Maximum Speed Research Articles

The Effect of Different Motocross Circuit Typologies on Internal Load and External Load Responses in Riders

Background: Several physical and physiological changes occur during a motocross race, mainly due to the type of circuits, and therefore the impact of different types of circuits on training load responses continues to need to be fully clarified. Objective: The main aim of the present study was to compare the internal load and external load responses of motocross riders from different classes and on circuits of different types. Method: A quasi experimental design research was used in the study.The sample consisted of 10 motocross riders (28.10 ± 7.53 years; 74.60 ± 9.70 kg; 176.50 ± 7.18 cm; 23.88 ± 2.18 BMI), male., distributed by the Mx Elite and Mx Hobby categories. The pilots were evaluated before and after the race in relation to indicators of external load (accelerations and decelerations, maximum speed and average speed and impacts) and internal load (Heart rate, blood lactate and rating of perceived exertion) on two circuits of different types. Results: There was a trend towards higher internal load responses in the Mx Hobby class compared to the Mx Elite class (p ≤ 0.05), regardless of the circuit. Regarding external load responses, the Mx Hobby class has a tendency towards higher maximum and average speeds, while the Mx Elite class presents the same tendency for accelerations and decelerations. Conclusions: Different circuit types appear to influence pilots’ internal load and external load responses.

Efficacy of Walking Adaptability Training on Walking Capacity in Ambulatory People With Motor Incomplete Spinal Cord Injury: A Multicenter Pragmatic Randomized Controlled Trial

Background and Objective Balance and walking capacity are often impaired in people with motor incomplete spinal cord injury (iSCI), frequently resulting in reduced functional ambulation and participation. This study aimed to assess the efficacy of walking adaptability training compared to similarly dosed conventional locomotor and strength training for improving walking capacity, functional ambulation, balance confidence, and participation in ambulatory people with iSCI. Methods We conducted a 2-center, parallel-group, pragmatic randomized controlled trial. Forty-one people with iSCI were randomized to 6 weeks of (i) walking adaptability training (11 hours of Gait Real-time Analysis Interactive Lab (GRAIL) training—a treadmill in a virtual reality environment) or (ii) conventional locomotor and strength training (11 hours of treadmill training and lower-body strength exercises). The primary measure of walking capacity was maximal walking speed, measured with an overground 2-minute walk test. Secondary outcome measures included the Spinal Cord Injury Functional Ambulation Profile (SCI-FAP), the Activities-specific Balance Confidence (ABC) scale, and the Utrecht Scale for Evaluation of Rehabilitation-Participation (USER-P). Results No significant difference in maximal walking speed between the walking adaptability (n = 17) and conventional locomotor and strength (n = 18) training groups was found 6 weeks after training at follow-up (−0.05 m/s; 95% CI = −0.12-0.03). In addition, no significant group differences in secondary outcomes were found. However, independent of intervention, significant improvements over time were found for maximal walking speed, SCI-FAP, ABC, and USER-P restrictions scores. Conclusions. Our findings suggest that walking adaptability training may not be superior to conventional locomotor and strength training for improving walking capacity, functional ambulation, balance confidence, or participation in ambulatory people with iSCI. Trial Registration Dutch Trial Register; Effect of GRAIL training in iSCI.

Design, structure analysis and shock control of aircraft landing gear system with MR damper

