High-intensity Performance Research Articles

Diaphragmatic Ultrasonography in Sports Performance: A Systematic Review

This paper aims to investigate and analyze the correlation between diaphragmatic parameters through ultrasonography and sports performance in various sports disciplines. This systematic review followed the PRISMA methodology. The search strategy was applied in the Medline database through Ovid, EMBASE, LILACS, the Cochrane Central Register of Controlled Trials, and Open Gray. Clinical trials, cohort, case–control, and cross-sectional studies were included, and animal experiments were excluded. A total of 388 studies were identified. After removing duplicates and screening titles and abstracts, sixteen studies were selected for full review, and six were included in the qualitative analysis. The results demonstrated a positive correlation between diaphragm excursion and thickness during inspiration with the anaerobic power, highlighting their importance in high-intensity performance. Additionally, one study reported a positive correlation between diaphragm thickness and aerobic power, suggesting the need for further research. The impact of inspiratory muscle training in Paralympic athletes was also evaluated, providing valuable insights into diaphragmatic adaptation in disabled populations. Ultrasonography is a feasible tool for evaluating the structure and function of the diaphragm, the main element of the respiratory process during sports practice. Its use could contribute to the evaluation and planning of sports training and be a possible indicator of performance improvement.

Boosting oxygen evolution reaction by FeNi hydroxide-organic framework electrocatalyst toward alkaline water electrolyzer

The oxygen evolution reaction plays a vital role in modern energy conversion and storage, and developing cost-efficient oxygen evolution reaction catalysts with industrially relevant activity and durability is highly desired but still challenging. Here, we report an efficient and durable FeNi hydroxide organic framework nanosheet array catalyst that competently affords long-term oxygen evolution reaction at industrial-grade current densities in alkaline electrolyte. The desirable high-intensity performance is attributed to three aspects as follows. First, two-dimensional nanosheet porous arrays with maximum specific surface facilitate mass/charge transfer to accommodate high-current-density catalysis. Second, in situ derived FeNi hydroxide motifs offer bimetallic synergistic catalysis centers with high intrinsic activity. Third, carboxyl ligands alleviate metal oxidation favorable for charge tolerability against peroxidation dissolution under strong polarization. As a result, this catalyst requires an overpotential of only 280 mV to deliver high current density up to 1 A/cm2 with long durability over 1000 h. Moreover, an alkaline water electrolyzer with this catalyst alternative demonstrates an increased economic effectiveness compared to commercial levels at present.

Endurance training volume cannot entirely substitute for the lack of intensity.

Very low intensity endurance training (LIT) does not seem to improve maximal oxygen uptake. The purpose of the present study was to investigate if very high volume of LIT could compensate the lack of intensity and is LIT affecting differently low and high intensity performances. Recreationally active untrained participants (n = 35; 21 females) cycled either LIT (mean training time 6.7 ± 0.7 h / week at 63% of maximal heart rate, n = 16) or high intensity training (HIT) (1.6 ± 0.2 h /week, n = 19) for 10 weeks. Two categories of variables were measured: Low (first lactate threshold, fat oxidation at low intensity exercise, post-exercise recovery) and high (aerobic capacity, second lactate threshold, sprinting power, maximal stroke volume) intensity performance. Only LIT enhanced pooled low intensity performance (LIT: p = 0.01, ES = 0.49, HIT: p = 0.20, ES = 0.20) and HIT pooled high intensity performance (LIT: p = 0.34, ES = 0.05, HIT: p = 0.007, ES = 0.48). Overall, very low endurance training intensity cannot fully be compensated by high training volume in adaptations to high intensity performance, but it nevertheless improved low intensity performance. Therefore, the intensity threshold for improving low intensity performance is lower than that for improving high intensity performance. Consequently, evaluating the effectiveness of LIT on endurance performance cannot be solely determined by high intensity performance tests.

Influence of Ingestion of Bicarbonate-Rich Water Combined with an Alkalizing or Acidizing Diet on Acid-Base Balance and Anaerobic Performance.

