Transcriptomic signatures of human single skeletal muscle fibers in response to high-intensity interval exercise.

The heterogeneous fiber type composition of skeletal muscle makes it challenging to decipher the molecular signaling events driving the health- and performance benefits of exercise. We developed an optimized workflow for transcriptional profiling of individual human muscle fibers before, immediately after, and after three hours of recovery from high-intensity interval cycling exercise. From a transcriptional point-of-view, we observe that there is no dichotomy in fiber activation, that could refer to a fiber being recruited or non-recruited. Rather, the activation pattern displays a continuum with a more uniform response within fast versus slow fibers during the recovery from exercise. The transcriptome-wide response immediately after exercise is characterized by some distinct signatures for slow versus fast fibers, although the most exercise-responsive genes are common between the two fiber types. The temporal transcriptional waves further converge the gene signatures of both fiber types towards a more similar profile during the recovery from exercise. Furthermore, a large heterogeneity among all resting and exercised fibers was observed, with the principal drivers being independent of a slow/fast typology. This profound heterogeneity extends to distinct exercise responses of fibers beyond a classification based on myosin heavy chains. Collectively, our single-fiber methodological approach points to a substantial between-fiber diversity in muscle fiber responses to high-intensity interval exercise.

Acute neuromuscular, cardiovascular, and muscle oxygenation responses to low-intensity aerobic interval exercises with blood flow restriction.

We investigated the influence of short- and long-interval cycling exercise with blood flow restriction (BFR) on neuromuscular fatigue, shear stress and muscle oxygenation, potent stimuli to BFR-training adaptations. During separate sessions, eight individuals performed short- (24 × 60 s/30 s; SI) or long-interval (12 × 120 s/60 s; LI) trials on a cycle ergometer, matched for total work. One leg exercised with (BFR-leg) and the other without (CTRL-leg) BFR. Quadriceps fatigue was quantified using pre- to post-interval changes in maximal voluntary contraction (MVC), potentiated twitch force (QT) and voluntary activation (VA). Shear rate was measured by Doppler ultrasound at cuff release post-intervals. Vastus lateralis tissue oxygenation was measured by near-infrared spectroscopy during exercise. Following the initial interval, significant (P < 0.05) declines in MVC and QT were found in both SI and LI, which were more pronounced in the BFR-leg, and accounted for approximately two-thirds of the total reduction at exercise termination. In the BFR-leg, reductions in MVC (-28 ± 15%), QT (-42 ± 17%), and VA (-15 ± 17%) were maximal at exercise termination and persisted up to 8 min post-exercise. Exercise-induced muscle deoxygenation was greater (P < 0.001) in the BFR-leg than CTRL-leg and perceived pain was more in LI than SI (P < 0.014). Cuff release triggered a significant (P < 0.001) shear rate increase which was consistent across trials. Exercise-induced neuromuscular fatigue in the BFR-leg exceeded that in the CTRL-leg and was predominantly of peripheral origin. BFR also resulted in diminished muscle oxygenation and elevated shear stress. Finally, short-interval trials resulted in comparable neuromuscular and haemodynamic responses with reduced perceived pain compared to long-intervals.

Metabolomic responses to high-intensity interval exercise in equine skeletal muscle: effects of rest interval duration.

High-intensity interval training has attracted considerable attention as a time-efficient strategy for inducing physiological adaptations, but the underlying mechanisms have yet to be elucidated. By using metabolomics techniques, we investigated changes in the metabolic network responses in Thoroughbred horses to high-intensity interval exercise performed with two distinct (15 min or 2 min) rest intervals. The peak plasma lactate level was higher during high-intensity exercise with a 2 min rest duration than that with a 15 min rest duration (24.5±6.8 versus 13.3±2.7 mmol l-1). The arterial oxygen saturation was lower at the end of all exercise sessions with a 2 min rest duration than that with a 15 min rest duration. Metabolomic analysis of skeletal muscle revealed marked changes in metabolite concentrations in the first and third bouts of the 15 min rest interval conditions. In contrast, there were no metabolite concentrations or pathways that significantly changed during the third bout of exercise performed with a 2 min rest interval. Our findings suggest that the activity of each energy production system is not necessarily reflected by apparent changes in metabolite concentrations, potentially due in part to a better match between metabolite flux into and out of the pathway and cycle, as well as between metabolite production and disposal. This study provides evidence that changes in metabolite concentrations vary greatly depending on the number of repetitions and the length of rest periods between exercises, even if the exercises themselves are identical.