This study proposes a new magneto-rheological aircraft main landing gear (MRAMLG) system and comprehensively treats from a mathematical modelling to drop testing for the evaluation of the landing efficiency. A mathematical model is formulated based on specifications and requirements of existing small aircraft Oleo type landing gear system. To ensure structural stability of the landing gear components such as main trust, column and trunnion, a transient structural analysis is carried out using the finite element method (FEM) and a fatigue life is analysed based on empirical formulas and the rainflow-counting (RC) algorithm. Subsequently, a novel controller is formulated to enhance the landing efficiency by integrating the time delay model and 3-stage hysteresis regulator. In the synthesis of the controller, a desired force model based on the energy law is added to accurately track the desired yield stress needed for the desired field-dependent force. In this work, the proposed control algorithm is named as the model-based force-tracking (MBFT) controller. To evaluate the landing efficiency or shock struct efficiency (SSE) of the proposed MRAMLG, an experimental apparatus for drop test is designed and manufactured by considering a dummy (sprung) mass of 640–720 kg at the maximum sink speed of 3 m s−1. The sink speed represents the rate of descent of the MRAMLG’s tire just before it touches the ground. It is demonstrated from simulation and experiment that the SSE with the MBFT controller is higher than 83% across various landing conditions with different sprung mass and sink speed, while the conventional controllers, proportional-integral and skyhook, compared to MBFT, do not show consistent performance depending on the sprung mass and sink speed.

Mining Trajectory Planning of Unmanned Excavator Based on Machine Learning

Trajectory planning plays a crucial role in achieving unmanned excavator operations. The quality of trajectory planning results heavily relies on the level of rules extracted from objects such as scenes and optimization objectives, using traditional theoretical methods. To address this issue, this study focuses on professional operators and employs machine learning methods for job trajectory planning, thereby obtaining planned trajectories which exhibit excellent characteristics similar to those of professional operators. Under typical working conditions, data collection and analysis are conducted on the job trajectories of professional operators, with key points being extracted. Machine learning is then utilized to train models under different parameters in order to obtain the optimal model. To ensure sufficient samples for machine learning training, the bootstrap method is employed to adequately expand the sample size. Compared with the traditional spline curve method, the trajectories generated by machine learning models reduce the maximum speeds of excavator boom arm, dipper stick, bucket, and swing joint by 8.64 deg/s, 10.24 deg/s, 18.33 deg/s, and 1.6 deg/s, respectively; moreover, the error does not exceed 2.99 deg when compared with curves drawn by professional operators; and, finally, the trajectories generated by this model are continuously differentiable without position or velocity discontinuities, and their overall performance surpasses that of those generated by the traditional spline curve method. This paper proposes a trajectory generation method that combines excellent operators with machine learning and establishes a machine learning-based trajectory-planning model that eliminates the need for manually establishing complex rules. It is applicable to motion path planning in various working conditions of unmanned excavators.

Visual cortex anodal transcranial direct current stimulation does not alter reading performance for Chinese presented character-by-character to normal peripheral vision in older adults.

Visual cortex anodal transcranial direct current stimulation (a-tDCS) has been shown to reduce crowding in normal peripheral vision and may improve the reading of English words in patients with macular degeneration. Given the different visual requirements of reading English words and Chinese characters, the effect of a-tDCS on peripheral reading performance in English might differ from Chinese. This study recruited 20 participants (59-73 years of age) with normal vision and tested the hypothesis that a-tDCS would improve the reading of Chinese characters presented at 10° eccentricity compared with sham stimulation. Chinese sentences of different print sizes and exposure durations were presented one character at a time, 10° below or to the left of fixation. The individual critical print size (CPS) - the smallest print size eliciting the maximum reading speed (MRS) - was determined. Reading accuracies for characters presented 0.2 logMAR smaller than the individually fitted CPS were measured at four time points: before, during, 5 min after, and 30 min after receiving active or sham visual cortex a-tDCS. Participants completed both the active and sham sessions in a random order following a double-blind, within-subject design. No effect of active a-tDCS on reading accuracy was observed, implying that a single session of a-tDCS did not improve Chinese character reading in normal peripheral vision. This may suggest that a-tDCS does not significantly reduce the crowding elicited within a single Chinese character. However, the effect of a-tDCS on between-character crowding is yet to be determined.