During high-intensity (HI) exercise, metabolic acidosis significantly impairs exercise performance. Increasing the body's buffering capacity through training and exogenous intake of alkalizing supplements may improve high-intensity performance. Manipulating water and diet intake may influence the acid-base balance. The aim of this study was to determine the effects of mineral water rich in bicarbonate ions (STY) or placebo water (PLA) on circulating biomarkers and anaerobic performance and to verify whether alkalizing (ALK) or acidizing (ACI) diet would modulate these effects. Twenty-four athletes, assigned either to ALK (n = 12) or ACI (n = 12) diet for four weeks, completed a 1-min rowing Wingate Test in a double-blind and randomized trial after one week of daily hydration (1.5 to 2L/d) with either STY or PLA. Blood samples were taken before and after each test, and urine samples were collected each week. Chronic consumption of bicarbonate-rich water significantly impacted resting urinary pH irrespective of alkalizing or acidizing dietary intake. STY induced a significant increase in blood pH, lactate, and HCO3 - ion concentration post-exercise compared to PLA. Similar changes were observed when STY was associated with the ALK diet. In contrast, STY combined with the ACI diet only significantly affected urine pH and peak blood lactate compared to PLA (p < 0.05). No effect of bicarbonate-rich water was reported on anaerobic performance (p > 0.05). Our results suggest that consumption of bicarbonate-rich water alters acid-base balance during a warm-up and after HI exercise, could potentiate beneficial effects of an alkalizing diet on the acid-base balance after HI exercise, and reduces the acid load induced by an acidifying diet.

Active ischemic pre-conditioning does not additively improve short-term high-intensity cycling performance when combined with caffeine ingestion in trained young men.

We investigated the effect of ischemic preconditioning (IPC) with and without caffeine supplementation on mean power output (MPO) during a 4-min cycling time-trial (TT). In a double-blinded, randomized, crossover-design, 11 trained men performed a TT on 4days separated by ∼1week. One hour before TT, participants ingested either caffeine (3mgkgbw-1) or placebo pills, after which femoral blood-flow was either restricted with occlusion cuffs inflated to ∼180mmHg (IPC), or sham-restricted (0-10mmHg; Sham) during 3×2-min low-intensity cycling (10% of incremental peak power output). Then, participants performed a standardized warm-up followed by the TT. Plasma lactate and K+ concentrations and ratings of perceived exertion (RPE) were measured throughout trials. TT MPO was 382±17W in Placebo+Sham and not different from Placebo+IPC (-1W; 95% CI: -9 to 7; p=0.848; d: 0.06), whereas MPO was higher with Caffeine+Sham (+6W; 95% CI: -2 to 14; p=0.115; d: 0.49) and Caffeine+IPC (+8W; 95% CI: 2-13; p=0.019; d: 0.79) versus Placebo+Sham. MPO differences were attributed to caffeine (caffeine main-effect: +7W; 95% CI: 2-13; p=0.015; d: 0.54. IPC main-effect: 0W; 95% CI: -6 to 7; p=0.891; d: 0.03; caffeine×IPC interaction-effect: p=0.580; d: 0.17). TT RPE and plasma variables were not different between treatments. In conlcusion, IPC with co-ingestion of placebo does not improve short-term high-intensity performance in trained men versus a double-placebo control (Placebo+Sham) and does not additively enhance performance with caffeine. These data do not support IPC as a useful strategy for athletes prior to competition but confirms caffeine's performance-enhancing effect.

Basics of exercise physiology: from Fick principle to the athlete's heart

Physical activity is undeniably associated with numerous health benefits. However, performance of high intensity and/or high-volume exercise poses a significant physiological challenge to the cardiovascular and respiratory systems, which must undergo several adaptations to meet the increased metabolic demands of the organism. Repeated and prolonged exposure to training leads to long-term cardiac remodeling aimed at optimizing the efficiency of the work performed by the heart during exertion. This article discusses some of the fundamental mechanisms of cardiovascular physiology during exercise including adaptive responses to acute bouts of exercise and longer term structural and functional characteristics of the athlete's heart.

