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Introduction: High-intensity interval exercise (HIIE) is more effective than moderate-intensity interval exercise (MICE) for improving macrovascular function (e.g., flow-mediated dilation), but less is known regarding the effect of HIIE on microvascular function. We used peripheral artery tonometry to measure the reactive hyperemia index (RHI) and examine the acute effects of HIIE and MICE on microvascular function., Methods: Ten healthy participants (50% men, age: 26 ± 5 years, mass: 75.6 ± 15.1 kg, height: 170 ± 10 cm, body mass index: 26.0 ± 3.1 kg∙m -2 ) performed single bouts of HIIE and MICE cycling on separate occasions. The MICE protocol was 20 min at 60% of maximum power output. The HIIE protocol was a 12-min warm up at 50% of maximum power output immediately followed by an 8-min Tabata protocol where participants alternated between cycling at ⩾ 100% max power (20 sec) and rest (10 sec). The RHI was measured before, immediately after, and 1 h after exercise and compared by two-way repeated measures analysis of variance (condition [MICE, HIIE] and time [pre-, post-, and 1-h postexercise])., Results: Compared to baseline, RHI increased 1 h after MICE only ( p = 0.02). Heart rate was higher during MICE at 5 and 10 min ( p = 0.02) and higher during HIIE at min 20 ( p < 0.01)., Conclusion: Within a sample of healthy adults, the RHI was improved 1 h after a single session of MICE but not HIIE. Future research is needed to determine the significance of the differential effects of exercise regimens on the macro- and microvasculature., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background : Diabetes patients' quality of life can be severely impacted by diabetic muscle atrophy. Aim : This study aimed to explore the impact of high-intensity exercise (HIE) alongside insulin treatment on muscle atrophy in a rat model of type 1 diabetes mellitus (T1DM). Methodology : Fifty rats were allocated into five groups; Group 1, control sedentary (CS), T1DM was elicited in the rest of the groups by giving them Streptozotocin (STZ) (60 mg/kg), where group 2 (DS) remained sedentary, while groups 3,4,5 were treated with insulin after induction of diabetes. Group 4 (DI+MIE) and 5 (DI+ HIE) underwent moderate and high-intensity exercise, respectively. Results : HIE for 14 days combined with insulin treatment significantly restored muscle strength and mass with a significant modification in the mitophagy-related proteins and fibroblast growth factor 21 (FGF 21) compared to other treated groups. Conclusion : This study concluded that there is a therapeutic role for HIE with insulin against T1DM-induced muscle atrophy.

Background: Regular exercise during pregnancy is beneficial, but athletes often exceed the recommended 150 min of moderate-intensity activity, incorporate high-intensity exercises. The upper limit for exercise intensity and duration on fetal and maternal safety remains uncertain. A concern is a maternal core body temperature of >39.0 °C, potentially increase the risk of heat-related fetal malformations and complications during pregnancy. Blood flow redirection for thermoregulation could compromise fetal cardiovascular function, increasing the risk of miscarriage and preterm labor. This study evaluated whether pregnant women (gestational weeks 25-35) were at risk of exceeding a core body temperature of 39.0 °C during high-intensity running. We also investigated effects on skin temperature, fluid loss, and thermal sensation, comparing pregnant athletes to non-pregnant controls., Methods: In this comparative cross-sectional study, 30 elite and recreational athletes (pregnant n = 15) completed up to five high-intensity treadmill-intervals. Core and skin temperature were continuously measured. Body weight was utilized to calculate the amount of fluid loss., Results: Highest core body temperature were 38.76 °C and 39.56 °C in one pregnant and non-pregnant participant, respectively. Pregnant participants had lower core body temperatures (mean difference -0.47 °C, p ≤ 0.001) initially and a smaller increase (0.10 °C, p ≤ 0.003) during later intervals compared with the non-pregnant controls. Pregnant participants also showed a greater increase in skin temperature (4.08 ± 0.72 °C vs. 3.25 ± 0.86 °C, p = 0.008) and fluid loss (0.81 ± 0.19 L vs. 0.50 ± 0.12 L, p˂0.001)., Conclusion: Physiological changes in pregnancy may enhance thermoregulation, indicating that high-intensity interval runs are unlikely to pose a risk of exceeding a core body temperature of 39 °C for pregnant athletes., Competing Interests: The authors declare there are no conflicts of interest. The source of funding did not have any role in the study's design, conduct, data collection, management, analysis, or interpretation, nor did it influence the manuscript's preparation, review, approval, or the decision to submit it for publication., (© 2024 The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd.)

Objective: This study aims to examine the comparative effects of 75 min of volume-matched once-weekly and thrice-weekly high-intensity interval training (HIIT) on body adiposity in adults with central obesity., Methods: This assessor-blinded, three-arm, randomized controlled trial will recruit 315 physically inactive adults with central obesity (aged ≥18 years, body mass index ≥23, waist circumference ≥90 cm for men and ≥80 cm for women). Participants will be randomly allocated to the once-weekly HIIT, thrice-weekly HIIT or usual care control group. Participants in the HIIT groups will receive weekly exercise training sessions for 16 weeks, prescribed either once or three times weekly. Each HIIT session will consist of a supervised program of four 4-min high-intensity intervals at 85%-95% peak heart rate (HR peak ) interspersed with 3-min active recovery intervals at 50%-70% HR peak . Participants in the once-weekly HIIT group will perform the 25-min HIIT bout three times with a break between each 25-min HIIT bout. The usual care control group will receive bi-weekly health education classes. The outcome assessments will be conducted at baseline, 16 weeks (post-intervention) and 32 weeks (follow-up). The primary outcome will be total body adiposity assessed by dual-energy X-ray absorptiometry (DXA). The secondary outcome measures will include markers of cardiovascular and metabolic health (body composition, cardiorespiratory fitness, blood pressure, and blood lipids), mental health, cognitive performance, health-related quality of life, sleep quality, habitual physical activity, diet, medication, adverse events and adherence to the intervention., Impact of the Project: The findings from this study are expected to consolidate the therapeutic efficacy of HIIT for the management of central obesity and inform the comparative compliance, feasibility and suitability of once-weekly and thrice-weekly HIIT as exercise strategies to manage obesity. In particular, the present study is expected to provide a novel perspective on the utility of low-frequency HIIT (i.e., once-weekly) as an effective and sustainable exercise strategy to tackle the obesity pandemic. The anticipated findings will hold substantial translational value by informing public health policies and enhancing exercise compliance in the physically inactive obese population., Trial Registration: ClinicalTrials.gov (NCT04887454)., Competing Interests: The authors declared no competing interests., (© 2024 The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd.)

Stroke survivors commonly face challenges such as reduced physical activity and cardiorespiratory fitness (CRF) as well as balance and gait impairments, exacerbating their disability. While high-intensity exercise interventions have demonstrated some potential, their effects on these items remain uncertain. Therefore, our study aimed to investigate the impact of high-intensity training protocols on CRF, gait ability, and balance in stroke survivor populations. Two independent investigators systematically searched five databases for relevant RCTs following the PICO model. Through a systematic review of 25 RCTs published up to 31 May 2023, including adult first-stroke survivors, comparing high-intensity exercise training versus low-to-mild or no exercises, we evaluated outcomes such as the Six-Minute Walking Test (6 MWT), peak oxygen uptake (VO2peak), Ten-Meter Walk Test (10 MWT), Berg Balance Scale (BBS), and Timed Up and Go test (TUG). The protocol was registered in PROSPERO (registration number CRD42023456773). Meta-analyses indicated significant enhancements in CRF, as measured by 6 MWT and VO2peak, following high-intensity exercise interventions. However, no significant differences were observed in BBS, 10 MWT, and TUG. Our findings underscore the potential of high-intensity exercise interventions in ameliorating CRF among stroke survivors, although further research involving standardized protocols and long-term follow-ups is imperative to optimize rehabilitation outcomes.

Background: The benefits of oral caffeine intake to enhance several aspects of physical performance, such as aerobic endurance, strength, power, and muscle endurance performance, are well supported. However, how the physical performance benefits of caffeine supplementation are translated into better specific actions in intermittent sports during real or simulated competition has been the topic of fewer investigations, and their results need to be appropriately reviewed and meta-analyzed., Objective: The aim of the study was to investigate the effects of acute caffeine intake on specific actions in intermittent sports involving decision making and high-intensity efforts (eg, team, racket, and combat sports) during real or simulated competitions., Methods: All studies included had blinded and crossover experimental designs, and we conducted a risk-of-bias analysis. In total, we included 24 studies. A meta-analysis was performed using the random-effects model to calculate the standardized mean difference (SMD) estimated by Hedges g and 95% CIs., Results: Caffeine ingestion increased high-intensity sport-specific actions during competition, such as the number of sprints (SMD: 0.48; 95% CI, 0.23-0.74), body impacts (SMD: 0.28; 95% CI, 0.08-0.49), accelerations (SMD: 0.35; 95% CI, 0.06-0.63), decelerations (SMD: 0.63; 95% CI, 0.12-1.14), and high-intensity offensive efforts (SMD: 0.36; 95% CI, 0.11-0.61). Additionally, caffeine ingestion induced a higher positive or success rate of actions during real or simulated competition (SMD: 0.44; 95% CI, 0.19-0.69)., Conclusion: The current meta-analysis provides evidence of caffeine supplementation in increasing high-intensity efforts and the success rate of sport-specific actions during real or simulated competition.

