet accumulation in the cytoplasm of cardiomyocytes and their nuclei in the HA and AD groups, while the accumulation of lipid droplets decreased significantly in the AHT and ADT groups. In both the AHT group and the ADT group, a single HIIT session led to a reduction in collagen fiber accumulation and fibrotic frameworks. Our research also revealed that diabetes caused a significant elevation in the levels of IGF-1, PI3K, and AKT proteins, but after eight weeks of HIIT, the levels of these proteins decreased significantly in the training groups. Overall, our findings suggest that HIIT may be a suitable non-pharmacological approach for improving histological and physiological changes in elderly individuals with T2DM. However, we recommend further research to examine the impact of HIIT training on both healthy and diseased elderly populations.

Cardiorespiratory Fitness and Performance Adaptations to High-Intensity Interval Training: Are There Differences Between Men and Women? A Systematic Review with Meta-Analyses

BACKGROUND

It is important to consider biological sex as a variable that might influence exercise adaptation in order to optimize exercise prescription for men and women.

OBJECTIVE

The aim of this study was to quantify the impact of biological sex on maximal oxygen uptake ([Formula: see text]O2max) and performance outcomes after high-intensity interval training (HIIT).

METHODS

A systematic search and review was conducted by two independent reviewers up to 8 September 2022 using MEDLINE, SPORTDiscus, and Sports Medicine & Education Index in ProQuest. Trials including healthy adults were included if they presented data for or compared male and female [Formula: see text]O2max or performance outcomes in response to HIIT. Performance outcomes included measures of exercise performance and concurrently measured physiological adaptations. Where appropriate, a random-effects, pre-post meta-analysis was undertaken. Data were sub-grouped for men and women, baseline training level, mean age, intervention type, and intervention length. Heterogeneity was assessed using Chi2, Cochran's Q, and Higgins I2 and sensitivity analyses, where required. Study quality was assessed using the Newcastle-Ottawa Scale and publication bias was assessed through visual inspection of funnel plots.

RESULTS

Thirty-three references from 28 trials were included in the review (n = 965; 462 women and 503 men). Meta-analyses included 19 studies for [Formula: see text]O2max, eight for peak power output from [Formula: see text]O2max testing (PPO), and five for threshold power (powerAT). Meta-analyses revealed similar increases in [Formula: see text]O2max in women (g = 0.57; 95% CI 0.44-0.69) and men (g = 0.57; 95% CI 0.42-0.72), and powerAT in women (g = 0.38; 95% CI 0.13-0.64) and men (g = 0.38; 95% CI 0.11-0.64). Raw mean differences for change in [Formula: see text]O2max were Δ 0.32 L·min-1 and 3.50 mL·kg-1·min-1 in men, versus Δ 0.20 L·min-1 and 3.34 mL·kg-1·min-1 for women. No significant sex differences were present for the primary analysis of any outcome. After sub-grouping, significant differences were present for PPO where the effect size was higher for well-trained women (g = 0.37) compared with well-trained men (g = 0.17), and for [Formula: see text]O2max where interventions with a duration of 4 weeks or less had significantly smaller effect sizes compared with those longer than 4 weeks (p < 0.001). Unweighted mean percentage change in [Formula: see text]O2max, PPO, and powerAT across studies was 11.16 ± 7.39%, 11.16 ± 5.99%, and 8.07 ± 6.55% for women, and 10.90 ± 5.75%, 8.22 ± 5.09%, and 7.09 ± 7.17% for men, respectively. Significant heterogeneity was present for both [Formula: see text]O2max and PPO (I2, range: 62.06-78.80%). Sub-grouping by baseline training status and intervention length decreased heterogeneity in most groups. A qualitative synthesis of other outcomes indicated similar improvements in fitness and performance for men and women with some evidence suggesting differences in the mechanisms of adaptation.

LIMITATIONS AND RISK OF BIAS

Publication bias is unlikely to have significantly influenced results for [Formula: see text]O2max or powerAT, but the meta-analysis of PPO could have benefitted from additional study data to strengthen results. The overlap in age categories and sensitivity of the analysis limits the accuracy of the results of the sub-grouping by age.

CONCLUSIONS

Findings indicated no sex-specific differences for any fitness or performance outcomes. Baseline training status and intervention length accounted for most variability in outcomes. PROSPERO registration number: CRD42021272615.