Effect of high-intensity interval training on self-care and anxiety-like behaviors in naive rats.

Self-care behavior covers individual's health, life and well-being to maintain the necessary activities. The aim of this study is to examine the self-care and possible anxiolytic effects of high-intensity interval exercise (HIIT). Eight-week-old Wistar Albino male rats were divided into Control (n = 8), and Exercise (n = 8). Rat exercised for 38 min a day, 5 days a week, for 8 weeks The animals were then subjected to open field test and splash test, and the behaviors were video recorded. Student t test and Shapiro-Wilk test were used as statistical tests. In the exercise group, spray-induced grooming behavior increased significantly in terms of duration and frequency (p < 0.05), but no significant difference was observed in the latency of grooming (p > 0.05). In the open-field test, the total distance traveled, which is a locomotor activity parameter, did not change between the groups. Anxiolytic-like behaviors such as total rearing behavior, unsupported rearing, central time, and central region entries increased remarkably in the exercise group vs. control (p < 0.0001). Freezing as an anxiogenic behavior decreased in the exercise group positively (p < 0.0001). Intermittent high-intensity exercise improved and increased self-care behaviors. Further, the present study shows that HIIT has beneficial effects on different aspects of behaviors such as exploratory behaviors, increasing anxiolytic behaviors, and reducing anxiogenic behavior. The present study is a preclinical study that will pave the way for new studies.

A comparison of continuous, interval, and accumulated workouts with equalized exercise volume: excess post-exercise oxygen consumption in women.

BACKGROUND: Despite the well-known health benefits of exercise, women's participation in exercise is low worldwide. As women are at risk of developing various chronic diseases as they age, suggesting effective exercise methods that can maximize energy consumption is needed to prevent such conditions. Excess post-exercise oxygen consumption (EPOC) can maximize energy consumption. In this crossover, randomized controlled trial, we aimed to compare the EPOC for different exercise modalities including continuous exercise (CE), interval exercise (IE), and accumulated exercise (AE) that spent the homogenized energy expenditure during exercise in healthy women. METHODS: Forty-four participants (age, 36.09 ± 11.73 years) were recruited and randomly allocated to three groups. The intensity of each modality was set as follows: CE was performed for 30 min at 60% peak oxygen uptake (VO2peak). IE was performed once for 2 min at 80% VO2peak, followed by 3 min at 80% VO2peak, and 1 min at 40% VO2peak, for a total of six times over 26 min. AE was performed for 10 min with a 60% VO2peak and was measured thrice a day. RESULTS: During exercise, energy metabolism was higher for IE and CE than that for AE. However, this was reversed for AE during EPOC. Consequently, the greatest energy metabolism was shown for AE during total time (exercise and EPOC). CONCLUSIONS: By encouraging regular exercises, AE can help maintain and improve body composition by increasing compliance with exercise participation, given its short exercise times, and by efficiently increasing energy consumption through the accumulation of EPOC. TRIAL REGISTRATION: Clinical number (KCT0007298), 18/05/2022, Institutional Review Board of Konkuk University (7001355-202201-E-160).

High-intensity interval training and cardiorespiratory fitness in adults: An umbrella review of systematic reviews and meta-analyses.