Objective. Myocardial fibrosis is a devastating condition causing millions of deaths yearly. Several factors, such as aging, cause myocardial fibrosis. The Wnt/β-catenin pathway is one of the critical intracellular signaling for the development of cardiac fibrosis. Molecular and cellular mechanism of myocardial fibrosis induced by intensive exercise is not well-understood. The current study evaluates the effects of short- and long-term intensive exercise on the Wnt1 gene expression in a heart left ventricle in an animal model. Methods. Twenty-one male Wistar rats (mean weight 250±50 g) were divided into three groups (n=7): 1) control group (C); 2) short-term regular intensive exercise group (S-RIE, high-intensity exercise for one month six days weekly for 60 min with speed of 35 m/min), and 3) long-term regular intensive exercise group (L-RIE, high-intensity exercise for six months six days daily for 60 min with speed of 35 m/min). The heart left ventricle was isolated at the end of the experiment, and the relative gene expression of the Wnt1 gene was measured by the Real-Time PCR. Results. The L-RIE group showed a significant increase in the Wnt1 expression compared to the S-RIE and the control group. Although no difference was observed in the Wnt1 mRNA level in the S-RIE group compared to the control group, Wnt1 mRNA level increased in the L-RIE group compared to the S-RIE group. Conclusion. The exercise duration was of a great importance in the Wnt1 gene expression. Regular intensive exercise may be involved in the formation of the myocardial fibrosis by increasing the expression of the Wnt1 gene., (© 2024 Farzam Sheikhzadeh et al., published by Sciendo.)

Evidence suggests that positive pacing strategy improves exercise performance and fatigue tolerance in athletic events lasting 1-5 min. This study investigated muscle metabolic responses to positive and negative pacing strategies in Thoroughbred horses. Eight Thoroughbred horses performed 2 min treadmill running using positive (1 min at 110% maximal O 2 uptake [V̇O 2 max], followed by 1 min at 90% V̇O 2 max) and negative (1 min at 90% V̇O 2 max, followed by 1 min at 110% V̇O 2 max) pacing strategies. The arterial-mixed venous O 2 difference did not significantly differ between the two strategies. Plasma lactate levels increased toward 2 min, with significantly higher concentrations during positive pacing than during negative pacing. Muscle glycogen level was significantly lower at 1 and 2 min of positive pacing than those of negative pacing. Metabolomic analysis showed that the sum of glycolytic intermediates increased during the first half of positive pacing and the second half of negative pacing. Regardless of pacing strategy, the sum of tricarboxylic acid cycle metabolites increased during the first half but remained unchanged thereafter. Our data suggest that positive pacing strategy is likely to activate glycolytic metabolism to a greater extent compared to negative pacing, even though the total workload is identical., (© 2024. The Author(s).)

We investigated fatigue and performance rates as decision-making criteria in pacing control during CrossFit ® . Thirteen male regional-level competitors completed conditions of all-out (maximum physical work from beginning to end) and controlled-split (controlled physical work in the first two rounds but maximum work in the third round) pacing throughout the Fight Gone Bad workout separated by one week. We assessed benchmarks, countermovement jumps and ratings of fatigue after each round. Benchmarks were lower in round 1 (99 vs. 114, p < .001) but higher in rounds 2 (98 vs. 80, p < .001) and 3 (97 vs. 80, p < .001) for controlled-split compared with all-out pacing. Reductions in countermovement jumps were higher after rounds 1 (-12.6% vs. 1.6%, p < .001) and 2 (-12.7% vs. -4.0%, p = .014) but similar after round 3 (-13.2% vs. -11.3%, p = .571) for all-out compared with controlled-split pacing. Ratings of fatigue were higher after rounds 1 (7 vs. 5 a.u., p < .001) and 2 (8 vs. 7 a.u, p = .023) but similar after round 3 (9 vs. 9 a.u., p = .737) for all-out compared with controlled-split pacing. During all-out pacing, countermovement jump reductions after round 2 correlated with benchmark drops across rounds 1 and 2 ( r = .78, p = .002) and rounds 1 and 3 ( r = -.77, p = .002) and with benchmark workout changes between pacing strategies ( r = -.58, p = .036), suggesting that the larger the countermovement jump reductions the higher the benchmark drops across rounds and workouts. Therefore, benchmarks, countermovement jumps and ratings of fatigue may assess exercise-induced fatigue as decision-making criteria to improve pacing strategy during workouts performed for as many repetitions as possible., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: To assess the effect of 2 work-matched efforts of different intensities on subsequent performance in well-trained cyclists., Methods: The present study followed a randomized controlled crossover design. Twelve competitive junior cyclists volunteered to participate (age, 17 [1] y; maximum oxygen uptake, 71.0 [4.7] mL·kg-1·min-1). The power-duration relationship was assessed through 2-minute, 5-minute, and 12-minute field tests under fresh conditions (control). On subsequent days and following a randomized order, participants repeated the aforementioned tests after 2 training sessions matched for mechanical work (∼15 kJ/kg) of different intensities (ie, a moderate-intensity continuous-training [60%-70% of critical power; CP] session or a session including high-intensity intervals [3-min repetition bouts at 110%-120% of the CP interspersed by 3-min rest periods])., Results: A significantly lower power output was found in the 2-minute test after the high-intensity training session compared not only with the control condition (-8%, P < .001) but also with the moderate-intensity continuous-training session (-7%, P = .003), with no significant differences between the latter conditions. No significant differences between conditions were found for the remaining tests. As a consequence, the high-intensity training session resulted in significantly lower W' values compared to both the control condition (-27%, P = .001) and the moderate-intensity continuous-training session (-26%, P = .012), with no differences between the 2 latter conditions and with no differences for CP., Conclusion: A session including high-intensity intermittent efforts induces a greater fatigue, particularly in short-duration efforts and W', than a work-matched continuous-training session of moderate intensity.

This study aimed to investigate the ability of highly trained athletes to consistently perform at their highest level during a simulated three-day 400 m race and to examine the impact of an alkaline diet associated with chronic consumption of bicarbonate-rich water or placebo on their blood metabolic responses before and after the three races. Twenty-two highly trained athletes, divided into two groups-one with an alkalizing diet and placebo water (PLA) and the other with an alkalizing diet and bicarbonate-rich water (BIC)-performed a 400 m race for three consecutive days. Performance metrics, urine and blood samples assessing acid-base balance, and indirect markers of neuro-muscular fatigue were measured before and after each 400 m race. The evolution of the Potential Renal Acid Load (PRAL) index and urinary pH highlights the combination of an alkalizing diet and bicarbonate-rich hydration, modifying the acid-base state ( p < 0.05). Athletes in the PLA group replicated the same level of performance during three consecutive daily races without an increase in fatigue-associated markers. Athletes experienced similar levels of metabolic perturbations during the three 400 m races, with improved lactate clearance 20 min after the third race compared to the first two ( p < 0.05). This optimization of the buffering capacity through ecological alkaline nutrition and hydration allowed athletes in the BIC group to improve their performance during the third 400 m race ( p < 0.01). This study highlights athletes' ability to replicate high-level performances over three consecutive days with the same extreme level of metabolic disturbances, and an alkaline diet combined with bicarbonate-rich water consumption appears to enhance performance in a 400 m race.

Purpose: The aim of this study was to analyze the reliability and validity of the predicted distance-time relationship in the severe-intensity domain from a 3-minute all-out running test (3MT)., Methods: Twelve runners performed two 3MTs (test #1 and test #2) on an outdoor 400-m track after familiarization. Eighteen-hertz Global Positioning System data were used to estimate critical speed (CS) and distance covered above CS (D'). Time to cover 1200 and 3600 m (T1200 and T3600, respectively) was predicted using CS and D' estimates from each 3MT. Eight runners performed 2 time trials in a single visit to assess real T1200 and T3600. Intraclass correlation coefficients (ICCs) and standard errors of measurement were calculated for reliability analysis., Results: Good to excellent reliability was found for CS, T1200, and T3600 estimates from 3MT (ICC > .95, standard error of measurement between 1.3% and 2.2%), and poor reliability was found for D' (ICC = .55, standard error of measurement = 27%). Predictions from 3MT were significantly correlated to actual T1200 (r = .87 and .85 for test #1 and test #2, respectively) and T3600 (r = .91 and .82 for test #1 and test #2, respectively). The calculation of error prediction showed a systematic error between predicted and real T3600 (6.4% and 7.8% for test #1 and test #2, respectively, P < .01) contrary to T1200 (P > .1). Random error was between 4.4% and 6.1% for both distances., Conclusions: Despite low reliability of D', 3MT yielded a reliable predicted distance-time relationship allowing repeated measures to evidence change with training adaptation. However, caution should be taken with prediction of performance potential of a single individual because of substantial random error and significant underestimation of T3600.

We analysed peak 1-, 2- and 5-min periods and the associated 5-min recovery period in matches from three consecutive seasons in the Danish Superliga. A semi-automatic multicamera system was used to collect high-speed running distance (≥5.5 m/s; HSRD), sprint distance (≥7.0 m/s; SpD) and distance covered during intense acceleration (≥3 m/s 2 ; AccD). Analysis included 479 players and 6042 to 9671 match observations using rolling average. Distances covered per minute during the peak periods were significantly higher than match averages: HSRD (207-772%), SpD (447-1793%), and AccD (383-1096%). Distances covered per min were lower during 1-min recovery periods than match average for HSRD following peak 1-, 2- and 5-min period (29%, 6%, 3%, 2%, 2%; 35%, 11%, 0%, 2%, 3%; and 45%, 29%, 13%, 8%, 4%; p  < 0.05, respectively), and for SpD (20%, 3%, 7%, 3% (4% higher in the 5th min); 24%, 12%, 3%, 0%, 7%; and 39%, 29%, 18%, 17%, 12%; p  < 0.05, respectively). Opposite, AccD increased in the following 1-min recovery periods following peak 1-, 2- and 5-min periods (68%, 89%, 94%, 88%, 90%; 47%, 86%, 93%, 90%, 88%; 23%, 56%, 76%, 85%, 87%; p  < 0.05) compared to match averages. Intensity was higher during shorter periods, whereas performance decrements were largest after longer peak periods for HSRD and SpD, whereas no decrement was observed in AccD.