Series Clutched Actuation for Collision-Tolerant High-Speed Robots

Abstract Collisions at high-speed can severely damage robots with non-backdrivable drivetrains. Adding an overload clutch in series can improve the robot’s collision tolerance without compromising its high dynamic performance. This paper aims at determining the speed above which overload clutches are required in a two-link manipulator arm. Furthermore, the optimal clutch topology as function of the impact velocity is investigated. Third, it is evaluated if adding clutches can lower the impact force on the arm. Finally, the maximum speed is identified below which impact-aware robot control is possible. The latter requires that none of the clutches decouple during an intentional collision with the environment. These answers are obtained through collision simulations and experiments with a custom build two-link arm. It was found that adding a clutch reduces the torque experienced by the drivetrain by an order of magnitude and below the limit momentary peak torque of the strain wave gears that are used. Adding a clutch to the elbow joint of the two-link arm was effective in protecting the shoulder as well if the impact occurred at the tool center point. With respect to a rigid elbow joint, the clutched elbow joint reduced the collision force at the tool by only 8%. To demonstrate that the arm is impact-aware, a box of 8 kg is approached, impacted, and pushed at 1 m/s without decoupling a clutch, nor damaging the robot’s hardware.

Evaluasi dan Optimalisasi Penyediaan Air Bersih Berbasis Masyarakat (Studi Kasus: Kawasan Langara Pesisir, Kab. Konawe Kepulauan)

The Langara Coastal area is the economic center area of the capital city of Konawe Islands Regency. However, the provision of clean water as a basic need is still not fulfilled, this is because the source of clean water in the Langara Coastal Area currently still depends on Community Self-Help, as a result, water distribution is carried out in shifts. This research aims to determine air needs, the condition of the existing distribution network, and optimize the clean water distribution system. Air requirements are calculated using an analysis of population projections for 15 years. Analysis of pipe hydraulics using EPANET 2.2 Software, and air flow by gravity using PVC pipes. The analysis results show that the population in 2036 will be 1816 people with peak hour water demand of 4.13 l/sec. The condition of the existing distribution network shows that all Junctions have an average pressure of 9 atm. Meanwhile, the pipe with the highest speed at P3 is 0.47 m/s and the speed at P15 is 0.04 m/s, indicating that the existing conditions do not meet the technical criteria of Minister of PUPR Regulation No. 27/PRT/M/2016. So to increase the flow speed it is necessary to change the pipe dimensions at several points. In peak hour optimization simulations, the maximum speed occurs in pipes P2, P3, P4, and P10, namely 2.61 m/s, while the lowest speed occurs in pipe P21, namely 0.30 m/s. The results of this optimization are by the speed criteria in Minister of PUPR Regulation No.27/PRT/M/2016

A Fast Online Elastic-Spine-Based Stiffness Adjusting Mechanism for Fishlike Swimming.

Fish tunes fishtail stiffness by coordinating its tendons, muscles, and other tissues to improve swimming performance. For robotic fish, achieving a fast and online fishlike stiffness adjustment over a large-scale range is of great significance for performance improvement. This article proposes an elastic-spine-based variable stiffness robotic fish, which adopts spring steel to emulate the fish spine, and its stiffness is adjusted by tuning the effective length of the elastic spine. The stiffness can be switched in the maximum adjustable range within 0.26 s. To optimize the motion performance of robotic fish by adjusting fishtail stiffness, a Kane-based dynamic model is proposed, based on which the stiffness adjustment strategy for multistage swimming is constructed. Simulations and experiments are conducted, including performance measurements and analyses in terms of swimming speed, thrust, and so on, and online stiffness adjustment-based multistage swimming, which verifies the feasibility of the proposed variable stiffness robotic fish. The maximum speed and lowest cost of transport for robotic fish are 0.43 m/s (equivalent to 0.81 BL/s) and 7.14 J/(kg·m), respectively.