The Effects of HIIT vs. MICT and Sedentary Controls on Blood Lipid Concentrations in Nondiabetic Overweight and Obese Young Adults: A Meta-analysis

With rates of obesity and dyslipidemia rising among young adults, this meta-analysis aimed to compare the effects of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) and sedentary controls (CON) on low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), and total cholesterol (TC) in nondiabetic overweight and obese young adults to determine if HIIT or MICT is more efficacious in improving dyslipidemia. Studies included in the analysis had to be randomized controlled trials or quasi-experimental studies, comparing the effects of HIIT versus MICT or CON on at least three variables of interest: LDL, HDL, TG, and TC, in nondiabetic adults, with body mass indexes (BMIs) above 25, and average ages between 18-30. The quality of the studies was evaluated using the Physiotherapy Evidence Database (PEDro) scale. Eight studies fulfilled the selection criteria, with a mean PEDro quality score of 5.8. Compared to CON, HIIT significantly decreased the concentrations of LDL (-12.14 mg/dL, p = < 0.00001) and TC (-9.27 mg/dL, p = 0.003), without significantly affecting HDL or TG. Compared to MICT, HIIT significantly decreased the concentrations of LDL (-6.23 mg/dL, p = 0.05) and TC (-7.85 mg/dL, p = 0.02), without significantly affecting HDL or TG concentrations. HIIT is superior to MICT and CON in improving the concentrations of LDL and TC in our target population. As early management of dyslipidemia improves long-term health, we recommend clinicians consider HIIT training protocols for their nondiabetic overweight and obese young adult patients.

High-intensity interval training improves metabolic syndrome in women with breast cancer receiving Anthracyclines

INTRODUCTION

Anthracycline chemotherapy is a frequent treatment for breast cancer, whereas it can increase risk of physiologic side-effects, such as metabolic syndrome (MetS). Exercise has been used as a non-pharmacological strategy to decrease MetS. Specifically, high-intensity interval training (HIIT) has been shown to improve MetS in patients with diabetes or cardiac rehabilitation patients; however, the effects of HIIT on MetS and associated biomarkers in patients with breast cancer receiving anthracycline chemotherapy have not been previously explored. Therefore, we purposed to determine the effects of HIIT on MetS in breast cancer patients undergoing anthracycline chemotherapy.

METHODS

In total, 30 patients with breast cancer were recruited prior to initiating treatment and randomized into HIIT (n = 15) or control (n = 15). The HIIT group attended supervised cycling sessions 3 days/week for 8 weeks. MetS was assessed by waist circumference, blood pressure, fasting levels of high-density lipoprotein cholesterol (HDL-C), triglycerides, and glucose. Circulating levels of MetS-related biomarkers were also measured (total cholesterol, insulin, HbA1c, leptin, adiponectin, and c-reactive protein).

RESULTS

After 8 weeks, MetS z-score was significantly improved in the HIIT group compared with controls (-7.60, 95% CI: -9.08 to -6.13, p < 0.001). MetS variables (HDL-C, glucose, and triglycerides) and circulating levels of MetS-related biomarkers were significantly improved in the HIIT group compared with controls (p < 0.001). Non-significant differences were found in body composition outcomes at the end of the study.

CONCLUSIONS

HIIT may be an effective strategy to improve MetS in breast cancer patients undergoing anthracycline chemotherapy. Furthermore, changes in MetS were independent of changes in body composition.

Physical Fitness Recovery of Athletes Based on High-Intensity Sports Intermittent Training

Baseball itself is a new sport. In the process of training, teachers often use traditional training methods, which leads to unsatisfactory training results. High-intensity intermittent and intensive interval training can better improve the efficiency of athletes' oxidation and energy supply and ultimately play a positive role in improving athletes' performance. This paper takes the influence of high-intensity and intensive interval training on the special endurance of baseball players as the research object. A series of functional training programs are developed through adaptive training, testing, coordination training, and recovery training. Through the use of experimental means to understand the influence of high-intensity interval training and intensive interval training on the physical fitness of baseball players, the paper is aimed at providing ways and means to improve the physical fitness level of baseball players in the future. Based on the experimental test data, functional training is different from traditional training methods to make up for the lack of training research. It is to improve the competitive ability of our baseball players and promote the development of our baseball. It plays an active role in improving the specific endurance, speed, and intermittent endurance of baseball players.