Strenuous exercise can result in disruption of intestinal barrier function and occurrence of gastrointestinal symptoms. The aim of this exploratory study was to elucidate systemic effects of increased intestinal permeability after high-intensity exercise. Forty-one endurance-trained subjects performed a 60-min treadmill run at 80% VO 2 max. Small intestinal permeability was measured as urinary excretion ratio of lactulose/rhamnose (L/R). Blood, saliva and feces were analyzed for gut barrier and immune-related biomarkers. The exercise challenge increased several markers of intestinal barrier disruption, immune function and oxidative stress. We found a negative correlation between L/R ratio and uric acid (r = -0.480), as well as a positive correlation between the L/R ratio and fecal chromogranin A in male participants (r = 0.555). No significant correlations were found between any of the markers and gastrointestinal symptoms, however, perceived exertion correlated with the combination of IL-6, IL-10 and salivary cortisol (r = 0.492). The lack of correlation between intestinal permeability and gastrointestinal symptoms could be due to minor symptoms experienced in lab settings compared to real-life competitions. The correlation between L/R ratio and uric acid might imply a barrier-protective effect of uric acid, and inflammatory processes due to strenuous exercise seem to play an important role regarding physical exhaustion., (© 2024 The Author(s). Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Objective: Sleep is an essential component of athletic performance and recovery. This study aimed to investigate the effects of different types of high-intensity exercise on sleep parameters in adolescent speed skaters., Methods: Eighteen male adolescent speed skaters underwent aerobic capacity testing, Wingate testing, and interval training in a randomized crossover design to assess strength output, heart rate, and blood lactate levels during exercise. Sleep quality after each type of exercise was evaluated using the Firstbeat Bodyguard 3 monitor., Results: The results showed that Wingate testing and interval training led to decreased sleep duration, increased duration of stress, decreased RMSSD, and increased LF/HF ratio ( p  < 0.01). Conversely, aerobic capacity testing did not significantly affect sleep ( p  > 0.05). The impact of interval training on sleep parameters was more significant compared to aerobic capacity testing ( p  < 0.01) and Wingate testing ( p  < 0.01)., Conclusion: High-intensity anaerobic exercise has a profound impact on athletes' sleep, primarily resulting in decreased sleep duration, increased stress duration, decreased RMSSD, and increased LF/HF ratio., Competing Interests: XW is employed by Zhejiang Qiangnao Technology Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Kong, Wei, Shen, Cheng and Feng.)

In skeletal muscle, glycogen particles are distributed both within and between myofibrils, as well as just beneath the sarcolemma. Their precise localisation may influence their degradation rate. Here, we investigated how exercise at different intensities and durations (1- and 15-min maximal exercise) with known variations in glycogenolytic rate and contribution from anaerobic metabolism affects utilisation of the distinct pools. Furthermore, we investigated how decreased glycogen availability achieved through lowering carbohydrate and energy intake after glycogen-depleting exercise affect the storage of glycogen particles (size, numerical density, localisation). Twenty participants were divided into two groups performing either a 1-min (n = 10) or a 15-min (n = 10) maximal cycling exercise test. In a randomised, counterbalanced, cross-over design, the exercise tests were performed following short-term consumption of two distinct diets with either high or moderate carbohydrate content (10 vs. 4 g kg -1 body mass (BM) day -1 ) mediating a difference in total energy consumption (240 vs. 138 g kg -1 BM day -1 ). Muscle biopsies from m. vastus lateralis were obtained before and after the exercise tests. Intermyofibrillar glycogen was preferentially utilised during the 1-min test, whereas intramyofibrillar glycogen was preferentially utilised during the 15-min test. Lowering carbohydrate and energy intake after glycogen-depleting exercise reduced glycogen availability by decreasing particle size across all pools and diminishing numerical density in the intramyofibrillar and subsarcolemmal pools. In conclusion, distinct subcellular glycogen pools were differentially utilised during 1-min and 15-min maximal cycling exercise. Additionally, lowered carbohydrate and energy consumption after glycogen-depleting exercise altered glycogen storage by reducing particle size and numerical density, depending on subcellular localisation. KEY POINTS: In human skeletal muscle, glycogen particles are localised in distinct subcellular compartments, referred to as intermyofibrillar, intramyofibrillar and subsarcolemmal pools. The intermyofibrillar and subsarcolemmal pools are close to mitochondria, while the intramyofibrillar pool is at a distance from mitochondria. We show that 1 min of maximal exercise is associated with a preferential utilisation of intermyofibrillar glycogen, and, on the other hand, that 15 min of maximal exercise is associated with a preferential utilisation of intramyofibrillar glycogen. Furthermore, we demonstrate that reduced glycogen availability achieved through lowering carbohydrate and energy intake after glycogen-depleting exercise is characterised by a decreased glycogen particle size across all compartments, with the numerical density only diminished in the intramyofibrillar and subsarcolemmal compartments. These results suggest that exercise intensity influences the subcellular pools of glycogen differently and that the dietary content of carbohydrates and energy is linked to the size and subcellular distribution of glycogen particles., (© 2024 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Myocarditis is a rare cardiomyocyte inflammatory process, typically caused by viruses, with potentially devastating cardiac sequalae in both competitive athletes and in the general population. Investigation into myocarditis prevalence in the Coronavirus disease 2019 (COVID-19) era suggests that infection with Severe acute respiratory syndrome coronavirus (SARS-CoV-2) is an independent risk factor for myocarditis, which is confirmed mainly through cardiovascular magnetic resonance imaging. Recent studies indicated that athletes have a decreased risk of myocarditis after recent COVID-19 infection compared to the general population. However, given the unique nature of competitive athletics with their frequent participation in high-intensity exercise, athletes possess distinct factors of susceptibility for the development of myocarditis and its subsequent severe cardiac complications (e.g., sudden cardiac death, fulminant heart failure, etc.). Under this context, this review focuses on comparing myocarditis in athletes versus non-athletes, owing special attention to the distinct clinical presentations and outcomes of myocarditis caused by different viral pathogens such as cytomegalovirus, Epstein-Barr virus, human herpesvirus-6, human immunodeficiency virus, and Parvovirus B19, both before and after the COVID-19 pandemic, as compared with SARS-CoV-2. By illustrating distinct clinical presentations and outcomes of myocarditis in athletes versus non-athletes, we also highlight the critical importance of early detection, vigilant monitoring, and effective management of viral and non-viral myocarditis in athletes and the necessity for further optimization of the return-to-play guidelines for athletes in the COVID-19 era, in order to minimize the risks for the rare but devastating cardiac fatality., (© 2024 Chengdu Sport University. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.)

The intestine functions as a barrier preventing the entry of extrinsic factors into the body. This barrier function is disrupted by oxidative damage along with an impaired mucosal layer. Excessive exercise can generate oxidative stress in the intestinal tissue; however, the effect of exercise-induced oxidative stress on intestinal permeability is unclear. In this study, we examined the involvement of oxidative stress in barrier function of the ileum of mice following high-intensity exercise. Male ICR mice (12-week-old) were divided into sedentary and exercise groups. Mice in the exercise group underwent a single bout of treadmill running, and the ileum was collected for histological and biochemical analyses. Plasma fluorescence intensity level after oral administration of fluorescein isothiocyanate-dextran gradually increased until 30 min after exercise in response to intensity of exercise. Relatively high levels of oxidative proteins and low level of claudin-1, a tight-junction protein, were observed in the exercise group. Treatment with a xanthine oxidase inhibitor suppressed exercise-induced increases in intestinal permeability. Moreover, excessive exercise training for two weeks led to relatively high intestinal permeability at rest. These results suggest that high-intensity exercise increases intestinal permeability and tight junction damage, which may be mediated by oxidative stress., Competing Interests: No potential conflicts of interest were disclosed., (Copyright © 2024 JCBN.)

This study investigated the impact of basketball-induced fatigue on 3-point jump shooting accuracy, the ball's entry angle (EA) into the hoop, shot release time (RT), their relationship with player positions in high-level basketball, and the correlation between cardiorespiratory fitness markers and potential shooting performance changes. Guards (n = 13), forwards (n = 13), and centers (n = 12) underwent physiological assessments. Sequentially, they performed 15 jump shots (PRE), a basketball exercise simulation (BEST) involving 24 × 30 s circuit activities, and a repeated shooting test (POST). The study design was double-blind. The results revealed significant differences ( p ≤ 0.05) in RT, EA, and successful shots (SSs) between PRE and POST in each group. The percentage changes from PRE to POST conditions across guards, forwards, and centers were for RT: 25.34% [95%CI: 1.7-48.98], 19.73% [95%CI: -1.9-41.36], 14.95% [95%CI: -5.23-35.13]; for EA: -3.89% [95%CI: -14.82-7.04], -3.13% [95%CI: -12.9-6.64], -3.47% [95%CI: -14.19-7.25]; and for SS: -14.42% [95%CI: -36.5-7.66], -16.76% [95%CI: -40.81-7.29], -19.44% [95%CI: -46.7-7.82], respectively. Post-test differences ( p ≤ 0.05) highlighted greater fatigue impact on RT, EA, and SS from guards to centers. Additionally, significant correlations ( p ≤ 0.05) were found between the ventilatory threshold, mean HR during BEST, and changes in RT, EA, and SS. This study highlights the substantial impact of basketball-induced fatigue on 3-point shooting parameters across player positions and the interplay with cardiorespiratory factors post-fatigue. Tailored training, considering heart rate, is crucial to optimizing shooting performance.

