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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study aimed to examine sex differences in acute caffeine intake on repeated sprint performance. Fifty‐two resistance‐trained individuals (age: 24.6 ± 4.5 years and sex (female/male): 26/26) participated in a randomized, triple‐blind, cross‐over, and placebo‐controlled study. Participants ingested 3 mg/kg caffeine or placebo and, after 60 min, performed 4 Wingate tests (Wt), consisting of a 30 s all‐out lower‐body sprint against an individualized resisted load, with 90 s rest periods between sprints. Mean (Wmean) and peak (Wpeak) power showed an interaction between sprint and supplement (P = 0.038, ηp2 = 0.095 and P < 0.001, ηp2 = 0.157, respectively), but only Wpeak reported a supplement and sex interaction (P = 0.049 and ηp2 = 0.166). Caffeine increased Wmean in Wt3 (3.5%, P = 0.004, and g = 1.059) and Wt4 (3.9%, P = 0.012, and g = 1.091) compared to placebo. Whereas, for Wpeak, caffeine increased Wpeak in the Wt1 (2.9%, P = 0.050 and g = 1.01) and Wt2 (3.2%, P = 0.050, and g = 1.01) in males and in Wt3 (5.2%, P = 0.008, and g = 1.79) and Wt4 (8.1%, P = 0.004, and g = 2.27) in female participants compared to placebo. No statistically significant sex differences were found in time to reach Wpeak, fatigue index. Acute caffeine intake stimulated a similar ergogenic effect on repeated sprint performance in men and women, except in peak power output, where caffeine increased performance during the first sprints in males and the last sprints in female participants. Highlights: A four‐repeated Wingate test is a valuable protocol for assessing and improving anaerobic capacity and power, tailoring training programs, monitoring recovery from injury, and evaluating the ability to sustain high‐intensity efforts over multiple bouts, which are critical components of many sports (e.g., cycling or soccer).Low doses (3 mg/kg) of caffeine consumed acutely improve repeated sprint performance in both male and female athletes.The pattern of the ergogenic effect seems to differ between sexes only in peak power output. In males, caffeine increases this variable in the first two sprints, whereas in women, it does it in the last two sprints. [ABSTRACT FROM AUTHOR]

Intake of New Zealand blackcurrant (NZBC) extract for 7 days has been shown to improve high-intensity intermittent running (HIIR) performance. Objectives: We examined the repeat response of NZBC extract on HIIR performance. Methods: Sixteen active males (age: 23 ± 3 yrs, height: 179 ± 5 cm, mass: 79 ± 11 kg, V ˙ O2max: 55.3 ± 5 mL∙kg−1∙min−1, velocity at V ˙ O2max: 17.2 ± 0.8 km∙h−1, mean ± SD) participated. Familiarized subjects completed the HIIR test at individualized exercise intensities with stages consisting of six 19 s high-intensity running bouts interspersed by 15 s of low-intensity running and 1 min of inter-stage rest. The test was repeated at increasing speeds until exhaustion, under four conditions; two with a daily dose of 600 mg of NZBC extract (CurraNZ™, providing 210 mg anthocyanins) and two with a placebo, each over 7 days. The study used a double-blind, randomized, cross-over design with a wash-out period of at least 14 days. Results: For the cohort, there were no differences between the placebo and NZBC conditions for mean heart rate (p = 0.071), mean oxygen uptake (p = 0.713), and mean lactate (p = 0.121) at exhaustion for the HIIR. The NZBC extract increased the mean total running distance and mean high-intensity running distance by 7.9% and 8.0% compared to the placebo. With NZBC extract, 8 of the 16 participants (50%) enhanced in both trials beyond the smallest worthwhile change for total running distance (≥173 m) and high-intensity running distance (≥111 m). For repeated responders, total running distance and high-intensity running distance was increased by 16.7% (95% CI [11.0, 22.4%] and 16.6% (95% CI [11.0, 22.2%]. Three participants had enhanced running performance in one trial beyond the SWC, and five participants were considered non-responders. Conclusions: This is the first study on the repeated response by an anthocyanin-rich supplement on high-intensity running performance. New Zealand blackcurrant extract can substantially enhance intermittent high-intensity running performance in consistent responders. Future work should examine dosing strategies of New Zealand blackcurrant, and whether a repeated response rate exceeding 50% can be attained. These findings suggest that NZBC extract could be beneficial for athletes participating in high-intensity team sports. [ABSTRACT FROM AUTHOR]