BACKGROUND: High-intensity interval training (HIIT) is characterized by repeated bouts of relatively intense exercise interspersed with recovery periods. Previous studies have evaluated this exercise strategy with various population subgroups, regimens, and comparator groups, limiting the generalizability of findings. We performed a novel umbrella review to generate an up-to-date synthesis of the available evidence regarding the effect of HIIT on cardiorespiratory fitness (CRF) in adults as compared to non-exercise control and traditional continuous forms of exercise such as moderate-intensity continuous training (MICT). METHODS: An umbrella review was conducted in accordance with the Preferred Reporting Items for Overviews of Reviews guideline. Seven databases (MEDLINE, EMBASE, Cochrane Database, CINAHL, Scopus, SPORTDiscus, and Web of Science) were searched until February 2024. Systematic reviews with meta-analyses comparing HIIT and active/non-active control conditions were included. Literature search, data extraction, and methodological quality assessment (AMSTAR-2) were conducted independently by two reviewers. RESULTS: Twenty-four systematic reviews with meta-analyses, representing 429 primary studies and 12 967 unique participants, met the inclusion criteria. Most of the systematic reviews received moderate-to-critically low AMSTAR-2 scores. The data showed that HIIT, including the particularly intense variant "sprint interval training" (SIT), significantly increases CRF in adults compared to non-exercise control (standardized mean difference [SMD]: 0.28 to 4.31; weighted mean difference [WMD]: 3.25 to 5.5 mL/kg/min) and MICT (SMD: 0.18 to 0.99; WMD: 0.52 to 3.76 mL/kg/min). This effect was consistently observed across specific groups of individuals (e.g., apparently healthy adults, individuals with overweight/obesity, older adults, and high-level athletes) and HIIT modalities (e.g., low-volume HIIT, whole-body HIIT, home-based HIIT, aquatic HIIT, and short SIT). CONCLUSION: Existing evidence from systematic reviews consistently supports the effect of HIIT on enhancing CRF in adults when compared to non-exercise control and MICT. Our findings offer a comprehensive basis that may potentially contribute to informing physical activity guidelines aimed at improving CRF in the general population.

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.

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

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

TBC1D1 Ser237 phosphorylation, but not insulin sensitivity, is higher following a bout of high-intensity interval exercise in healthy males as compared with females.

Interval training has been found to lower glucose concentrations and increase insulin sensitivity in males but not in females, which may be due to inherent sex-based differences in metabolism. Twenty-four (12/sex) participants completed a bout of high-intensity interval exercise (HIIE, 10 × 1 min at 90% HRmax) to evaluate whether sex influenced the physiological effects of HIIE on postexercise glycemic control during an oral glucose tolerance test (OGTT). Given that body anthropometrics influence postprandial glucose, data were also expressed as a function of the normalized glucose dose. In addition, we examined whether sex differences in postexercise glycemic control were related to sex differences in muscle metabolism and/or insulin signaling proteins. HIIE increased insulin sensitivity in both sexes as characterized by the Matsuda (P = 0.03, ηp2= 0.20) and HOMA-IR (P = 0.047, ηp2 = 0.17) indices. HIIE also lowered insulin concentration during the OGTT (P = 0.04, ηp2 = 0.18) as compared with control. When normalized for glucose dose relative to lean mass, glucose area under the curve (AUC) was lower in females than in males (P ≤ 0.001, ηp2 = 0.47). TBC1D1 Ser237 phosphorylation increased in males, but not in females, postexercise (P = 0.03, ηp2 = 0.19). There was no difference in total insulin signaling protein content, muscle glycogen utilization, or AMPK activation during exercise between the sexes. These findings indicate that when the glucose dose is normalized for differences in body composition glycemic handling is better in females and that an acute bout of HIIE improves insulin sensitivity equally in healthy males and females.

Circulating Gal-3 and sST2 are associated with acute exercise-induced sustained endothelial activation: Possible relevance for fibrosis development?

