Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes

Interactive effects of low-volume interval exercise and nutrition on glycemic control

Low-volume interval training has been demonstrated to improve indices of 24 h glycemic control using continuous glucose monitoring in individuals with or at risk for metabolic diseases. Nonetheless, there are inconsistencies in the literature with respect to the effects of interval exercise on 24 h glycemia, which may partly result from different nutritional conditions and/or controls adopted across various studies. This current opinion aims to provide a concise overview of the effects of acute and chronic interval exercise on 24 h glycemic control, while also describing how nutrition can influence and modify these responses. Given the distinct impact of dietary intake on blood glucose regulation, the adoption of diverse dietary control strategies during measurement of 24 h glycemia-spanning from using the participant's habitual diet to providing standardized meals customized to individual energy requirements-may contribute to varying conclusions across studies regarding the influence of interval exercise on 24 h glycemia. In addition, nutritional manipulations surrounding exercise, including whether interval exercise commences in the fasted or fed state, the macronutrient composition of post-exercise meals, and the presence of an energy and/or carbohydrate deficit among participants, offer important context when considering the effects of interval exercise on 24 h glycemia. Additional well-controlled studies are warranted to explore the interactive effects of interval exercise and nutrition on 24 h glycemia. These efforts will assist in refining exercise and nutrition recommendations aimed at improving glycemic control.

Reduced-exertion high-intensity interval training (REHIT): a feasible approach for improving health and fitness?

In recent years, research investigating the dose-response to sprint interval training (SIT) has provided evidence that the number and duration of repetitions in a SIT session can be reduced whilst preserving the beneficial health-related adaptations. Together this research has led to the development of protocols involving minimal doses of SIT: regularly performing just two or three 20-30 s all-out sprints in a 10 min training session has been shown to elicit beneficial metabolic and cardiovascular adaptations. These SIT protocols, which we originally termed "reduced-exertion high-intensity interval training" (or REHIT), have the potential to remove many of the common barriers associated with other SIT protocols, as well as with HIT and aerobic exercise. Here, we critically review the evidence on the efficacy, feasibility and acceptability, and effectiveness of REHIT for improving health and fitness.

The effects of affect-guided interval training on pleasure, enjoyment, and autonomy: A registered report

This registered report tested the effects of a novel exercise protocol, namely affect-guided interval training, on motivationally relevant variables of remembered pleasure, forecasted pleasure, enjoyment, and autonomy. Affect-guided interval training (AIT) consisted of 60-s intervals that alternated between the highest pleasant intensity and lowest pleasant intensity for 20 min; this was intended to minimize the potential displeasure of traditional high-intensity interval training. The novel protocol was compared to self-selected exercise intensity (30 min) and high-intensity interval training (60-s intervals for 20 min). All sessions were, on average, vigorous in intensity (80-89% peak heart rate). Data indicate that the AIT session was experienced as the most pleasant, had the most pleasant slope of affect, was remembered as the most pleasant, resulted in the most positive affective forecasts, and was the most enjoyable. Both the affect-guided interval session and self-selected exercise session resulted in greater autonomy than high-intensity interval training. Several evaluative and motivationally relevant variables, including (a) remembered pleasure, (b) enjoyment, and (c) forecasted pleasure were predicted by (a) experienced pleasure, the (b) pleasure experienced at the end of exercise, and (c) the slope of pleasure experienced throughout the exercise session. Overall, this study suggests that affect-guided interval training is a feasible and positive alternative that can be included as a viable option for exercise programming.

The Best Exercise Modality and Dose to Reduce Glycosylated Hemoglobin in Patients with Type 2 Diabetes: A Systematic Review with Pairwise, Network, and Dose-Response Meta-Analyses

BACKGROUND

Persistently elevated glycosylated hemoglobin (HbA1c) is associated with a higher risk of long-term vascular complications.

OBJECTIVE

We evaluated the effect of different exercise modalities and doses on HbA1c levels in patients with type 2 diabetes.

METHODS

A systematic search for randomized controlled trials involving exercise interventions in patients with type 2 diabetes was conducted across seven electronic databases, encompassing data from their inception up to October 2023. Two independent reviewers assessed the quality of the literature. Pairwise, network, and dose-response meta-analyses using the random-effects model were conducted to analyze the effect of exercise on HbA1c levels.

RESULTS

A total of 85 randomized controlled trials with 5535 participants were included. The network meta-analysis showed that high-intensity interval training (HIIT) has the highest ranked (MD =  - 0.78% [- 8.50 mmol/mol]; 95% CrI:  - 1.04, - 0.51), followed by combined aerobic and resistance exercise (CE) (MD =  - 0.54% [- 5.90 mmol/mol]; 95% CrI: - 0.69, - 0.40), yoga (MD =  - 0.45% [- 4.92 mmol/mol]; 95% CrI: - 0.77, - 0.13), and continuous aerobic exercise (CAE) (MD =  - 0.42% [- 4.58 mmol/mol]; 95% CrI: - 0.54, - 0.30). In addition, a significant improvement in HbA1c levels can be observed when the total exercise dose reaches 840 metabolic equivalent of tasks-min/week.

CONCLUSIONS

There was low-quality evidence that HIIT, CE, yoga, and CAE may be effective treatment modalities for improving HbA1c in patients with type 2 diabetes, and there was no significant difference in efficacy. Moreover, a non-linear dose-response relationship was found for total exercise and HbA1c levels. Future research should further investigate the specific effects of different exercise doses on HbA1c levels in patients with type 2 diabetes and provide a more personalized exercise prescription.

Effects of different types of exercise intensity on improving health-related physical fitness in children and adolescents: a systematic review

A substantial body of empirical evidence reveals that physical activity is associated with a wide range of positive physical and mental health outcomes. However, an absence of comprehensive syntheses is observed concerning the varying effects of different exercise intensities on the improvement of physical health among children and adolescents. The aim of this review is to systematically investigate the effects of different exercise intensities on the physical fitness of children and adolescents, to analyses the optimal exercise intensities for improving physical fitness, and to provide a relevant theoretical basis for optimizing school physical education curricula. A systematic search strategy was used in this study in four online databases (PubMed, Scopus, EBSCO and Web of Science). Intervention studies that met the inclusion criteria underwent a thorough screening process, and their methodological quality was assessed utilizing the PEDro scale. The selected literature was systematically analyzed and evaluated through induction, summary, analysis, and evaluation. These findings indicate that high-intensity exercise training exerts significant positive effects on body composition, cardiopulmonary function and muscle fitness in children and adolescents. Therefore, we suggest that schools should focus on high-intensity sports in their physical education curriculum, which can further improve the student's PHYSICAL FITNESS.

Impaired skeletal muscle regeneration in diabetes: From cellular and molecular mechanisms to novel treatments

Diabetes represents a major public health concern with a considerable impact on human life and healthcare expenditures. It is now well established that diabetes is characterized by a severe skeletal muscle pathology that limits functional capacity and quality of life. Increasing evidence indicates that diabetes is also one of the most prevalent disorders characterized by impaired skeletal muscle regeneration, yet underlying mechanisms and therapeutic treatments remain poorly established. In this review, we describe the cellular and molecular alterations currently known to occur during skeletal muscle regeneration in people with diabetes and animal models of diabetes, including its associated comorbidities, e.g., obesity, hyperinsulinemia, and insulin resistance. We describe the role of myogenic and non-myogenic cell types on muscle regeneration in conditions with or without diabetes. Therapies for skeletal muscle regeneration and gaps in our knowledge are also discussed, while proposing future directions for the field.

The effects of extracellular vesicles and their cargo on metabolism and its adaptation to physical exercise in insulin resistance and type 2 diabetes

Lifestyle modification represents the first-line strategy for the prevention and treatment of type 2 diabetes mellitus (T2DM), which is frequently associated with obesity and characterized by defective pancreatic insulin secretion and/or insulin resistance. Exercise training is an essential component of lifestyle modification and has been shown to ameliorate insulin resistance by reducing body fat mass and by enhancing skeletal muscle mitochondrial biogenesis and insulin-independent glucose uptake. Additionally, exercising stimulates the release of exerkines such as metabolites or cytokines, but also long non-coding RNA, microRNAs, cell-free DNA (cf-DNA), and extracellular vesicles (EVs), which contribute to inter-tissue communication. There is emerging evidence that EV number and content are altered in obesity and T2DM and may be involved in several metabolic processes, specifically either worsening or improving insulin resistance. This review summarizes the current knowledge on the metabolic effects of exercise training and on the potential role of humoral factors and EV as new biomarkers for early diagnosis and tailored treatment of T2DM.