Zinc and iron as two important essential minerals for testis functions are controlled by Zinc transporters. It has been reported that zinc and its transporters are affected by nutrition and training. The main goals of the current experimentation were to the influences of training in combination with extraction of Ajwain seeds on rat testicular zinc and zinc transporters. Forty male rats were randomly assigned into four groups. Rats were orally received an aqueous Ajwain seed extraction (200 mg kg-1) and the saline groups were treated in the same manner. Results showed that gene expression of Znt5 had meaningfully changed in the ST group in comparison with SC (p = 0.004) and AT (p = 0.001) groups. Expression of this gene had meaningfully alteration in the AT group in comparison with ST (p = 0.036) and AC (p = 0.001) groups. Gene expression of Znt8 was also significantly increased in AT group compared to AC group (P = 0.010). Expression of Znt9 was also significantly increased in AT group in comparison with AC (P = 0.008) and ST (P = 0.026) groups. Expression of the other genes (Znt6, Zip7, Zip8, and Zip14) and also the content of Zn, Fe and glycogen did not show significant differences. The concurrent implementation of training and supplementation with the extract of Ajwain seed significantly modulated the expression levels of certain zinc transporters. These discoveries can offer new understandings into the underlying mechanisms of the effects of exercise and nutrition on testicular tissue. [ABSTRACT FROM AUTHOR]

The brain-derived neurotrophic factor (BDNF) is a crucial protein in the development of the cognitive system. It regulates the growth of neurons and glial cells, synaptic plasticity, and neuroprotection. Background/Objectives: It has been suggested that high-intensity exercise could modulate the mechanisms of BDNF release, with potentially significant implications in the professional sports world. However, this is not yet fully proven, and the underlying physiological alterations are unknown. Methods: This paper reviews the current scientific literature to clarify the uncertainties about how high-intensity physical exercise influences BDNF release and its relationship with high-performance sports. Results: Strenuous exercise appears to increase BDNF synthesis through the action of lactate and the PGC-1α/FNDC5 pathway. Additionally, cognitive function has been described as an element to consider for maximizing sports performance. Conclusions: In this regard, this review provides a solid starting point for further investigation into the molecular mechanisms that promote BDNF expression mediated by exercise, as well as for seeking a direct correlation between the role of cognitive development and athletic performance in high-performance athletes. [ABSTRACT FROM AUTHOR]

Sprint interval training (SIT) leads to similar improvements in maximal oxygen uptake (V̇O2max) and maximal cardiac output as previously reported for traditional endurance training, but the exercise‐induced effects on cardiac remodeling are still largely unknown. The aim of the current study was therefore to explore the effects of SIT on cardiac structure and function assessed by echocardiography in relation to, and controlling for, changes in both blood volume (BV) and heart rate (HR). Healthy men and women (n = 28) performed 6 weeks of SIT. V̇O2max and total BV were measured, and echocardiography was performed before and after the intervention. There was a robust increase in BV (+7.1%; p < 0.001) and V̇O2max (+10.1%; p < 0.001) and a decrease in resting HR (−3.9%; p = 0.013) following the SIT intervention. Machine‐learning‐based feature selection and univariate analysis indicated that several measures of left ventricular dimension (+14.3% LVEDV, p = 0.013; +17.4% LVESV, p = 0.018; +12.3% LVSV, p = 0.031), left ventricular diastolic function (MVA, MVD‐slope, MVDT), and left ventricular stroke volume (LVOT VTI) were altered by 6 weeks of SIT. When controlling for the exercise‐induced changes in BV and HR, left ventricular dimensions remained significantly changed. Our data indicate that several measures of cardiac function are likely only indirectly affected by SIT, driven by increased BV. However, the disproportionate increase in left ventricular size exceeds what can be explained by changes in BV and HR alone, indicating volume‐independent structural cardiac remodeling. [ABSTRACT FROM AUTHOR]