Introduction: The acute and isolated ingestion of sodium bicarbonate (NaHCO3) and caffeine (CAF) improves performance and delays fatigue in high-intensity tasks. However, it remains to be elucidated if the coingestion of both dietary supplements stimulates a summative ergogenic effect. This study aimed to examine the effect of the acute coingestion of NaHCO3 and CAF on repeated-sprint performance., Methods: Twenty-five trained participants (age: 23.3 [4.0] y; sex [female/male]: 12/13; body mass: 69.6 [12.5] kg) participated in a randomized, double-blind, placebo (PLA) -controlled, crossover study. Participants were assigned to 4 conditions: (1) NaHCO3 + CAF, (2) NaHCO3, (3) CAF, or (4) PLA. Thus, they ingested 0.3 g/kg of NaHCO3, 3 mg/kg of CAF, or PLA. Then, participants performed 4 Wingate tests (Wt), consisting of a 30-second all-out sprint against an individualized resisted load, interspersed by a 1.5-minute rest period between sprints., Results: Peak (Wpeak) and mean (Wmean) power output revealed a supplement and sprint interaction effect (P = .009 and P = .049, respectively). Compared with PLA, NaHCO3 + CAF and NaHCO3 increased Wpeak performance in Wt 3 (3%, P = .021) and Wt 4 (4.5%, P = .047), while NaHCO3 supplementation increased mean power performance in Wt 3 (4.2%, P = .001). In Wt 1, CAF increased Wpeak (3.2%, P = .054) and reduced time to Wpeak (-8.5%; P = .008). Plasma lactate showed a supplement plus sprint interaction (P < .001) when NaHCO3 was compared with CAF (13%, P = .031) and PLA (23%, P = .021)., Conclusion: To summarize, although the isolated ingestion of CAF and NaHCO3 improved repeated-sprint performance, the coingestion of both supplements did not stimulate a synergic ergogenic effect.

Purpose: Concentration- and time-dependent effect of lactate on physiological adaptation (i.e., glycolytic adaptation and mitochondrial biogenesis) have been reported. Subtetanic neuromuscular electrical stimulation (NMES) with voluntary exercise (VOLES) can increase blood lactate accumulation. However, whether this is also true that VOLES can enhance the blood lactate accumulation during sprint exercise is unknown. Thus, we investigated whether VOLES before the Wingate test can enhance blood lactate accumulation without compromising Wingate exercise performance., Methods: Fifteen healthy young males (mean [SD], age: 23 [4] years, body mass index: 22.0 [2.1] kg/m 2 ) volunteered. After resting measurement, participants performed a 3-min intervention: VOLES (NMES with free-weight cycling) or voluntary cycling alone, which matched exercise intensity with VOLES (VOL, 43.6 [8.0] watt). Then, they performed the Wingate test with 30 min free-weight cycling recovery. The blood lactate concentration ([La] b ) was assessed at the end of resting and intervention, and recovery at 1, 3, 5, 10, 20, and 30 min., Results: [La] b during intervention was higher with VOLES than VOL (P = 0.011). The increase in [La] b after the Wingate test was maintained for longer with VOLES than VOL at 10- and 20-min recovery (P = 0.014 and 0.023, respectively). Based on the Wingate test, peak power, mean power, and the rate of decline were not significantly different between VOLES and VOL (P = 0.184, 0.201, and 0.483, respectively)., Conclusion: The combination of subtetanic NMES with voluntary exercise before the Wingate test has the potential to enhance blood lactate accumulation. Importantly, this combined approach does not compromise Wingate exercise performance compared to voluntary exercise alone., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Despite the abundance of research investigating the efficacy of caffeine supplementation on exercise performance, the physiological and biochemical responses to caffeine supplementation during intermittent activities are less evident. This study investigated the acute effects of caffeine supplementation on measures of exercise performance, ratings of perceived exertion, and biomarkers of oxidative stress induced by an acute bout of sprint interval training. In a randomized crossover design, 12 healthy males (age: 26 ± 4 years, height: 177.5 ± 6 cm, body mass: 80.7 ± 7.6 kg) ingested 6 mg/kg of caffeine or placebo 60 min prior to performing sprint interval training (12 × 6 s "all-out sprints" interspersed by 60 s of rest). Performance scores and ratings of perceived exertion were assessed after every sprint. Blood samples were collected before supplementation, prior to and following each sprint, and 5 and 60 min after the last sprint. Caffeine had no effect on any performance measures, ratings of perceived exertion, or biomarkers of oxidative stress (p > .05). In conclusion, caffeine supplementation does not improve performance or decrease oxidative stress after an acute bout of sprint interval training.

Pre-exercise mangiferin-quercetin may enhance athletic performance. This study investigated the effect of mangiferin-quercetin supplementation on high-level male basketball players during a basketball exercise simulation test (BEST) comprising 24 circuits of 30 s activities with various movement distances. The participants were divided into two groups (EXP = 19 and CON = 19) and given a placebo one hour before the BEST (PRE-condition). The following week, the EXP group received mangiferin-quercetin (84 mg/140 mg), while the CON group received a placebo (POST-condition) before the BEST in a double-blind, cross-over design. The mean heart rate (HR) and circuit and sprint times (CT and ST) during the BEST were measured, along with the capillary blood lactate levels (La - ), the subjective rating of muscle soreness (RPMS), and the perceived exertion (RPE) during a resting state prior to and following the BEST. The results showed significant interactions for the mean CT ( p = 0.013) and RPE ( p = 0.004); a marginal interaction for La - ( p = 0.054); and non-significant interactions for the mean HR, mean ST, and RPMS. Moreover, the EXP group had significantly lower values in the POST condition for the mean CT (18.17 ± 2.08 s) and RPE (12.42 ± 1.02) compared to the PRE condition (20.33 ± 1.96 s and 13.47 ± 1.22, respectively) and the POST condition of the CON group (20.31 ± 2.10 s and 13.32 ± 1.16, respectively) ( p < 0.05). These findings highlight the potential of pre-game mangiferin-quercetin supplementation to enhance intermittent high-intensity efforts in sports such as basketball.