Research on vibration characteristics of a straddle-type station induced by moving trains

The novelty of straddle-type railway stations as a modern railway infrastructure necessitates thoroughly examining their vibration behavior under high-speed train-induced vibrations. This study focuses on Shangrao station, the inaugural straddle-type high-speed railway station in China, to investigate its vibration properties induced by high-speed trains. A comprehensive finite element model is developed and validated against empirical data to ensure accuracy. The vibration response and propagation patterns induced by railway operations are extensively studied under diverse operational conditions. The results illustrate that the peak acceleration in the vertical (Z) direction significantly exceeds that in the horizontal (X and Y) directions in most test cases. Moreover, under consistent train speed and axle load, the multiple parallel traffic scenario results in higher peak accelerations in all directions compared to the grade separation traffic scenario. Additionally, a positive correlation exists between the railway platform’s maximum amplitude, corresponding frequency, and train speed. Furthermore, increased train axle load leads to higher peak accelerations in the station building. The findings of this research offer valuable insights for the predictive modeling and design of high-speed straddle-type railway stations, providing essential technical support for future station projects.

The air conditioning in the nose of mammals depends on their mass and on their maximal running speed

The nose of the mammals is responsible for filtering, humidifying, and heating the air before entering the lower respiratory tract. This conditioning avoids, notably, dehydration of the bronchial and alveolar mucosa. However, since this conditioning is not perfect, exercising in cold air can induce lung inflammation, both for human and non-human mammals. This work aims to compare the air conditioning in the noses of various mammals during inspiration. We build our study on computational fluid dynamics simulations of the heat exchanges in the lumen of the upper respiratory tract of these mammals. These simulations show that the efficiency of the air conditioning in the nose during inspiration does not relate only to the mass m of the mammal but also to its maximal running speed v. More precisely, the results allow establishing a scaling law relating the efficiency of air conditioning in the nose of mammals to the ratio v/log10(m)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$v/\\log _{10}(m)$$\\end{document}. The simulations also correlate the resistance to the flow in the nose to the efficiency of this air conditioning. The obtained scaling law allows predicting the air temperature at the top of the trachea during inspiration for nasal-breathing mammals, and thus notably for humans of various ages.

Effects of rehabilitation on functional independence in daily life, exercise tolerance and quality of life in patients with relapsing-remitting multiple sclerosis

Objective: to evaluate the efficacy of a comprehensive rehabilitation program on functional independence in daily life, exercise tolerance and quality of life (QoL) in patients with relapsing-remitting multiple sclerosis (RRMS) in remission.Material and methods. 38 patients with RRMS were analyzed (33 women and 5 men; age – 41.6±7.7 years; EDSS – 4.0 [3.5; 5.0] points, duration of MS – 8.0 [3.0; 21.0] years). The patients received comprehensive rehabilitation in a hospital for 2.5 weeks. The examination was carried out before and after the rehabilitation program. Independence in daily activities was assessed using the Functional Independence Scale, the Get Up and Go Test and the Berg Balance Scale. Exercise tolerance was determined using a cardiopulmonary exercise test (CPET) on a cycle ergometer. The following parameters were measured: oxygen consumption during exercise (VO2 peak oxygen uptake), percentage from the predicted VO2 peak (% pred VO2 peak) and maximal workload in metabolic units (MET). Walking speed was measured according to the Davis protocol in the SMART-D laboratory (Italy). QoL was determined using the SF-36 questionnaire, which assesses physical functioning (PF), general health (GH), vital activity (VT) and social functioning (SF). Cognitive functioning was assessed using the Montreal Cognitive Scale (MoCA) and depression using the Beck Depression Inventory (BDI). Results. After completion of the rehabilitation course, there was a significant increase in VO2 peak (from 18.8±3.8 to 20.4±4.3 ml/kg/min), % pred VO2 peak (from 59±13 to 63±14%), maximal workload (from 5.4±1.2 to 5.8±1.2 MET), maximal heart rate (from 140±14 to 147±13) and walking speed (from 0.84±0.29 to 0.97±0.28 m/s). At the same time, despite an improvement the patients did not reach the age- and gender adjusted reference values for exercise tolerance. QoL indicators also increased, reaching or exceeding the populational values obtained for the Russian population: PF – from 45 to 52.2; GH – from 51 to 52; VT – from 45 to 50; SF – from 62.5 to 75. The number of points on the BDI also decreased significantly (from 9 to 6), and the increase on the MoCA scale had tendency to significant difference (p=0.064). Conclusion. A comprehensive rehabilitation program in patients with RRMS in remission helps to increase exercise tolerance and improve functional independence and QoL.