Relationship between Body Composition Asymmetry and Specific Performance in Taekwondo Athletes: A Cross-Sectional Study

Currently, there is interest in investigating how interlimb asymmetries (IA) of body composition impact sport-specific performance outcomes. This study aimed to examine the relationship between body composition inter-limb asymmetry and specific performance outcomes in taekwondo athletes. Seventeen national and international athletes (males, n = 8, mean age = 23.3 ± 3.1 years, mean stature = 177.2 ± 8.5 cm, mean body mass = 80.0 ± 7.3 kg; females, n = 9, mean age = 25.0 ± 4.0 years, mean stature = 161.1 ± 4.4 cm, mean body mass = 59.8 ± 5.7 kg) participated in the study. During a non-consecutive 2-day period, body composition (BC) and IA were assessed using dual X-ray absorptiometry, and the magnitude (%) of IA was calculated. Specific-performance included taekwondo specific agility test (TSAT) and Frequency Speed of Kick Test Multiple (FSKTMULT). The relationship between BC asymmetry and performance outcomes was analyzed using a partial correlation approach (controlling for gender, age, and training time). The influence of the significant results was examined using forward stepwise linear regression models. The main results showed no significant differences between the lower limbs (p &lt; 0.05). The IA ranged from 1.37% to 2.96%. Moderate to large negative correlations (r = −0.56 to −0.76, p &lt; 0.05) were documented between IA of body mass, free fat mass (FFM), and lean soft tissue mass (LSTM) with most FSKTMULT outcomes. Bone mineral density (BMD) was correlated with set 5 (rho = −0.49, p = 0.04). The FFM and LSTM asymmetries influenced the KDI reduction by 21%. Meanwhile, IA BMD negatively influenced set 5 performance by 48%. The findings of our study indicate that asymmetries independent of the magnitude of muscle and bone mass-related outcomes may have detrimental effects on high-intensity performance in taekwondo athletes. This underscores the importance of implementing comprehensive training programs and paying attention to achieving body composition inter-limb symmetry to improve overall performance levels in this sport.

Lead-free medium-entropy (Na0.47(1-x)Bi0.47(1-x)Ba0.06(1-x)Sr0.7xNd0.2x)TiO3 relaxor ceramics with robust energy-storage performance

High-entropy engineering is becoming a new strategy in dielectric energy storage capacitors. However, high-entropy strategy alone is insufficient to produce good energy storage performance, as the polarization intensity is greatly reduced by the highly disordered state. We, herein, propose an “entropy engineering + polyphase” strategy and highlight that materials with medium entropy values, no necessity of high entropy values, can yield good energy storage performance under condition that polyphases are introduced in the materials. To illustrate the effectiveness of this strategy, the medium-entropy ceramics (Na0.47(1-x)Bi0.47(1-x)Ba0.06(1-x)Sr0.7xNd0.2x)TiO3 with x = 0.1, 0.2, 0.3, 0.4, and 0.5 were designed by doping ions with different ionic radii and valence states at the A-site. Investigations on the energy storage performance reveal that the sample of x = 0.4, with the maximum entropy value of 1.39R, has the largest recyclable energy storage density Wrec = 8.71 J/cm3 with a high efficiency η = 88.5%. The sample also shows excellent thermal stability of dielectric constant (Δε′/ε25oC′≤ ±15%) over a temperature range of −61–144 °C. The excellent performance is due to the introduction of multiphase in the medium entropy ceramics, which effectively refines the grain and domain sizes, leading to a high polarization intensity (44.23 μC/cm2) and excellent energy storage performance. This work shows that “entropy engineering + polyphase” is an effective strategy for excellent energy storage performance and paves a way of developing new energy storage materials by entropy engineering.

Time Decay in the Performance Benefits From Repeated-Sprint Training in Hypoxia in World-Class Short-Track Speed Skaters.

