A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms

High-intensity interval training is superior to moderate intensity training on aerobic capacity in rats: Impact on hippocampal plasticity markers

The use of endurance regimens could be improved by defining their respective effectiveness on aerobic fitness and brain health that remains controversial. We aimed at comparing work-matched high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) on aerobic performance and muscular plasticity markers in healthy rats. Cognitive functions and brain plasticity markers were also investigated following the 8-week training. Rats performed the incremental exercise test and behavioural tests before and after training at day 1 (D1), D15, D29 and D57. Key cerebral markers were assessed by Western blot and quantitative polymerase chain reaction to provide information on brain function related to angiogenesis, aerobic metabolism and neurotrophin activity at D59. Muscular protein levels involved in angiogenesis and aerobic metabolism were measured in both triceps brachii and soleus muscles. HIIT induced superior improvement of aerobic fitness compared to MICT, as indicated by enhancement of speed associated with lactate threshold (S_LT) and maximal speed (S_max). In the triceps brachii muscle, markers of angiogenesis and aerobic activity were upregulated as well as myokines involved in neuroplasticity. Moreover, levels of key brain plasticity markers increased in the hippocampus after 8 weeks of HIIT, without improving cognitive functions. These findings might contribute to define physical exercise guidelines for maintaining brain health by highlighting the promising role of HIIT when using S_LT for distinguishing low running speed from high running speed. Further studies are required to confirm these brain effects by exploring synaptic plasticity and neurogenesis mechanisms when exercise intensity is standardized and individualized.

Profile of blood pressure and glycemic responses after interval exercise in older women attending (in) a public health physical activity program

BACKGROUND

and purpose: Interval exercise causes a positive impact on health status. Our aim was to evaluate the effects of a feasible and low-cost interval exercise on blood pressure and glycemic responses in people with controlled systemic arterial hypertension.

METHODS

Thirteen women with hypertension (HG; age: 60.2 ± 2.8 years) and 11 without hypertension (CG; age: 54.4 ± 3.8 years) were recruited. Groups performed one session of interval exercise with elastic resistance (10 series of 1:1 min/effort:rest).

RESULTS

There were slight reductions of absolute systolic blood pressure values for HG at 10, 30, and 60 min (4, 9, and 8 mmHg, respectively) at post-compared to pre-exercise. Glycemia was reduced (respectively, 17.6%, 17.6%, 19.4%, and 23.1%; p < 0.05) at pre-exercise vs. 0 min and 10, 30, and 60 min post-exercise for the HG.

CONCLUSION

A single session of a feasible and low-cost interval exercise modifies and promotes significant clinical effects in blood pressure and glycemic levels in female older adults with and without hypertension.

Low Frequency Severe-Intensity Interval Training Markedly Alters Respiratory Compensation Point During Incremental Exercise in Untrained Male

This study investigated the effect of low-frequency severe-intensity interval training on the respiratory compensation point (RCP) during incremental exercise test. Eighteen healthy males (age; 20.7 ± 2.2 years, range 18 to 29 years, height; 174.0 ± 5.6 cm, weight; 68.8 ± 13.5 kg) were randomly assigned to an interval training group or a control group. Interval training was conducted once weekly for 3 months. Each session consisted of three bouts of bicycle ergometer exercise at 80% maximum work rate until volitional fatigue. Before (baseline) and after the 3-month intervention, incremental exercise test was performed on a bicycle ergometer for determination of ventilatory threshold (VT), RCP, and peak oxygen consumption (V̇_{O 2} peak). The training program resulted in significant increases of V̇_{O 2} peak (+ 14%, p < 0.001, η p 2 = 0.437), oxygen consumption (V̇_{O 2}) at VT (+ 18%, p < 0.001, η p 2 = 0.749) and RCP (+ 15%, p = 0.03, η p 2 = 0.239) during incremental exercise test in the training group. Furthermore, a significant positive correlation was observed between the increase in V̇_{O 2} peak and increase in V̇_{O 2} at RCP after intervention (r = 0.87, p = 0.002) in the training group. Tidal volumes at VT (p = 0.04, η p 2 = 0.270) and RCP (p = 0.01, η p 2 = 0.370) also increased significantly after intervention compared to baseline. Low-frequency severe-intensity interval training induced a shift in RCP toward higher work rate accompanied by higher tidal volume during incremental exercise test.

HIIT is superior than MICT on cardiometabolic health during training and detraining

PURPOSE

This study investigated the cardiometabolic health of overweight/obese untrained individuals in response to 8 weeks of HIIT and MICT using a field approach, and to 4 weeks of training cessation (TC).

METHODS

Twenty-two subjects performed 8 weeks of moderate intensity continuous training (MICT-n = 11) or high-intensity interval training (HIIT-n = 11) (outdoor running), followed by 4 weeks of TC. Cardiorespiratory fitness, body composition, arterial blood pressure, glucose metabolism and blood lipids were measured pre-training (PRE), post-training (POST) and TC.

RESULTS

HIIT improved eight indicators of cardiometabolic health ([Formula: see text], BMI, body fat, visceral fat, systolic blood pressure, total cholesterol, fasting glucose and triglycerides-p  < 0.05) while MICT only three ([Formula: see text], BMI, and visceral fat-p  < 0.05). After 4 weeks of TC, four positive adaptations from HIIT were negatively affected ( [Formula: see text], visceral fat, systolic blood pressure and total cholesterol-p  < 0.05) and three in the MICT group ([Formula: see text], BMI and visceral fat, p  < 0.05).

CONCLUSION

Eight weeks of HIIT performed in a real-world setting promoted a greater number of positive adaptations in cardiometabolic health of individuals with overweight/obese compared to MICT. Most of the positive effects of the HIIT protocol were also found to be longer lasting and maintained after the suspension of high-intensity interval running for 4 weeks. Conversely, all positive effects of MICT protocols were reversed after TC.

Aquatic high intensity interval training to improve aerobic capacity is feasible in adolescents with cerebral palsy: pilot randomised controlled trial

OBJECTIVE

To investigate feasibility of aquatic high intensity interval training for adolescents with cerebral palsy, who can ambulate independently but may choose a mobility aid in some circumstances.

DESIGN

Pilot randomised controlled trial.

METHOD

Following baseline assessments, participants were randomised to usual care or ten weeks of twice weekly aquatic high intensity interval training. Each class comprised 10 one-minute exercise intervals separated by one-minute rest. High intensity exercise was defined as the attainment of ⩾80% of peak heart rate measured by telemetry.

SETTING

Tertiary paediatric hospital.

MAIN MEASURES

Primary outcomes related to the feasibility of the protocol to progress to a definitive trial. Consumer feedback was obtained.

RESULTS

Of 119 potential participants, 46 appeared eligible and 17 consented, resulting in a recruitment fraction of 37% (95% CI 23-52). Twelve completed baseline assessments and were randomised (5 males; 14 years 7 months SD 2 years 0 months). In the intervention group, of the 1190 exercise stations (across all participants and sessions), heart rate data were available for 1180 stations and high intensity exercise was achieved during 1111 stations (93%, 95% CI 92-95). All randomised participants completed the study and reported that the intervention was fun and provided friendship opportunities. There were no major adverse events or exacerbation of pain.

