Change Of Direction Research Articles

Evaluating the Effects of Consecutive Phases of Plyometric Jump Training on Athletic Performance in Male Soccer Players: The Effect of Training Frequency and Volume Manipulations.

Moran, J, Vali, N, Tallent, J, Howe, L, Clemente, FM, Chaabene, H, and Ramirez-Campillo, R. Evaluating the effects of consecutive phases of plyometric jump training on athletic performance in male soccer players: The effect of training frequency and volume manipulations. J Strength Cond Res 38(6): 1082-1089, 2024-This 14-week, 2-phase study aimed to determine the relative effects of 1 day or 2 days of volume-matched plyometric training on athletic performance (10- and 40-m sprints, change of direction [COD], and vertical jump [VJ]) in male soccer players (phase 1). The objective of phase 2 was to determine the relative effects of higher- and lower-volume plyometric training protocols in maintaining any previously attained increases in athletic performance from phase 1. A randomized parallel-group trial design was utilized. In phase 1, subjects ( n = 24; mean age: 19.5 ± 1.2 years; mean height: 179.7 ± 7.1 cm; mean weight: 69.8 ± 6.9 kg) were randomly allocated to 1 of 2 groups to receive either 1 day or 2 days of volume- and intensity-matched plyometric training for a 7-week period. For the second 7-week period (phase 2), half of each group was randomized into either a lower-volume or higher-volume plyometric training group. In phase 1, both the 1-day group and the 2-day group attained comparably significant ( p < 0.001) increases in performance in all fitness tests ranging from effect sizes (ESs) ( d ) of 0.4 (95% confidence interval: 0.11 to 0.70) for 10-m sprint to 1.51 (0.42-2.60) for VJ. There were no significant differences between the performance increases in the 2 groups. In phase 2, neither group increased or decreased performance, maintaining all previously attained increases with only trivial ESs observed (-0.02 [-0.58 to 0.53] to 0.11 [-0.38 to 0.61]). Increases in 10- and 40-m sprint speed, COD speed, and VJ height can be achieved and maintained with as little as 1 plyometric training session per week. Sessions can include 120 jumps to induce increases of the reported magnitudes, with 60 jumps to maintain these increases thereafter, in male soccer players.

Statistical shape analysis and computational modeling reveal novel relationships between tibiofemoral bony geometry and knee mechanics in young, female athletes

Young female athletes participating in sports requiring rapid changes of direction are at heightened risk of suffering traumatic knee injury, especially noncontact rupture of the anterior cruciate ligament (ACL). Clinical studies have revealed that geometric features of the tibiofemoral joint are associated with increased risk of suffering noncontact ACL injury. However, the relationship between three-dimensional (3D) tibiofemoral geometry and knee mechanics in young female athletes is not well understood. We developed a statistically augmented computational modeling workflow to determine relationships between 3D geometry of the knee and tibiofemoral kinematics and ACL force in response to an applied loading sequence of compression, valgus, and anterior force, which is known to load the ACL. This workflow included 3D characterization of tibiofemoral bony geometry via principal component analysis and multibody dynamics models incorporating subject-specific knee geometries. A combination of geometric features of both the tibia and the femur that spanned all three anatomical planes was related to increased ACL force and to increased kinematic coupling (i.e., anterior, medial, and distal tibial translations and internal tibial rotation) in response to the applied loads. In contrast, a uniplanar measure of tibiofemoral geometry that is associated with ACL injury risk, sagittal plane slope of the lateral tibial plateau subchondral bone, was not related to ACL force. Thus, our workflow may aid in developing mechanics-based ACL injury screening tools for young, active females based on a unique combination of bony geometric features that are related to increased ACL loading.

Increased power capture efficiency of large-scale wind turbines using model-free coordinated pitch, yaw, and torque control with wind direction estimation in diverse environmental conditions

Offshore large-scale wind turbine systems (LSWTS) face challenges in pitch and yaw management mainly due to unreliable wind direction measurements, delayed responses, and redundant yaw movements, reducing their optimal efficiency under various offshore renewable environmental conditions. To address this problem and increase power capture, this study introduces a model-free coordinated super-twisting pitch, yaw, and generator torque control for LSWTS under various wind speed and direction conditions. To achieve this, a dynamic model of the weather vane is first designed to accurately measure the wind directions under fluctuating wind speed and environmental conditions. At the same time, the onshore/offshore LSWTS weather vane model is formulated to operate under optimal conditions considering air density, temperature, humidity, and external disturbances. Then, super-twisting control based on an enhanced adaptive barrier function is proposed for the coordinated control operation of the pitch, yaw, and generator torque actuators for stable maximum power extraction of the offshore LSWTS. Finally, simulation and comparative studies are presented to signify the increased power capture ability of the proposed scheme for both a 4.8 MW benchmark and a 20 MW PMVG-based offshore LSWTS to verify robustness against wind gusts, direction changes, and model uncertainties.

SAQ training on sprint, change-of-direction speed, and agility in U-20 female football players.