In short-track speed skating, athletes need to possess specific physiological capabilities to perform explosive starts and to finish races with faster lap times than their opponents. Repeated-sprint training in hypoxia (RSH) can enhance repeated-sprint ability and high-intensity performance. This study aimed to evaluate the relationship between on- and off-ice performance indicators for training and testing purposes and how these are optimized with RSH in world-class short-track speed skaters including world and Olympic champions. RSH training was administered for 3 consecutive weeks, 3 times per week, at 3500m of simulated altitude. Testing sessions (on-ice: 3-lap, 27-lap; off-ice: cycling incremental test, 7-s and 30-s Wingate) were performed immediately before and 2 and 4weeks after RSH to determine the time course of decay. On-ice top speed showed a small and possibly beneficial change of ∼0.9% for the women and large and almost certain ∼0.7% improvement for the men 2weeks post-RSH. Cycling peak power showed a moderate and probable ∼5.4% improvement for the men 2weeks after RSH. These adaptations reverted to baseline 4weeks post-RSH. Wingate average power showed a small and possibly beneficial gain (∼3.4%) in performance 4weeks post-RSH. Although scientific controls could not be added due to the extremely high caliber of these athletes and low sample size of the national team, this study suggests that cycling RSH can be added immediately after on-ice training and can transfer into meaningful improvements on the ice in both male and female skaters.

The effects of sodium bicarbonate ingestion on swimming interval performance in trained competitive swimmers

The use of sodium bicarbonate (NaHCO3) supplementation to improve repeated high-intensity performance is recommended; however, most swimming performance studies examine time trial efforts rather than repeated swims with interspersed recovery that are more indicative of training sessions. The aim of this study, therefore, was to investigate the effects of 0.3 g.kg−1 BM NaHCO3 supplementation on sprint interval swimming (8 × 50 m) in regionally trained swimmers. Fourteen regionally competitive male swimmers (body mass (BM): 73 ± 8 kg) volunteered for this double-blind, randomised, crossover designed study. Each participant was asked to swim 8 × 50 m (front crawl) at a maximum intensity from a diving block, interspersed with 50 m active recovery swimming. After one familiarisation trial, this was repeated on two separate occasions whereby participants ingested either 0.3 g.kg−1 BM NaHCO3 or 0.05 g.kg−1 BM sodium chloride (placebo) in solution 60 min prior to exercise. Whilst there were no differences in time to complete between sprints 1–4 (p > 0.05), improvements were observed in sprint 5 (p = 0.011; ES = 0.26), 6 (p = 0.014; ES = 0.39), 7 (p = 0.005; ES = 0.60), and 8 (p = 0.004; ES = 0.79). Following NaHCO3 supplementation, pH was greater at 60 min (p < 0.001; ES = 3.09), whilst HCO3− was greater at 60 min (p < 0.001; ES = 3.23) and post-exercise (p = 0.016; ES = 0.53) compared to placebo. These findings suggest NaHCO3 supplementation can improve the latter stages of sprint interval swimming performance, which is likely due to the augmentation of pH and HCO3− prior to exercise and the subsequent increase in buffering capacity during exercise.

Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males.