Retinal OCT biomarkers associated with reading performance in patients with persistent vs. resolved diabetic macular edema.

Recent advancements in imaging technologies, particularly structural optical coherence tomography (OCT), have improved the understanding of diabetic macular edema (DME) pathophysiology and provided valuable biomarkers for disease progression and visual outcomes. This prospective study aimed to investigate the association between specific retinal biomarkers identified through OCT imaging and reading performance metrics in patients with previously treated persistent versus resolved DME and good visual acuity. Forty-nine eyes from 35 patients with a history of DME were enrolled. Reading performance was assessed using the Radner reading charts, which include standardized sentences with geometrically progressing print sizes. Structural alterations in the inner and outer retina, as well as the retinal pigment epithelium (RPE), were graded based on OCT images. Reading performance, measured as maximum reading speed, was associated with specific retinal biomarkers. The disruption of the ellipsoid zone (EZ) in the parafoveal region and the presence of disorganization of the inner retinal layers (DRIL) in the parafovea were correlated with reduced reading speed. These associations were independent of the presence of intraretinal or subretinal fluid. Understanding the relationship between retinal biomarkers and reading performance could contribute to a comprehensive evaluation of visual function and quality of life in patients with DME, leading to better management strategies and treatment outcomes.

A numerical study on energy transfer between near-inertial internal waves and super-inertial internal waves in the South China sea under the influence of a typhoon

The energy transfer between near-inertial internal waves (NIWs) and super-inertial internal waves (SIWs) in the South China Sea (SCS) after the passage of Typhoon Son-tinh was investigated on the basis of a three-dimensional numerical model. Our model nicely reproduces the spectral peak (6.6 × 10−2 m2 s−2 cpd−1) within the near-inertial frequency band, which agrees well with that (6.5 × 10−2 m2 s−2 cpd−1) in the in-situ observations at the Xisha mooring. Model results demonstrate that the energy transfer rate from NIWs (0.8f∼1.8f) to SIWs (>1.8f) within the mixed layer in the wake of typhoon Son-tinh is an order of magnitude larger than that during the typhoon-free period. Analogously, the super-inertial shear variance increases by nearly an order of magnitude as well. The increase in the energy of SIWs is mainly due to the energy cascade of NIWs through the nonlinear wave-wave interaction. The interaction between NIWs and SIWs was also revealed by the bicoherence spectrum. Compared with that on the left side of the typhoon track, the NIW kinetic energy on the right side is stronger, where the interaction between NIWs and SIWs is more intense. Several sensitivity experiments were designed to further investigate the effects of three typhoon parameters, namely the radius of maximum typhoon wind speed (Rmax), the maximum typhoon wind speed (Vmax) and the moving speed of typhoon (Um), on the energy transfer rate (ETR) from NIWs to SIWs. It is shown that, the ETR increases linearly with Rmax. Among three parameters, Vmax has the strongest effects on the ETR which grows in power with increasing Vmax. The ETR increases and then decreases with the enhancement of Um, which gets maximum when Um is about 6∼6.5 m/s. Overall, our results highlight the energy transfer between near-inertial internal waves and super-inertial internal waves under the influence of a typhoon.

Beyond gait speed: exploring the added value of Inertial Measurement Unit-based measurements of gait in the estimation of the walking ability in daily life.