CONCLUSIONS

Aquatic high intensity interval training in ambulant adolescents with cerebral palsy is feasible, while maintaining adherence and fidelity. Uncertainty remains on the efficacy of the intervention, highlighting the need for a large definitive trial.

Affective responses to high-intensity interval training with continuous and respite music

Music has been shown to enhance affective responses to continuous exercise, but the most effective application of music during interval exercise is poorly understood. This study examined two contrasting applications of music designed to assuage the decline in pleasure often experienced during high-intensity interval training (HIIT). In a repeated measures crossover design, 18 recreationally active participants (10 men and 8 women; M _age = 25.1 ± 5.1 years; M _BMI = 23.08 ± 2.01 kg/m 2; M VO_2max = 38.82 ± 10.73 ml/kg/min) completed three HIIT sessions (10 x 60 s efforts at 100% Wmax, separated by 75 s recovery) on a cycle ergometer. Participants completed two experimental conditions: respite music (applied only during the recovery periods), continuous music (applied throughout the entire HIIT session); and a no-music control condition. Results indicated that music did not influence affective valence during the work bouts or recovery periods of the HIIT sessions (ps >.05), but that listening to music continuously elicited greater post-task enjoyment (p =.032, d = 0.66) and remembered pleasure (p =.044, d = 0.5). This study is the first to investigate the application of music during a practical HIIT protocol and to compare the effects of respite versus continuous music during interval exercise.

Exercise training improves adipose tissue metabolism and vasculature regardless of baseline glucose tolerance and sex

INTRODUCTION

We investigated the effects of a supervised progressive sprint interval training (SIT) and moderate-intensity continuous training (MICT) on adipocyte morphology and adipose tissue metabolism and function; we also tested whether the responses were similar regardless of baseline glucose tolerance and sex.

RESEARCH DESIGN AND METHODS

26 insulin-resistant (IR) and 28 healthy participants were randomized into 2-week-long SIT (4-6×30 s at maximum effort) and MICT (40-60 min at 60% of maximal aerobic capacity (VO_2peak)). Insulin-stimulated glucose uptake and fasting-free fatty acid uptake in visceral adipose tissue (VAT), abdominal and femoral subcutaneous adipose tissues (SATs) were quantified with positron emission tomography. Abdominal SAT biopsies were collected to determine adipocyte morphology, gene expression markers of lipolysis, glucose and lipid metabolism and inflammation.

RESULTS

Training increased glucose uptake in VAT (p<0.001) and femoral SAT (p<0.001) and decreased fatty acid uptake in VAT (p=0.01) irrespective of baseline glucose tolerance and sex. In IR participants, training increased adipose tissue vasculature and decreased CD36 and ANGPTL4 gene expression in abdominal SAT. SIT was superior in increasing VO_2peak and VAT glucose uptake in the IR group, whereas MICT reduced VAT fatty acid uptake more than SIT.

CONCLUSIONS

Short-term training improves adipose tissue metabolism both in healthy and IR participants independently of the sex. Adipose tissue angiogenesis and gene expression was only significantly affected in IR participants.

The Molecular Adaptive Responses of Skeletal Muscle to High-Intensity Exercise/Training and Hypoxia

High-intensity exercise/training, especially interval exercise/training, has gained popularity in recent years. Hypoxic training was introduced to elite athletes half a century ago and has recently been adopted by the general public. In the current review, we have summarised the molecular adaptive responses of skeletal muscle to high-intensity exercise/training, focusing on mitochondrial biogenesis, angiogenesis, and muscle fibre composition. The literature suggests that (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) PGC-1α, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor 1-alpha (HIF1-α) might be the main mediators of skeletal muscle adaptations to high-intensity exercises in hypoxia. Exercise is known to be anti-inflammatory, while the effects of hypoxia on inflammatory signalling are more complex. The anti-inflammatory effects of a single session of exercise might result from the release of anti-inflammatory myokines and other cytokines, as well as the downregulation of Toll-like receptor signalling, while training-induced anti-inflammatory effects may be due to reductions in abdominal and visceral fat (which are main sources of pro-inflammatory cytokines). Hypoxia can lead to inflammation, and inflammation can result in tissue hypoxia. However, the hypoxic factor HIF1-α is essential for preventing excessive inflammation. Disease-induced hypoxia is related to an upregulation of inflammatory signalling, but the effects of exercise-induced hypoxia on inflammation are less conclusive. The effects of high-intensity exercise under hypoxia on skeletal muscle molecular adaptations and inflammatory signalling have not been fully explored and are worth investigating in future studies. Understanding these effects will lead to a more comprehensive scientific basis for maximising the benefits of high-intensity exercise.

Characterizing the Heart Rate Response to the 4 × 4 Interval Exercise Protocol

High intensity interval training is frequently implemented using the 4 × 4 protocol where four 4-min bouts are performed at heart rate (HR) between 85 and 95% HR max. This study identified the HR and power output response to the 4 × 4 protocol in 39 active men and women (age and VO₂ max = 26.0 ± 6.1 years and 37.0 ± 5.4 mL/kg/min). Initially, participants completed incremental cycling to assess VO₂ max, HR max, and peak power output (PPO). They subsequently completed the 4 × 4 protocol, during which HR and power output were monitored. Data showed that 12.9 ± 0.4 min of 16 min were spent between 85 and 95% HR max, with time spent significantly lower in interval 1 (2.7 ± 0.6 min) versus intervals 2–4 (3.4 ± 0.4 min, 3.4 ± 0.3 min, and 3.5 ± 0.3 min, d = 2.4–2.7). Power output was highest in interval 1 (75% PPO) and significantly declined in intervals 2–4 (63 to 54% PPO, d = 0.7–1.0). To enhance time spent between 85 and 95% HR max for persons with higher fitness, we recommend immediate allocation of supramaximal intensities in interval one.

Efficacy of a Six-Week Dispersed Wingate-Cycle Training Protocol on Peak Aerobic Power, Leg Strength, Insulin Sensitivity, Blood Lipids and Quality of Life in Healthy Adults

The aim of this study was to evaluate the efficacy of a six-week dispersed Wingate Anaerobic test (WAnT) cycle exercise training protocol on peak aerobic power (VO_2peak), isokinetic leg strength, insulin sensitivity, lipid profile and quality of life, in healthy adults. Methods: We conducted a match-controlled cohort trial and participants were assigned to either the training (intervention, INT, N = 16) or non-training (control, CON, N = 17) group. INT performed 30-s WAnT bouts three times a day in the morning, afternoon and evening with each bout separated by ~4 h of rest, performed for 3 days a week for 6 weeks. Criterion measures of peak oxygen uptake (VO_2peak), leg strength, insulin markers such as homeostatic model assessment (HOMA) and quantitative insulin-sensitivity check index (QUICKI), blood lipids profile and health-related quality of life (HRQL) survey were assessed before and after 6 weeks in both groups. Results: Absolute VO_2peak increased by 8.3 ± 7.0% (p < 0.001) after INT vs. 0.9 ± 6.1% in CON (p = 0.41) group. Maximal voluntary contraction at 30°·s^-1 of the dominant lower-limb flexors in INT increased significantly post-training (p = 0.03). There were no changes in the INT individuals' other cardiorespiratory markers, HOMA, QUICKI, blood lipids, and HRQL measures (all p > 0.05) between pre- and post-training; but importantly, no differences were observed between INT and CON groups (all p > 0.05). Conclusions: The results indicate that 6 weeks of dispersed sprint cycle training increased cardiorespiratory fitness and dynamic leg strength but had minimal impact on insulin sensitivity, blood lipids and quality of life in the exercising individuals.