High carbohydrate, low fat (HCLF) diets have been the predominant nutrition strategy for athletic performance, but recent evidence following multi-week habituation has challenged the superiority of HCLF over low carbohydrate, high fat (LCHF) diets, along with growing interest in the potential health and disease implications of dietary choice. Highly trained competitive middle-aged athletes underwent two 31-day isocaloric diets (HCLF or LCHF) in a randomized, counterbalanced, and crossover design while controlling calories and training load. Performance, body composition, substrate oxidation, cardiometabolic, and 31-day minute-by-minute glucose (CGM) biomarkers were assessed. We demonstrated: (i) equivalent high-intensity performance (@∼85%VO2max), fasting insulin, hsCRP, and HbA1c without significant body composition changes across groups; (ii) record high peak fat oxidation rates (LCHF:1.58 ± 0.33g/min @ 86.40 ± 6.24%VO2max; 30% subjects > 1.85 g/min); (iii) higher total, LDL, and HDL cholesterol on LCHF; (iv) reduced glucose mean/median and variability on LCHF. We also found that the 31-day mean glucose on HCLF predicted 31-day glucose reductions on LCHF, and the 31-day glucose reduction on LCHF predicted LCHF peak fat oxidation rates. Interestingly, 30% of athletes had 31-day mean, median and fasting glucose > 100 mg/dL on HCLF (range: 111.68-115.19 mg/dL; consistent with pre-diabetes), also had the largest glycemic and fat oxidation response to carbohydrate restriction. These results: (i) challenge whether higher carbohydrate intake is superior for athletic performance, even during shorter-duration, higher-intensity exercise; (ii) demonstrate that lower carbohydrate intake may be a therapeutic strategy to independently improve glycemic control, particularly in those at risk for diabetes; (iii) demonstrate a unique relationship between continuous glycemic parameters and systemic metabolism.

Optimalresistive Force Selection and Upper Body Contribution in the Assessment of Power during High Intensity Cycle Ergometry: An Unresolved Issue

The purpose of this study is to outline and comment on the issue of optimal resistive force selection and the upper body contribution during high intensity performance using cycle ergometers. The paper provides an historical perspective of the experimental research in developing optimal resistive forces, and the upper body contribution to the test. To date, these issues are still unresolved and further work is needed to provide valid and reliable optimal resistive forces, and to consider the upper body contribution during anaerobic performance assessment of specific subject populations. Studies are needed to identify the optimal resistive force and velocity for subjects who span a wide range of body masses and abilities. These studies should include athletes of various specialties and proficiency. Further to this, the studies should also explore individuals with disabilities and muscular and neurovascular disorders such as, obesity, muscular sclerosis and muscular dystrophy.

Effects of Four Weeks of Plyometric Training Performed in Different Training Surfaces on Physical Performances in School Children: Age and Sex Comparisons.

Short- to middle-term plyometric training has been shown to be an effective method to promote youth fitness and health. However, there is no knowledge of previous studies that investigated the sex and age effects on physical fitness following different PT surfaces (i.e., firm vs. sand) in schoolchildren. This study examined the effects of age and sex on explosive and high-intensity responses following plyometric training (4 weeks, twice/week) performed on firm vs. sand surfaces in untrained schoolchildren. Ninety girls and ninety boys (under 8: age = 7.1 ± 0.5 and 7.1 ± 0.4 years; under 10: age = 9.0 ± 0.4 and 9.0 ± 0.5 years; under 12: age = 11.0 ± 0.5 and 11.0 ± 0.5 years, respectively) participated in a randomized and parallel training design with pre-to-post testing. Participants were allocated (i.e., 30 boys and 30 girls for each group) into either two experimental groups (firm group: performing plyometrics on a clay surface and sand group: performing plyometrics on a dry surface of 20 cm deep sand) or a control group (CG, habitual physical education classes) within their corresponding age groups. Children were tested for sprint, jumping and change of direction speed performances before and after 4 weeks of plyometric training. Both experimental groups induced more significant improvements in all assessed variables than CG (p &lt; 0.0001; effect size &gt; 0.80), whereas both surfaces induced similar improvements (p &gt; 0.05). Older boys achieved better performances than their younger counterparts (p &lt; 0.05) and older girls (p &lt; 0.0001), respectively. This finding showed that age and sex could affect explosive and high-intensity performances during childhood after a short-term plyometric training. In contrast, the training-induced fitness changes were not influenced by the type of surface.

Characterizing Carbon Emissions and the Associations with Socio-Economic Development in Chinese Cities.