Background: High-intensity interval training (HIIT) has emerged as an alternative training method to increase brain-derived neurotrophic factor (BDNF) levels, a crucial molecule involved in plastic brain changes. Its effect compared to moderate-intensity continuous training (MICT) is controversial. We aimed to estimate, and to comparatively evaluate, the acute and chronic effects on peripheral BDNF levels after a HIIT, MICT intervention or a control condition in adults., Methods: The CINAHL, Cochrane, PubMed, PEDro, Scopus, SPORTDiscus, and Web of Science databases were searched for randomized controlled trials (RCTs) from inception to June 30, 2023. A network meta-analysis was performed to assess the acute and chronic effects of HIIT versus control condition, HIIT versus MICT and MICT versus control condition on BDNF levels. Pooled standardized mean differences (SMDs) and their 95% confidence intervals (95% CIs) were calculated for RCTs using a random-effects model., Results: A total of 22 RCTs were selected for the systematic review, with 656 participants (aged 20.4-79 years, 34.0% females) and 20 were selected for the network meta-analysis. Network SMD estimates were significant for HIIT versus control condition (1.49, 95% CI: 0.61, 2.38) and MICT versus control condition (1.08, 95% CI: 0.04, 2.12) for acutely BDNF increase. However, pairwise comparisons only resulted in a significant effect for HIIT versus control condition., Conclusions: HIIT is the best training modality for acutely increasing peripheral BDNF levels in adults. HIIT may effectively increase BDNF levels in the long term., (© 2023 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Background: Currently, endoplasmic reticulum stress is studied utilizing a dephosphorylation inhibitor (Sal). The traditional Chinese patent medicine and simple formulation Shensong Yangxin Capsule is a commonly used medication for the treatment of arrhythmia. However, the efficacy and underlying mechanism of the capsule in treating post-ischemic heart failure in myocardial tissue have not yet been investigated., Objective: The therapeutic effects and the underlying mechanism of the Shensong Yangxin Capsule (SSYX) and the dephosphorylation inhibitor Salubrinal (Sal) on heart failure (HF) induced by high-intensity exercise in rats with acute myocardial infarction (AMI) were investigated., Methods: Male infants of 8 weeks Spragge-Dawley (SD) rats were randomly assigned to one of four groups: sham surgery group, AMI+placebo group, AMI+Shensong Yangxin Capsule group (AMI+SSYX), and AMI+Sal administration group. Rats' myocardial infarction was induced by left coronary artery ligation. Rats were subjected to a 3-week high-intensity exercise program to simulate heart failure after 7 days of postoperative rest. After the fourth postoperative week, echocardiography was applied to determine the left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), and left ventricular systolic volume (LVESV) in each group. HE and TUNEL labeling were employed to examine the morphology of cardiac cells and measure the percentage of apoptosis in each group; Western blotting was applied to detect the cardiomyocyte apoptosis-related proteins p-JNK, p-P38, and NOX2, while ELISA was used to detect glutathione(GSH), malondialdehyde (MDA), and superoxide dismutase (SOD) in serum., Results: Following a 4-week drug intervention:(1)LVFS and LVEF in the AMI+placebo group were statistically significantly reduced, while LVESV were significantly higher, compared to those in the sham surgery group (P<0.05); The AMI+SSYX group performed statistically significantly better than the AMI+placebo group(P<0.05). (2) The myocardial cells in the AMI+placebo group exhibited significant swelling and inflammatory cell infiltration; the myocardial cells in the AMI+SSYX group and AMI+Sal group displayed mild swelling and minimal inflammatory cell infiltration; the AMI+SSYX group's myocardial cell morphology was superior to that of the AMI+Sal group; (3) The apoptosis rate of the AMI+placebo group was around 95%, greater than that of the sham surgery group (2.55%). The apoptosis rate of the AMI+SSYX group is approximately 21%, while the apoptosis rate of the AMI+Sal group is about 43%. (4) In the AMI+placebo group, p-JNK, p-P38, and NOX2 protein expression dramatically increased compared to the sham surgery group. The expression of p-P38, NOX2, and p-JNK/t-JNK was considerably reduced in the AMI+Shensong group and AMI+Sal group, compared to the AMI+placebo group. (P<0.01)The AMI+SSYX group's result is superior to that of the AMI+Sal group. (5) Compared to the sham surgery group, the serum levels of SOD and GSH were significantly lower, and MDA was significantly higher in the AMI+placebo group. Compared to the AMI+placebo group, the serum levels of SOD and GSH were significantly higher, and MDA was significantly lower in the AMI+SSYX group and the AMI+Sal group. (P<0.05) Conclusion: In rats with acute myocardial infarction in high-intensity exercise-induced heart failure, Shensong Yangxin Capsule dramatically reduces myocardial cell death and cardiac dysfunction. SSYX has a shorter course of treatment and a better therapeutic effect than Sal., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Ice hockey is an intense team sport characterized by repeated bursts of fast-paced skating, rapid changes in speed and direction and frequent physical encounters. These are performed in on-ice shifts of ~30-80 s interspersed with longer sequences of passive recovery, resulting in about 15-25 min on-ice time per player. Nearly 50% of the distance is covered at high-intensity skating speeds and with an accentuated intense activity pattern in forwards compared to defensemen. During ice hockey match-play, both aerobic and anaerobic energy systems are significantly challenged, with the heart rate increasing toward maximum levels during each shift, and with great reliance on both glycolytic and phosphagen ATP provision. The high-intensity activity pattern favors muscle glycogen as fuel, leading to pronounced reductions despite the relatively brief playing time, including severe depletion of a substantial proportion of individual fast- and slow-twitch fibers. Player-tracking suggests that the ability to perform high-intensity skating is compromised in the final stages of a game, which is supported by post-game reductions in repeated-sprint ability. Muscle glycogen degradation, in particular in individual fibers, as well as potential dehydration and hyperthermia, may be prime candidates implicated in exacerbated fatigue during the final stages of a game, whereas multiple factors likely interact to impair exercise tolerance during each shift. This includes pronounced PCr degradation, with potential inadequate resynthesis in a proportion of fast-twitch fibers in situations of repeated intense actions. Finally, the recovery pattern is inadequately described, but seems less long-lasting than in other team sports., (© 2022 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Exercise training (ET) can lower platelet reactivity in patients with cardiovascular risk factors. However, the effects of ET on platelet reactivity in higher-risk patients is unknown. The aim of this study was to evaluate the effects of ET on platelet reactivity in patients with recent myocardial infarction (MI). Ninety patients were randomly assigned 1 month post-MI to the intervention (patients submitted to a supervised ET program) or control group. All patients were on dual antiplatelet therapy (DAPT). Platelet reactivity by VerifyNow-P2Y 12 (measured by P2Y 12 reaction units - PRUs) test was determined at baseline and at the end of 14 ± 2 weeks of follow-up at rest (primary endpoint), and multiplate electrode aggregometry (MEA) adenosine diphosphate (ADP) and aspirin (ASPI) tests were performed immediately before and after the maximal cardiopulmonary exercise test (CPET) at the same time points (secondary endpoints). Sixty-five patients (mean age 58.9 ± 10 years; 73.8% men; 60% ST elevation MI) completed follow-up (control group, n = 31; intervention group, n = 34). At the end of the follow-up, the mean platelet reactivity was 172.8 ± 68.9 PRUs and 166.9 ± 65.1 PRUs for the control and intervention groups, respectively (p = .72). Platelet reactivity was significantly increased after the CPET compared to rest at the beginning and at the end of the 14-week follow-up (among the intervention groups) by the MEA-ADP and MEA-ASPI tests (p < .01 for all analyses). In post-MI patients on DAPT, 14 weeks of supervised ET did not reduce platelet reactivity. Moreover, platelet reactivity was increased after high-intensity exercise (ClinicalTrials.gov: NCT02958657; https://clinicaltrials.gov/ct2/show/NCT02958657).

Menopause is associated with reduced nitric oxide bioavailability and vascular function. Although exercise is known to improve vascular function, this is blunted in estrogen-deficient females post-menopause (PM). Here, we examined the effects of acute exercise at differing intensities with and without inorganic nitrate (NO 3 - ) supplementation on vascular function in females PM. Participants were tested in a double-blinded, block-randomized design, consuming ∼13 mmol NO 3 - in the form of beetroot juice (BRJ; n = 12) or placebo (PL; n = 12) for 2 days before experimental visits and 2 h before testing. Visits consisted of vascular health measures before ( time point 0 ) calorically matched high-intensity exercise (HIE), moderate-intensity exercise (MIE), and a nonexercise control (CON). Blood was sampled at rest and 5-min postexercise for NO time points 60, 90, 120, 150 , and 180 ) calorically matched high-intensity exercise (HIE), moderate-intensity exercise (MIE), and a nonexercise control (CON). Blood was sampled at rest and 5-min postexercise for NO 3 - , NO 2 - , and ET-1. BRJ increased N-oxides and decreased ET-1 compared with PL, findings which were unchanged after experimental conditions ( P < 0.05). BRJ improved peak Δflow-mediated dilation (FMD) compared with PL ( P < 0.05), defined as the largest ΔFMD for each individual participant across all time points. FMD across time revealed an improvement ( P This study compared exercise-induced changes in flow-mediated dilation after acute moderate- and high-intensity exercise in females postmenopause supplementing either inorganic nitrate (beetroot juice) or placebo. BRJ improved peak ΔFMD postexercise, and BRJ + HIE increased FMD measured as FMD over time. Neither PL + MIE nor PL + HIE improved FMD. These findings suggest that inorganic nitrate supplementation combined with high-intensity exercise may benefit vascular health in females PM.3 - supplementation combined with HIE improved FMD in postmenopausal females. NO 3 - supplementation combined with MIE may offer an alternative to those unwilling to perform HIE. Future studies should test whether long-term exercise training at high intensities with NO 3 - supplementation can enhance vascular health in females PM. NEW & NOTEWORTHY This study compared exercise-induced changes in flow-mediated dilation after acute moderate- and high-intensity exercise in females postmenopause supplementing either inorganic nitrate (beetroot juice) or placebo. BRJ improved peak ΔFMD postexercise, and BRJ + HIE increased FMD measured as FMD over time. Neither PL + MIE nor PL + HIE improved FMD. These findings suggest that inorganic nitrate supplementation combined with high-intensity exercise may benefit vascular health in females PM.

When high-intensity exercise is performed until exhaustion a "functional reserve" (FR) or capacity to produce power at the same level or higher than reached at exhaustion exists at task failure, which could be related to reactive oxygen and nitrogen species (RONS)-sensing and counteracting mechanisms. Nonetheless, the magnitude of this FR remains unknown. Repeated bouts of supramaximal exercise at 120% of VO 2 max interspaced with 20s recovery periods with full ischaemia were used to determine the maximal FR. Then, we determined which muscle phenotypic features could account for the variability in functional reserve in humans. Exercise performance, cardiorespiratory variables, oxygen deficit, and brain and muscle oxygenation (near-infrared spectroscopy) were measured, and resting muscle biopsies were obtained from 43 young healthy adults (30 males). Males and females had similar aerobic (VO 2 max per kg of lower extremities lean mass (LLM): 166.7 ± 17.1 and 166.1 ± 15.6 ml kg LLM -1 .min -1 , P = 0.84) and anaerobic fitness (similar performance in the Wingate test and maximal accumulated oxygen deficit when normalized to LLM). The maximal FR was similar in males and females when normalized to LLM (1.84 ± 0.50 and 2.05 ± 0.59 kJ kg LLM -1 , in males and females, respectively, P = 0.218). This FR depends on an obligatory component relying on a reserve in glycolytic capacity and a putative component generated by oxidative phosphorylation. The aerobic component depends on brain oxygenation and phenotypic features of the skeletal muscles implicated in calcium handling (SERCA1 and 2 protein expression), oxygen transport and diffusion (myoglobin) and redox regulation (Keap1). The glycolytic component can be predicted by the protein expression levels of pSer 40 -Nrf2, the maximal accumulated oxygen deficit and the protein expression levels of SOD1. Thus, an increased capacity to modulate the expression of antioxidant proteins involved in RONS handling and calcium homeostasis may be critical for performance during high-intensity exercise in humans., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

This study aimed to assess the predictive capability of different critical power (CP) models on cycling exercise tolerance in the severe- and extreme-intensity domains. Nineteen cyclists (age: 23.0 ± 2.7 y) performed several time-to-exhaustion tests (Tlim) to determine CP, finite work above CP (W'), and the highest constant work rate at which maximal oxygen consumption was attained (I HIGH ). Hyperbolic power-time, linear power-inverse of time, and work-time models with three predictive trials were used to determine CP and W'. Modeling with two predictive trials of the CP work-time model was also used to determine CP and W'. Actual exercise tolerance of I HIGH and intensity 5% above I HIGH (I HIGH+5% ) were compared to those predicted by all CP models. Actual I HIGH (155 ± 30 s) and I HIGH+5% (120 ± 26 s) performances were not different from those predicted by all models with three predictive trials. Modeling with two predictive trials overestimated Tlim at I HIGH+5% (129 ± 33 s; p = 0.04). Bland-Altman plots of I HIGH+5% presented significant heteroscedasticity by all CP predictions, but not for I HIGH . Exercise tolerance in the severe and extreme domains can be predicted by CP derived from three predictive trials. However, this ability is impaired within the extreme domain., Competing Interests: The authors declare no conflict of interest., (Copyright: © Academy of Physical Education in Katowice.)