Mitochondrial oxygen affinity increases after sprint interval training and is related to the improvement in peak oxygen uptake

AIMS

The body responds to exercise training by profound adaptations throughout the cardiorespiratory and muscular systems, which may result in improvements in maximal oxygen consumption (VO₂ peak) and mitochondrial capacity. By convenience, mitochondrial respiration is often measured at supra-physiological oxygen levels, an approach that ignores any potential regulatory role of mitochondrial affinity for oxygen (p50_mito ) at physiological oxygen levels.

METHODS

In this study, we examined the p50_mito of mitochondria isolated from the Vastus lateralis and Triceps brachii in 12 healthy volunteers before and after a training intervention with seven sessions of sprint interval training using both leg cycling and arm cranking. The changes in p50_mito were compared to changes in whole-body VO₂ peak.

RESULTS

We here show that p50_mito is similar in isolated mitochondria from the Vastus (40 ± 3.8 Pa) compared to Triceps (39 ± 3.3) but decreases (mitochondrial oxygen affinity increases) after seven sessions of sprint interval training (to 26 ± 2.2 Pa in Vastus and 22 ± 2.7 Pa in Triceps, both P < .01). The change in VO₂ peak modelled from changes in p50_mito was correlated to actual measured changes in VO₂ peak (R²  = .41, P = .002).

CONCLUSION

Together with mitochondrial respiratory capacity, p50_mito is a critical factor when measuring mitochondrial function, it can decrease with sprint interval training and should be considered in the integrative analysis of the oxygen cascade from lung to mitochondria.

MitoTimer-based high-content screen identifies two chemically-related benzothiophene derivatives that enhance basal mitophagy

Mitochondrial turnover is required for proper cellular function. Both mitochondrial biogenesis and mitophagy are impaired in several degenerative and age-related diseases. The search for mitophagy activators recently emerged as a new therapeutical approach; however, there is a lack in suitable tools to follow mitochondrial turnover in a high-throughput manner. We demonstrate that the fluorescent protein, MitoTimer, is a reliable and robust probe to follow mitochondrial turnover. The screening of 15 000 small molecules led us to two chemically-related benzothiophenes that stimulate basal mitophagy in the beta-cell line, INS1. Enhancing basal mitophagy was associated with improved mitochondrial function, higher Complex I activity and Complex II and III expressions in INS1 cells, as well as better insulin secretion performance in mouse islets. The possibility of further enhancing mitophagy in the absence of mitochondrial stressors points to the existence of a 'basal mitophagy spare capacity'. To this end, we found two small molecules that can be used as models to better understand the physiological regulation of mitophagy.

Targeting mitochondrial fitness as a strategy for healthy vascular aging

Cardiovascular diseases (CVD) are the leading cause of death worldwide and aging is the primary risk factor for CVD. The development of vascular dysfunction, including endothelial dysfunction and stiffening of the large elastic arteries (i.e., the aorta and carotid arteries), contribute importantly to the age-related increase in CVD risk. Vascular aging is driven in large part by oxidative stress, which reduces bioavailability of nitric oxide and promotes alterations in the extracellular matrix. A key upstream driver of vascular oxidative stress is age-associated mitochondrial dysfunction. This review will focus on vascular mitochondria, mitochondrial dysregulation and mitochondrial reactive oxygen species (ROS) production and discuss current evidence for prevention and treatment of vascular aging via lifestyle and pharmacological strategies that improve mitochondrial health. We will also identify promising areas and important considerations ('research gaps') for future investigation.

Combined high-intensity interval training and green tea supplementation enhance metabolic and antioxidant status in response to acute exercise in overweight women

Thirty sedentary overweight women were randomly assigned to three groups (n = 10), including HIIT + green tea, HIIT + placebo and green tea. The training program included 3 sessions/week HIIT while the supplement consuming groups took 3 * 500 mg of green tea tablets/day for 10 weeks. Results indicated that 10 weeks of HIIT and green tea meaningfully pronounced baseline serum levels of SIRT1 (P ≤ 0.0001), PGC-1α (P ≤ 0.0001) and CAT (P ≤ 0.0001). In addition, significant increase was observed in three indicators in HIIT + green tea group in comparison with two other research groups. Further, the responses of SIRT1 (P ≤ 0.01) and CAT (P ≤ 0.002) increased significantly to second acute exercise in all three groups. The combination of HIIT and green tea consumption may induce increasing SIRT1 and CAT in response to acute exercise and can improve antioxidant system, body composition and VO2 max results rather than green tea and training alone, in young sedentary overweight women.

Effect of practical hyperoxic high-intensity interval training on exercise performance

This study investigated the effect of a practical hyperoxic high-intensity interval training (HIIT) on aerobic and anaerobic exercise capacity. Sixteen male athletes were randomized into 2 groups: normoxic HIIT (NHIIT, n = 8) group or hyperoxic HIIT (HHIIT, n = 8) group and trained for 3 weeks (2 days/week) on a cycle ergometer (2-min intervals, with 2-min rest between intervals) at maximal workload, which was obtained during a maximal graded exercise test under normoxia. All training sessions were performed until exhaustion. Participants performed maximal graded exercise, submaximal exercise, and 90-s maximal exercise tests before and after the training period. Maximal oxygen uptake (P < 0.01) increased significantly in both groups. Blood lactate curve during submaximal exercise improved significantly only in the HHIIT group (P < 0.01). Mean power output during maximal exercise increased significantly only in the HHIIT group (P = 0.02). This study demonstrated that a practical hyperoxic HHIIT might be effective for improving aerobic capacity and anaerobic performance.

Metabolomics of Endurance Capacity in World Tour Professional Cyclists

The study of elite athletes provides a unique opportunity to define the upper limits of human physiology and performance. Across a variety of sports, these individuals have trained to optimize the physiological parameters of their bodies in order to compete on the world stage. To characterize endurance capacity, techniques such as heart rate monitoring, indirect calorimetry, and whole blood lactate measurement have provided insight into oxygen utilization, and substrate utilization and preference, as well as total metabolic capacity. However, while these techniques enable the measurement of individual, representative variables critical for sports performance, they lack the molecular resolution that is needed to understand which metabolic adaptations are necessary to influence these metrics. Recent advancements in mass spectrometry-based analytical approaches have enabled the measurement of hundreds to thousands of metabolites in a single analysis. Here we employed targeted and untargeted metabolomics approaches to investigate whole blood responses to exercise in elite World Tour (including Tour de France) professional cyclists before and after a graded maximal physiological test. As cyclists within this group demonstrated varying blood lactate accumulation as a function of power output, which is an indicator of performance, we compared metabolic profiles with respect to lactate production to identify adaptations associated with physiological performance. We report that numerous metabolic adaptations occur within this physically elite population (n = 21 males, 28.2 ± 4.7 years old) in association with the rate of lactate accumulation during cycling. Correlation of metabolite values with lactate accumulation has revealed metabolic adaptations that occur in conjunction with improved endurance capacity. In this population, cycling induced increases in tricarboxylic acid (TCA) cycle metabolites and Coenzyme A precursors. These responses occurred proportionally to lactate accumulation, suggesting a link between enhanced mitochondrial networks and the ability to sustain higher workloads. In association with lactate accumulation, altered levels of amino acids before and after exercise point to adaptations that confer unique substrate preference for energy production or to promote more rapid recovery. Cyclists with slower lactate accumulation also have higher levels of basal oxidative stress markers, suggesting long term physiological adaptations in these individuals that support their premier competitive status in worldwide competitions.