No Sex Differences in Perceptual Responses to High-Intensity Interval Training or Sprint Interval Training

ABSTRACT

Coe, LN and Astorino, TA. No sex differences in perceptual responses to high-intensity interval training or sprint interval training. J Strength Cond Res 36(6): 1025-1032, 2024-High-intensity interval training (HIIT) elicits similar and, in some cases, superior benefits vs. moderate-intensity continuous training (MICT). However, HIIT is typically more aversive than MICT because of the higher intensity and in turn, greater blood lactate accumulation (BLa). This study explored potential sex differences in perceptual responses to acute HIIT and sprint interval training. Fifteen men (age and V̇O2max = 29 ± 8 years and 39 ± 3 ml·kg-1·min-1) and 13 women (age and V̇O2max = 22 ± 2 years and 38 ± 5 ml·kg-1·min-1) who are healthy and recreationally active initially underwent testing of maximal oxygen uptake (V̇O2max) on a cycle ergometer. In randomized order on 3 separate occasions, they performed the 10 × 1-minute protocol at 85% of peak power output, 4 × 4-minute protocol at 85-95% maximal heart rate (%HRmax), or reduced exertion high intensity interval training consisting of 2 "all-out" 20-second sprints at a load equal to 5% body mass. Before and throughout each protocol, rating of perceived exertion (rating of perceived exertion [RPE] 6-20 scale), affective valence (+5 to -5 of the Feeling Scale), and BLa were assessed. Five minutes postexercise, enjoyment was measured using the Physical Activity Enjoyment scale survey. Results showed no difference in RPE (p = 0.17), affective valence (0.27), or enjoyment (p = 0.52) between men and women. Blood lactate accumulation increased in response to all protocols (p < 0.001), and men showed higher BLa than women (p = 0.03). Previous research suggests that interval exercise protocols are not interchangeable between men and women, yet our data reveal that men and women having similar V̇O2max exhibit no differences in perceptual responses to interval exercise.

Increasing aerobic exercise intensity fails to consistently improve the glycemic response in people living with prediabetes or type 2 diabetes mellitus: the INTENSITY trial

Some individuals with prediabetes or type 2 diabetes mellitus (T2DM) who engage in exercise will not experience the anticipated improvements in glycemic control, referred to as non-responders. Increasing exercise intensity may improve the proportion of individuals who become responders. The objectives were to (i) identify responders and non-responders based on changes in glycated hemoglobin (HbA1c) in individuals with prediabetes or T2DM following 16 weeks of aerobic exercise; (ii) investigate if increasing exercise intensity enhances the responders' status for individuals not previously responding favourably to the intervention. Participants (n = 40; age = 58.0 years (52.0-66.0); HbA1c = 7.0% (6.0-7.2)) engaged in a two-phase, randomized study design. During phase one, participants performed 16 weeks of treadmill-based, supervised, aerobic exercise at 4.5 metabolic equivalents (METs) for 150 min per week. Thereafter, participants were categorized as responders, non-responders, or unclear based on the 90% confidence interval above, below, or crossing a 0.3% reduction in HbA1c. For phase two, participants were randomized to a maintained intensity (4.5 METs) or increased intensity (6.0 METs) group for 12 weeks. Following phase one, two (4.1%) participants were categorized as responders, four (8.2%) as non-responders, and 43 (87.7%) as unclear. Following phase two, two from the increased intensity group and one from the maintained intensity group experienced an improvement in response categorization. There were no significant between or within group (maintained vs. increased) differences in HbA1c. For most people with prediabetes or T2DM, increasing exercise intensity by 1.5 METs does not improve response categorization.

Effect of high-intensity interval training and moderate-intensity continuous training on cardiovascular risk factors in adolescents: Systematic review and meta-analysis of randomized controlled trials

BACKGROUND

In recent years, cardiovascular diseases in adolescents have become more serious. High intensity interval training (HIIT) and moderate intensity continuous training (MICT) have been shown to improve cardiovascular diseases in adolescents. Meta-analysis was conducted to compare the effects of HIIT and MICT on cardiovascular risk factors in adolescents.

METHODS

Randomised controlled trials of HIIT and MICT for cardiovascular risk factors in adolescents up to January 2023 were searched using authoritative databases such as CNKI, Web of Science, PubMed, and EBSCO. Data analysis was performed using Review Manage 5.4 and Stata 14.0.

RESULTS

A total of 12 studies involving 468 participants, mean age 15.19±4.35, were included in the study. The findings showed that compared with MICT, HIIT reduced adolescents' body weight (SMD=-0.18, 95 %CI=-0.58, 0.21) and increased maximal oxygen uptake (SMD=0.56, 95 %CI=0.20, 0.93) and high-density lipoprotein (SMD=-0.47, 95 % CI=-1.11, 0.17), and improved systolic blood pressure (SMD=-0.35, 95 %CI=-0.78, 0.09), glucose (SMD=-1.53, 95 %CI=-2.93, -0.13), and insulin (SMD=-0.66, 95 % CI=-1.73, 0.41), p<0.05. HIIT and MICT improved BMI, fat mass, diastolic blood pressure, triglycerides, total cholesterol, and LDL, with no significant difference between these training types.

CONCLUSION

HIIT was better than MICT for improving cardiovascular health in adolescents, with better effects on body weight, BMI, fat mass, systolic blood pressure, diastolic blood pressure, maximal oxygen uptake, triglyceride, total cholesterol, LDL, HDL, glucose, and insulin levels.

Effects of high-intensity interval training and its different protocols on lipid profile and glycaemic control in type 2 diabetes: A meta-analysis

This meta-analysis of randomised clinical trials aimed to compare the effects of high-intensity interval training (HIIT) and its different protocols versus moderate-intensity continuous training (MICT) and/or control on total cholesterol, HDL, LDL, triglycerides, HbA1c levels, and fasting glucose in individuals with type 2 diabetes mellitus (T2DM). The search strategy was performed in PubMed/MEDLINE, Cochrane CENTRAL, EMBASE, Web of Science, Sport DISCUS, and PEDro, until January 2023. A total of 31 studies (1092 individuals) were included. When compared to control, HIIT decreased total cholesterol by -0.31 mmol/L (95% CI -0.49; -0.12), LDL by -0.31 mmol/L (95% CI -0.49; -0.12), triglycerides by -0.27 mmol/L (95% CI -0.33; -0.2), HbA1c by -0.75% (95% CI -0.97; -0.53), fasting glucose by -1.15 mmol/L (95% CI -1.44; -0.86), and increased HDL by 0.24 mmol/L (95% CI 0.06; 0.42). No difference was found in the comparison between HIIT versus MICT for any of the outcomes analysed, however subgroup analysis showed that a moderate-interval (>30s to < 2 min) and moderate-term (>4 to < 12 weeks) HIIT protocol reduced total cholesterol, when compared to MICT. HIIT is able to improve lipid profile and glycaemic control in T2DM individuals, and specific protocols can be recommended for improving total cholesterol levels.

Effect of high-intensity interval training on cardiorespiratory in children and adolescents with overweight or obesity: a meta-analysis of randomized controlled trials

Objective

This meta-analysis aimed to examine the effect of high-intensity interval training on cardiorespiratory fitness in children and adolescents with overweight or obesity, and to explore the optimal dose of high-intensity interval training to improve cardiorespiratory fitness in children and adolescents with overweight or obesity.

Methods

Randomized controlled trials on the effects of HIIT on cardiorespiratory fitness in children and adolescents with overweight or obesity were retrieved from six electronic databases, including PubMed, Web of Science, Cochrane Library, CNKI, Wanfang, and VIP. The quality assessment of the included studies was conducted following the revised quality evaluation method based on the PRISMA principles. Keywords for literature search mainly include high-intensity interval, cardiorespiratory fitness, overweight, obese, children, and adolescent, etc.

Results

(1) A total of 18 studies, comprising 581 participants (288 in the intervention group and 293 in the control group), were included and all of them were of moderate to high quality. (2) HIIT had a positive effect on the cardiorespiratory fitness levels of in children and adolescents with overweight or obesity (SMD = 0.91; 95% CI: 0.66, 1.15; p < 0.00001). (3) The improvement in cardiorespiratory fitness was more significant when the HIIT intervention lasted for more than 10 weeks (SMD = 1.04; 95% CI: 0.74, 1.34; p < 0.00001), was conducted 3 times per week, with 2 to 8 sets per session (SMD = 1.13; 95% CI: 0.71, 1.55; p < 0.00001), and maintained a ratio of approximately 1:1 between exercise and rest intervals (SMD = 1.11; 95% CI: 0.73, 1.50; p < 0.00001).

Conclusion and recommendations

(1) Long-term HIIT can improve cardiorespiratory fitness in children and adolescents with overweight or obesity. (2) To achieve significant improvements in cardiorespiratory fitness in a short period, children and adolescents with overweight or obesity can engage in HIIT programs lasting for more than 10 weeks, conducted 3 times per week, with 2 to 8 sets per session, and a ratio of approximately 1:1 between exercise and rest intervals.

Systematic Review Registration

Identifier: INPLASY202350033.

Feasibility and preliminary efficacy of different intensities of functional training in elderly type 2 diabetes patients with cognitive impairment: a pilot randomised controlled trial

BACKGROUND

Aging and type-2 diabetes (T2D) are the most important risk factors for cognitive impairment and Alzheimer's disease. Exercise training is an effective, safe, and practical intervention in improving glucose metabolism, physical function, and cognitive disorders. This pilot study investigated the feasibility and preliminary efficacy of high-intensity low-volume (HIFT) vs. low-intensity high-volume (LIFT) functional training in elderly T2D patients with cognitive impairment.