Reducing carbon emissions in cities is crucial for addressing climate change, while the city-level emissions of different compositions and their relationships with socio-economic features remain largely unknown in China. Here, we explored the city-level emission pattern from the industrial, transportation, and household sectors and the emission intensity, as well as their associations with socio-economic features in China, using the up-to-date (2020) CO2 emissions based on 0.1° grid (10 × 10 km) emission data. The results show that: (1) CO2 emissions from the industrial sector were considerably dominant (78%), followed by indirect (10%), transportation (8%), and household (2%) emissions on the national scale; (2) combining total emissions with emission intensity, high emission-high intensity cities, which are the most noteworthy regions, were concentrated in the North, while low emission-low intensity types mainly occurred in the South-West; (3) cities with a higher GDP tend to emit more CO2, while higher-income cities tend to emit less CO2, especially from the household sector. Cities with a developed economy, as indicated by GDP and income, would have low emissions per GDP, representing a high emission efficiency. Reducing the proportion of the secondary sector of the economy could significantly decrease CO2 emissions, especially for industrial cities. Therefore, the carbon reduction policy in China should focus on the industrial cities in the North with high emission-high intensity performance. Increasing the income and proportion of the tertiary industry and encouraging compact cities can effectively reduce the total emissions during the economic development and urbanization process.

Low and Moderate Doses of Caffeinated Coffee Improve Repeated Sprint Performance in Female Team Sport Athletes.

Simple SummaryThe bulk of research on caffeine as an ergogenic aid has been on endurance performance, however there is evidence that caffeine can enhance short-term high-intensity performance. Caffeine may have an ergogenic impact during anaerobic exercise by facilitating central effects by antagonizing adenosine receptors, hence decreasing the detrimental effects of adenosine on neurotransmission, arousal, and pain perception. Caffeine intake also activates the central nervous system, which promotes alertness and concentration. Additionally, athletes typically consume coffee containing caffeine. To date, the bulk of study has focused on the administration of 3–9 mg/kg of anhydrous caffeine, as opposed to the readily accessible source of caffeine, coffee, and has mostly been conducted on males. Consequently, there is a dearth of study evaluating the ergogenic impact of caffeine on females, particularly when consuming alternative caffeine delivery methods, such as coffee. The current study is the first to investigate the effects of low (3 mg/kg) and moderate (6 mg/kg) doses of caffeine from coffee on repeated sprint performance in females.The aim of this study was to determine the effect of low and moderate doses of caffeine ingestion via caffeinated coffee on repeated sprint test (RST) and plasma catecholamine concentration in trained female team-sport athletes. In a randomized, double-blind, crossover design, 13 female team-sport athletes (VO2max: 48.7 ± 4 mL·kg·min−1) completed three RST trials, separated by 4-day, 60 min post-ingestion of either 3 mg·kg−1 (LCOF) or 6 mg·kg−1 (MCOF) or placebo (PLA). The RST consisted of 12 × 4 s sprints on a cycle ergometer interspersed with 20 s of active recovery. Blood lactate (BLa) and glucose (GLU) and epinephrine and norepinephrine concentrations were collected before and 60 min after coffee ingestion, and after RST. Heart rate (HR) and ratings of perceived exertion (RPE) were measured at the beginning of RST, and after the 6th and 12th sprints. Average peak power score during RST was significantly improved after LCOF (p = 0.016) and MCOF (p = 0.041) compared to PLA, but peak and mean power output of the individual sprints, and fatigue index were not different between trials (all p > 0.05). Epinephrine and norepinephrine concentrations were significantly higher before and after RST in LCOF and MCOF compared to PLA (all p < 0.05). BLa was also higher after RST in both LCOF and MCOF compared to PLA (p = 0.005). HR, RPE, and GLU were not different between conditions (p > 0.05). In conclusion, low and moderate dose of caffeine ingestion can enhance the average peak power score during repeated sprints. These findings partly support low and moderate doses of caffeine supplementation via coffee as a nutritional ergogenic aid for trained female team-sport players during repeated sprint exercise.

Four Weeks of Intensified Training Enhances On-Ice Intermittent Exercise Performance and Increases Maximal Oxygen Consumption of Youth National-Team Ice Hockey Players.