High-intensity interval training for 12 weeks improves cardiovascular autonomic function but not somatosensory nerve function and structure in overweight men with type 2 diabetes

AIMS/HYPOTHESIS

It remains unclear whether and which modality of exercise training as a component of lifestyle intervention may exert favourable effects on somatosensory and autonomic nerve tests in people with type 2 diabetes.

METHODS

Cardiovascular autonomic and somatosensory nerve function as well as intraepidermal nerve fibre density (IENFD) were assessed in overweight men with type 2 diabetes (type 2 diabetes, n = 20) and male glucose-tolerant individuals (normal glucose tolerance [NGT], n = 23), comparable in age and BMI and serving as a control group, before and after a supervised high-intensity interval training (HIIT) intervention programme over 12 weeks. Study endpoints included clinical scores, nerve conduction studies, quantitative sensory testing, IENFD, heart rate variability, postural change in systolic blood pressure and spontaneous baroreflex sensitivity (BRS).

RESULTS

After 12 weeks of HIIT, resting heart rate decreased in both groups ([mean ± SD] baseline/12 weeks: NGT: 65.1 ± 8.2/60.2 ± 9.0 beats per min; type 2 diabetes: 68.8 ± 10.1/63.4 ± 7.8 beats per min), while three BRS indices increased (sequence analysis BRS: 8.82 ± 4.89/14.6 ± 11.7 ms²/mmHg; positive sequences BRS: 7.19 ± 5.43/15.4 ± 15.9 ms²/mmHg; negative sequences BRS: 12.8 ± 5.4/14.6 ± 8.7 ms²/mmHg) and postural change in systolic blood pressure decreased (-13.9 ± 11.6/-9.35 ± 9.76 mmHg) in participants with type 2 diabetes, and two heart rate variability indices increased in the NGT group (standard deviation of R-R intervals: 36.1 ± 11.8/55.3 ± 41.3 ms; coefficient of R-R interval variation: 3.84 ± 1.21/5.17 ± 3.28) (all p<0.05). In contrast, BMI, clinical scores, nerve conduction studies, quantitative sensory testing, IENFD and the prevalence rates of diabetic sensorimotor polyneuropathy and cardiovascular autonomic neuropathy remained unchanged in both groups. In the entire cohort, correlations between the changes in two BRS indices and changes in [Formula: see text] over 12 weeks of HIIT (e.g. sequence analysis BRS: r = 0.528, p=0.017) were observed.

CONCLUSIONS/INTERPRETATION

In male overweight individuals with type 2 diabetes, BRS, resting heart rate and orthostatic blood pressure regulation improved in the absence of weight loss after 12 weeks of supervised HIIT. Since no favourable effects on somatic nerve function and structure were observed, cardiovascular autonomic function appears to be more amenable to this short-term intervention, possibly due to improved cardiorespiratory fitness.

Structural Equation Modelling for Predicting the Relative Contribution of Each Component in the Metabolic Syndrome Status Change

Understanding the factor weighting in the development of metabolic syndrome (MetS) may help to predict the progression for cardiovascular and metabolic diseases. Thus, the aim of this study was to develop a confirmatory model to describe and explain the direct and indirect effect of each component in MetS status change. A total of 3581 individuals diagnosed with MetS, aged 18−102 years, were selected between January 2019 and December 2020 from a community-representative sample of Portuguese adults in a north-eastern Portuguese region to test the model’s goodness of fit. A structural equation modelling (SEM) approach and a two-way ANOVA (age × body composition) were performed to compare the relative contribution of each MetS component using joint interim statement (JIS). Waist circumference (β = 0.189−0.373, p < 0.001), fasting glucose (β = 0.168−0.199, p < 0.001) and systolic blood pressure (β = 0.140−0.162, p < 0.001) had the highest direct effect on the change in MetS status in the overall population and concerning both sexes. Moreover, diastolic blood pressure (DBP), triglycerides (TG) and high-density lipoprotein cholesterol (HDL-c) had a low or non-significant effect. Additionally, an indirect effect was reported for age and body composition involving the change in MetS status. The findings may suggest that other components with higher specificity and sensitivity should be considered to empirically validate the harmonised definition of MetS. Current research provides the first multivariate model for predicting the relative contribution of each component in the MetS status change, specifically in Portuguese adults.