Short-term hypoxic training increases monocarboxylate transporter 4 and phosphofructokinase activity in Thoroughbreds

The aim of this study was to investigate effects of short-term hypoxic training on lactate metabolism in the gluteus medius muscle of Thoroughbreds. Using crossover design (3 months washout), eight Thoroughbred horses were trained for 2 weeks in normoxia (FI O2  = 21%) and hypoxia (FI O2  = 18%) each. They ran at 95% maximal oxygen consumption (V̇O2max ) on a treadmill inclined at 6% for 2 min (3 days/week) measured under normoxia. Before and after each training period, all horses were subjected to an incremental exercise test (IET) under normoxia. Following the 2-week trainings, V̇O2max in IET increased significantly under both oxygen conditions. The exercise duration in IET increased significantly only after hypoxic training. The monocarboxylate transporter (MCT) 1 protein levels remained unchanged after training under both oxygen conditions, whereas MCT4 protein levels increased significantly after training in hypoxia but not after training in normoxia. Phosphofructokinase activity increased significantly only after hypoxic training, whereas cytochrome c oxidase activity increased significantly only after normoxic training. Our results suggest that hypoxic training efficiently enhances glycolytic capacity and levels of the lactate transporter protein MCT4, which facilitates lactate efflux from the skeletal muscle.

Effect of HIIT with Tabata Protocol on Serum Irisin, Physical Performance, and Body Composition in Men

High-intensity interval training (HIIT) is frequently utilized as a method to reduce body mass. Its intensity of work results in a number of beneficial adaptive changes in a relatively short period of time. Irisin is a myokine and adipokine secreted to the blood during exercise and it takes part in the regulation of energy metabolism. It is a vital issue from the prophylaxis point of view as well as treatment through exercise of different diseases (e.g., obesity, type-2 diabetes). The aim of this study was to evaluate changes in irisin concentration, body composition, and aerobic and anaerobic performance in men after HIIT. Eight weeks of HIIT following the Tabata protocol was applied in the training group (HT) (n = 15), while a sedentary group (SED) (n = 10) did not participate in fitness activities within the same time period. Changes of irisin, body composition, and aerobic and anaerobic performance were evaluated after graded exercise test (GXT) and Wingate anaerobic test (WAnT) before and after eight weeks of training. Training resulted in an increased of blood irisin concentration (by 29.7%) p < 0.05), VO_2max increase (PRE: 44.86 ± 5.74 mL·kg⁻¹·min⁻¹; POST: 50.16 ± 5.80 mL kg⁻¹·min⁻¹; p < 0.05), reduction in percent body fat (PRE: 14.44 ± 3.33%; POST: 13.61 ± 3.16%; p < 0.05), and increase of WAnT parameters (p < 0.05) in the HT group. No changes were observed in the SED group. HIIT resulted in beneficial effects in the increase in blood irisin concentration, physical performance, and reduced fat content. The HIIT may indicate an acceleration of base metabolism. This effect can be utilized in the prevention or treatment of obesity.

The effect of sleep restriction, with or without high-intensity interval exercise, on myofibrillar protein synthesis in healthy young men

Key points

Sleep restriction has previously been associated with the loss of muscle mass in both human and animal models.

The rate of myofibrillar protein synthesis (MyoPS) is a key variable in regulating skeletal muscle mass and can be increased by performing high‐intensity interval exercise (HIIE), although the effect of sleep restriction on MyoPS is unknown.

In the present study, we demonstrate that participants undergoing a sleep restriction protocol (five nights, with 4 h in bed each night) had lower rates of skeletal muscle MyoPS; however, rates of MyoPS were maintained at control levels by performing HIIE during this period.

Our data suggest that the lower rates of MyoPS in the sleep restriction group may contribute to the detrimental effects of sleep loss on muscle mass and that HIIE may be used as an intervention to counteract these effects.

Abstract

The present study aimed to investigate the effect of sleep restriction, with or without high‐intensity interval exercise (HIIE), on the potential mechanisms underpinning previously‐reported sleep‐loss‐induced reductions to muscle mass. Twenty‐four healthy, young men underwent a protocol consisting of two nights of controlled baseline sleep and a five‐night intervention period. Participants were allocated into one of three parallel groups, matched for age, V˙O2peak, body mass index and habitual sleep duration; a normal sleep (NS) group [8 h time in bed (TIB) each night], a sleep restriction (SR) group (4 h TIB each night), and a sleep restriction and exercise group (SR+EX, 4 h TIB each night, with three sessions of HIIE). Deuterium oxide was ingested prior to commencing the study and muscle biopsies obtained pre‐ and post‐intervention were used to assess myofibrillar protein synthesis (MyoPS) and molecular markers of protein synthesis and degradation signalling pathways. MyoPS was lower in the SR group [fractional synthetic rate (% day^–1), mean ± SD, 1.24 ± 0.21] compared to both the NS (1.53 ± 0.09) and SR+EX groups (1.61 ± 0.14) (P < 0.05). However, there were no changes in the purported regulators of protein synthesis (i.e. p‐AKT^ser473 and p‐mTOR^ser2448) and degradation (i.e. Foxo1/3 mRNA and LC3 protein) in any group. These data suggest that MyoPS is acutely reduced by sleep restriction, although MyoPS can be maintained by performing HIIE. These findings may explain the sleep‐loss‐induced reductions in muscle mass previously reported and also highlight the potential therapeutic benefit of HIIE to maintain myofibrillar remodelling in this context.

Sleep restriction has previously been associated with the loss of muscle mass in both human and animal models.

The rate of myofibrillar protein synthesis (MyoPS) is a key variable in regulating skeletal muscle mass and can be increased by performing high‐intensity interval exercise (HIIE), although the effect of sleep restriction on MyoPS is unknown.

In the present study, we demonstrate that participants undergoing a sleep restriction protocol (five nights, with 4 h in bed each night) had lower rates of skeletal muscle MyoPS; however, rates of MyoPS were maintained at control levels by performing HIIE during this period.

Our data suggest that the lower rates of MyoPS in the sleep restriction group may contribute to the detrimental effects of sleep loss on muscle mass and that HIIE may be used as an intervention to counteract these effects.

High-intensity interval training produces a significant improvement in fitness in less than 31 days before surgery for urological cancer: a randomised control trial

Objectives

To assess the efficacy of high-intensity interval training (HIIT) for improving cardiorespiratory fitness (CRF) in patients awaiting resection for urological malignancy within four weeks.

Subjects/patients and methods

A randomised control trial of consecutive patients aged (>65 years) scheduled for major urological surgery in a large secondary referral centre in a UK hospital. The primary outcome is change in anaerobic threshold (VO_2AT) following HIIT vs. standard care.