High-intensity exercise requires substantial energy, often resulting in exhaustion and reduced performance. Fatigue during exercise can stem from various factors, including energy depletion, accumulation of lactic acid, neurological impairments, and psychological influences. Dates (Phoenix dactylifera Linn) are a rich source of glucose and bioactive compounds, making them potential components of energy bars designed to enhance performance. This study investigated the anti-fatigue and performance-enhancing effects of date extract during intensive cycling activities. The research used a crossover design, enrolling eight male trained inline skaters with a mean age of 19.13 (0.35) years. These individuals regularly engaged in skating sessions lasting over 1.5 h at least three days a week and had prior experience in competitive events. The participants engaged in two separate high-intensity cycling sessions: one involving date extract ingestion (1 g/kg body weight, consumed 15 min before exercise commencement) and one without. A two-day washout period separated these sessions. Blood glucose levels exhibited a significant increase 15 min after date extract ingestion (pre-exercise: 90.38 (12.93) mg/dL vs. 15-min post 124.63 (25.12) mg/dL; p = 0.002). However, blood glucose levels at the end of exercise were comparable between both conditions. Notably, blood lactate levels increased in both groups, but these values were not significantly different. Performance during high-intensity cycling was significantly enhanced in the group that consumed date extract. Both duration (794.75 (74.89) s vs. 699.88 (84.82) s; p = 0.033) and distance (8,003.72 (784.48) m vs. 6,961.3 (1,036.7) m; p = 0.04) were greater compared to those in the control group, while power and speed remained unaffected. Notably, the maximum rate of perceived exertion was reached at a more advanced stage of high-intensity exercise by the participants in the intervention group compared to those in the control group. These findings suggest that date extract ingestion improves glucose availability for energy production, delays the onset of exercise-induced fatigue, and enhances performance during high-intensity exercise. [ABSTRACT FROM AUTHOR]

High-intensity exercise can cause excessive generation of ROS and induce oxidative stress injury in the body, which is a major reason accounting for muscle damage following exercise. The previous study demonstrated that IBS008738, the activator of TZA, was able to enhance myogenesis in mouse myogenic C2C12 cells, prevent dexamethasone-induced muscle atrophy, and facilitate muscle repair in cardiotoxin-induced muscle injury. Accordingly, our study was designed to probe into the potential role of IBS008738 in muscle damage in mouse models induced by high-intensity exercise. Mice were first administrated with IBS008738, and then subjected to high-intensity eccentric exercise to induce muscle damage after 24 h. During the experiment, mouse weight change and food take were recorded. At the end of the experiment, blood samples were collected through cardiac puncture and centrifugated. Serum levels of blood urea nitrogen (BUN), creatinine, glucose, lactate dehydrogenase (LDH), creatinine kinase (CK), and C-related protein were evaluated using an autoanalyzer. After mice were sacrificed, the gastrocnemius muscles were dissected for DCFH-DA assay of ROS generation, thiobarbituric acid-reactive substances (TBARS) assay of MDA content, hematoxylin‐eosin (H&E) staining of histological examination, and western blotting analysis of Akt/mTOR/S6K1 signaling expression. IBS008738 and/or exercise exert significant effects on mouse weight and food take. High-intensity exercise markedly increased ROS generation and lipid peroxidation, upregulated serum levels of CK, LDH, and C-related protein, ameliorated muscle histological damage, and reduced TAZ, phosphorylated (p)-Akt, p-mTOR, and p-S6K1 protein levels in mice. However, IBS008738 administration reversed the above changes induced by high-intensity exercise in mice. IBS008738 alleviates oxidative stress and muscle damage in mice after high-intensity exercise by activating TAZ and the Akt/mTOR/S6K1 signaling pathway. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background/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 (HRpeak) interspersed with 3-min active recovery intervals at 50%–70% HRpeak. 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).

Background/Objective: 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.

Abstract 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 O2 uptake [V̇O2max], followed by 1 min at 90% V̇O2max) and negative (1 min at 90% V̇O2max, followed by 1 min at 110% V̇O2max) pacing strategies. The arterial-mixed venous O2 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.