The present study aimed to evaluate the effects of age and sex on the rating of perceived exertion (RPE) during high-intensity exercise and determine whether mechanical and physiological parameters could be predictors of RPE during childhood and adolescence. Forty-three boys and 36 girls performed a 60-s all-out test on a rowing ergometer and were categorized by age group (10.0-11.9; 12.0-13.9; 14.0-15.9; 16.0-17.9 years) and sex. Ratings of perceived exertion were assessed using the 6-20 RPE and CR-10 scales and analyzed with respect to mechanical work rate (W tot ), post-exercise peak blood lactate concentration ([La] peak ), and peak minute ventilation (V̇E peak ). Multilevel regression modeling revealed a significant influence of W tot , [La] peak and V̇E peak on 6-20 RPE and CR-10 scores (r 2  = .34 and .36, p < .001, respectively). However, while boys perceived high-intensity exercise as being subjectively more difficult than girls at all ages (p < .05) except 12.0-13.9 years, significant higher mechanical work rate and greater associated metabolic responses in boys than girls were only found from the age of 14 years (W tot and V̇E peak ) or 16 years ([La] peak ), suggesting that the association between RPE and mechanical/physiological parameters could not be held before the age of 12 years. To conclude, RPE increased with increasing age, with boys exhibiting higher scores than girls at all ages except 12.0-13.9 years. This finding is probably explained by the higher W tot and greater concomitant metabolic responses in boys at the time of puberty. However, other factors should be considered at least in children before the age of 12 years., (© 2023 Society for Psychophysiological Research.)

Background: Research has shown that ingesting 0.3 g·kg -1 body mass sodium bicarbonate (NaHCO 3 ) can improve time-to-exhaustion (TTE) cycling performance, but the influence of psychophysiological mechanisms on ergogenic effects is not yet understood., Objective: This study retrospectively examined whether changes in TTE cycling performance are mediated by positive expectations of receiving NaHCO 3 and/or the decline in blood bicarbonate during exercise., Methods: In a randomised, crossover, counterbalanced, double-blind, placebo-controlled design, 12 recreationally trained cyclists (maximal oxygen consumption, 54.4 ± 5.7 mL·kg·min -1 ) performed four TTE cycling tests 90 min after consuming: (1) 0.3 g·kg -1 body mass NaHCO 3 in 5 mL·kg -1 body mass solution, (2) 0.03 g·kg -1 body mass sodium chloride in solution (placebo), (3) 0.3 g·kg -1 body mass NaHCO 3 in capsules and (4) cornflour in capsules (placebo). Prior to exercise, participants rated on 1-5 Likert type scales how much they expected the treatment they believe had been given would improve performance. Capillary blood samples were measured for acid-base balance at baseline, pre-exercise and post-exercise., Results: Administering NaHCO 3 in solution and capsules improved TTE compared with their respective placebos (solution: 27.0 ± 21.9 s, p = 0.001; capsules: 23.0 ± 28.1 s, p = 0.016). Compared to capsules, NaHCO 3 administered via solution resulted in a higher expectancy about the benefits on TTE cycling performance (Median: 3.5 vs. 2.5, Z = 2.135, p = 0.033). Decline in blood bicarbonate during exercise was higher for NaHCO 3 given in solution compared to capsules (2.7 ± 2.1 mmol·L -1 , p = 0.001). Mediation analyses showed that improvements in TTE cycling were indirectly related to expectancy and decline in blood bicarbonate when NaHCO 3 was administered in solution but not capsules., Conclusions: Participants' higher expectations when NaHCO 3 is administered in solution could result in them exerting themselves harder during TTE cycling, which subsequently leads to a greater decline in blood bicarbonate and larger improvements in performance., Key Points: Ingesting 0.3 g·kg -1 body mass sodium bicarbonate in solution and capsules improved time-to-exhaustion cycling performance Positive expectancy about the benefits of sodium bicarbonate and decline in blood bicarbonate were higher when sodium bicarbonate was administered in solution compared with capsules Improvements in time-to-exhaustion cycling performance for sodium bicarbonate administered in solution were related to expectancy and the enhanced extracellular buffering response., (© 2023. The Author(s).)

Gastrointestinal (GI) symptoms may limit performance, but their prevalence and impact among team sports athletes is not well-documented. The objective of this study was to examine the prevalence of GI symptoms in a small sample of collegiate DI American football athletes, using a survey including the Gastrointestinal Symptoms Ratings Scale (GSRS). Forty-six athletes responded to the survey and reported scores for the 15-question GSRS with additional questions about dietary habits and supplement use. A total of 44 athletes were included in the study (45% of the current roster, age: 20.7 ± 1.7 years, 50% Afro-American or black, 39% skill position, 18% NSAIDs use, and 41% reporting protein supplement use); approximately half of the athletes (52%) reported experiencing GI complaints during exercise. Two-thirds of the athletes (61%) reported at least one or more GI symptoms in general, and 50% reported at least four moderate complaints. Seven athletes (16%) reported ≥2 severe GI symptoms with 5-13 moderate complaints. The most reported symptom was stomach pain (39%, n = 17), followed by hunger pain (36%, n = 16). Athletes reporting the use of protein supplements reported a higher GSRS score (22.0 and interquartile range (IQR) 17.0-31.8) vs. athletes not reporting protein use (15.0 and IQR 15.0-19.3), p = 0.001. Most athletes surveyed reported experiencing GI symptoms. A small group of these athletes reported multiple, varied, and severe symptoms that were associated with self-reported protein supplement use. In conclusion, the number of complaints varied among athletes, confirming the value of integrating the GSRS for screening purposes, and the expected need for individual dietary treatment approaches.

Looking for useful and motivational strategies for promoting healthy habits and improving cognitive functioning in young populations, the aim of the present study was to determine if a single bout of high-intensity interval exercise could stimulate mood and working memory in college students. A total of 25 male subjects (mean ± SD, age: 21.7 ± 2.1 years; height: 1.77 ± 0.06 m; weight: 72.6 ± 8.4 kg; body mass index: 23.1 ± 1.4 kg/m 2 ; VO 2peak : 47.1 ± 9.3 mL/kg/min) participated voluntarily in this study. Participants underwent a high-intensity interval exercise consisting of 10 × 1 min of cycling at VO 2peak power output. The Profile of Mood States (POMS) questionnaire and Digit Span Test (DST) were administered at three assessment time points: (a) pre-intervention assessment, (b) post-intervention assessment, and (c) 30 min post-intervention. The mood states decreased significantly after exercise; however, a significant increase in mood was found after 30 min of recovery. A significant post-exercise increase in DST performance was observed; moreover, DST scores obtained 30 min after exercise remained higher than those assessed pre-exercise. In conclusion, a single bout of HIIT induces acute positive changes in mood states in male college students and seems to be a powerful stimulus for cognitive functioning.

Zynamite PX ® , a mango leaf extract combined with quercetin, enhances exercise performance by unknown molecular mechanisms. Twenty-five volunteers were assigned to a control (17 males) or supplementation group (8 males, receiving 140 mg of Zynamite ® + 140 mg quercetin/8 h for 2 days). Then, they performed incremental exercise to exhaustion (IE) followed by occlusion of the circulation in one leg for 60 s. Afterwards, the cuff was released, and a 30 s sprint was performed, followed by 90 s circulatory occlusion (same leg). Vastus lateralis muscle biopsies were obtained at baseline, 20 s after IE (occluded leg) and 10 s after Wingate (occluded leg), and bilaterally at 90 s and 30 min post exercise. Compared to the controls, the Zynamite PX ® group showed increased basal protein expression of Thr 287 -CaMKIIδ D (2-fold, p = 0.007) and Ser 9 -GSK3β (1.3-fold, p = 0.005) and a non-significant increase of total NRF2 (1.7-fold, p = 0.099) and Ser 40 -NRF2 (1.2-fold, p = 0.061). In the controls, there was upregulation with exercise and recovery of total NRF2, catalase, glutathione reductase, and Thr 287 -CaMKIIδ D (1.2-2.9-fold, all p < 0.05), which was not observed in the Zynamite PX ® group. In conclusion, Zynamite PX ® elicits muscle signaling changes in resting skeletal muscle resembling those described for exercise training and partly abrogates the stress kinases responses to exercise as observed in trained muscles.