Summary of the best evidence of diet and physical activity management in patients with metabolic syndrome

To evaluate and summarize the evidence of diet and physical activity management in patients with metabolic syndrome (MS). BMJ Best Practice, UpToDate, Joanna Briggs Institute (JBI) database, Agency for Healthcare Research and Quality (AHRQ) network, National Institute for Health and Clinical Excellence (NICE) network, Scottish Intercollegiate Guidelines Network (SIGN), Guidelines International Network (GIN), Medlive, Registered Nurses' Association of Ontario (RNAO) network, American Diabetes Association (ADA) network, New Zealand Guideline Group (NZGG) network, Canadian medical association clinical practice guidelines network, PubMed, EmBase, Web of Science, CINAHL, Cochrane Library, CNKI, China Science and Technology Journal Database, Wanfang Knowledge Data Service Platform and Chinese biomedical database were searched systematically to obtain guidelines, evidence summary, expert consensus, best practice information book, clinical decision-making, recommended practice, and systematic review on diet and physical activity management in patients with MS. The retrieval period is from the establishment of database to November 2021. Two researchers with evidence-based medicine background evaluated the quality and evidence level of the included literature. A total of 36 articles met the criteria, including 3 guidelines, 5 expert consensus, 1 clinical decision and 27 systematic reviews. We summarized 49 pieces of evidence related to diet and physical activity in patients with MS, involving 15 aspects, namely diet goals, diet patterns, diet time, carbohydrate intake, fat intake, fiber intake, salt intake, fruits, vegetables and grains intake, coffee intake, effects of diet, principle of physical activity, intensity, form, time of physical activity, effects of physical activity, physical activity prescription of patients with MS and cardiovascular disease, and the joint effects of diet and physical activity. Diet and physical activity management can effectively improve the health outcomes of patients with MS. Health professionals should choose and apply the best evidence with consideration of the clinical situation and patient preference.

Effects of Low-Volume, High-Intensity Interval Training Compared with Continuous Training on Regional and Global Body Composition in Adults with Metabolic Syndrome: A post hoc Analysis of a Randomized Clinical Trial

OBJECTIVE

The aim of this study was to compare the effects of low-volume, high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT) on body composition in adults with metabolic syndrome (MS).

METHODS

This is a post hoc analysis of the randomized clinical trial Intraining-MET. Sixty adults (40-60 years old) were randomized to an MICT (n = 31) or HIIT (n = 29) supervised programme 3 days/week for 12 weeks. MICT sessions were conducted for 36 min at 60% of peak oxygen consumption (VO2peak). HIIT sessions included 6 intervals at 90% VO2peak for 1 min, followed by 2 min at 50% VO2peak. Body composition was assessed with dual energy X-ray absorptiometry.

RESULTS

Body weight did not change from pre- to post-training in either MICT (78.9 ± 15.6 kg; 77.7 ± 16.5 kg, p = 0.280) or HIIT groups (76.3 ± 13.4 kg; 76.3 ± 13.7 kg, p = 0.964). Body fat percentage and fat mass (FM) decreased post-training in the MICT (-0.9%; 95% confidence interval [CI]: -0.27 to -1.47 and -0.7 kg; 95% CI: -0.12 to -1.30) and HIIT groups (-1.0%; 95% CI: -0.32 to -1.68 and -0.8 kg; 95% CI: -0.17 to -1.47). Compared to the HIIT programme, MICT significantly reduced android FM (-0.14 kg; 95% CI: -0.02 to -0.26). Lean mass (LM) increased post-training in MICT (+0.7 kg; 95% CI: 0.01-1.41) and HIIT groups (+0.9 kg; 95% CI: 0.12-1.64), but only HIIT increased the trunk LM (+0.6 kg; 95% CI: 0.06-1.20).

CONCLUSIONS

Both MICT and HIIT reduced FM without changing body weight in adults with MS. MICT had additional benefits by reducing the android FM, whereas HIIT seemed to increase LM. Given the characteristics of the post hoc analysis, further research is required to confirm these results.