We investigated whether 4 weeks of intensified training consisting of speed endurance training (SET) enhanced high-intensity exercise performance in youth national-team ice hockey players. Utilizing a randomized crossover design, we subjected 17 players to 4 weeks of SET, comprising 6 to 10 × 20 seconds at maximal effort (>95% maximum ice skating speed) with 120-second recovery performed 3 times weekly, or maintenance of regular training (control period). Before and after each period, players completed ice-hockey-specific tests on ice, including a Yo-Yo Intermittent Recovery Level 1 test, a 30-m sprint test, and an agility test. On a separate day, players were assessed for body composition with dual-energy X-ray absorptiometry and performed countermovement jump, maximal voluntary isometric knee extensor contraction, a 15-second maximal sprint test, and a submaximal and incremental test on a bike ergometer in which pulmonary oxygen consumption was determined. Yo-Yo Intermittent Recovery Level 1 test performance increased (P < .001) by 14% (95% CI, 201-496 m) during the SET period. Maximal pulmonary oxygen consumption (P < .05) and time to exhaustion (P < .05) were 4.8% and 6.5% higher, respectively, after the SET period than before. Fat-free mass increased (P < .01) during the SET period by 1.7 kg (95% CI, 1.0-2.5), whereas fat mass remained unchanged. These effects were superior to the control period. These findings underpin the effectiveness of SET for improving on-ice high-intensity performance and highlight that elite ice hockey players can benefit from implementing SET.

Ketone Monoester Ingestion Alters Metabolism and Simulated Rugby Performance in Professional Players

Ketone ingestion can alter metabolism but effects on exercise performance are unclear, particularly with regard to the impact on intermittent-intensity exercise and team-sport performance. Nine professional male rugby union players each completed two trials in a double-blind, randomized, crossover design. Participants ingested either 90 ± 9g carbohydrate (CHO; 9% solution) or an energy matched solution containing 20 ± 2g CHO (3% solution) and 590mg/kg body mass β-hydroxybutyrate monoester (CHO + BHB-ME) before and during a simulated rugby union-specific match-play protocol, including repeated high-intensity, sprint and power-based performance tests. Mean time to complete the sustained high-intensity performance tests was reduced by 0.33 ± 0.41s (2.1%) with CHO + BHB-ME (15.53 ± 0.52s) compared with CHO (15.86 ± 0.80s) placebo (p = .04). Mean time to complete the sprint and power-based performance tests were not different between trials. CHO + BHB-ME resulted in blood BHB concentrations that remained >2mmol/L during exercise (p < .001). Serum lactate and glycerol concentrations were lower after CHO + BHB-ME than CHO (p < .05). Coingestion of a BHB-ME with CHO can alter fuel metabolism (attenuate circulating lactate and glycerol concentrations) and may improve high-intensity running performance during a simulated rugby match-play protocol, without improving shorter duration sprint and power-based efforts.

Can caffeine supplementation reverse the impact of time of day on cognitive and short-term high intensity performances in young female handball players?

ABSTRACT The aim of the present study was to explore whether caffeine (CAF) intake counteracts the morning reduction in cognitive and short-term maximal physical performances related to the daily variation pattern in young female handball players. In a randomized order, 15 active young female handball players [mean (SD) age:16.3 ± 0.8 y, height: 166.1 ± 5.3 cm; body mass: 58.7 ± 9.1 kg; BMI: 21.3 ± 3.1 kg/m2] performed the simple reaction time (SRT), the attention (AT), the squat jump (SJ), the Illinois agility (IAT) and the 5 m run shuttles (to determine total (TD) and peak (PD) distances) tests at 08:00 h and 18:00 h, 60 min after a placebo (cellulose) or CAF (6 mg·kg−1) intake. The results revealed a significant diurnal variation during both the placebo and the CAF conditions, with improvement of cognitive and physical performances from 08:00 h to 18:00 h (P < .05). Moreover, the improvement of SRT and AT after CAF was better in the morning compared to the afternoon (e.g., 5.3% vs. 2.8% for SRT and 4.2% vs. 0.9% for AT). At 08:00 h and 18:00 h, SJ, IAT, TD, and PD were higher after CAF intake than Placebo (p < .05). This improvement was greater at 08:00 h than 18:00 h (e.g., 4.2% vs 1% for SJ, 1.6% vs 0.2% for IAT, 2.4% vs. 0.3% for TD, and 6% vs. 0.9% for PD). In conclusion, the dose of 6 mg·kg−1 CAF intake improves the cognitive and physical performances in young female handball players and reduces the intraday variation of these parameters. Abbreviations CAF: Caffeine PLC: Placebo SRT: Simple Reaction Time AT: Attention Test SJ: Squat Jump IAT: Illinois Agility Test OT: Oral Temperature QUEST: Questionnaire RPE: Rating of Perceived Exertion PD: Peak Distance TD: Total Distance