Gait speed is often used to estimate the walking ability in daily life in people after stroke. While measuring gait with inertial measurement units (IMUs) during clinical assessment yields additional information, it remains unclear if this information can improve the estimation of the walking ability in daily life beyond gait speed. We evaluated the additive value of IMU-based gait features over a simple gait-speed measurement in the estimation of walking ability in people after stroke. Longitudinal data during clinical stroke rehabilitation were collected. The assessment consisted of two parts and was administered every three weeks. In the first part, participants walked for two minutes (2MWT) on a fourteen-meter path with three IMUs attached to low back and feet, from which multiple gait features, including gait speed, were calculated. The dimensionality of the corresponding gait features was reduced with a principal component analysis. In the second part, gait was measured for two consecutive days using one ankle-mounted IMU. Next, three measures of walking ability in daily life were calculated, including the number of steps per day, and the average and maximal gait speed. A gait-speed-only Linear Mixed Model was used to estimate the association between gait speed and each of the three measures of walking ability. Next, the principal components (PC), derived from the 2MWT, were added to the gait-speed-only model to evaluate if they were confounders or effect modifiers. Eighty-one participants were measured during rehabilitation, resulting in 198 2MWTs and 135 corresponding walking-performance measurements. 106 Gait features were reduced to nine PCs with85.1% explained variance. The linear mixed models demonstrated that gait speed was weakly associated with the average and maximum gait speed in daily life and moderately associated with the number of steps per day. The PCs did not considerably improve the outcomes in comparison to the gait speed only models. Gait in people after stroke assessed in a clinical setting with IMUs differs from their walking ability in daily life. More research is needed to determine whether these discrepancies also occur in non-laboratory settings, and to identify additional non-gait factors that influence walking ability in daily life.

Analytical and adaptable initial conditions for dry and moist baroclinic waves in the global hydrostatic model OpenIFS (CY43R3)

Abstract. This article presents a description of an analytical, stable, and flexible initial background state for both dry and moist baroclinic wave simulation on an aquaplanet in order to test the dynamical core of numerical weather prediction models and study the dynamics and evolution of extratropical cyclones. The initial background state is derived from an analytical zonal wind speed field, or jet structure, and the hydrostatic primitive equations for moist adiabatic and frictionless flow in spherical coordinates. A baroclinic wave can develop if a perturbation is added to the zonal wind speed field. This new baroclinic wave configuration has been implemented in the Open Integrated Forecasting System (OpenIFS) CY43R3, a global numerical weather prediction model developed by the European Centre for Medium-Range Weather Forecasts. In total, seven parameters can be used to control the generation of the initial background state and hence the development of the baroclinic waves in the OpenIFS configuration file: the jet's width, the jet's height, the maximum zonal mean wind speed of the jet, the horizontal mean of the surface virtual temperature, the surface relative humidity, the lapse rate, and the surface roughness. Nine dry and nine moist initial background states have been generated to test their stability without perturbations. The meteorological stability of the initial states is investigated by examining the spatial distributions of the equivalent potential temperature, the absolute vorticity, and the Brunt–Väisälä frequency. Moreover, the root mean square error (RMSE) of the zonal wind speed has been computed to assess their numerical stability. Finally, six dry and six moist initial background state have been used with an unbalanced perturbation to ensure that the baroclinic life cycles that develop are physically realistic. The resulting baroclinic wave is shown to be sensitive to the jet's width. This configuration for baroclinic wave simulations will be used to create a large ensemble of baroclinic life cycles to study how extratropical cyclones may evolve in the future.

Effects of Eccentric Speed during Front Squat Conditioning Activity on Post-activation Performance Enhancement of Hip and Thigh Muscles.

The phenomenon of post-activation performance enhancement plays an unidentified role in movement eccentric speed and individual muscle group responses. Therefore, this study aimed to determine whether the loaded front squat (FSq) speed of the eccentric phase would influence the post-activation performance enhancement effect and whether the FSq would elicit similar performance enhancement of knee flexion, knee extension, hip flexion, and hip extension muscles. Twenty resistance-trained handball players performed the FSq under maximum eccentric-concentric speed and 2-s eccentric speed (only the eccentric phase performed), while pre- and post-front squat countermovement jump, knee, and hip isokinetic flexion/extension performance were tested. The FSq conditioning activity was performed in a single set of three repetitions with either 90% (maximum eccentric-concentric speed) or 120% (2-s eccentric speed) of one repetition maximum, and post-performance was measured 4-12 min after the FSq. Athletes randomly changed the FSq eccentric speed and tested the hip or knee isokinetic flexion/extension strength at 180°/s. ANOVA showed that the rate of force development during the jump increased (Cohen d = 0.59-0.77) with no differences between 2-s eccentric and maximum speed eccentric protocols. Isokinetic strength increased after the 2-s eccentric FSq in hip extension (d = 0.76-0.86), knee flexion (d = 0.74-0.88), and hip flexion (d = 0.82), with no differences in knee extension strength. After maximum eccentric-concentric speed, isokinetic strength increased in hip extension (d = 1.25). In conclusion, the FSq conditioning activity enhances hip extensors' performance more than knee extensors' performance. Different eccentric types of muscle action during a conditioning activity alter the level of local muscle enhancement.