Abstract\nKey pointsBackground: 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.T1DM induces loss of skeletal muscle mass and strength.T1DM enhances muscle atrophy-related genes (MAFbx and MuRF1) and impairs mitochondrial function.HIE alongside insulin treatment restores muscle mass, strength, and histological architecture in T1DM-induced muscle atrophy model.HIE alongside insulin treatment over MIE moderated the mitochondrial dysfunction via modulation of the mitophagy-related mediators (BNIP3, Parkin, P62, and LC3II/LC3I) and FGF 21 expression.T1DM induces loss of skeletal muscle mass and strength.T1DM enhances muscle atrophy-related genes (MAFbx and MuRF1) and impairs mitochondrial function.HIE alongside insulin treatment restores muscle mass, strength, and histological architecture in T1DM-induced muscle atrophy model.HIE alongside insulin treatment over MIE moderated the mitochondrial dysfunction via modulation of the mitophagy-related mediators (BNIP3, Parkin, P62, and LC3II/LC3I) and FGF 21 expression. [ABSTRACT FROM AUTHOR]

Endurance and flat race are entirely different efforts and thus require completely different organism adaptations to achieve the performance. This study aimed to examine the difference in basal lipid metabolism in Arabian horses undergoing different training regimens for endurance and race and possible gender differences. The study enrolled sixty male and female' Arabian horses; thirty were trained for race, and thirty were trained for 80 km endurance races. The analyses included body condition score, body weight, body mass index, % body fat, and blood collected to determine triglycerides, total cholesterol, low-density proteins, high-density proteins, and non-esterified fatty acids. Ultrasonography was used to measure the thickness of the subcutaneous fat layer in the longissimus dorsi muscle, as well as the thickness of the rump fat and the cross-section of the gluteus medius muscle. This study showed that lipid profile is more influenced by type of exercise than by gender, being more efficient on endurance horses. [ABSTRACT FROM AUTHOR]

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. 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. 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). 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. [ABSTRACT FROM AUTHOR]

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. 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. 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. ClinicalTrials.gov (NCT04887454). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 O2 uptake [V̇O2max], followed by 1 min at 90% V̇O2max) and negative (1 min at 90% V̇O2max, followed by 1 min at 110% V̇O2max) pacing strategies. The arterial-mixed venous O2 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. [ABSTRACT FROM AUTHOR]

Purpose: This study examined the impact of a 5-wk sprint interval training (SIT) intervention on time to task failure (TTF) during severe-intensity constant work rate (CWR) exercise, as well as in glycolytic enzymatic content and activity, and glycogen content. Methods: Fourteen active males were randomized into either a SIT group (n = 8) composed of 15 SIT sessions over 5 wk, or a control group (n = 6). At pretraining period, participants performed i) ramp incremental test to measure the cardiorespiratory function; ii) CWR cycling TTF at 150%of the power output (PO) at the respiratory compensation point (RCP-PO) with muscle biopsies at rest and immediately following task failure. After 5 wk, the same evaluations were repeated (i.e., exercise intensities matched to current training status), and an additional cycling CWR matched to pretraining 150% RCP-PO was performed only for TTF evaluation. The content and enzymatic activity of glycogen phosphorylase (GPhos), hexokinase (HK), phosphofructokinase (PFK), and lactate dehydrogenase (LDH), as well as the glycogen content, were analyzed. Content ofmonocarboxylate transporter isoform 4 (MCT4) and muscle buffering capacity were also measured. Results: Despite improvements in total work performed at CWR posttraining, no differences were observed for TTF. The GPhos, HK, PFK, and LDHcontent and activity, and glycogen content also improved after training only in the SIT group. Furthermore, theMCT4 concentrations andmuscle buffering capacitywere also improved only for the SIT group. However, no difference in glycogen depletion was observed between groups and time. Conclusions: Five weeks of SIT improved the glycolytic pathway parameters and total work performed; however, glycogen depletion was not altered during CWR severe-intensity exercise, and TTF remained similar. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The implementation of cooling techniques plays a crucial role in minimizing exercise-induced hyperthermia, thereby enhancing performance and preserving cognitive function during training. However, studies on the effect of cooling techniques on cognitive function have yielded mixed results due to inconsistent methodologies, unclear implementation guidelines, variations in cooling protocols, types of exercise, different environmental temperature, and variations in subject fitness levels. Therefore, this study compared the effectiveness of different cooling techniques in improving cognitive function during high-intensity exercise. Eleven young, healthy adult men, aged 18 to 28 years, with a Body Mass Index (BMI) ranging from 18.5 to 24.9 kg/m², normal blood pressure, and a resting heart rate (RHR) between 60 and 100 bpm, were recruited for this study. This research employed a crossover design. The subjects received three types of interventions in a random order: 1) pre-cooling using an ice vest for 30 minutes before training; 2) pre-cooling by consuming an ice slushy at a dosage of 7 g/kg of body weight over 30 minutes; and 3) a combination of both methods. The washout period between interventions was 72 hours. The results indicate a significant decrease in cognitive performance in the pre-cooling and per-cooling groups, with p-values of