METHODS

Forty-eight elderly T2D patients (31 female, 17 male, age 67.5 ± 5.8 years, MMSE score 18.8 ± 2.6, FBG 209.5 ± 37.9) were randomly assigned to HIFT, LIFT and control groups. Cognitive impairment was diagnosed with MMSE ≤ 23 based Iranian society. The SDMT, CVLT-II, BVMT-R, and Stroop tests were used to evaluated processing speed, learning, memory and attention respectively. Physical fitness tests include: tandem stance and walk test; TUG; 6MWT, 10MWT; SSST; 5TSTS; and hand grip was used to evaluated static and dynamic balance, agility, walking endurance, gait speed, lower limb function and lower and upper body strength respectively. As well as, Biochemical (FBG, insulin, HOMA-IR, HbA1c) and physiological outcomes (SBP, and DBP) were assessed. The HIFT group performed six weeks of functional training (three sessions per week) with 120-125% of the lactate threshold. The LIFT group performed six weeks of functional training (five sessions per week) with a 70-75% lactate threshold. Feasibility, safety, and acceptability of exercise programs were assessed at the end of the study.

RESULT

HIFT showed a higher adherence rate (91% vs. 87.5%), safety, and acceptability compared to LIFT. MMSE and Stroop scores, 6MWT, FBG, insulin, HOMA-IR, HbA1c, SBP, and DBP significantly improved in HIFT (all, P ≤ 0.004) and LIFT (all, P ≤ 0.023). Changes in 6MWT, FBG, insulin, HOMA-IR, and HbA1c in HIFT (all, P ≤ 0.001) and LIFT (all, P ≤ 0.008) were significant compared to the control group. Changes in Stroop scores were significant only in the HIFT group compared to the control group (P = 0.013). SDMT, CVLT-II, BVMT-R, balance test, 10MWT, SSST, TUG and hang grip significantly improved only in HIFT (all, P ≤ 0.038).

CONCLUSION

HIFT vs. LIFT is a safe, feasible, and effective approach for improving some aspects of physical, biochemical, and cognitive function in elderly T2D patients with cognitive impairment. This pilot study provides initial proof-of-concept data for the design and implementation of an appropriately powered randomised controlled trial (RCT) of HIFT vs. LIFT in a larger sample of elderly T2D patients with cognitive impairment.

TRIAL REGISTRATION

Randomized controlled trial (RCT) (Iranian Registry of Clinical Trials, trial registration number: IRCT20230502058055N1. Date of registration: 11/06/2023.

Lung molecular and histological changes in type 2 diabetic rats and its improvement by high-intensity interval training

BACKGROUND

Type 2 diabetes (T2D) leads to serious respiratory problems. This study investigated the effectiveness of high-intensity interval training (HIIT) on T2D-induced lung injuries at histopathological and molecular levels.

METHODS

Forty-eight male Wistar rats were randomly allocated into control (CTL), Diabetes (Db), exercise (Ex), and Diabetes + exercise (Db + Ex) groups. T2D was induced by a high-fat diet plus (35 mg/kg) of streptozotocin (STZ) administration. Rats in Ex and Db + Ex performed HIIT for eight weeks. Tumor necrosis factor-alpha (TNFα), Interleukin 10 (IL-10), BAX, Bcl2, Lecithin, Sphingomyelin (SPM) and Surfactant protein D (SPD) levels were measured in the bronchoalveolar lavage fluid (BALF) and malondialdehyde (MDA) and total antioxidant capacity (TAC) levels were measured in lung tissue. Lung histopathological alterations were assessed by using H&E and trichrome mason staining.

RESULTS

Diabetes was significantly associated with imbalance in pro/anti-inflammatory, pro/anti-apoptosis and redox systems, and reduced the SPD, lecithin sphingomyelin and alveolar number. Performing HIIT by diabetic animals increased Bcl2 (P < 0.05) and IL10 (P < 0.01) levels as well as surfactants components and TAC (P < 0.05) but decreased fasting blood glucose (P < 0.001), TNFα (P < 0.05), BAX (P < 0.05) and BAX/Bcl2 (P < 0.001) levels as well as MDA (P < 0.01) and MDA/TAC (P < 0.01) compared to the diabetic group. Furthermore, lung injury and fibrosis scores were increased by T2D and recovered in presence of HIIT.

CONCLUSION

These findings suggested that the attenuating effect of HIIT on diabetic lung injury mediated by reducing blood sugar, inflammation, oxidative stress, and apoptosis as well as improving pulmonary surfactants components.

Sex differences in hemodynamic response to high-intensity interval exercise

Sex differences in the cardiorespiratory and hemodynamic response to exercise exist due to differences in heart size, blood volume, and hemoglobin mass, eliciting higher maximal oxygen uptake (VO2max ) in men versus women. Data are equivocal whether sex differences in training responsiveness occur. This study investigated potential sex differences in the hemodynamic response (stroke volume (SV) and cardiac output (CO)) to high-intensity interval exercise (HIIE). Habitually active men (n = 15) and women (n = 13) underwent VO2max testing, followed by three HIIE sessions consisting of the 4 × 4, 10 × 1, and reduced exertion high-intensity training (REHIT), whose order was randomized. During exercise, oxygen uptake (VO2 ) and hemodynamic responses were determined. Results showed no sex difference in peak relative VO2 (p = 0.263), CO (p = 0.277), or SV (p = 0.116), although absolute values were higher in men (p < 0.05). Peak absolute (127.3 ± 20.6 vs. 115.2 ± 16.6 mL/beat, p = 0.004, d = 0.66) and relative SV (111.0 ± 15.5 vs. 100.7 ± 11.1% max, p = 0.005, d = 0.78) were higher with REHIT versus 4 × 4. No sex differences in mean relative VO2 , CO, or SV occurred (p > 0.05). Data showed lower mean VO2 during REHIT versus 4 × 4 (59.3 ± 6.8 vs. 65.8 ± 5.8 %VO2max , p < 0.001, d = 1.05) and 10 × 1 (59.3 ± 6.8 vs. 69.1 ± 7.4 %VO2max , p < 0.001, d = 1.4). Mean CO was lower in REHIT than 10 × 1 (79.8 ± 8.6 vs. 84.0 ± 7.4% max, p = 0.012, d = 0.53). Previously reported differences in VO2max response to HIIE may not be due to unique hemodynamic responses.

Mitochondria as a target for exercise-mitigated type 2 diabetes

Type 2 diabetes mellitus (T2DM) is one of most common metabolic diseases and continues to be a leading cause of death worldwide. Although great efforts have been made to elucidate the pathogenesis of diabetes, the underlying mechanism still remains unclear. Notably, overwhelming evidence has demonstrated that mitochondria are tightly correlated with the development of T2DM, and the defects of mitochondrial function in peripheral insulin-responsive tissues, such as skeletal muscle, liver and adipose tissue, are crucial drivers of T2DM. Furthermore, exercise training is considered as an effective stimulus for improving insulin sensitivity and hence is regarded as the best strategy to prevent and treat T2DM. Although the precise mechanisms by which exercise alleviates T2DM are not fully understood, mitochondria may be critical for the beneficial effects of exercise.

Cardiorespiratory Responses to an Acute Bout of High Intensity Interval Training and Moderate Intensity Continuous Training on a Recumbent Handcycle in People With Spinal Cord Injury: A Within-Subject Design

Objectives

To compare acute cardiorespiratory responses during high intensity interval training (HIIT) and moderate intensity continuous training (MICT) on a recumbent handcycle in persons with spinal cord injury (PwSCI).

Methods

Eleven males and nine females with chronic SCI (T3 - L5), aged 23 (9) years, participated in this within-subject design. Based off peak power outputs from an incremental test to exhaustion, participants engaged in a HIIT and MICT session at matched workloads on a recumbent handcycle. Workloads (Joules), time, oxygen uptake (VO2), metabolic equivalent of task (MET), heart rate (HR), and energy expenditure (kcal) were recorded during HIIT and MICT.

Results

Total workload was similar across HIIT (87820 ± 24021 Joules) and MICT sessions (89044 ± 23696 Joules; p > .05). HIIT (20.00 [.03] minutes) was shorter in duration than MICT (23.20 [2.56]; p < .01). Average VO2 (20.96 ± 4.84 vs. 129.38 ± 19.13 mL/kg/min O2), MET (7.54 ± 2.00 vs. 6.21 ± 1.25), and HR (146.26 ± 13.80 vs. 129.38 ± 19.13 beats per minute) responses were significantly greater during HIIT than MICT (p < .01). Participants burned significantly more kilocalories during HIIT (128.08 ± 35.65) than MICT (118.93 ± 29.58; p < .01) and at a faster rate (6.40 ± 1.78 [HIIT] vs. 5.09 ± 1.14 [MICT] kcal/min; p < .01).

Conclusion

HIIT elicits greater increases in oxygen uptake and HR than MICT in PwSCI. In significantly less time, HIIT also burned more calories than MICT.