Results

Forty patients were recruited (mean age 72 years, male (39): female (1)) with 34 completing the protocol. Intention to treat analysis showed significant improvements in anaerobic threshold (VO_2AT; mean difference (MD) 2.26 ml/kg/min (95% CI 1.25–3.26)) following HIIT. Blood pressure (BP) also significantly reduced in following: HIIT (SBP: −8.2 mmHg (95% CI −16.09 to −0.29) and DBP: −6.47 mmHg (95% CI −12.56 to −0.38)). No reportable adverse safety events occurred during HIIT and all participants achieved >85% predicted maximum heart rate during sessions, with protocol adherence of 84%.

Conclusions

HIIT can improve CRF and cardiovascular health, representing clinically meaningful and achievable pre-operative improvements. Larger randomised trials are required to investigate the efficacy of prehabilitation HIIT upon different cancer types, post-operative complications, socio-economic impact and long-term survival.

Similar Cardioventilatory but Greater Neuromuscular Stimuli With Interval Drop Jump Than With Interval Running

CONTEXT

Drop jumps and high-intensity interval running are relevant training methods to improve explosiveness and endurance performance, respectively. Combined training effects might, however, be achieved by performing interval drop jumping.

PURPOSE

To determine the acute effects of interval drop jumping on oxygen uptake (V˙O2)-index of cardioventilatory/oxidative stimulation level and peripheral fatigue-a limiting factor of explosiveness.

METHODS

Thirteen participants performed three 11-minute interval training sessions during which they ran 15 seconds at 120% of the velocity that elicited maximal V˙O2 (V˙O2max) (ITrun), or drop jumped at 7 (ITDJ7) or 9 (ITDJ9) jumps per 15 seconds, interspersed with 15 seconds of passive recovery. V˙O2 and the time spent above 90% of V˙O2max (V˙TO2max) were collected. Peripheral fatigue was quantified via preexercise to postexercise changes in evoked potentiated quadriceps twitch (ΔQT). Power output was estimated during ITDJs using optical sensors.

RESULTS

All participants reached 90% of V˙O2max or higher during ITrun and ITDJ9, but only 11 did during ITDJ7. V˙TO2max was not different between ITrun and ITDJ9 (145 [76] vs 141 [151] s; P = .92) but was reduced during ITDJ7 (28 [26] s; P = .002). Mean ΔQT in ITDJ9 and ITDJ7 was not different (-17% [9%] vs -14% [8%]; P = .73) and greater than in ITrun (-8% [7%]; P = .001). No alteration in power output was found during ITDJs (37 [10] W·kg-1).

CONCLUSION

Interval drop jumping at a high work rate stimulated the cardioventilatory and oxidative systems to the same extent as interval running, while the exercise-induced increase in fatigue did not compromise drop jump performance. Interval drop jumping might be a relevant strategy to get concomitant improvements in endurance and explosive performance.

Supplements and Nutritional Interventions to Augment High-Intensity Interval Training Physiological and Performance Adaptations-A Narrative Review

High-intensity interval training (HIIT) involves short bursts of intense activity interspersed by periods of low-intensity exercise or rest. HIIT is a viable alternative to traditional continuous moderate-intensity endurance training to enhance maximal oxygen uptake and endurance performance. Combining nutritional strategies with HIIT may result in more favorable outcomes. The purpose of this narrative review is to highlight key dietary interventions that may augment adaptations to HIIT, including creatine monohydrate, caffeine, nitrate, sodium bicarbonate, beta-alanine, protein, and essential amino acids, as well as manipulating carbohydrate availability. Nutrient timing and potential sex differences are also discussed. Overall, sodium bicarbonate and nitrates show promise for enhancing HIIT adaptations and performance. Beta-alanine has the potential to increase training volume and intensity and improve HIIT adaptations. Caffeine and creatine have potential benefits, however, longer-term studies are lacking. Presently, there is a lack of evidence supporting high protein diets to augment HIIT. Low carbohydrate training enhances the upregulation of mitochondrial enzymes, however, there does not seem to be a performance advantage, and a periodized approach may be warranted. Lastly, potential sex differences suggest the need for future research to examine sex-specific nutritional strategies in response to HIIT.

Acute Sprint Interval Exercise Increases Both Cognitive Functions and Peripheral Neurotrophic Factors in Humans: The Possible Involvement of Lactate

There is increasing attention to sprint interval exercise (SIE) training as a time-efficient exercise regime. Recent studies, including our own (Kujach et al., 2018), have shown that acute high-intensity intermittent exercise can improve cognitive function; however, the neurobiological mechanisms underlying the effect still remain unknown. We thus examined the effects of acute SIE on cognitive function by monitoring the peripheral levels of growth and neurotrophic factors as well as blood lactate (LA) as potential mechanisms. Thirty-six young males participated in the current study and were divided into two groups: SIE (n = 20; mean age: 21.0 ± 0.9 years) and resting control (CTR) (n = 16; mean age: 21.7 ± 1.3 years). The SIE session consisted of 5 min of warm-up exercise and six sets of 30 s of all-out cycling exercise followed by 4.5 min of rest on a cycling-ergometer. Blood samples to evaluate the changes of serum concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), and blood LA were obtained at three time points: before, immediately after, and 60 min after each session. A Stroop task (ST) and trail making test (TMT) parts A and B were used to assess cognitive functions. Acute SIE shortened response times for both the ST and TMT A and B. Meanwhile, the peripheral levels of BDNF, IGF-1, and VEGF were significantly increased after an acute bout of SIE compared to those in CTR. In response to acute SIE, blood LA levels significantly increased and correlated with increased levels of BDNF, IGF-1, and VEGF. Furthermore, cognitive function and BDNF are found to be correlated. The current results suggest that SIE could have beneficial effects on cognitive functions with increased neuroprotective factors along with peripheral LA concentration in humans.

Pterostilbene Enhances Endurance Capacity via Promoting Skeletal Muscle Adaptations to Exercise Training in Rats

It has been demonstrated that skeletal muscle adaptions, including muscle fibers transition, angiogenesis, and mitochondrial biogenesis are involved in the regular exercise-induced improvement of endurance capacity and metabolic status. Herein, we investigated the effects of pterostilbene (PST) supplementation on skeletal muscle adaptations to exercise training in rats. Six-week-old male Sprague Dawley rats were randomly divided into a sedentary control group (Sed), an exercise training group (Ex), and exercise training combined with 50 mg/kg PST (Ex + PST) treatment group. After 4 weeks of intervention, an exhaustive running test was performed, and muscle fiber type transformation, angiogenesis, and mitochondrial content in the soleus muscle were measured. Additionally, the effects of PST on muscle fiber transformation, paracrine regulation of angiogenesis, and mitochondrial function were tested in vitro using C2C12 myotubes. In vivo study showed that exercise training resulted in significant increases in time-to-exhaustion, the proportion of slow-twitch fibers, muscular angiogenesis, and mitochondrial biogenesis in rats, and these effects induced by exercise training could be augmented by PST supplementation. Moreover, the in vitro study showed that PST treatment remarkably promoted slow-twitch fibers formation, angiogenic factor expression, and mitochondrial function in C2C12 myotubes. Collectively, our results suggest that PST promotes skeletal muscle adaptations to exercise training thereby enhancing the endurance capacity.