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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% VO2max. 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. [ABSTRACT FROM AUTHOR]

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/s2; 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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/m2) 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. [ABSTRACT FROM AUTHOR]

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.

Background and purpose: Post-traumatic stress disorder (PTSD), a type of psychiatric disorder that occurs after exposure to traumatic events, is associated with anxiety and abnormality in the activity of hypothalamic-pituitary-adrenal axis and cognitive functions. Physical activity can improve symptoms of somatic and neuropsychiatric disorders; however, appropriate exercise intensity and duration are still in question. In the present study, the effects of high-intensity exercise on anxiety-like behaviors, fear extinction, serum insulin-like growth factor (IGF-1), brain-derived neurotrophic factor (BDNF), and expression of apoptosis-related genes were investigated in the prefrontal cortex of the rat PTSD model. Materials and methods: In this experimental study, single prolonged stress (SPS) was used to induce PTSD in adult male Wistar rats. After 10 days, the animals in the exercise groups were subjected to high-intensity treadmill exercise (20 m/min, 5 days/week) for four weeks. Next, anxiety-like behaviors and fear extinction were examined using open field and shuttle box tests, respectively. Thereafter, serum IGF-1 and brain BDNF were measured by ELISA kits; and expression of Bax, Bcl-2, and caspase-3 in the prefrontal cortex were measured by real-time PCR. Results: SPS rats showed increased anxiety and decreased fear extinction, serum IGF-1, and prefrontal BDNF compared to the control animals. In addition, SPS induced apoptosis by an increase in Bax and caspase-3 and a decrease in Bcl-2. High-intensity exercise reduced apoptosis and increased serum IGF-1 significantly (P

ObjectiveSleep 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.MethodsEighteen 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.ResultsThe 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 0.05). The impact of interval training on sleep parameters was more significant compared to aerobic capacity testing (p

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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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-P2Y12 (measured by P2Y12 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 highintensity exercise (ClinicalTrials.gov: NCT02958657; https://clinicaltrials.gov/ct2/show/NCT02958657). [ABSTRACT FROM AUTHOR]

This study aims to determine the role of Cinnamomum burmanii supplementation in increasing CD8+ T cells or cytotoxic T cells. It employed the posttest-only control group design. The experimental units in this study were 41 male mouse (Mus musculus) of the BALB/c strain, which were randomly divided into four groups. The first group of 10 mice was a control group that received no treatment. The second group was treated with 200 mg/kg BW of cinnamon extract without exercise. The third group consisted of 10 mice undergoing a high-intensity exercise regimen and receiving a placebo treatment. The fourth group both received the cinnamon supplementation at 200 mg/kg BW and underwent an exercise regimen. The exercise regimen took the form of a regular 7-day-long high-intensity downhill treadmill training with a load of 80-90% of maximum capacity and an inclination angle of -15°. On the 8 th day, twelve hours after exercise, the spleen of the mice was taken for a flow cytometric examination to count the numbers of CD8+ T cells and CD8+ T cells expressing IFN-γ and TNF-α. The counts of CD8+ T cells were significantly different among the groups (p = 0.004), with the median value of the control group being 5.79 ± 2.19, in comparison to that of the fourth group (5.23 ± 1.84). There were significant differencesin the counts of CD8+ T cells expressing IFNγ among the groups (p = 0.027), with the median value of the control group being 18.73 ± 11.94, in comparison to that of the fourth group (10.58 ± 3.78). However, the counts of CD8+ T cells expressing TNF-α lacked significant differences among the groups (p = 0.857), with the median value of the control group being 11.61 ± 10.27, in comparison to that of the fourth group (8.86 ± 3.50). In summary, cinnamon supplementation to high-intensity exercise led to significant increases in the relative counts of CD8+ T cells (p = 0.004) and CD8+ T cells expressing IFN- γ (p = 0.027), but it did not show any significant difference in the relative count of CD8+ T cells expressing TNF-α. [ABSTRACT FROM AUTHOR]