Long-term, intense endurance exercise training can occasionally induce endothelial micro-damage and cardiac fibrosis. The underlying mechanisms are incompletely understood. Twenty healthy, well-trained male participants (10 runners and 10 cyclists) performed a strenuous high-intensity interval training (HIIT) session matched by age, height, weight and maximal oxygen consumption. We assessed the acute exercise response of novel cardiac biomarkers of fibrosis [e.g., galectin-3 (Gal-3) and soluble suppression of tumorigenicity 2 (sST2)] per exercise modality and their relationship with haemodynamic contributors, such as preload, afterload and cardiac contractility index (CTi), in addition to endothelial damage by sustained activation and shedding of endothelial cells (ECs). Serum Gal-3 and sST2 concentrations were investigated by enzyme-linked immunosorbent assays; haemodynamics were analysed via impedance plethysmography and circulating ECs by flow cytometry. The Gal-3 and sST2 concentrations and ECs were elevated after exercise (P < 0.001), without interaction between exercise modalities. Circulating Gal-3 and sST2 concentrations both showed a positive relationship with ECs (rrm  = 0.68, P = 0.001 and rrm  = 0.57, P = 0.010, respectively, both n = 18). The EC association with Gal-3 was significant only in cyclists, but equally strong for both modalities. Gal-3 was also related to exercise-induced CTi (rrm  = 0.57, P = 0.011, n = 18). Cardiac wall stress is increased after an acute HIIT session but does not differ between exercise modalities. Exercise-released Gal-3 from cardiac macrophages could very probably drive systemic endothelial damage, based on an enhanced CTi. The importance of acute exercise-induced vascular resistances and cardiac contractility for the release of fibrotic biomarkers and any long-term pathological endothelial adaptation should be investigated further, also relative to the exercise modality. NEW FINDINGS: What is the central question of this study? Circulating biomarkers of cardiac wall stress and fibrosis are influenced by physical exercise. The underlying mechanisms per exercise modality are still unclear. What is the main finding and its importance? We show that galectin-3 (Gal-3) and soluble suppression of tumorigenicity 2 (sST2) are increased after acute exercise but do not differ between running and cycling. One haemodynamic contributor to the secretion of Gal-3 is an enhanced cardiac contractility. Acute exercise-released Gal-3 and sST2 are linked to sustained endothelial activation and cell shedding. This could be relevant in the context of fibrosis development and could identify athletes at risk for pathological endothelial adaptations.

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).

Is moderate-intensity interval training more tolerable than high-intensity interval training in adults with obesity?

Interval training (IT) has been shown to be a time-effective alternative to traditional training programmes in the management of obesity. Nevertheless, studies comparing the effects of different IT intensities on inflammation, muscle and liver damage, and perceptual responses in people with obesity are relatively scarce. This study aimed to compare the acute effects of two different IT protocols matched by the mean load and duration on biochemical and perceptual responses in sedentary adults with obesity. Twenty-two volunteers (age = 33.40 ± 10.01 years, BMI = 38.29 ± 7.09 kg/m²) were randomized to perform two conditions: moderate-intensity IT (MIIT) 5 × 3 min (70% of peak power output (PPO))/2 min (45%PPO) and high-intensity IT (HIIT) 8 × 1 min (90%PPO)/2 min (45%PPO). Blood samples were drawn before and after exercise for biochemical and haematological measurements. Rating of perceived exertion (RPE) was assessed during and after exercise. Perceptual pain was evaluated before, throughout and after exercise. C-reactive protein, white blood cells and neutrophils increased only after HIIT (p < 0.001, for all). Aspartate aminotransferase, alanine aminotransferase, creatine kinase and lactate dehydrogenase increased in both HIIT and MIIT (p < 0.001, for all), without any difference between sessions. HIIT induced a greater increase of blood lactate compared to MIIT (p < 0.05). Pain and RPE scores were higher during HIIT vs. MIIT (p < 0.001 and p < 0.01, respectively). MIIT induced fewer immune system perturbations and less muscle pain and was perceived as more tolerable compared to HIIT session. Therefore, MIIT could be used as a first step to promote body adaptations before starting a HIIT programme in sedentary people with obesity.

Reassessing the evidence: prandial state dictates glycaemic responses to exercise in individuals with type 1 diabetes to a greater extent than intensity.

Recent guidelines suggest that adding anaerobic (high intensity or resistance) activity to an exercise session can prevent blood glucose declines that occur during aerobic exercise in individuals with type 1 diabetes. This theory evolved from earlier study data showing that sustained, anaerobic activity (high intensity cycling) increases blood glucose levels in these participants. However, studies involving protocols where anaerobic (high intensity interval) and aerobic exercise are combined have extremely variable glycaemic outcomes, as do resistance exercise studies. Scrutinising earlier studies will reveal that, in addition to high intensity activity (intervals or weight lifting), these protocols had another common feature: participants were performing exercise after an overnight fast. Based on these findings, and data from recent exercise studies, it can be argued that participant prandial state may be a more dominant factor than exercise intensity where glycaemic changes in individuals with type 1 diabetes are concerned. As such, a reassessment of study outcomes and an update to exercise recommendations for those with type 1 diabetes may be warranted.

Reduced post-exercise muscle microvascular perfusion with compression is offset by increased muscle oxygen extraction: Assessment by contrast-enhanced ultrasound.