A Narrative Literature Review on the Role of Exercise Training in Managing Type 1 and Type 2 Diabetes Mellitus

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia associated with impaired carbohydrate, lipid, and protein metabolism, with concomitant absence of insulin secretion or reduced sensitivity to its metabolic effects. Patients with diabetes mellitus have a 30% more risk of developing heart failure and cardiovascular disease compared to healthy people. Heart and cardiovascular problems are the first cause of death worldwide and the main complications which lead to high healthcare costs. Such complications can be delayed or avoided by taking prescribed medications in conjunction with a healthy lifestyle (i.e., diet and physical activity). The American College of Sports Medicine and the American Diabetes Association recommend that diabetic people reduce total sedentary time by incorporating physical activity into their weekly routine. This narrative literature review aims to summarize and present the main guidelines, pre-exercise cardiovascular screening recommendations, and considerations for patients with diabetes and comorbidities who are planning to participate in physical activity programs.

Physical Exercise Methods and Their Effects on Glycemic Control and Body Composition in Adults with Type 2 Diabetes Mellitus (T2DM): A Systematic Review

The prevalence of T2DM represents a challenge for health agencies due to its high risk of morbidity and mortality. Physical Activity (PA) is one of the fundamental pillars for the treatment of T2DM, so Physical Exercise (PE) programs have been applied to research their effectiveness. The objective of the study was to analyze the effects of PE methods on glycemic control and body composition of adults with T2DM. A systematic review without meta-analysis was performed, using the PubMed database. Quasi-experimental and pure experimental clinical trials were included, which were available free of charge and were published during 2010-2020. In the results, 589 articles were found and 25 passed the inclusion criteria. These were classified and analyzed according to the methods identified (AE, IE, RE, COM, and others), duration and variable(s) studied. It is concluded that PE is effective for glycemic control and body composition in adults with T2DM using different methods (AE, IE, RE, COM, and others), both in the short and long term. Adequate organization of PE components such as frequency, duration, volume, and intensity, is essential.

Benefits beyond cardiometabolic health: the potential of frequent high intensity 'exercise snacks' to improve outcomes for those living with and beyond cancer

High intensity interval training (HIIT) has been shown to consistently elicit rapid and significant adaptations in a number of physiological systems, across many different healthy and clinical populations. In addition, there is increasing interest in how some acute, yet transient responses to high intensity exercise potentially reduce the risks of particular diseases. Recent work has shown that discrete, brief bouts of high intensity exercise (termed 'exercise snacks') can improve glucose control and vascular health and thus counter the negative cardiometabolic consequences of prolonged, uninterrupted periods of inactivity. In this brief review, we advance the case, using evidence available from pre-clinical studies in the exercise oncology literature, that brief, frequently completed bouts of high intensity exercise embedded within an individual's overall daily and weekly physical activity schedule, may transiently impact the tumour microenvironment and improve the health outcomes for those who have been diagnosed and treated for cancer.

Role of diet and exercise in aging, Alzheimer's disease, and other chronic diseases

Alzheimer's disease (AD) is a progressive neurodegenerative disease, characterized by memory loss and multiple cognitive impairments. Genetic mutations cause a small proportion (1-2%) of early-onset AD, with mutations in amyloid precursor protein (APP), presenilin 1 (PS1) and presenilin 2 (PS2). Major contributing factors of late-onset AD are ApoE4 genotype, traumatic brain injury, diabetes, obesity, hypertension, cardiovascular conditions, in addition to lifestyle factors, such as unhealthy diet and lack of physical exercise. Disease progression can be delayed and/or prevented to a greater extent by adopting healthy lifestyle with balanced and antioxidant enriched diet and daily exercise. The interaction and interplay of diet, exercise, age, and pharmacological interventions holds a crucial role in the progression, pathogenesis and management of AD and its comorbidities, including diabetes, obesity, hypertension and cardiovascular conditions. Antioxidant enriched diet contributes to brain health, glucose control, weight management, and cardiovascular well-being. Regular exercise removes toxins including free radicals and enhances insulin sensitivity, and supports cardiovascular function. In the current article, we discussed, the role of diet, and exercise in aging, AD and other conditions including diabetes, obesity, hypertension, cardiovascular conditions. This article also highlights the impact of medication, socioeconomic and lifestyle factors, and pharmacological interventions. These aspects were discussed in different races and ethnic groups in Texas, and the US.

Both moderate- and high-intensity exercise training increase intramyocellular lipid droplet abundance and modify myocellular distribution in adults with obesity

Exercise training modifies lipid metabolism in skeletal muscle, but the effect of exercise training on intramyocellular lipid droplet (LD) abundance, size, and intracellular distribution in adults with obesity remains elusive. This study compared high-intensity interval training (HIIT) with more conventional moderate-intensity continuous training (MICT) on intramyocellular lipid content, as well as LD characteristics (size and number) and abundance within the intramyofibrillar (IMF) and subsarcolemmal (SS) regions of type I and type II skeletal muscle fibers in adults with obesity. Thirty-six adults with obesity [body mass index (BMI) = 33 ± 3 kg/m2] completed 12 wk (4 days/wk) of either HIIT (10 × 1 min, 90% HRmax + 1-min active recovery; n = 19) or MICT (45-min steady-state exercise, 70% HRmax; n = 17), while on a weight-maintaining diet throughout training. Skeletal muscle biopsies were collected from the vastus lateralis before and after training, and intramyocellular lipid content and intracellular LD distribution were measured by immunofluorescence microscopy. Both MICT and HIIT increased total intramyocellular lipid content by more than 50% (P < 0.01), which was attributed to a greater LD number per µm2 in the IMF region of both type I and type II muscle fibers (P < 0.01). Our findings also suggest that LD lipophagy (autophagy-mediated LD degradation) may be transiently upregulated the day after the last exercise training session (P < 0.02 for both MICT and HIIT). In summary, exercise programs for adults with obesity involving either MICT or HIIT increased skeletal muscle LD abundance via a greater number of LDs in the IMF region of the myocyte, thereby providing more lipid in close proximity to the site of energy production during exercise.NEW & NOTEWORTHY In this study, 12 wk of either moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) enhanced skeletal muscle lipid abundance by increasing lipid droplet number within the intramyofibrillar (IMF) region of muscle. Because the IMF associates with high energy production during muscle contraction, this adaptation may enhance lipid oxidation during exercise. Despite differences in training intensity and energy expenditure between MICT and HIIT, their effects on muscle lipid abundance and metabolism were remarkably similar.

Moderate Effects of Hypoxic Training at Low and Supramaximal Intensities on Skeletal Muscle Metabolic Gene Expression in Mice

The muscle molecular adaptations to different exercise intensities in combination with hypoxia are not well understood. This study investigated the effect of low- and supramaximal-intensity hypoxic training on muscle metabolic gene expression in mice. C57BL/6 mice were divided into two groups: sedentary and training. Training consisted of 4 weeks at low or supramaximal intensity, either in normoxia or hypoxia (FiO2 = 0.13). The expression levels of genes involved in the hypoxia signaling pathway (Hif1a and Vegfa), the metabolism of glucose (Gys1, Glut4, Hk2, Pfk, and Pkm1), lactate (Ldha, Mct1, Mct4, Pdh, and Pdk4) and lipid (Cd36, Fabp3, Ucp2, Hsl, and Mcad), and mitochondrial energy metabolism and biogenesis (mtNd1, mtNd6, CytC, CytB, Pgc1a, Pgc1β, Nrf1, Tfam, and Cs) were determined in the gastrocnemius muscle. No physical performance improvement was observed between groups. In normoxia, supramaximal intensity training caused upregulation of major genes involved in the transport of glucose and lactate, fatty acid oxidation, and mitochondrial biogenesis, while low intensity training had a minor effect. The exposure to hypoxia changed the expression of some genes in the sedentary mice but had a moderate effect in trained mice compared to respective normoxic mice. In hypoxic groups, low-intensity training increased the mRNA levels of Mcad and Cs, while supramaximal intensity training decreased the mRNA levels of Mct1 and Mct4. The results indicate that hypoxic training, regardless of exercise intensity, has a moderate effect on muscle metabolic gene expression in healthy mice.

The Effects of Exercise on Synaptic Plasticity in Individuals With Mild Cognitive Impairment: Protocol for a Pilot Intervention Study

BACKGROUND

Mild cognitive impairment (MCI) is a syndrome preceding more severe impairment characterized by dementia. MCI affects an estimated 15% to 20% of people older than 65 years. Nonpharmacological interventions including exercise are recommended as part of overall MCI management based on the positive effects of exercise on cognitive performance. Interval training involves brief intermittent bouts of exercise interspersed with short recovery periods. This type of exercise promotes cognitive improvement and can be performed in individuals with MCI. Synaptic plasticity can be assessed in vivo by the neurophysiological response to repetitive transcranial magnetic stimulation (rTMS). A method to assess synaptic plasticity uses an intermittent theta burst stimulation (iTBS), which is a patterned form of rTMS. Individuals with MCI have decreased responses to iTBS, reflecting reduced synaptic plasticity. It is unknown whether interval training causes changes in synaptic plasticity in individuals living with MCI.