Following a 4-week control period, 24 older men and women (55–91 years) attended a 4-week progressive jumping program to determine whether assisted jumping could be safely and effectively implemented as a novel stimulus in healthy older adults. Bodyweight countermovement jump performance, isometric and isokinetic strength, postural stability, and exercise enjoyment were assessed before the control period, before the training intervention, and after the training intervention. Following the 4-week intervention, eccentric quadriceps strength increased by 19 N·m (95% confidence interval [2, 36], p =.013), bodyweight countermovement jump height increased by 1.7 cm (95% CI [0.5, 2.9], p <.001), postural sway improved by 2.1 mm/s (95% CI [0.3, 4.0], p =.026), and the participants' perceived exercise enjoyment improved (p =.026). Therefore, using assisted jumping to induce an overspeed training stimulus in a jump training program resulted in similar performance improvements as in previous studies in older populations but with less training volume and a shorter training duration. [ABSTRACT FROM AUTHOR]

Abstract Background Research has shown that ingesting 0.3 g·kg−1 body mass sodium bicarbonate (NaHCO3) 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 NaHCO3 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 NaHCO3 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 NaHCO3 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 NaHCO3 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, NaHCO3 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 NaHCO3 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 NaHCO3 was administered in solution but not capsules. Conclusions Participants’ higher expectations when NaHCO3 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

Purpose: This study examined whether a higher protein diet following strenuous exercise can alter markers of muscle damage and inflammation in older adults. Methods: Using a double-blind, independent group design, 10 males and eight females (age 57 ± 4 years; mass 72.3 ± 5.6 kg; height 1.7 ± 6.5 m) were supplied with a higher protein (2.50 g·kg−1·day−1) or moderate protein (1.25 g·kg−1·day−1) diet for 48 hr after 140 squats with 25% of their body mass. Maximal isometric voluntary contractions, muscle soreness, creatine kinase, Brief Assessment of Mood Adapted, and inflammatory markers were measured preexercise, and 24 hr and 48 hr postexercise. Results: The maximal isometric voluntary contractions decreased postexercise (p = .001, η2p = .421), but did not differ between groups (p = .822, η2p = .012). Muscle soreness peaked at 24 hr post in moderate protein (44 ± 30 mm) and 48 hr post in higher protein (70 ± 46 mm; p = .005; η2p = .282); however, no group differences were found (p = .585; η2p = .083). Monocytes and lymphocytes significantly decreased postexercise, and eosinophils increased 24 hr postexercise (p < 0.05), but neutrophils, creatine kinase, interleukin-6, C-reactive protein, monocyte chemotactic protein-1, and Brief Assessment of Mood Adapted were unchanged by exercise or the intervention (p > .05). Conclusion: In conclusion, 2.50 g·kg−1·day−1 of protein is not more effective than 1.25 g·kg−1·day−1 for attenuating indirect markers of muscle damage and inflammation following strenuous exercise in older adults. [ABSTRACT FROM AUTHOR]

Experimental sleep restriction (SR) has demonstrated reduced insulin sensitivity in healthy individuals. Exercise is well-known to be beneficial for metabolic health. A single bout of exercise has the capacity to increase insulin sensitivity for up to 2 days. Therefore, the current study aimed to determine if sprint interval exercise could attenuate the impairment in insulin sensitivity after one night of SR in healthy males. Nineteen males were recruited for this randomized crossover study which consisted of four conditions—control, SR, control plus exercise, and sleep restriction plus exercise. Time in bed was 8 hr (2300–0700) in the control conditions and 4 hr (0300–0700) in the SR conditions. Conditions were separated by a 1-week entraining period. Participants slept at home, and compliance was assessed using wrist actigraphy. Following the night of experimental sleep, participants either conducted sprint interval exercise or rested for the equivalent duration. An oral glucose tolerance test was then conducted. Blood samples were obtained at regular intervals for measurement of glucose and insulin. Insulin concentrations were higher in SR than control (p =.022). Late-phase insulin area under the curve was significantly lower in sleep restriction plus exercise than SR (862 ± 589 and 1,267 ± 558; p =.004). Glucose area under the curve was not different between conditions (p =.207). These findings suggest that exercise improves the late postprandial response following a single night of SR. [ABSTRACT FROM AUTHOR]