Short-Term Acute Exercise Preconditioning Reduces Neurovascular Injury After Stroke Through Induced eNOS Activation

Physical exercise is known to reduce cardiovascular risk but its role in ischemic stroke is not clear. It was previously shown that an acute single bout of exercise reduced increased eNOS activation in the heart and reduced myocardial infarction. However, the impact of a single bout or short-term exercise on eNOS-induced neuroprotection after stroke was not previously studied. Accordingly, this study was designed to test the hypothesis that short-term acute exercise can provide "immediate neuroprotection" and improve stroke outcomes through induced eNOS activation. Male Wistar rats (300 g) were subjected to HIIT treadmill exercise for 4 days (25 min/day), break for 2 days, and then one acute bout for 30 min. Exercised animals were subjected to thromboembolic stroke 1 h, 6 h, 24 h, or 72 h after the last exercise session. At 24 h after stroke, control (sedentary) and exercised rats were tested for neurological outcomes, infarct size, and edema. The expression of active eNOS (p-S1177-eNOS) and active AMPK (p-T172-AMPK) was measured in the brain, cerebral vessels, and aorta. In an additional cohort, animals were treated with the eNOS inhibitor, L-NIO (I.P, 20 mg/kg), and stroked 1 h after exercise and compared with non-exercise animals. Acute exercise significantly reduced infarct size, edema, and improved functional outcomes, and significantly increased the expression of peNOS and pAMPK in the brain, cerebral vessels, and aorta. eNOS inhibition abolished the exercise-induced improvement in outcomes. Short-term acute preconditioning exercise reduced the neurovascular injury and improved functional outcomes after stroke through eNOS activation.

Sarcopenia: Tilting the Balance of Protein Homeostasis

Sarcopenia, defined as age-associated decline of muscle mass and function, is a risk factor for mortality and disability, and comorbid with several chronic diseases such as type II diabetes and cardiovascular diseases. Clinical trials showed that nutritional supplements had positive effects on muscle mass, but not on muscle function and strength, demonstrating our limited understanding of the molecular events involved in the ageing muscle. Protein homeostasis, the equilibrium between protein synthesis and degradation, is proposed as the major mechanism underlying the development of sarcopenia. As the key central regulator of protein homeostasis, the mammalian target of rapamycin (mTOR) is proposed to be essential for muscle hypertrophy. Paradoxically, sustained activation of mTOR complex 1 (mTORC1) is associated with a loss of sensitivity to extracellular signaling in the elderly. It is not understood why sustained mTORC1 activity, which should induce muscle hypertrophy, instead results in muscle atrophy. Here, recent findings on the implications of disrupting protein homeostasis on muscle physiology and sarcopenia development in the context of mTOR/protein kinase B (AKT) signaling are reviewed. Understanding the role of these molecular mechanisms during the ageing process will contribute towards the development of targeted therapies that will improve protein metabolism and reduce sarcopenia.

Two Weeks of Interval Training Enhances Fat Oxidation during Exercise in Obese Adults with Prediabetes

Prediabetes is associated with impaired oxidative capacity and altered substrate utilization during exercise. The effects of continuous (CONT) versus interval (INT) exercise training on fat oxidation during an acute exercise bout at the same absolute and relative intensities are unknown in this population. Obese females/males (n = 17, n = 5) with prediabetes (BMI 32.2 ± 1.2 kg·m-2; age 62.8 ± 1.6 y; fasting glucose 103.4 ± 1.6 mg·dL-1; 2-hour glucose 153.7 ± 7.1 mg·dL-1; VO2peak 19.9 ± 1.0 mL·kg-1·min-1) were screened with a 75g OGTT. Subjects completed a peak oxygen consumption test and a submaximal exercise substrate utilization test consisting of 5min stages at absolute (30W) and relative (70%HRpeak) intensities before and after randomization to 12 sessions (60min each) of CONT (70% HRpeak) or INT (alternating 3min 90% HRpeak, 3min 50% HRpeak) over a two-week period. Body mass decreased and VO2peak increased more after INT than CONT (INT: -0.6 ± 0.2 kg, CONT: -0.1 ± 0.2 kg; p = 0.04; INT: 1.9 ± 0.6 mL/kg/min, CONT: 0.1 ± 0.6 mL·kg-1·min-1; p = 0.04). Training increased fat oxidation by 0.7 ± 0.2 mL·kg-1·min-1 during the absolute intensity test (p < 0.001), independent of intensity. During the relative intensity test, fat oxidation increased more after INT than CONT (INT: 1.3 ± 0.4 mL·kg-1·min-1, CONT: 0.3 ± 0.3 mL·kg-1·min-1; p = 0.03), with no difference in exercise energy expenditure between groups. Enhanced fat oxidation during the relative test was correlated with increased VO2peak (r = 0.53 p = 0.01). High intensity INT training enhances fat oxidation during the same relative intensity exercise in people with prediabetes.

High intensity interval training and molecular adaptive response of skeletal muscle

Increased cardiovascular fitness, V˙O_2max, is associated with enhanced endurance capacity and a decreased rate of mortality. High intensity interval training (HIIT) is one of the best methods to increase V˙O_2max and endurance capacity for top athletes and for the general public as well. Because of the high intensity of this type of training, the adaptive response is not restricted to Type I fibers, as found for moderate intensity exercise of long duration. Even with a short exercise duration, HIIT can induce activation of AMPK, PGC-1α, SIRT1 and ROS pathway as well as by the modulation of Ca²⁺ homeostasis, leading to enhanced mitochondrial biogenesis, and angiogenesis. The present review summarizes the current knowledge of the adaptive response of HIIT.

Effect of β-alanine supplementation during high-intensity interval training on repeated sprint ability performance and neuromuscular fatigue

The study investigated the influence of β-alanine supplementation during a high-intensity interval training (HIIT) program on repeated sprint ability (RSA) performance. This study was randomized, double-blinded, and placebo controlled. Eighteen men performed an incremental running test until exhaustion (TINC) at baseline and followed by 4-wk HIIT (10 × 1-min runs 90% maximal TINCvelocity [1-min recovery]). Then, participants were randomized into two groups and performed a 6-wk HIIT associated with supplementation of 6.4 g/day of β-alanine (Gβ) or dextrose (placebo group; GP). Pre- and post-6-wk HIIT + supplementation, participants performed the following tests: 1) TINC; 2) supramaximal running test; and 3) 2 × 6 × 35-m sprints (RSA). Before and immediately after RSA, neuromuscular function was assessed by vertical jumps, maximal isometric voluntary contractions of knee extension, and neuromuscular electrical stimulations. Muscle biopsies were performed to determine muscle carnosine content, muscle buffering capacity in vitro (βmin vitro), and content of phosphofructokinase (PFK), monocarboxylate transporter 4 (MCT4), and hypoxia-inducible factor-1α (HIF-1α). Both groups showed a significant time effect for maximal oxygen uptake (Gβ: 6.2 ± 3.6% and GP: 6.5 ± 4.2%; P > 0.01); only Gβ showed a time effect for total (−3.0 ± 2.0%; P = 0.001) and best (−3.3 ± 3.0%; P = 0.03) RSA times. A group-by-time interaction was shown after HIIT + Supplementation for muscle carnosine (Gβ: 34.4 ± 2.3 mmol·kg−1·dm−1and GP: 20.7 ± 3.0 mmol·kg−1·dm−1; P = 0.003) and neuromuscular voluntary activation after RSA (Gβ: 87.2 ± 3.3% and GP: 78.9 ± 12.4%; P = 0.02). No time effect or group-by-time interaction was shown for supramaximal running test performance, βm, and content of PFK, MCT4, and HIF-1α. In summary, β-alanine supplementation during HIIT increased muscle carnosine and attenuated neuromuscular fatigue, which may contribute to an enhancement of RSA performance.