In-Season Training Load Variation - Heart Rate Recovery, Perceived Recovery Status, and Performance in Elite Male Water Polo Players: A Pilot Study.

Increased training and competition demands of the in-season period may disturb athlete fatigue and recovery balance. The aim of this study was to describe the training load distribution applied in a competitive period and the training adaptations and fatigue/recovery status of elite water polo players. Effective workload management during tapering (TAP) would restore player recovery and enhance performance. Case series. Level 4. Training load, perceived recovery, maximal speed in 100- and 200-meter swim, heart rate (HR) during submaximal swimming (HRsubmax) and HR recovery (HRR) were assessed in 7 outfield water polo players a week before starting a normal training microcycle (NM), after NM, and after congested (CON) and TAP training blocks in the lead-up to the Final Eight of the European Champions League. Training load was higher in NM compared with CON and TAP by 28.9 ± 2.6% and 42.8 ± 2.1% (P < 0.01, d = 11.54, and d = 13.45, respectively) and higher in CON than TAP by 19.4 ± 4.2% (P < 0.01, d = 3.78). Perceived recovery was lower in CON compared with NM and TAP (P < 0.01, d = 1.26 and d = 3.11, respectively) but not different between NM and TAP (P = 0.13, d = 0.62). Both 100- and 200-meter swim performance was improved in TAP compared with baseline (P < 0.01, d = 1.34 and d = 1.12, respectively). No differences were detected among other training blocks. HRsubmax and most HRR were similar among the training periods. Effective management of training load at TAP can restore recovery and improve swimming performance without affecting HR responses. Despite lower workloads, CON training impairs perceived recovery without affecting performance; however, a short-term training load reduction after a CON fixture restores recovery and improves performance.

Assessing the individual relationships between physical test improvements and external load match parameters in male professional football players-a brief report.

This study aimed to explore whether a meaningful improvement in physical performance following an in-season strength training intervention can be related to external load match parameters at an individual level in professional male football players. Eight male professional football players (25.4 ± 3.1 years, 184.1 ± 3.4 cm, 79.3 ± 2.2 kg) completed a 10-week strength intervention period in addition to football-specific training and matches. Commonly used physical and external load measures were assessed before and after intervention. Physical performance improvements had to exceed the measurement's typical error and the smallest worthwhile difference (SWD) to be considered meaningful. External load match parameters were assessed before and after the intervention period using SWD and non-overlap of all pairs (NAP) analysis. A Bayesian pairwise correlation analysis was performed to evaluate relationships between changes in physical performance and external load match parameters. Three players displayed meaningful improvements in two to five physical performance measures. However, positive changes exceeding the SWD and positive effects in NAP results were observed for all players in external load match parameters. Kendall's tau correlation analysis showed evidence (base factor >3) for only one correlation (maximum speed - decelerations, τ = -0.62) between the changes in physical performance and external load measures, while the remaining comparisons exhibited no relation. The findings suggest that improvements in physical performance may not necessarily translate to improvements in external load match parameters. Further research, with larger sample sizes, is needed to understand potential mechanisms between acute and chronic physical performance changes and football external load parameters during training and matches.