Purpose: Dietary supplementation with inorganic nitrate (NO3−) can enhance high-intensity exercise performance by improving skeletal muscle contractility and metabolism, but the extent to which this might be linked to altered psychophysiological processes is presently unclear. The purpose of this study was to assess the effects of NO3−-rich beetroot juice (BJ) supplementation on profile of mood states, ratings of perceived exertion (RPE), and performance in a 30-second Wingate cycle test. Methods: In a double-blind, randomized, cross-over study, 15 subjects completed 2 laboratory sessions after ingesting NO3−-rich or NO3−-depleted (placebo) BJ. Participants initially completed the profile of mood states questionnaire. Subsequently, participants completed a warm-up followed by a 30-second all-out Wingate cycling test. After the Wingate test, participants immediately indicated the RPE of their leg muscles (RPEmuscular), cardiovascular system (RPEcardio), and general RPE (RPEgeneral). Results: Compared with the placebo condition, supplementation with BJ increased peak power output (Wpeak) (+4.4%, 11.5 [0.7] vs 11.1 [1.0] W·kg−1; P =.039) and lowered the time taken to reach Wpeak (7.3 [0.9] vs 8.7 [1.5] s; P =.002) during the Wingate test. The profile of mood states score linked to tension was increased prior to the Wingate test (4.8 [3.0] vs 3.4 [2.4]; P =.040), and RPEmuscular was lowered immediately following the Wingate test (17.7 [1.6] vs 18.3 [1.0]; P =.031), after BJ compared with placebo ingestion. Conclusions: Acute BJ supplementation improved pre-exercise tension, 30-second Wingate test performance, and lowered postexercise RPEmuscular. [ABSTRACT FROM AUTHOR]

Background and purpose: Post-traumatic stress disorder (PTSD), a type of psychiatric disorder that occurs after exposure to traumatic events, is associated with anxiety and abnormality in the activity of hypothalamic-pituitary-adrenal axis and cognitive functions. Physical activity can improve symptoms of somatic and neuropsychiatric disorders; however, appropriate exercise intensity and duration are still in question. In the present study, the effects of high-intensity exercise on anxiety-like behaviors, fear extinction, serum insulin-like growth factor (IGF-1), brain-derived neurotrophic factor (BDNF), and expression of apoptosis-related genes were investigated in the prefrontal cortex of the rat PTSD model. Materials and methods: In this experimental study, single prolonged stress (SPS) was used to induce PTSD in adult male Wistar rats. After 10 days, the animals in the exercise groups were subjected to high-intensity treadmill exercise (20 m/min, 5 days/week) for four weeks. Next, anxiety-like behaviors and fear extinction were examined using open field and shuttle box tests, respectively. Thereafter, serum IGF-1 and brain BDNF were measured by ELISA kits; and expression of Bax, Bcl-2, and caspase-3 in the prefrontal cortex were measured by real-time PCR. Results: SPS rats showed increased anxiety and decreased fear extinction, serum IGF-1, and prefrontal BDNF compared to the control animals. In addition, SPS induced apoptosis by an increase in Bax and caspase-3 and a decrease in Bcl-2. High-intensity exercise reduced apoptosis and increased serum IGF-1 significantly (P<0.05). Conclusion: High-intensity exercise decreases anxiety-like behaviors by increasing serum IGF-1 and inhibiting apoptosis in the prefrontal cortex of PTSD rats. [ABSTRACT FROM AUTHOR]

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-toexhaustion tests (Tlim) to determine CP, finite work above CP (W'), and the highest constant work rate at which maximal oxygen consumption was attained (IHIGH). 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 IHIGH and intensity 5% above IHIGH (IHIGH+5%) were compared to those predicted by all CP models. Actual IHIGH (155 ± 30 s) and IHIGH+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 IHIGH+5% (129 ± 33 s; p = 0.04). Bland-Altman plots of IHIGH+5% presented significant heteroscedasticity by all CP predictions, but not for IHIGH. 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. [ABSTRACT FROM AUTHOR]