NEW & NOTEWORTHY β-Alanine supplementation during a high-intensity interval training program increased repeated sprint performance. The improvement of muscle carnosine content induced by β-alanine supplementation may have contributed to an attenuation of central fatigue during repeated sprint. Overall, β-alanine supplementation may be a useful dietary intervention to prevent fatigue.

Regulation of Skeletal Muscle Glucose Transport and Glucose Metabolism by Exercise Training

Aerobic exercise training and resistance exercise training are both well-known for their ability to improve human health; especially in individuals with type 2 diabetes. However, there are critical differences between these two main forms of exercise training and the adaptations that they induce in the body that may account for their beneficial effects. This article reviews the literature and highlights key gaps in our current understanding of the effects of aerobic and resistance exercise training on the regulation of systemic glucose homeostasis, skeletal muscle glucose transport and skeletal muscle glucose metabolism.

Does a HIIT modulate BDNF levels, and epigenetic and muscle damage markers in postmenopausal obese women?

Recent clinical studies demonstrated that single bouts of exercise including high intensity interval training (HIIT) protocols are able to modulate muscle damage and epigenetic markers as well as brain-derived neurotrophic factor (BDNF) levels in different populations, however, this relationship is lacking in obese women. To evaluate the impact of a single bout of HIIT on creatine kinase (CK), BDNF and global histone H3 and H4 acetylation levels in obese postmenopausal women. The sample consisted of 10 volunteers with a body mass index of 27 to 39.9 kg / m2 that were submitted to a single session of HIIT on a cycle ergometer for 60 s (separated by 75 s of active recovery). In order to measure the biomarkers, blood samples (15 ml) were collected immediately before and immediately after the intervention. Our protocol did not modify any biomarkers (P>0.05), although a negative correlation between fat mass and global histone H3 levels (P=0.022) and between oxygen consumption and global histone H4 levels (P=0.003) were found. A single bout of HIIT on a cycle ergometer is not an effective strategy to modulate histone acetylation status, CK and BDNF levels in postmenopausal obese women. Future studies considering different exercise protocols should be done in order to elucidate this issue.

Logistics performance collaboration strategy and information sharing with logistics capability as mediator variable (study in Gafeksi East Java Indonesia)

Purpose

The purpose of this paper is to analyze the effect of collaboration, capability and information sharing (IS) on logistic performance, the effect of collaboration and IS on capabilities, the effect of collaboration on logistic performance through capabilities, the influence of IS on logistic performance through capabilities and the effect of logistics capabilities on logistics performance.

Design/methodology/approach

This study uses a quantitative approach and is included in explanatory research. This research uses cross section research design. The research populations are all companies incorporated in GAFEKSI (Joint Forwarder and Expedition Indonesia) of East Java. Sampling in this research is by using a purposive sample. The sample of this study amounted to 47 forwarder and expedition companies. Data analysis method used is partial least square.

Findings

Collaboration has a positive impact on capabilities (CAP); capability (LOC) positive impact on logistic performance; collaboration does not directly affect the logistics performance; and construct capabilities (LOC) is the mediation of IS in building business logistics performance. Increasing the intensity of IS has no direct contribution to increased flexibility, and collaboration is driven by partnership and network, whereas CT (trust) can be ignored, as it is not proven to make a dominant contribution to collaboration.

Originality/value

The novelty of this research is found in the strategic role of capabilities as the dominant latent variable in building business performance of logistic companies. This study finds dual mediation, where both mediations are expressed as full mediation, because the direct effect of mediator latent variables is significant (Little et al., 2010; Hair et al., 1995).

Dietary protein and exercise for preservation of lean mass and perspectives on type 2 diabetes prevention

Sedentary lifestyle and aging favor the increasing prevalence of obesity and type 2 diabetes and their comorbidities. The loss of lean body mass reduces muscle strength, resulting in impaired functional capacity and leading to increased risks of chronic diseases with advancing age. Besides aging, conditions such as inappetence, social isolation, and inadequate dietary intake cause the loss of lean body mass and increased abdominal fatty mass, resulting in sarcopenic obesity and predisposition to type 2 diabetes. Compared to younger people, this condition is more common in the elderly owing to natural changes in body composition associated with aging. Lifestyle changes such as increased physical activity and improved dietary behaviors are effective for preventing the occurrence of comorbidities. Regarding muscle nutrition, besides caloric adequacy, meeting the requirements for the consumption of dietary amino acids and proteins is important for treating sarcopenia and sarcopenic obesity because muscle tissue mainly consists of proteins and is, therefore, the largest reservoir of amino acids in the body. Thus, this review discusses the effects of dietary protein on the preservation of lean body mass, improvements in the functional capacity of muscle tissue, and prevention of chronic diseases such as type 2 diabetes. In addition, we address the effects of regular physical training associated with dietary protein strategies on lean body mass, body fat loss, and muscle strength in the elderly at a risk for type 2 diabetes development.

SIX HIT TREADMILL SESSIONS IMPROVE LIPID OXIDATION AND VENTILATORY THRESHOLD INTENSITIES

ABSTRACT Introduction: High-intensity interval training (HIT) has been used as an alternative to cardiorespiratory training performed continuously at submaximal intensity and over long periods. Objectives: Propose a treadmill HIT protocol and verify the influence of six HIT sessions with this protocol on ventilatory anaerobic thresholds (VATs) and substrate oxidation pattern during submaximal continuous exercise (SCE). Methods: Fifteen sporadically active subjects underwent maximal progressive testing before and after six HIT treadmill running sessions to determine peak oxygen uptake (VO2peak), peak velocity (Vpeak), and VATs followed by SCE to determine lipid (LIPox) and carbohydrate (CHOox) oxidation rates. The HIT sessions consisted of eight sets of 60s at 100%Vpeak, interspersed with 75s of passive recovery between sets and a 48h interval between sessions. Results: Our results showed increases in VAT intensities of 4.4% for VAT1 and 8.8% for VAT2, a decrease of 12.8% in CHOox and an increase of 23.7% for LIPox; accordingly, the relative energy derived from LIPox was 20.3% higher after the training period. Vpeak was ~15 km/h, producing intensities corresponding to ~84%VO2peak and ~91%FCpeak over the training period. Conclusion: The proposed protocol produced adaptations and intensities which are similar to those described in the literature, but unlike others, it can be applied in sporadically active individuals. Level of Evidence II; Comparative prospective study.