OBJECTIVE

This research will determine whether interval training performed using a cycle ergometer enhances synaptic plasticity in individuals with MCI. The three aims are to (1) quantify synaptic plasticity after interval training performed at a self-determined intensity in individuals with MCI; (2) determine whether changes in synaptic plasticity correlate with changes in serum brain-derived neurotrophic factor, osteocalcin, and cognition; and (3) assess participant compliance to the exercise schedule.

METHODS

24 individuals diagnosed with MCI will be recruited for assignment to 1 of the 2 equally sized groups: exercise and no exercise. The exercise group will perform exercise 3 times per week for 4 weeks. Synaptic plasticity will be measured before and following the 4-week intervention. At these time points, synaptic plasticity will be measured as the response to single-pulse TMS, reflected as the percent change in the average amplitude of 20 motor-evoked potentials before and after an iTBS rTMS protocol, which is used to induce synaptic plasticity. In addition, individuals will complete a battery of cognitive assessments and provide a blood sample from the antecubital vein to determine serum brain-derived neurotrophic factor and osteocalcin.

RESULTS

The study began in September 2023.

CONCLUSIONS

The proposed research is the first to assess whether synaptic plasticity is enhanced after exercise training in individuals with MCI. If exercise does indeed modify synaptic plasticity, this will create a new avenue by which we can study and manipulate neural plasticity in these individuals.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05663918; https://clinicaltrials.gov/study/NCT05663918.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/50030.

Randomized Controlled Trial of Moderate- and High-Intensity Exercise Training in Patients With Hypertrophic Cardiomyopathy: Effects on Fitness and Cardiovascular Response to Exercise

Background Moderate intensity exercise training (MIT) is safe and effective for patients with hypertrophic cardiomyopathy, yet the efficacy of high intensity training (HIT) remains unknown. This study aimed to compare the efficacy of HIT compared with MIT in patients with hypertrophic cardiomyopathy. Methods and Results Patients with hypertrophic cardiomyopathy were randomized to either 5 months of MIT, or 1 month of MIT followed by 4 months of progressive HIT. Peak oxygen uptake (V˙O2; Douglas bags), cardiac output (acetylene rebreathing), and arteriovenous oxygen difference (Fick equation) were measured before and after training. Left ventricular outflow gradient and volumes were measured by echocardiography. Fifteen patients completed training (MIT, n=8, age 52±7 years; HIT, n=7, age 42±8 years). Both HIT and MIT improved peak V˙O2 by 1.3 mL/kg per min (P=0.009). HIT (+1.5 mL/kg per min) had a slightly greater effect than MIT (+1.1 mL/kg per min) but with no statistical difference (group×exercise P=0.628). A greater augmentation of arteriovenous oxygen difference occurred with exercise (Δ1.6 mL/100 mL P=0.005). HIT increased left ventricular end-diastolic volume (+17 mL, group×exercise P=0.015) compared with MIT. No serious arrhythmias or adverse cardiac events occurred. Conclusions This randomized trial of exercise training in patients with hypertrophic cardiomyopathy demonstrated that both HIT and MIT improved fitness without clear superiority of either. Although the study was underpowered for safety outcomes, no serious adverse events occurred. Exercise training resulted in salutary peripheral and cardiac adaptations. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03335332.

Differential Effects of Very-Low-Volume Exercise Modalities on Telomere Length, Inflammation, and Cardiometabolic Health in Obese Metabolic Syndrome Patients: A Subanalysis from Two Randomized Controlled Trials

Oxidative stress (OS) and inflammation are features of metabolic syndrome (MetS) that can contribute to the shortening of telomere length (TL), a marker of cellular ageing. Research indicates that exercise can positively influence MetS-associated conditions and TL. However, the effects of low-volume exercise types on TL are still unknown. We investigated the impact of very-low-volume high-intensity interval training (LV-HIIT), one-set resistance training (1-RT), and whole-body electromyostimulation (WB-EMS) on TL, inflammation, and cardiometabolic indices in 167 MetS patients. Data were derived from two randomized controlled trials where patients were allocated to an exercise group (2 sessions/week, for 12 weeks) or a control group. All groups received standard-care nutritional weight loss counselling. TL was determined as the T/S ratio (telomere to single-copy gene amount). All groups significantly reduced body weight (p < 0.05), but the T/S-ratio (p < 0.001) only increased with LV-HIIT. OS-related inflammatory markers (C-reactive protein, interleukin-6, and lipopolysaccharide-binding protein) only decreased (p < 0.05) following LV-HIIT. The MetS severity z-score improved with LV-HIIT (p < 0.001) and 1-RT (p = 0.014) but not with WB-EMS. In conclusion, very-low-volume exercise modalities have differential effects on telomeres, inflammation, and cardiometabolic health. Only LV-HIIT but not strength-based low-volume exercise increased TL in MetS patients, presumably due to superior effects on OS-related inflammatory markers.

Winter Holidays and Their Impact on Eating Behavior-A Systematic Review

(1) Background: There has been a growing interest in understanding the causes of obesity and developing effective prevention strategies. Lifestyle change programs are often considered the gold standard for weight reduction, and they can help individuals with obesity achieve an annual weight loss of around 8-10%. The aim of this review was to evaluate the effect of food during the winter holidays. This knowledge will serve as a valuable foundation for the development of targeted interventions and prevention programs. (2) Methods: We conducted a systematic search of the literature via one database (PubMed). The search was limited to studies published in English in the last 10 years, with adult participants, but without specifying limits regarding the study design. We excluded articles that addressed intermittent fasting diets or weight loss intervention methods during the holidays through various diets. (3) In separate sections, we analyzed the psychological causes of gaining weight during the winter holidays, behavioral patterns, prevention strategies and the nutritional composition of the different types of food served during the festive period. Results: Using the combination of the terms "holiday and obesity", "holiday and weight gain", "festive season and obesity", and "festive season and weight gain" we obtained 216 results involving the addressed topic. Thus, only ten articles remained after screening, with a total of 4627 participants. Most participants experienced weight fluctuations during the study period, particularly during holidays. One concerning observation was that most of the weight gained during these periods was maintained even after the end of the studies, especially in those with obesity. A supervised exercise program and a controlled diet at work over the Christmas period are effective strategies for avoiding weight gain and its deleterious effects in people with metabolic syndrome or weight problems. (4) In addition, attention must be focused on the psycho-social factors during the holidays because for some people it is a stressful period and can cause a much higher caloric consumption. The simplest method to approach during the holidays is to implement small tips and tricks during this period that will prevent individuals from gaining extra pounds. Conclusions: It is essential to acknowledge that obesity is a multifaceted condition that requires a comprehensive and multidisciplinary approach to address its underlying factors and provide ongoing assistance to individuals in their weight-management endeavors. Even the most effective short-term interventions are likely to produce continued positive outcomes with persistent intervention and support.

Maternal and Fetal Cardiovascular Responses to Acute High-Intensity Interval and Moderate-Intensity Continuous Training Exercise During Pregnancy: A Randomized Crossover Trial

OBJECTIVE

We aimed to compare maternal and fetal cardiovascular responses to an acute bout of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) during pregnancy.

METHODS

Fifteen women with a singleton pregnancy (27.3 ± 3.5 weeks of gestation, 33 ± 4 years of age) were recruited. Following a peak fitness test, participants engaged in a session of HIIT (10 × 1-min intervals ≥ 90% maximum heart rate [HRmax]) interspersed with 1 min of active recovery) and MICT (30 min at 64-76% HRmax) 48 h apart in random order. Maternal HR, blood pressure, middle (MCAv), and posterior cerebral artery blood velocity (PCAv), as well as respiratory measures were monitored continuously throughout HIIT/MICT. Fetal heart rate, as well as umbilical systolic/diastolic (S/D) ratio, resistive index (RI), and pulsatility index (PI) were assessed immediately before and after exercise.

RESULTS

Average maternal heart rate was higher for HIIT (82 ± 5% HRmax) compared with MICT (74 ± 4% HRmax; p < 0.001). During the HIIT session, participants achieved a peak heart rate of 96 ± 5% HRmax (range of 87-105% HRmax). Maternal cerebral blood velocities increased with exercise but was not different between HIIT and MICT for MCAv (p = 0.340) and PCAv (p = 0.142). Fetal heart rate increased during exercise (p = 0.244) but was not different between sessions (HIIT: Δ + 14 ± 7 bpm; MICT: Δ + 10 ± 10 bpm). Metrics of umbilical blood flow decreased with exercise and were not different between exercise sessions (PI: p = 0.707; S/D ratio: p = 0.671; RI: p = 0.792). Fetal bradycardia was not observed, and S/D ratio, RI, and PI remained within normal ranges both before and immediately after all exercise sessions.

CONCLUSIONS

An acute bout of HIIT exercise consisting of repeated 1-min near-maximal to maximal exertions, as well as MICT exercise is well tolerated by both mother and fetus.

CLINICAL TRIAL REGISTRATION

NCT05369247.