The microvasculature is important for both health and exercise tolerance in a range of populations. However, methodological limitations have meant changes in microvascular blood flow are rarely assessed in humans during interventions designed to affect skeletal muscle blood flow such as the wearing of compression garments. The aim of this study is, for the first time, to use contrast-enhanced ultrasound to directly measure the effects of compression on muscle microvascular blood flow alongside measures of femoral artery blood flow and muscle oxygenation following intense exercise in healthy adults. It was hypothesized that both muscle microvascular and femoral artery blood flows would be augmented with compression garments as compared with a control condition. Ten recreationally active participants completed two repeated-sprint exercise sessions, with and without lower-limb compression tights. Muscle microvascular blood flow, femoral arterial blood flow (2D and Doppler ultrasound), muscle oxygenation (near-infrared spectroscopy), cycling performance, and venous blood samples were measured/taken throughout exercise and the 1-hour post-exercise recovery period. Compared with control, compression reduced muscle microvascular blood volume and attenuated the exercise-induced increase in microvascular velocity and flow immediately after exercise and 1 hour post-exercise. Compression increased femoral artery diameter and augmented the exercise-induced increase in femoral arterial blood flow during exercise. Markers of blood oxygen extraction in muscle were increased with compression during and after exercise. Compression had no effect on blood lactate, glucose, or exercise performance. We provide new evidence that lower-limb compression attenuates the exercise-induced increase in skeletal muscle microvascular blood flow following exercise, despite a divergent increase in femoral artery blood flow. Decreased muscle microvascular perfusion is offset by increased muscle oxygen extraction, a potential mechanism allowing for the maintenance of exercise performance.

Effect of Intermittent Exercise on Performance in 3D Multiple Objects Tracking in Children, Young and Older Adults-A Pilot Study.

BACKGROUND: Although an extensive body of literature is trying to verify the acute effects of exercise, findings are highly contradictory due to many different study protocols. The number of studies using an intermittent exercise (IE) protocol is limited, especially with regard to comparison across the life span. We examined whether the effects of a HIIE protocol on performance in a perceptual-cognitive task (NeuroTracker® (NT)) differed between children, young adults, and older adults to address this gap. METHODS: A total of 36 participants participated in the present study: 12 children (CH, 6 females, 9.83 ± 1.19 years), 12 young adults (YA, 6 females, 23.5 ± 3.55 years), and 12 older adults (OA, 4 females, 66.92 ± 4.08 years). The IE treadmill protocol used in the present study consisted of eleven 30-second intervals at 90% VO2max, interspersed with 2-minute active recovery periods at 50% VO2max. Before and during this exercise protocol, three series of the NeuroTracker® task were performed after 5, 15, and 25 minutes. RESULTS: We observed a significant main effect time and a significant main effect group regarding absolute NT scores and progression during IE. YA had significantly higher absolute NT scores than CH and OA. The normalized perceptual-cognitive task progression was observed in OA and YA but not in CH. YA, in particular, showed progression in the NT performance during IE. CONCLUSIONS: The present study confirmed previous findings on age-related differences in NT performance. Based on these findings, the effects of different exercise protocols (e.g., continuous vs. intermittent) seem to be a worthwhile subject for future investigations. Normalized speed thresholds should best capture improvement differences between groups to compare results across studies better, as pre-test values are taken as the baseline.

The Immediate and Sustained Effects of Exercise-Induced Hemodynamic Response on Executive Function During Fine Motor-Cognitive Tasks Using Functional Near-Infrared Spectroscopy.