Aim: To quantify the physiological demands and impact of muscle function t of the Fran workout, one of the most popular CrossFit benchmarks., Methods: Twenty experienced CrossFitters-16 male: 29 (6) years old and 4 female: 26 (5) years old- performed 3 rounds (with 30-s rests in between) of 21-21, 15-15, and 9-9 front squats to overhead press plus pull-up repetitions. Oxygen uptake and heart rate were measured at baseline, during the workout, and in the recovery period. Rating of perceived exertion, blood lactate, and glucose concentrations were assessed at rest, during the intervals, and in the recovery period. Muscular fatigue was also monitored at rest and at 5 minutes, 30 minutes, and 24 hours postexercise. Repeated-measures analysis of variance was performed to compare time points., Results: Aerobic (52%-29%) and anaerobic alactic (30%-23%) energy contributions decreased and the anaerobic lactic contribution increased (18%-48%) across the 3 rounds of the Fran workout. Countermovement jump height decreased by 8% (-12 to -3) mean change (95% CI), flight duration by 14% (-19 to -7), maximum velocity by 3% (-5 to -0.1), peak force 4% (-7 to -0.1), and physical performance (plank prone 47% [-54 to -38]) were observed., Conclusions: It appears that the Fran workout is a physically demanding activity that recruits energy from both aerobic and anaerobic systems. This severe-intensity workout evokes substantial postexercise fatigue and corresponding reduction in muscle function.

Purpose: The purpose of this study was to observe the influence of level physical training intensity on left ventricular (LV) adaptation in elite air force soldiers compared to regular basic military training., Methods: The LV adaptation of special military physical training for elite air force soldiers was compared with basic military training for regular troops. A group of the nonmilitary subject was also evaluated as a control group. The presence of LV adaptation was evaluated using some echocardiography parameters, including LV mass index (LVMI), LV ejection fraction (LVEF), global longitudinal strain (GLS), and myocardial work index. The parameters of the myocardial work index include global constructive work (GCW), global wasted work (GWW), global work index (GWI), and global work efficiency (GWE)., Results: Forty-three elite air force soldiers underwent special military training, 43 regular troops underwent basic military training, and 23 nonmilitary subjects as a control group. Age, heart rate, blood pressure, and Cooper test results significantly differed among the three groups. Multivariate analysis among all groups showed that the level of physical training was associated with the LVMI (coefficient β = 6.061; 95% confidence interval [CI] = 1.91-10.22; P = 0.005), LVEF (coefficient β = -1.409; 95% CI = -2.41-[-0.41]; P = 0.006), LVGLS (coefficient β = 1.726; 95% CI = 1.20-2.25; P < 0.001), GWW (coefficient β = -13.875; 95% CI = -20.88-[-6.87]; P < 0.001), GWE (coefficient β = 0.954; 95% CI = 0.62-1.26; P < 0.001), GCW (coefficient β = 176.128; 95% CI = 121.16-231.10; P < 0.001), and GWI (coefficient β = 196.494; 95% CI = 144.61-248.38; P < 0.001)., Conclusions: Higher intensity of physical training observed in a special military training is associated with higher LV GLS, GWE, GCW, GWI, and lower GWW value suggesting greater physiological adaptation than the lower intensity training., Competing Interests: There are no conflicts of interest., (Copyright: © 2023 Journal of Cardiovascular Echography.)

Cardiovascular adverse effects caused by high-intensity exercise (HIE) have become a public health problem of widespread concern. The therapeutic effect and metabolic regulation mechanism of myricetin, a phytochemical with potential therapeutic effects, have rarely been studied. In this study, we established mice models of different doses of myricetin intervention with 1 week of HIE after intervention. Cardiac function tests, serology, and pathological examinations were used to evaluate the protective effect of myricetin on the myocardium. The possible therapeutic targets of myricetin were obtained using an integrated analysis of metabolomics and network pharmacology and verified using molecular docking and RT-qPCR experiments. Different concentrations of myricetin improved cardiac function, significantly reduced the levels of myocardial injury markers, alleviated myocardial ultrastructural damage, reduced the area of ischemia/hypoxia, and increased the content of CX43. We obtained the potential targets and regulated metabolic network of myricetin by combined network pharmacology and metabolomics analysis and validated them by molecular docking and RT-qPCR. In conclusion, our findings suggest that myricetin exerts anti-cardiac injury effects of HIE through the downregulation of PTGS2 and MAOB and the upregulation of MAP2K1 and EGFR while regulating the complicated myocardial metabolic network.

This study aimed to characterize neuromuscular, perceptual, and cardiorespiratory responses to high-intensity interval training (HIIT) with superimposed blood flow restriction in males and females. Twenty-four, healthy individuals ( n = 12 females) completed two cycling HIIT protocols to task failure (1-min work phases at 90% of peak power output interspersed by 1-min rest phases). The blood flow restriction (BFR) and control (CON) protocols were identical except for the presence and absence of BFR during rest phases, respectively. The interpolated twitch technique, including maximal voluntary isometric knee extension (MVC) and femoral nerve electrical stimuli, was performed at baseline, every six intervals, and task failure. Perceptual and cardiorespiratory responses were recorded every three intervals and continuously during exercise, respectively. Bayesian inference was used to obtain the joint posterior distribution for all parameters and evidence of an effect was determined via the marginal posterior probability (PP). The BFR shortened task duration by 57.3% compared with CON (PP > 0.99), without a sex difference. The application of BFR exacerbated the rate of decline in neuromuscular measures (MVC and twitch force output), increase of perceptual responses (perceived effort, pain, dyspnea, fatigue), and development of cardiorespiratory parameters (minute ventilation and heart rate), compared with CON (PP > 0.95). In addition, BFR exacerbated the neuromuscular, perceptual, and cardiorespiratory responses to a greater extent in females than males (PP > 0.99). Our results suggest that superimposition of blood flow restriction exacerbates psychophysiological responses to a HIIT protocol to a greater extent in females than males. NEW & NOTEWORTHY To our knowledge, no study has explored sex differences in the neuromuscular, perceptual, and cardiorespiratory indices characterizing exercise tolerance during high-intensity interval training (HIIT) with blood flow restriction (BFR) applied only during rest periods. Our results suggest that BFR elicited a decline in exercise performance that could be attributed to integration of psychophysiological responses. However, this integration was sex-dependent where females demonstrated an exacerbated rate of change in these responses compared with males.

Purpose: Exercise has transient effects on the immune system that could influence infection risk and tissue recovery after exercise. Little is known about how the menstrual cycle interacts with the immune responses to acute exercise. This exploratory study sought to evaluate the effect of menstrual-cycle phase on peripheral blood mononuclear cell counts before and immediately after a bout of intense aerobic exercise., Methods: Seven naturally menstruating women (age: 27 [3] y) completed three 5-km cycling time trials coinciding with the early-follicular, late-follicular, and mid-luteal stage, confirmed by hormonal measurement. Venous blood samples were taken and examined for the presence of immune cell types using flow cytometry., Results: Reductions in circulating CCR7+CD45RA+ naïve CD4+ T cells, CD4+CD25+ regulatory T cells, and CD56+CD57+ natural killer cells observed during the early-follicular phase were attenuated when exercise was performed during the late-follicular phase. Similarly, reductions in circulating CD56+CD57+ natural killer cells and CD14+TLR4+ monocytes following exercise in the early-follicular phase were abolished when exercise was performed in the midluteal phase., Conclusions: These preliminary findings indicate that the effect of acute high-intensity exercise on immune-cell mobilization and activation varies across the menstrual cycle, potentially impacting the anti-inflammatory effects of regulatory T cells and the cell-mediated effects of both natural killer CD57+ cells and monocytes expressing TLR4.

Regular exercise might reduce postmenopausal symptoms, however even short-moderate periods of absence from exercise training might significantly reduce these positive effects. The aim of the study was thus to determine detraining effects on postmenopausal symptoms after a 3-month detraining period in early post-menopausal women. After 13 months, the exercise group (EG: n  = 27; 54.6 ± 2.0; 23.6 ± 3.3 kg/m 2 ) had to abruptly stop their supervised, facility-based, high intensity aerobic and resistance group exercise conducted three times per week due to the COVID-19 pandemic and the corresponding lockdown of all training facilities in Germany. In parallel, the control group (CG: n  = 27; 55.6 ± 1.6 years, 25.2 ± 5.2 kg/m 2 ) had to terminate their low-intensity exercise program performed once per week. Study endpoint as determined after 3 months of detraining was menopausal symptoms as determined by the Menopausal Rating Scale II (MRS II). The intention to treat principle with multiple imputation was applied. After 13 months of intense multicomponent exercise and significant exercise-induced effects on menopausal symptoms, a further 3 months of detraining resulted in non-significant deteriorations ( p  = .106) in the exercise group, while non-significant improvements were observed in the control group ( p  = .180). Corresponding group differences were significant ( p  = .036) after detraining. Of importance, self-reported individual outdoor activities increased by about 40% in both groups during the three-month lock-down period. Three months of absence from a supervised high-intensity group exercise protocol resulted in detraining effects on postmenopausal symptoms even when outdoor physical activity was increased significantly., Trial Registration Number: ClinicalTrials.gov: NCT03959995., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Jungmann, Hettchen, Kohl and Kemmler.)