Protein arginine methyltransferase biology in humans during acute and chronic skeletal muscle plasticity

Protein arginine methyltransferases (PRMTs) are a family of enzymes that catalyze the methylation of arginine residues on target proteins. While dysregulation of PRMTs has been documented in a number of the most prevalent diseases, our understanding of PRMT biology in human skeletal muscle is limited. This study served to address this knowledge gap by exploring PRMT expression and function in human skeletal muscle in vivo and characterizing PRMT biology in response to acute and chronic stimuli for muscle plasticity. Fourteen untrained, healthy men performed one session of sprint interval exercise (SIE) before completing four bouts of SIE per week for 6 wk as part of a sprint interval training (SIT) program. Throughout this time course, multiple muscle biopsies were collected. We found that at basal, resting conditions PRMT1, PRMT4, PRMT5, and PRMT7 were the most abundantly expressed PRMT mRNAs in human quadriceps muscle. Additionally, the broad subcellular distribution pattern of PRMTs suggests methyltransferase activity throughout human myofibers. A spectrum of PRMT-specific inductions, and decrements, in expression and activity were observed in response to acute and chronic cues for muscle plasticity. In conclusion, our findings demonstrate that PRMTs are present and active in human skeletal muscle in vivo and that there are distinct, enzyme-specific responses and adaptations in PRMT biology to acute and chronic stimuli for muscle plasticity. This work advances our understanding of this critical family of enzymes in humans.NEW & NOTEWORTHY This is the first report of protein arginine methyltransferase (PRMT) biology in human skeletal muscle in vivo. We observed that PRMT1, -4, -5, and -7 were the most abundant PRMT mRNAs in human muscle and that PRMT proteins exhibited a broad subcellular localization that included myonuclear, cytosolic, and sarcolemmal compartments. Acute exercise and chronic training evoked PRMT-specific alterations in expression and activity. This study reveals a hitherto unknown complexity to PRMT biology in human muscle.

High-intensity interval training for health benefits and care of cardiac diseases - The key to an efficient exercise protocol

Aerobic capacity, which is expressed as peak oxygen consumption (VO_2peak), is well-known to be an independent predictor of all-cause mortality and cardiovascular prognosis. This is true even for people with various coronary risk factors and cardiovascular diseases. Although exercise training is the best method to improve VO_2peak, the guidelines of most academic societies recommend 150 or 75 min of moderate- or vigorous- intensity physical activities, respectively, every week to gain health benefits. For general health and primary and secondary cardiovascular prevention, high-intensity interval training (HIIT) has been recognized as an efficient exercise protocol with short exercise sessions. Given the availability of the numerous HIIT protocols, which can be classified into aerobic HIIT and anaerobic HIIT [usually called sprint interval training (SIT)], professionals in health-related fields, including primary physicians and cardiologists, may find it confusing when trying to select an appropriate protocol for their patients. This review describes the classifications of aerobic HIIT and SIT, and their differences in terms of effects, target subjects, adaptability, working mechanisms, and safety. Understanding the HIIT protocols and adopting the correct type for each subject would lead to better improvements in VO_2peak with higher adherence and less risk.

Long-term voluntary wheel running does not alter vascular amyloid burden but reduces neuroinflammation in the Tg-SwDI mouse model of cerebral amyloid angiopathy

BACKGROUND

Cardiovascular exercise (CVE) has been shown to be protective against cognitive decline in aging and the risk for dementias, including Alzheimer's Disease (AD). CVE has also been shown to have several beneficial effects on brain pathology and behavioral impairments in mouse models of AD; however, no studies have specifically examined the effects of CVE on cerebral amyloid angiopathy (CAA), which is the accumulation of amyloid-beta (Aβ) in the cerebral vasculature. CAA may be uniquely susceptible to beneficial effects of CVE interventions due to the location and nature of the pathology. Alternatively, CVE may exacerbate CAA pathology, due to added stress on already compromised cerebral vasculature.

METHODS

In the current study, we examined the effects of CVE over many months in mice, thereby modeling a lifelong commitment to CVE in humans. We assessed this voluntary CVE in Tg-SwDI mice, a transgenic mouse model of CAA that exhibits behavioral deficits, fibrillar vascular Aβ pathology, and significant perivascular neuroinflammation. Various "doses" of exercise intervention (0 h ("Sedentary"), 1 h, 3 h, 12 h access to running wheel) were assessed from ~ 4 to 12 months of age for effects on physiology, behavior/cognitive performance, and pathology.

RESULTS

The 12 h group performed the greatest volume of exercise, whereas the 1 h and 3 h groups showed high levels of exercise intensity, as defined by more frequent and longer duration running bouts. Tg-SwDI mice exhibited significant cerebral vascular Aβ pathology and increased expression of pro-inflammatory cytokines as compared to WT controls. Tg-SwDI mice did not show motor dysfunction or altered levels of anxiety or sociability compared to WT controls, though Tg-SwDI animals did appear to exhibit a reduced tendency to explore novel environments. At all running levels, CAA pathology in Tg-SwDI mice was not significantly altered, but 12-h high-volume exercise showed increased insoluble Aβ burden. However, CVE attenuated the expression of pro-inflammatory cytokines TNF-α and IL-6 and was generally effective at enhancing motor function and reducing anxiety-like behavior in Tg-SwDI mice, though alterations in learning and memory tasks were varied.

CONCLUSIONS

Taken together, these results suggest that CAA can still develop regardless of a lifespan of substantial CVE, although downstream effects on neuroinflammation may be reduced and functional outcomes improved.

Comparison of excess post-exercise oxygen consumption of different exercises in normal weight obesity women

[Purpose]

The purpose of this study was to compare the excess post-exercise oxygen consumption (EPOC) between different types of exercises in women with normal weight obesity (NWO).

[Methods]

Nine university students with NWO having body mass index <25 kg/m² and body fat percentage >30% participated in the study. First, continuous exercise (CEx) on an ergometer for 30 minutes at 60% of maximal oxygen consumption (VO_2max) and interval exercise (IEx) at 80% VO_2max for 2 minutes were performed. This was followed by exercise performed at 40% VO_2max for 1 minute and at 80% VO_2max for 3 minutes, performed 6 times repeatedly for a total of 26 minutes. The accumulation of short duration exercise (AEx) was performed for 3-bouts of 10 minutes each at 60% VO_2max.

[Results]

The major findings were as follows: energy consumption during the exercises showed no significant difference between CEx, IEx, and AEx; EPOC was higher in IEx and AEx as compared to CEx for all dependent variables (e.g. total oxygen consumption, total calorie, summation of heart rate, and EPOC duration); and the lipid profile showed no significant difference.

[Conclusion]

Our study confirmed that when homogenizing the energy expenditure for various exercises in NWO individuals, EPOC was higher in IEx and AEx than in CEx. Therefore, IEx and AEx can be considered as effective exercise methods for increasing energy expenditure in NWO females.

Stay Fit, Stay Young: Mitochondria in Movement: The Role of Exercise in the New Mitochondrial Paradigm

Skeletal muscles require the proper production and distribution of energy to sustain their work. To ensure this requirement is met, mitochondria form large networks within skeletal muscle cells, and during exercise, they can enhance their functions. In the present review, we discuss recent findings on exercise-induced mitochondrial adaptations. We emphasize the importance of mitochondrial biogenesis, morphological changes, and increases in respiratory supercomplex formation as mechanisms triggered by exercise that may increase the function of skeletal muscles. Finally, we highlight the possible effects of nutraceutical compounds on mitochondrial performance during exercise and outline the use of exercise as a therapeutic tool in noncommunicable disease prevention. The resulting picture shows that the modulation of mitochondrial activity by exercise is not only fundamental for physical performance but also a key point for whole-organism well-being.