BACKGROUND: Several studies have shown that acute exercise has a small positive effect on cognitive performance. However, it is still unclear what type of exercise has a sustained impact on cognitive performance during post-exercise recovery. Therefore, the purpose of our study was to investigate cognitive performance at the behavioral level, and their neural correlates after a 10-minute post-exercise recovery period with two different types of exercise intervention (high-intensity interval exercise (HIIE) vs. Moderate-intensity continuous exercise (MCE)). METHODS: A total of 29 healthy young adults (7 women) between the ages of 19 and 33 with fair to good cardiovascular fitness were submitted to two different exercise protocols and a recovery session. Cognitive function was assessed using a digital Trail-Making-Test (dTMT). Cortical activity in the prefrontal and the motor cortex using functional near-infrared spectroscopy (fNIRS) was measured before, after acute exercise, and during recovery. The statistical analysis of fNIRS data was performed by comparing the slope and mean of the hemodynamic response. RESULTS: High levels of hemodynamic responses were observed in the prefrontal and motor cortex on the brain during performing the dTMT while walking from pre- to post-exercise and decreased again in post-recovery, accompanied by improvement and maintenance of cognitive performance. Notably, a high hemodynamic response in the left motor area of the brain was maintained by HIIE in post-recovery compared with MCE. CONCLUSIONS: The high cortical activation in the left motor area from post-exercise to recovery for the HIIE group may be due to the additional availability of neural resources for fine motor and postural control by high-intensity exercise-induced fatigue. Additionally, the improved cognitive performance may have effectively utilized the available neural resources in the frontal lobe, depending on the condition (sitting and walking) and the two types of exercise protocol (HIIE and MCE).

Physical Activity and Post-Transcriptional Regulation of Aging Decay: Modulation of Pathways in Postmenopausal Osteoporosis.

Background and Objectives: Bones and the skeletal muscle play a key role in human physiology as regulators of metabolism in the whole organism. Bone tissue is identified as a complex and dynamic living unit that could react to physical activity. Hormones, growth factors, signaling factors, and environmental factors control osteogenesis, and it could be regulated at a post-transcriptional level. MicroRNAs (miRNAs) can interfere with mRNAs translation. Increasing data suggest that miRNAs, through different pathways, are involved in the regulation of bone marrow mesenchymal stem cells (BMSCs) differentiation and physical activity-induced bone remodeling. The purpose of this narrative review is to investigate the potential protective role played by physical activity in affecting miRNAs expression in close tissues and elaborate on the complex network of interplay that could drive various metabolic responses of the bone to physical activity. Materials and Methods: A bibliographic search of the scientific literature was carried out in scientific databases to investigate the possible effect of physical activity on age-related features detected in the musculoskeletal system. Results: Several studies suggested that the musculoskeletal system interacting at a biomolecular level could establish crosstalk between bone and muscle in an endocrine or paracrine way through myokines released by muscle at the periosteal interface or in the bloodstream, such as irisin. Mechanical stimuli have a key role in bone formation and resorption, increasing osteogenesis and downregulating adipogenesis of BMSC via regulation of expression of runt-related transcription factor 2 (Runx2) and peroxisome proliferator-activated receptor gamma (PPARγ), respectively. Conclusions: Increasing data suggest that miRNAs, through different pathways, are involved in the regulation of BMSCs differentiation and physical activity-induced bone remodeling. Modulation of miRNAs following physical exercise represents an interesting field of investigation since these non-coding RNAs may be considered defenders against degenerative diseases and as well as useful prognostic markers in skeletal and muscle-skeletal diseases, such as osteoporosis.

The effect of aquatic High Intensity Interval Training on cardiometabolic and physical health markers in women: A systematic review and meta-analysis.

BACKGROUND: We performed a meta-analysis of randomized controlled trials (RCTs) assessing the effect of Aquatic High Intensity Interval Training (AHIIT) on cardiometabolic and physical health markers in women. METHODS: Systematic search used 7 databases (MEDLINE, PubMed, SPORTDiscus, Cochrane, Embase, CINAL complete, PsycINFO). The Physiotherapy Evidence Database (PEDro) score was used to evaluate the methodological quality of the studies. Clinical trials compared AHIIT with a control group that receive no exercise training. We integrated randomized controlled trials published in English, and participants were women aged ≥18 years. The outcome of interest was the change in cardiometabolic and physical health markers. RESULTS: Among 242 articles screened, 18 articles (13 trials) were included in this meta-analysis comparing AHIIT (n = 261) with a control group (n = 215). The median PEDro score was 5.5 out of 10 (range, 4-8). AHIIT significantly improved peak oxygen uptake (Hedges' g 0.610; 95% CI 0.277-0.943; P < 0.001), reduced resting heart rate (Hedges' g -0.495; 95% CI -0.866 to -0.124; P < 0.05), as well as chair to stand test. (Hedges' g 0.548; 95% CI 0.019 to 1.077; P < 0.05). CONCLUSION: AHIIT has a moderate effect in improving cardiometabolic and physical health markers in women.