High-intensity exercise in athletes results in mainly the production of excess reactive oxygen species (ROS) in skeletal muscle, and thus athletes should maintain greater ROS scavenging activity in the body. We investigated the changes in six different ROS-scavenging activities in athletes following high-intensity anaerobic exercise. A 30-s Wingate exercise test as a form of high-intensity anaerobic exercise was completed by 10 male university track and field team members. Blood samples were collected before and after the exercise, and the ROS-scavenging activities (OH•, O2•−, 1O2, RO• and ROO•, and CH3•) were evaluated by the electron spin resonance (ESR) spin-trapping method. The anaerobic exercise significantly increased RO• and ROO• scavenging activities, and the total area of the radar chart in the ROS-scavenging activities increased 178% from that in pre-exercise. A significant correlation between the mean power of the anaerobic exercise and the 1O2 scavenging activity was revealed (r = 0.72, p < 0.05). The increase ratio in OH• scavenging activity after high-intensity exercise was significantly greater in the higher mean-power group compared to the lower mean-power group (n = 5, each). These results suggest that (i) the scavenging activities of some ROS are increased immediately after high-intensity anaerobic exercise, and (ii) an individual’s OH• scavenging activity responsiveness may be related to his anaerobic exercise performance. In addition, greater pre-exercise 1O2 scavenging activity might lead to the generation of higher mean power in high-intensity anaerobic exercise.

Background: Exercise-induced gastrointestinal syndrome (GIS) has symptoms commonly induced by strenuous sports. The study aimed to determine the effect of dihydromyricetin (DHM) administration on high-intensity exercise (HIE)-induced intestinal barrier dysfunction and the underlying mechanism involved with intestinal intraepithelial lymphocytes (IELs)., Methods: The HIE model was established with male C57BL/6 mice using a motorized treadmill for 2 weeks, and DHM was given once a day by oral gavage. After being sacrificed, the small intestines of the mice were removed immediately., Results: We found that DHM administration significantly suppressed HIE-induced intestinal inflammation, improved intestinal barrier integrity, and inhibited a HIE-induced increase in the number of IELs and the frequency of CD8αα + IELs. Meanwhile, several markers associated with the activation, gut homing and immune functions of CD8αα + IELs were regulated by DHM. Mechanistically, luciferase reporter assay and molecular docking assay showed DHM could activate the aryl hydrocarbon receptor (AhR)., Conclusions: These data indicate that DHM exerts a preventive effect against HIE-induced intestinal barrier dysfunction, which is associated with the modulation of the quantity and phenotype of IELs in the small intestine. The findings provide a foundation to identify novel preventive strategies based on DHM supplementation for HIE-induced GIS.

Hypoxia during supramaximal exercise reduces aerobic metabolism with a compensatory increase in anaerobic metabolism without affecting exercise performance. A similar response is elicited by preexercise voluntary hypocapnic hyperventilation, but it remains unclear whether hypocapnic hyperventilation and hypoxia additively reduce aerobic metabolism and increase anaerobic metabolism during supramaximal exercise. To address that issue, 12 healthy subjects (8 males and 4 females) performed the 30-second Wingate anaerobic test (WAnT) after (1) spontaneous breathing in normoxia (control, ∼21% fraction of inspired O2 [FiO2]), (2) voluntary hypocapnic hyperventilation in normoxia (hypocapnia, ∼21% FiO2), (3) spontaneous breathing in hypoxia (hypoxia, ∼11% FiO2), or (4) voluntary hypocapnic hyperventilation in hypoxia (combined, ∼11% FiO2). Mean power output during the 30-second WAnT was similar among the control (561 [133] W), hypocapnia (563 [140] W), hypoxia (558 [131] W), and combined (560 [133] W) trials (P = .778). Oxygen uptake during the 30-second WAnT was lower in the hypocapnia (1523 [318] mL/min), hypoxia (1567 [300] mL/min), and combined (1203 [318] mL/min) trials than in the control (1935 [250] mL/min) trial, and the uptake in the combined trial was lower than in the hypocapnia or hypoxia trial (all P < .001). Oxygen deficit, an index of anaerobic metabolism, was higher in the hypocapnia (38.4 [7.3] mL/kg), hypoxia (37.8 [6.8] mL/kg), and combined (40.7 [6.9] mL/kg) trials than in the control (35.0 [6.8] mL/kg) trial, and the debt was greater in the combined trial than in the hypocapnia or hypoxia trial (all P < .003). Our results suggest that voluntary hypocapnic hyperventilation and hypoxia additively reduce aerobic metabolism and increase anaerobic metabolism without affecting exercise performance during the 30-second WAnT.

The current study aimed to examine the effects of adding specific high-load resistance exercises to a high-intensity functional training (HIFT) program on healthy adults’ physical fitness and body composition. Twenty recreationally active volunteers (30 ± 4 y, 12 females, 8 males) were randomly assigned to either a HIFT-control (HIFT-C, n = 10) or HIFT-power (HIFT-P, n = 10) group and trained three times per week for eight weeks. The HIFT-C protocol included four rounds of an 8-exercise circuit (30:15 s work: rest, 2 min rest after the second round). The exercises used were clean-and-press, box jump, TRX chest press, wall ball throws, burpees, repeated 10 m sprints, sumo squat-and-upright row, and abdominal crunches. The HIFT-P-group replaced TRX chest press with bench press and squat-and-upright row with squat, both at an intensity of 80% 1 RM. Before and after the intervention, participants underwent an evaluation of body composition, cardiorespiratory fitness, vertical jump, 1 RM bench press, and the maximum number of abdominal crunches in 1 min. In both groups, cardiorespiratory fitness, squat jump, countermovement jump, bench press 1 RM, and percent body fat improved significantly after the intervention (p < 0.050), while a trend towards significant time x group interaction was found for bench press 1 RM (p = 0.076), indicating a superiority of HIFT-P over HIFT-C. Muscle mass significantly increased by 3.3% in the HIFT-P group, while abdominal muscle endurance improved by 16.2% in the HIFT-C group (p < 0.050). Short-term HIFT resulted in improvements in whole-body cardiorespiratory and neuromuscular fitness and reduction of body fat. The addition of high-load resistance exercises was well tolerated and resulted in increased muscle mass and upper body maximal strength. HIFT-P programs can be suitable for individuals seeking to enhance muscle mass and physical fitness in a short time.

To explore the effect of time of day (TOD) on several components of cognitive performance prior and post to a physically exhaustive task in a sample of adolescent elite athletes. In a counterbalanced and randomized order, fourteen highly trained male karate athletes (17 ± 0.96 years; 1.75 ± 0.07 m; 68.0 ± 9.50 kg; BMI 22.15 ± 0.54 kg.m -2 ) completed two test sessions at 09h00 and 16h00. Cognitive performance was evaluated before and after the karate specific test (KST). During each session, participants completed the profile of mood state (POMS), simple (SRT) and choice (CRT) reaction times, comparison test (COMT), mental rotation test (MRT), egocentric distance estimation (DE), and the rating of perceived exertion (RPE). KST was not TOD dependent (p > .05, d = 0.33). RPE scores were higher in the afternoon compared to the morning (p < .05, d = 0.68). Before the KST, SRT (p < .01, d = 0.69), CRT (p < .01, d = 0.47), COMT (p < .01, d = 0.62) and MRT (p < .001, d = 0.65) were better in the afternoon than in the morning. However, DE was not affected by the TOD (P > .05). KST improved SRT (p < .01, d = 0.078), CRT (p < .001, d = 0.72), COMT (p < .001, d = 1.31) and MRT (p < .001, d = 0.80) performances only in the morning. Cognitive performances are TOD dependent with higher performances realized in the afternoon. Performing a high intensity exercise in the morning, but not in the afternoon, enhanced several aspects of cognitive performances. The current results indicate that an intensive warm-up could be beneficial when a morning competition requires high cognitive readiness.

This study aimed to examine the effects of hydrogen gas (H 2 ) produced by intestinal microbiota on participant conditioning to prevent intense exercise-induced damage. In this double-blind, randomized, crossover study, participants ingested H 2 -producing milk that induced intestinal bacterial H 2 production or a placebo on the trial day, 4 h before performing an intense exercise at 75% maximal oxygen uptake for 60 min. Blood marker levels and respiratory variables were measured before, during, and after exercise. Visual analog scale scores of general and lower limb muscle soreness evaluated were 3.8- and 2.3-fold higher, respectively, on the morning after treatment than that before treatment during the placebo trial, but not during the test beverage consumption. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations and production rates significantly increased with placebo consumption; no changes were observed with test beverage consumption. After exercise, relative blood lactate levels with H 2 -producing milk consumption were lower than those with placebo consumption. A negative correlation was observed between the variation of 8-OHdG and the area under the curve (AUC) of breath H 2 concentrations. Lipid oxidation AUC was 1.3-fold higher significantly with H 2 -producing milk than with placebo consumption. Conclusively, activating intestinal bacterial H 2 production by consuming a specific beverage may be a new strategy for promoting recovery and conditioning in athletes frequently performing intense exercises.

This study aims to quantify the kinematics, kinetics and muscular activity of all-out handcycling exercise and examine their alterations during the course of a 15-s sprint test. Twelve able-bodied competitive triathletes performed a 15-s all-out sprint test in a recumbent racing handcycle that was attached to an ergometer. During the sprint test, tangential crank kinetics, 3D joint kinematics and muscular activity of 10 muscles of the upper extremity and trunk were examined using a power metre, motion capturing and surface electromyography (sEMG), respectively. Parameters were compared between revolution one (R1), revolution two (R2), the average of revolution 3 to 13 (R3) and the average of the remaining revolutions (R4). Shoulder abduction and internal-rotation increased, whereas maximal shoulder retroversion decreased during the sprint. Except for the wrist angles, angular velocity increased for every joint of the upper extremity. Several muscles demonstrated an increase in muscular activation, an earlier onset of muscular activation in crank cycle and an increased range of activation. During the course of a 15-s all-out sprint test in handcycling, the shoulder muscles and the muscles associated to the push phase demonstrate indications for short-duration fatigue. These findings are helpful to prevent injuries and improve performance in all-out handcycling.