Repeated-sprint sets test: a new method for evaluating and forecasting fitness in elite young male soccer players

The objective of the current study was to explore the correlation between repeated sprint sets (RSS) ability and several physical attributes, including maximum sprint speed, maximal aerobic speed, maximal anaerobic speed, aerobic capacity, and explosive strength. Moreover, the aim was to assess the suitability of RSS as a comprehensive evaluation tool for physical qualities and to determine which physical field tests most accurately predict RSS in elite young male soccer players. A total of thirty-two young elite male soccer players (mean age 14.6 ± 0.3 years; predicted years from peak height velocity (PHV): − 0.4 ± 0.3; years in training: 3.7 ± 0.5) voluntarily participated in the study. The players participated in eight consecutive specific physical tests, with a minimum 72-h recovery between each session to minimize the impact of fatigue during the second trial. The participants completed the tests in the following order: RSS test, Vam-Eval test, a constant velocity test performed until exhaustion at 100% of vVO2max (tlim100), 20-m Multi-Stage Shuttle Run test (VMSRT), Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1), Maximal Anaerobic Shuttle Running Test (VMASRT), Maximal Sprinting Speed Test (20-m flying sprint), Countermovement Jump (CMJ), and Standing Long Jump test (SLJ). The results of the study showed that there were very large negative correlations between tlim100 and SST (sum of sprint times), and large negative correlations between Yo-Yo IR1, Vam-Eval, and SST during RSS in young elite male soccer players (p < 0.05). Additionally, VMASRT and SLJ demonstrated a moderate negative correlation with SST (p < 0.05). In contrast, significant positive correlations were found between 20-m flying sprint and the SST (p < 0.05). According to the stepwise multiple linear regression analysis, the primary predictors of SST, ranked by importance, were tlim100 and Yo-Yo IR1. These two predictors collectively accounted for 72% of the variance in players’ SST (p < 0.0001). Due to the importance of aerobic capacity and short repeated accelerations/sprint sets for overall competitive performance in soccer, in conclusion, our results suggest that elite young male soccer players should perform both high intensity interval training and aeorobic capactity exercises as part of soccer training if the primary outcome is to improve repeated sprint ability performance.

The Expected Dynamics for the Extreme Wind and Wave Conditions at the Mouths of the Danube River in Connection with the Navigation Hazards

The entrance in the Sulina channel in the Black Sea is the target area of this study. This represents the southern gate of the seventh Pan-European transport corridor, and it is usually subjected to high navigation traffic. The main objective of the work is to provide a more comprehensive picture concerning the past and future expected dynamics of the environmental matrix in this coastal area, including especially the extreme wind and wave conditions in connection with the possible navigation risks. The methodology considered assumes analyses performed at three different levels. First, an analysis of some in situ measurements at the zero-kilometer point of the Danube is carried out for the 15-year period of 2009–2023. Together with the maximum wind speed and the maximum value of the wind gusts, the water level variation was analyzed at this point. As a second step, the analysis is based on wind speed data provided by regional climate models. Two periods, each spanning 30 years, are considered. These are the recent past (1976–2005), when comparisons with ERA5 reanalysis data were also performed, and the near future (2041–2070), when two different models and three climate scenarios were considered. The focus was on the extreme wind speed values, performing comparisons between the past and future expected extreme winds. Finally, the third analysis is related to the wave conditions. Thus, using as a forcing factor each of the wind fields that was previously analyzed, simulations employing a spectral wave model were carried out. The wave modeling system was focused using three different computational domains with increasing resolution towards the target area, and the nearshore wave conditions were evaluated. The results show that both the extreme wind and wave conditions are expected to slightly increase in the future. Especially in the wintertime, strong wind fields are often expected in this area, with wind gusts exceeding more than 70% of the hourly average wind velocity. With regard to the waves, due to the complex nearshore phenomena, considerable enhancements in terms of significant wave heights are induced, and there is also an elevated risk of the occurrence of rogue waves. This work is still ongoing, and taking into account the high navigation risks highlighted, the next step would be to elaborate the risk assessment of severe shipping conditions, particularly related to the likelihood or probability of adverse conditions with the potential of generating hazardous situations in this coastal environment.