The purpose of the study was to investigate the effects of an 8-week speed, agility, and quickness (SAQ) training on performance changes in linear sprint speed, change-of-direction (COD) speed, and reactive agility of U-20 female football players. Nineteen female football players randomly served as either experimental (n = 9) or control groups (n = 10). The players were tested for physical fitness tests: linear sprint speed including both short and long distances (5- and 10-m sprints without a ball and 20- and 30-m sprints with and without dribbling), COD speed (arrowhead agility test with and without dribbling a ball, Southeast Missouri [SEMO] agility test, and 22-m repeated slalom dribbling test), and reactive agility. Significant group × time interactions were observed for sprint over long distances and COD speed but not for short sprint and reactive agility performances. Paired t-tests revealed considerable improvements in all performances from the pre-test to post-test for the SAQ group, except for the arrowhead agility (left; p = .07). The control group only exhibited significant improvements in 10-m sprint performance after general football training. Eight weeks of SAQ training were effective at enhancing acceleration, maximum sprint speed, and agility performances amongst highly trained U-20 female football players.

Implementation of Traffic System Management to Overcome Congestion at the Intersection

This study aims to determine the performance of two roads in Medan, namely Jamin Ginting Road and Dr. Mansyur Road with the change of traffic direction and to determine the application of traffic management system. After the change in traffic flow, Dr. Mansyur Road obtained the highest volume with traffic flow (Q) = 1663.4 vehicles per hour, side obstacles = 128.8 per hour, travel speed (Vs) = 6.00 m/s, Degree of Saturation (DoS) = 0.49. Then the analysis of the Jalan Jamin Ginting Road section obtained the highest volume with traffic flow (Q) = 2171.4 vehicles per hour, side obstacles = 77.6 per hour, travel speed (Vs) = 5.72 m / s, Degree of Saturation (DoS) = 0.64. As well as the application of appropriate traffic management in the area of both roads, namely applying capacity management with the application of parking space engineering for vehicles, applying priority management from minor roads to major roads, and applying traffic sign management. Keywords: Traffic management, PKJI2014.

Influence of changing loading directions on damage in sheet metal forming

The impact of the stress state on damage evolution, fracture behavior, and product performance is well understood for proportional loading. However, many complex sheet forming operations involve non-proportional loading, which affect the material's hardening and fracture characteristics. This study investigates the influence of a loading direction change on damage evolution in a dual phase steel DP800. Specimens are pre-strained by tensile tests and subsequently loaded in either the same or orthogonal direction to the initial pre-strain direction by additional tensile tests and bending tests. Damage quantification by scanning electron microscopy reveals lower damage evolution after an orthogonal change of loading direction in contrast to monotonic loading directions. The load paths, defined as a history of triaxiality and Lode parameter during loading, are identified numerically under consideration of kinematic hardening. Since kinematic hardening leads to higher triaxialities after orthogonal changes, the load path is not the dominant influence on damage. A possible explanation for the experimental results is the void characteristics after tensile load. After the pre-straining in tensile test, voids are oriented orthogonally to the tensile direction and located between hard martensitic phases. The influence of this morphology on subsequent void growth is illustrated by a simulation verifying that an orthogonal change of loading direction results in void shrinkage, while monotonic loading directions lead to further void growth.

Prediction of fractures by using the stress field in medium to deep shale gas reservoirs: A case study of Late Ordovician–early Silurian shale gas reservoirs in the Nanchuan region, South China

Containing representative shale gas reservoirs, the Wufeng–Longmaxi Formations in the Nanchuan region in South China have been modified by three compressional tectonic movements (in the Late Jurassic to Early Cretaceous, Late Cretaceous, and Cenozoic to present). These movements formed deeply buried reservoirs with complex in situ stresses and rapid directional changes, influencing the state of shale gas reservoirs fractures. Numerical modeling applied to model the stress field in the three periods showed that the maximum compressive horizontal principal stress (σHmax), strain rate, and fault slip rate regimes transformed from a thrust and strike-slip regime to a thrust and strike-slip regime to a thrust regime. The σHmax direction changed from NW–SE and WNW–ESE to WNW–ESE and nearly E–W and then to multiple directions. The magnitude of strain rate changed from -16 ∼ -15 to -17.7 ∼ -15.6 to -18.8 ∼ -15.8. The fault slip rate changed from 0 to 0.029 mm/a to 0–0.0026 mm/a to 0–0.0012 mm/a. These data strongly agree with data from drilled wells and outcrops and show that the present-day stress field is the superposed effect of multistage movements. Semiquantitative research was conducted on shale gas fracture openness and fracture development. Fracture openness is favorable when the angle between the σHmax direction and nearby faults is ≤45° and the distance from the fault is >2 km, and fracture development is favorable when the magnitude of the strain rate is <-17.6 and the fault slip rate is <0.00036 mm/a. Accordingly, we predicted fractured shale gas reservoirs.