Shade induces contrasting light photosynthetic performance between Signal and Guinea Grasses

Signal grass (Urochloa decumbens) and guinea grass (Megathyrsus maximus) are African grasses that are well established in the Brazilian Savannah and we tested their adaptation to different light intensity. Plants were grown for 45 days under 0% shade (full sun) and 25, 40, and 80% induced shade to evaluate their photosynthetic performance. Light curves showed higher values of electron transport rate, photochemical quenching, and effective quantum yield in plants subjected to 0 and 25% shade for signal grass and in 25 and 40% shade for guinea grass. The potential quantum yield evaluations revealed that signal grass felt the effects of excessive light around 11:30 am on plants subjected to 0 and 25% shade. Conversely, guinea grass showed these photoinhibition effects at the same shade level but in a longer time range (9:30 am to 1:30 pm). As shade increased, there was a reduction tendency of the pigment content in signal grass and the opposite was observed for guinea grass. Stomatal conductance showed different values during the day and among different shade levels and there were no differences in relative water content between treatments and species. Results indicated better photosynthetic performance for signal grass under high intensity and better photosynthetic performance for guinea grass subjected to intermediate and higher levels of shade. Altogether, the results indicate that guinea grass seems to be a more appropriate choice for silvopasture systems.

The Effects of a 30-Minute Napping Opportunity after a Night of Partial Sleep Denied on Cognitive and Short-Term High-Intensity Performance and Mood States

Background: It is suggested that there is a relationship between a 30-minute napping opportunity after a night of partial sleep denied on cognitive and short-term high-intensity performance and mood states. Aim: The purpose of this study was to look at the effects of a 30-minute nap on cognitive and short-term high-intensity performance, as well as mood states, following a night of partial sleep deprivation. Methods: On a voluntary basis, 15 elite male athletes took part in the study. The study was carried out as a quantitative study using an experimental design with pre-test and post-test groups. After four weeks of training on five days a week, the athletes were given a 30-minute nap (laying down) between 13:00 and 15:00. The Pittsburgh sleep quality index, vertical jump test, and pulmonary function test were administered to the athletes who napped at 17:00. The Shapiro-Wilk Normality Test was used to determine the data's normality distribution. In accordance with the experimental model and research design, the differences between measurement results were determined using the paired samples t-test (paired samples t-test). The threshold for significance was set at p0.05. Results: Maximum anaerobic power (W), average anaerobic power (W), minimum anaerobic power (W), vertical jump (cm), FVC(L), FEV1(L), FEV1/FVC (%) and FEF25 of the athletes participating in the research. A significant difference was determined between -75(L/s) pre-test values and post-test values (p&lt;0.05). Athletes' anaerobic power (W), average anaerobic power (W), minimum anaerobic power (W), vertical jump (cm), FVC(L), FEV1(L), and FEF25-75 (L/s) post-test The athletes' FEV1/FVC (percent) post-test values were higher than the pre-test values and lower than the pre-test values (p0.05). Conclusion: As a result, short nap sessions have anaerobic power. It has been demonstrated that it improves respiratory functions and vertical jump parameters. Keywords: Cognitive level, napping, mood, high-intensity performance.