Methods to match high-intensity interval exercise intensity in hypoxia and normoxia - A pilot study.

The aim of this study was to compare high-intensity interval exercise (HIIE) sessions prescribed on the basis of a maximal value (peak power output, PPO) and a submaximal value (lactate threshold, LT) derived from graded exercise tests (GXTs) in normoxia and hypoxia. METHODS: A total of ten males (aged 18-37) volunteered to participate in this study. The experimental protocol consisted of a familiarization procedure, two GXTs under normoxia (FiO2 = 0.209) and two GXTs under normobaric hypoxia (FiO2 = 0.140), and three HIIE sessions performed in a random order. The HIIE sessions included one at hypoxia (HY) and two at normoxia (one matched for the absolute intensity in hypoxia, designated as NA, and one matched for the relative intensity in hypoxia, designated as NR). RESULTS: The data demonstrated that there was significant lower peak oxygen uptake (V̇O2peak), peak heart rate (HRpeak), PPO, and LT derived from GXTs in hypoxia, with higher respiratory exchange ratio (RER), when compared to those from GXTs performed in normoxia (p < 0.001). Among the three HIIE sessions, the NA session resulted in lower percentage of HRpeak (85.0 ± 7.5% vs 94.4 ± 5.0%; p = 0.002) and V̇O2peak (74.1 ± 9.1% vs 88.7 ± 7.7%; p = 0.005), when compared to the NR session. HIIE sessions in HY and NR resulted in similar percentage of HRpeak and V̇O2peak, as well as similar rating of perceived exertion and RER. The blood lactate level increased immediately after all the three HIIE sessions (p < 0.001), while higher blood lactate concentrations were observed immediately after the HY (p = 0.0003) and NR (p = 0.014) sessions when compared with NA. CONCLUSION: Combining of PPO and LT derived from GXTs can be used to prescribe exercise intensity of HIIE in hypoxia.

Alternating high-intensity interval training and continuous training is efficacious in improving cardiometabolic health in obese middle-aged men.

BACKGROUND: High-intensity interval training (HIIT) or moderate-intensity continuous training (MICT) alone has been shown to improve metabolic health, but the effects of alternating the two training approaches as often practiced in real life remained unclear. PURPOSE: To examine the effects of HIIT or MICT alone or alternating HIIT-MICT on cardiometabolic responses in inactive obese middle-aged men. METHODS: Forty-two participants (age: 42 ± 5 y; BMI: 26.3 ± 2.1 kg m-2) were randomly assigned to four groups: HIIT (12 x 1-min running bouts at 80-90% HRmax interspersed with 1-min active recovery at 50% HRmax), MICT (40-min brisk walk at 65-70% HRmax), alternating HIIT-MICT or a non-exercise control group (CON). Exercise sessions were conducted three times per week for 16 weeks. Maximal oxygen uptake (VO2max), body composition (by bioelectrical impedance analysis), blood pressure, fasting blood glucose, insulin resistance (HOMA-IR) and lipid profile were assessed at baseline and after the 16-week intervention. Enjoyment and self-efficacy were also assessed at the end of intervention. RESULTS: All exercise groups showed a similar VO2max increase of ∼15% (HIIT: 34.3 ± 4.4 vs 39.1 ± 5.4; MICT: 34.9 ± 5.0 vs 39.4 ± 7.2; and alternating HIIT-MICT: 34.4 ± 5.0 vs 40.3 ± 4.6 mL kg-1min-1) compared to baseline and CON (all p < 0.05). Weight, BMI, % fat and waist circumference also showed similar reductions in all exercise groups compared to baseline and CON (all p < 0.05). No significant group difference was observed for all blood markers. Compared to baseline, total cholesterol decreased after HIIT-MICT, while HIIT significantly decreased fasting insulin level and improved insulin resistance (p < 0.05). Enjoyment, self-efficacy and adherence were similar among all exercise groups. CONCLUSION: HIIT or MICT alone or alternating HIIT-MICT similarly improve cardiovascular fitness and body composition in obese middle-aged men despite differences in total training volume and time commitment.