High-Intensity Interval Training Improves Glycemic Control, Cellular Apoptosis, and Oxidative Stress of Type 2 Diabetic Patients

Background and Objectives: Physical exercise is an important therapeutic modality for treating and managing diabetes. High-intensity interval training (HIIT) is considered one of the best non-drug strategies for preventing and treating type 2 diabetes mellitus (T2DM) by improving mitochondrial biogenesis and function. This study aimed to determine the effects of 12 weeks of HIIT training on the expression of tumor suppressor protein-p53, mitochondrial cytochrome c oxidase (COX), and oxidative stress in patients with T2DM. Methods: A total of thirty male sedentary patients aged (45-60 years) were diagnosed with established T2DM for more than five years. Twenty healthy volunteers, age- and sex-matched, were included in this study. Both patients and control subjects participated in the HIIT program for 12 weeks. Glycemic control variables including p53 (U/mL), COX (ng/mL), total antioxidant capacity (TAC, nmole/µL), 8-hydroxy-2'-deoxyguanosine (8-OHdG, ng/mL), as well as genomic and mitochondrial DNA content were measured in both the serum and muscle tissues of control and patient groups following exercise training. Results: There were significant improvements in fasting glucose levels. HbA1c (%), HOMA-IR (mUmmol/L2), fasting insulin (µU/mL), and C-peptide (ng/mL) were reported in T2DM and healthy controls. A significant decrease was also observed in p53 protein levels. COX, 8-OhdG, and an increase in the level of TAC were reported in T2DM following 12 weeks of HIIT exercise. Before and after exercise, p53; COX, mt-DNA content, TAC, and 8-OhdG showed an association with diabetic control parameters such as fasting glucose (FG), glycated hemoglobin (HbA1C, %), C-peptide, fasting insulin (FI), and homeostatic model assessment for insulin resistance (HOMA-IR) in patients with T2DM. These findings support the positive impact of HIIT exercise in improving regulation of mitochondrial biogenesis and subsequent control of diabetes through anti-apoptotic and anti-oxidative pathways. Conclusions: A 12-week HIIT program significantly improves diabetes by reducing insulin resistance; regulating mitochondrial biogenesis; and decreasing oxidative stress capacity among patients and healthy controls. Also; p53 protein expression; COX; 8-OhdG; and TAC and mt-DNA content were shown to be associated with T2DM before and after exercise training.

Propulsion kinetics of recumbent handcycling during high and moderate intensity exercise

People with spinal cord injuries (PwSCI) are at high risk of developing cardiovascular disease (CVD). While regular exercise can reduce risk of CVD, PwSCI face various barriers to exercise, including high rates of upper limb injuries, especially in the shoulder. Handcycling high intensity interval training (HIIT), which consists of periods of high intensity exercise followed by rest, is a potential exercise solution, but the musculoskeletal safety of HIIT is still unknown. In this study, we characterized three-dimensional continuous applied forces at the handle during handcycling HIIT and moderate intensity continuous training (MICT). These applied forces can give an early indication of joint loading, and therefore injury risk, at the shoulder. In all three directions (tangential, radial, and lateral), the maximum applied forces during HIIT were larger than those in MICT at all timepoints, which may indicate higher contact forces and loads on the shoulder during HIIT compared to MICT. The tangential and radial forces peaked twice in a propulsion cycle, while the lateral forces peaked once. Throughout the exercises, the location of tangential peak 2 and radial peak 1 was later in HIIT compared to MICT. This difference in maximum force location could indicate either altered kinematics or muscular fatigue at the end of the exercise protocol. These changes in kinematics should be more closely examined using motion capture or other modeling techniques. If we combine this kinetic data with kinematic data during propulsion, we can create musculoskeletal models that more accurately predict contact forces and injury risk during handcycling HIIT in PwSCI.

Exercise, exerkines, and cardiometabolic health: from individual players to a team sport

Exercise confers numerous salutary effects that extend beyond individual organ systems to provide systemic health benefits. Here, we discuss the role of exercise in cardiovascular health. We summarize major findings from human exercise studies in cardiometabolic disease. We next describe our current understanding of cardiac-specific substrate metabolism that occurs with acute exercise and in response to exercise training. We subsequently focus on exercise-stimulated circulating biochemicals ("exerkines") as a paradigm for understanding the global health circuitry of exercise, and discuss important concepts in this emerging field before highlighting exerkines relevant in cardiovascular health and disease. Finally, this Review identifies gaps that remain in the field of exercise science and opportunities that exist to translate biologic insights into human health improvement.

Effects of high-intensity interval training on trajectories of gas-exchange measures and blood lactate concentrations during cardiopulmonary exercise tests in cardiac rehabilitation-A randomized controlled trial

BACKGROUND

The optimal allocation of training time to different intensities in cardiac rehabilitation is still under debate. The objective of this study was to explore whether in a 12-week cardiac rehabilitation program, replacement of two of four usual continuous endurance training (CET) sessions per week with energy expenditure-matched high-intensity interval training (HIIT) affects the trajectories of cardiopulmonary exercise test (CPET) variables such as ventilatory equivalents for O₂ (EqO₂ ) and CO₂ (EqCO₂ ), and blood lactate (BLa) during CPET.

METHODS

Eighty-two male patients undergoing outpatient cardiac rehabilitation after an acute coronary syndrome were randomized to CET (age [mean ± SD] 61.7 ± 9.8 years, body mass index [BMI] 28.1 ± 3.4) or HIIT+CET (60.0 ± 9.4 years, BMI 28.5 ± 3.5). CPET was performed at baseline, after 6 and after 12 weeks. HIIT consisted of ten 60-s bouts of cycling at an intensity of 100% of the maximal power output (P_max ) achieved in an incremental test to exhaustion, interspersed with 60 s at 20% P_max . CET was performed at 60% P_max with equal duration. Training intensities were adjusted after 6 weeks to account for the training-induced improvement in cardiorespiratory fitness. The entire functions defining the relationship between EqO₂ , EqCO₂ , and BLa, with power output were modeled using linear mixed models to assess how these trajectories are affected by HIIT.

RESULTS

After 6 and 12 weeks, P_max increased to 112.9% and 117.5% of baseline after CET, and to 113.9% and 124.7% after HIIT+CET (means). Twelve weeks of HIIT+CET elicited greater reductions of EqO₂ and EqCO₂ than CET alone (p < 0.0001 each) in a range above 100% baseline P_max . Specifically, at 100% of baseline P_max , least squares arithmetic mean EqO₂ values of CET and HIIT+CET patients were 36.2 versus 33.5. At 115% and 130% of baseline P_max , EqO₂ values were 41.2 versus 37.1 and 47.2 versus 41.7. Similarly, corresponding EqCO₂ values of CET and HIIT+CET patients were 32.4 versus 31.0, 34.3 versus 32.2, and 37.0 versus 34.0. Conversely, mean BLa levels (mM) were not differently affected (p = 0.64). At 100%, 115%, and 130% of baseline P_max after 12 weeks, BLa levels did not differ to a relevant extent (least squares geometric means, 3.56 vs. 3.63, 5.59 vs. 5.61, 9.27 vs. 9.10).

CONCLUSIONS

While HIIT+CET reduced ventilatory equivalents more effectively than CET alone, specifically when patients were approaching their maximal performance during CPET, both training strategies were equally effective in reducing BLa levels.

The effect of two concurrent exercise modalities on serum concentrations of FGF21, irisin, follistatin, and myostatin in men with type 2 diabetes mellitus

This study investigated the effect of concurrent training (CT) sequences on fibroblast growth factor 21 (FGF21), irisin, myostatin (MSTN), and follistatin (FST) among adults with type 2 diabetes mellitus (T2DM). Fifty-one diabetic men were randomly selected and assigned to concurrent aerobic-resistance (A-R) training and concurrent resistance-aerobic (R-A) training, and non-exercise control (CON) groups. The training protocols consisted of three sessions per week for 12 weeks. The A-R and R-A groups received the same CT protocols and performed with different sequences. The subjects' blood samples were obtained at baseline and 48 hours after the last session of the intervention. The results showed that the concentration of FGF21 did not change significantly after the 12 weeks of CT with different sequences (p > .05, η² = 0.123), but the serum concentration of irisin (A-R = 2.93 μg.L^-1 (95% CI = 1.45-4.42, d = -0.57) and R-A = 3.31 μg.L^-1 (95% CI = 1.13-5.49, d = -0.68)) and FST (A-R = 4.96 ng.mL^-1 (95% CI = 3.41-6.5, d = -0.39) and R-A = 4.19 ng.mL^-1 (95% CI = 2.82-5.56, d = -0.55)) significantly increased while the serum MSTN concentration (A-R = 152.32 ng.L^-1 (95% CI = 61.83-242.82, d = 1.31) and R-A = 173 ng.L^-1 (95% CI = 35.89-227.5, d = 0.83)) of both A-R and R-A groups mainly decreased (p < .01). There was no significant difference between A-R and R-A groups' irisin, FST, and MSTN concentration (p > .05), though the CT improved the body compositions, strength, and peak oxygen uptake in both groups (p < .01). Regardless of the CT sequences, it was found that CT acted as a therapeutic modality of training for T2DM patients by increasing their irisin and FST and decreasing their MSTN concentrations.

Low-Volume High-Intensity Interval Training Sessions With Different Work-Recovery Durations and Muscle Damage in Trained Men

Purpose: This study compared the effect of low-volume high-intensity training (LV-HIIT) sessions with different work-recovery durations on muscle damage markers.Methods: Twenty-four trained adult males (22.3 ± 2.9 years; 24.6 ± 2.7 kg∙m-2) performed two LV-HIIT sessions (10 x 60 s and 20 x 30 s at 100% of maximal aerobic speed on treadmill (Vmax) interspersed with equal time passive recovery, respectively) in a randomized, counter-balanced order, separated by a 1-week interval. Delayed onset muscle soreness (DOMS) and countermovement vertical jump height (CVJH) performance were assessed before, and 24-h and 48-h post sessions.Results: Pressure-pain threshold (PPT), pressure-pain tolerance (PPTol) and perceived pain intensity (PPI) using pressure algometry assessed DOMS in the rectus rectus femoris, biceps femoris and gastroctemius. A non-significant session by time interaction for PPT, PPTol and PPI in all muscles analyzed was observed (all P > 0.260). Additionally, a non-significant session by time interaction was observed for CVJH performance (P = 0.836).Conclusion: LV-HIIT sessions with different work-recovery durations elicited non-significant changes on muscle damage markers following 24- and 48-h in trained males.

High-intensity interval training in children and adolescents with special educational needs: a systematic review and narrative synthesis

BACKGROUND

High-intensity interval training (HIIT) has been promoted as a time-efficient exercise strategy to improve health and fitness in children and adolescents. However, there remains little consensus in the literature regarding its efficacy in children and adolescents with special educational needs (SEN). This study aimed to examine HIIT as a means of improving key health and fitness parameters in children and adolescents with SEN.

METHODS

A systematic search was conducted on eight databases (MEDLINE, Embase, SPORTDiscus, Web of Science, Scopus, PsycINFO, CINAHL, and Cochrane Library). Studies were eligible if they 1) included an HIIT protocol, 2) examined parameters related to both physical and mental aspects of health and fitness, and 3) examined children and adolescents with SEN aged 5-17 years.

RESULTS

Of the 1727 studies yielded by the database search, 13 (453 participants) were included and reviewed. We found that HIIT generally improved body composition, physical fitness, and cardiometabolic risk biomarkers across a spectrum of SEN (e.g., attention deficit hyperactivity disorder, cerebral palsy, developmental coordination disorder, and mental illness). Improvements in mental health and cognitive performance following HIIT have also been observed.

CONCLUSION

This review provides up-to-date evidence for HIIT as a viable exercise strategy for children and adolescents with SEN. Further research investigating the benefits of HIIT in a wider range of SEN populations is warranted.

TRIAL REGISTRATION

This study was registered in the International Prospective Register of Systematic Review (PROSPERO; registration number CRD42022352696).

The role of exercise and hypoxia on glucose transport and regulation

Muscle glucose transport activity increases with an acute bout of exercise, a process that is accomplished by the translocation of glucose transporters to the plasma membrane. This process remains intact in the skeletal muscle of individuals with insulin resistance and type 2 diabetes mellitus (T2DM). Exercise training is, therefore, an important cornerstone in the management of individuals with T2DM. However, the acute systemic glucose responses to carbohydrate ingestion are often augmented during the early recovery period from exercise, despite increased glucose uptake into skeletal muscle. Accordingly, the first aim of this review is to summarize the knowledge associated with insulin action and glucose uptake in skeletal muscle and apply these to explain the disparate responses between systemic and localized glucose responses post-exercise. Herein, the importance of muscle glycogen depletion and the key glucoregulatory hormones will be discussed. Glucose uptake can also be stimulated independently by hypoxia; therefore, hypoxic training presents as an emerging method for enhancing the effects of exercise on glucose regulation. Thus, the second aim of this review is to discuss the potential for systemic hypoxia to enhance the effects of exercise on glucose regulation.

The effect of HIIT on body composition, cardiovascular fitness, psychological well-being, and executive function of overweight/obese female young adults

Purpose

To evaluate the effect of a short-term HIIT program on the selected health-related parameters for overweight/obese young adult women in a university context.

Methods

A total of 48 participants were randomly divided into two groups. The exercise group (HIIT) received a HIIT intervention of aerobics for 4 weeks, while the control group (CON) received no training. Body composition including waist circumference (WC), body fat percentage (BF %), Cardiorespiratory fitness (VO2max), the score of Self-Rating Depression Scale (SDS), and Stroop word-color test (SCWT) results were assessed before and after the intervention along with within- and between-group comparisons.

Results

All the indices were significantly improved in HIIT group (p < 0.01) after 4 weeks of intervention. No significant changes were found in CON. There were significant differences between HIIT and CON in cardiovascular fitness (p < 0.01), SDS (p < 0.01) and SCWT (p < 0.05) before and after 4 weeks. In addition, weekly measurements of HIIT effects showed significant changes (p < 0.01) from the second week in the variables of body composition, VO2max, SDS and SCWT when compared with the baseline and maintained the tendency till the end of program.

Conclusion

The short-term HIIT aerobics of the campus program conducted in a non-lab setting induced significant improvements in body composition, cardiovascular fitness, psychological well-being and executive function in overweight young female adults.

The effect of low volume high-intensity interval training on metabolic and cardiorespiratory outcomes in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

Aims

The present systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to investigate the effect of low volume high-intensity interval training (LVHIIT) on the metabolic and cardiorespiratory outcomes in patients with type 2 diabetes mellitus (T2DM).

Methods

Relevant articles were sourced from PubMed, EBSCO, Web of Science, Embase, and the Cochrane Library from inception to October 2022. The study search strategy and all other processes were implemented in accordance with the PRISMA statement.

Results

Five randomized controlled trials that satisfied the inclusion criteria were included in this meta-analysis. The LVHIIT group had significantly lower fasting blood glucose levels (RR= -1.21; 95% CI= -2.02- -0.40, p = 0.0032) and HbA1c levels (RR= -0.65; 95% CI= -1.06- -0.23, p = 0.002) and higher levels of insulin resistance indicator HOMA-IR (RR= -1.34; 95% CI = -2.59- -0.10, p = 0.03) than the control group. Moreover, our results show that LVHIIT can reduce body mass (RR = -0.94, 95% CI = -1.37- -0.51, p<0.0001) and body mass index (RR = -0.31, 95% CI = -0.47- -0.16, p<0.0001). LVHIIT had a better therapeutic effect on blood lipid metabolism, such as total cholesterol, high-density lipoprotein, low-density lipoprotein and triglycerides. However, the change in fasting insulin levels was not statistically significant (RR= -1.43; 95% CI = -3.46- 0.60, p =0.17). Furthermore, LVHIIT reduced the systolic blood pressure (RR =-4.01, 95% CI = -4.82 - -3.21, p<0.0001) and improved peak oxygen uptake (VO2peak) compared to the control group (RR= 5.45; 95% CI = 1.38 - 9.52, p =0.009).

Conclusion

After a certain period of LVHIIT, glycaemic control, insulin resistance, body weight, lipid profile and cardiorespiratory outcomes were significantly improved in T2DM patients.

5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes-2023

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, a multidisciplinary expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Light-intensity exercise improves memory dysfunction with the restoration of hippocampal MCT2 and miRNAs in type 2 diabetic mice

Cognitive decline associated with type 2 diabetes mellitus (T2DM) is a risk factor to impair human health. Although light-intensity exercise prevents hippocampal memory dysfunction in pre-symptomatic T2DM animals by altering hippocampal lactate transport and neurotrophic factors, the effects of light-intensity exercise in an advanced stage of T2DM animals remain unclear. Here, ob/ob mice, an animal model of T2DM, were subjected to light-intensity exercise (5.0 m/min) for 30 min/day, five days/week for four weeks. The effects of light-intensity exercise on hippocampal complications, mRNA expressions of monocarboxylate transporter (MCT), and miRNA levels were assessed. The light-intensity exercise improved hippocampal memory retention in ob/ob mice. Downregulated hippocampal Mct2 mRNA levels in T2DM were improved with light-intensity exercise. Hippocampal mRNA levels of Mct1 and Mct4 were unchanged within groups. Based on miRNA sequencing, sedentary ob/ob mice exhibited that 71 miRNAs were upregulated, and 77 miRNAs were downregulated in the hippocampus. In addition, the exercise significantly increased 24 miRNAs and decreased 4 miRNAs in the T2DM hippocampus. The exercise reversed T2DM-induced alterations of hippocampal 9 miRNAs, including miR-200a-3p. Our findings imply that miR-200a-3p/Mct2 in the hippocampus would be a possible clinical target for treating T2DM-induced memory dysfunction.

High-Intensity Interval Training Versus Moderate-Intensity Continuous Training for Improving Physical Health in Elderly Women

In elderly women, a lack of regular physical exercise may result in faster decreases in general health and functional performance. Although high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) have been effectively applied in young and clinical groups, there is no evidence to support their use in elderly women to achieve health benefits. Thus, the major goal of this study was to investigate how HIIT affected health-related outcomes in elderly women. Twenty-four inactive elderly women agreed to participate in the 16-week HIIT and MICT intervention. Body composition, insulin resistance, blood lipids, functional capacity, cardiorespiratory fitness, and quality of life were all measured before and after the intervention. The number of differences between groups was determined using Cohen's effect sizes, and the pre-post intra-group changes were compared using paired t-tests. Using 2 × 2 ANOVA, the time × group interaction effects between HIIT and MICT were evaluated. Body fat percentage, sagittal abdominal diameter, waist circumference, and hip circumference all were improved significantly in the 2 groups. HIIT substantially improved fasting plasma glucose and cardiorespiratory fitness as compared to the MICT. HIIT improved the lipid profile and functional ability more significantly compared to the MICT group. These findings show that HIIT is a useful exercise for improving elderly women's physical health.

A combination of exercise and calorie restriction improves the development of obesity-related type 2 diabetes mellitus in KKAy mice

We observed that exercise and calorie restriction reduced the body weight and blood glucose levels, concurrently improving insulin resistance and glucose tolerance in obese/diabetic model KKAy mice. Analysis of gene expression in the skeletal muscle showed enhanced mRNA levels of GLUT4 (glucose uptake), ATGL (lipolytic enzyme), and slow-twitch myosin heavy chain, which may contribute to the antiobesity and antidiabetic effects.

Efficacy of Different Modalities and Frequencies of Physical Exercise on Glucose Control in People with Prediabetes (GLYCEX Randomised Trial)

To assess the efficacy of different modalities and frequencies of physical exercise on glycaemic control in adults with prediabetes. A two-phase, parallel, randomised, controlled clinical trial will be carried out, in 210 participants. In phase 1, 120 participants will be randomized into four arms: (1) aerobic exercise, (2) aerobic exercise combined with resistance, (3) high-intensity intervallic exercise and (4) control group. In phase 2, 90 new participants will be randomized into three arms, using the exercise modality that showed the best glycaemic control in phase 1 in the following manner: (1) frequency of 5 days/week, (2) frequency of 3 days/week and (3) frequency of 2 days/week. The control group (n = 30) will be included in phase 1 to evaluate the effect of any type of intervention versus no intervention. Data collection will be performed at baseline and after 15 weeks of follow up. Sociodemographic data, medication, comorbidity, blood biochemical parameters, blood pressure, anthropometric measurements, body composition, physical activity, sedentary lifestyle, diet, smoking, alcohol consumption, quality of life and sleep questionnaires will be collected. Physical activity, sedentary behaviour and sleep will be further determined with an accelerometer, and continuous glycaemia will be determined with a glycaemic monitor, both during seven days, at two time points. The main dependent variable will be the reduction in the mean amplitude of glycaemic excursions. The impact of these interventions on health will also be evaluated through gene expression analysis in peripheral blood cells. The results of this study will contribute to a better understanding of the mechanisms behind the glucose response to physical exercise in a population with prediabetes as well as improve physical exercise prescriptions for diabetes prevention. Increasing glycaemic control in people with prediabetes through physical exercise offers an opportunity to prevent diabetes and reduce associated comorbidities and health costs.

Effects of two workload-matched high intensity interval training protocols on regulatory factors associated with mitochondrial biogenesis in the soleus muscle of diabetic rats

Aims: High intensity interval training (HIIT) improves mitochondrial characteristics. This study compared the impact of two workload-matched high intensity interval training (HIIT) protocols with different work:recovery ratios on regulatory factors related to mitochondrial biogenesis in the soleus muscle of diabetic rats.

Materials and methods: Twenty-four Wistar rats were randomly divided into four equal-sized groups: non-diabetic control, diabetic control (DC), diabetic with long recovery exercise [4–5 × 2-min running at 80%–90% of the maximum speed reached with 2-min of recovery at 40% of the maximum speed reached (DHIIT1:1)], and diabetic with short recovery exercise (5–6 × 2-min running at 80%–90% of the maximum speed reached with 1-min of recovery at 30% of the maximum speed reached [DHIIT2:1]). Both HIIT protocols were completed five times/week for 4 weeks while maintaining equal running distances in each session.

Results: Gene and protein expressions of PGC-1α, p53, and citrate synthase of the muscles increased significantly following DHIIT1:1 and DHIIT2:1 compared to DC (p ˂ 0.05). Most parameters, except for PGC-1α protein (p = 0.597), were significantly higher in DHIIT2:1 than in DHIIT1:1 (p ˂ 0.05). Both DHIIT groups showed significant increases in maximum speed with larger increases in DHIIT2:1 compared with DHIIT1:1.

Conclusion: Our findings indicate that both HIIT protocols can potently up-regulate gene and protein expression of PGC-1α, p53, and CS. However, DHIIT2:1 has superior effects compared with DHIIT1:1 in improving mitochondrial adaptive responses in diabetic rats.

The complex relationship between physical activity and diabetes: an overview

Diabetes mellitus (DM) is a widespread condition, representing a challenging disease to manage. Exercise is being increasingly recommended as part of the therapeutic regimen for DM but the management of different forms of physical activity is difficult for individuals with diabetes, trainers, and physicians. Regular exercise can improve health and well-being, helping individuals to achieve their target lipid profile, body composition, cardio-respiratory fitness, and glycemic goals. People with diabetes tend to be as inactive as the general population, with a large percentage of individuals not achieving the minimum amount of recommended physical activity levels. Indeed, several barriers to exercise exist for persons with diabetes, including sports eligibility, multi-modality management of diabetic athletes, and inadequate knowledge about adequate type and intensity of exercise. The aim of the present review is to provide the current understanding of mechanisms, recommendations, and beneficial effects of different modalities of exercise for the treatment of DM.

Isolated and combined impact of dietary olive oil and exercise on markers of health and energy metabolism in female mice

An olive oil (OO) rich diet or high-intensity interval training (HIIT) independently improve markers of health and energy metabolism, but it is unknown if combining OO and HIIT synergize to improve these markers. This study characterized the isolated and combined impact of OO and HIIT on markers of health and energy metabolism in various tissues in C57BL/6J female mice. Nine-week-old mice were divided into four groups for a 12-week diet and/or exercise intervention including: (1) Control Diet without HIIT (CD), (2) Control Diet with HIIT (CD+HIIT), (3) OO diet (10% kcal from olive oil) without HIIT, and (4) OO diet with HIIT (OO+HIIT). Neither dietary OO or HIIT altered body weight, glucose tolerance, or serum lipids. HIIT, regardless of diet, increased aerobic capacity and HDL cholesterol levels. In liver and heart tissue, OO resulted in similar adaptations as HIIT including increased mitochondrial content and fatty acid oxidation but combining OO with HIIT did not augment these effects. In skeletal muscle, HIIT increased mitochondrial content in type II fibers similarly between diets. An RNA sequencing analysis on type I fibers revealed OO reduced muscle regeneration and lipid metabolism gene abundance, whereas HIIT increased the abundance of these genes, independent of diet. HIIT training, independent of diet, induced subcutaneous white adipose tissue (sWAT) hypertrophy, whereas OO induced gonadal white adipose tissue (gWAT) hypertrophy, an effect that was augmented with HIIT. These data highlight the pleiotropic effects of OO and HIIT, although their combination does not synergize to further improve most markers of health and energy metabolism.

Glycemic response to acute high-intensity interval versus moderate-intensity continuous exercise during pregnancy

The present study investigated the glycemic response to an acute high-intensity interval training (HIIT) session (10 one-minute intervals ≥90% HRmax interspersed with one-minute of active recovery) versus a moderate-intensity continuous training (MICT) session (30 min at 64%-76% HRmax ) during pregnancy. Twenty-four normoglycemic females with a singleton pregnancy (27.8 ± 4.7 weeks of gestation, 31.5 ± 4.1 years of age, body mass index: 25.2 ± 11.3) participated in a randomized crossover design study. A flash glucose monitor and accelerometer were worn continuously for 7 days recording glycemic response, physical activity, and sleep. Nutritional intake and enjoyment of the exercise were self-reported. Average heart rate during exercise was higher for HIIT (82 ± 4% HRmax ) compared with MICT (74 ± 4% HRmax ; p < 0.001) and participants achieved a peak heart rate of 92 ± 3% during HIIT (range 85%-97% HRmax ) compared with 81 ± 4% during MICT (p < 0.001). The change in glucose values from pre-to-postexercise were not different between conditions (HIIT: -0.62 ± 1.00 mmol/L; MICT: -0.81 ± 1.05 mmol/L; p = 0.300) with the exception that fewer individuals experienced postexercise hypoglycemia immediately following HIIT compared with MICT (8% versus 33% respectively; p = 0.041). Other glucose variables was not different between exercise protocols. Physical activity (p = 0.07) and caloric intake did not differ (p = 0.10). The majority of participants preferred HIIT (87.5%) and had greater perceived enjoyment compared to MICT (HIIT: 7.8 ± 1.5; MICT: 6.6 ± 2.0; p = 0.015). Sleep duration was 52 ± 73 min longer after participating in HIIT compared with the night prior (main effect for time p = 0.017); no significant changes for MICT. Overall, an acute session of HIIT appears to be well tolerated and demonstrates no adverse effects on maternal glycemic response.