Change Of Direction Actions in Goal Scoring Situations in Male and Female Professional Soccer

The aim of this study was to analyse the frequency of change of direction (COD) actions in goal scoring situations. Data was collected through time motion analysis of goal scoring actions from teams participating in English Premier League (EPL) and Women’s Super League (WSL) during the 2018/2019 season using a modified version of the Bloomfield Movement Classification with differences analysed through chi-square (p &lt; 0.05).&#x0D; In (total percentage [95% CI] 71.6% (±1.7%) and 70.6% (±3.1%) of players involvements in EPL and WSL there was a COD action. For EPL and WSL, respectively, attackers performed COD actions in 71.9% (±2.3%) and 72.9% (±4.1%) of the involvements while defenders in 71.2% (±2.6%) and 67.8% (±4.7%). In 56.1% (±1.9%) and 57.1% (±3.3%) of the involvements there was at least 1 COD action performed at high intensity for EPL and WSL, respectively.&#x0D; Soccer players are frequently exposed to different COD actions during goal involvements, with these being performed frequently at high intensity and so, this physical ability could play an important role in the performance outcomes of a match. Therefore, emphasis should be placed on increasing player’s COD speed capabilities taking into account the tendency for specific COD actions for different players’ based on their roles.

A Charge-Charge Flux-Dipole Flux Analysis of Simple Molecular Systems with Halogen Bonds.

The presence of halogen bonds (R-X···B; R = substituent group, X = halogen, and B = Lewis base) provides quite amazing molecular systems for electronic structure investigations, presenting unique characteristics of fundamental relevance to supramolecular chemistry among other areas. Here, we use a double-hybrid approach from Density Functional Theory and triple-ζ basis sets augmented with diffuse functions (B2PLYP/def2-TZVPD) to deal with a large group of simple molecular systems containing halogen bonds (XBs), focusing on geometrical structures, binding energies, harmonic vibrational frequencies, and fundamental infrared intensities. Next, the electron densities and their variations on vibrations are carefully studied with the Quantum Theory of Atoms in Molecules (QTAIM) formalism and the charge-charge flux-dipole flux (CCFDF) model. We notice that the R-X stretching mode usually shows vibrational frequency decrements and infrared intensifications during the XB formation. Such features were also observed in hydrogen bonds, although the explanation for the band strengthening is different. Surprisingly, the most important contribution to these intensity increments due to complexation is now the interaction term between the charge flux and dipole flux (CF × DF). Thus, the use of atomic dipoles is mandatory to fully understand this phenomenon. In fact, the huge charge flux contributions to changes in dipole moment derivatives of R-X stretchings on halogen bonding are no longer accompanied by opposite variations of similar magnitudes in polarizations described by atomic dipole fluxes, which provided nearly unaltered values during the XB formation. Thus, the electronic charge flux direction change that takes place in complexes (from B to R) now reinforces dipole moment derivative terms from such atomic polarizations (mainly from the X atom). This intermolecular charge flux seems to be responsible for the unusual features noticed in the R-X stretching mode with the CCDDF/QTAIM model.

Effects of Postactivation Potentiation enhacement on sprint and change–of–direction performance in athletes: A systematic review

BackgroundTraining interventions like Resisted Sled Training, Complex Training, Plyometric training, and recently, Postactivation Potentiation Enhancement (PAPE) protocols are being employed by sportsmen for performance enhancement. Currently, there is no conclusive evidence on the effectiveness of the PAPE protocols and methods to integrate them into the training. The current systematic review aims to critically summarize the current evidence on PAPE protocols’ effect on Sprint and Change of Direction (COD) performance in Athletes and study the influence of the Type of PAPE protocols, Recovery duration, Volumes, and loads of PAPE protocols. MethodsA systematic computerized literature search was performed from December 2020 to June 2022 on the databases: MEDLINE (assessed by PubMed), CENTRAL (Cochrane Library Central Register of Controlled Trials), PeDro, and Science direct. The major criteria for inclusion were Athletes (Population) who performed PAPE protocol as Intervention before Sprint and/or COD assessment tests. The studies were individually assessed for Risk of Bias using EPHPP (Effective Public Health Practice Project) Tool. ResultsA total of sixteen studies were included. For Linear sprint, nine studies reported a significant PAPE effect whereas, six studies reported insignificant effects. Whereas, for COD performance, two studies reported insignificant results and one study reported significant CODS enhancements The recovery duration ranged from 15 s up to 16 min. ConclusionPAPE protocols can be incorporated provided the recovery duration is of Moderate duration (3–8mins) or Individualized durations, using multiple sets (2–6), moderate-high loads (>85% 1-RM), type of protocol is Barbell Hip Thrust, Plyometrics or Unilateral biomechanically similar exercises to Running.

Stress field in northeastern Japan and its relationship with faults of recent earthquakes

Inversion tectonics, in which old normal faults act as reverse faults in current stress fields, are frequently observed in northeastern Japan (Tohoku District); however, the conditions that control these fault activities remain unclear. To improve the identification of faults that are more favorable to slip under current stress conditions, the regional fault mechanisms in the Tohoku District must be better understood. The stress field in the Tohoku District and the likelihood of fault activities were thus estimated using slip tendency (ST) analysis. The results show that in the eastern margin of the Japan Sea (EMJS), the reverse fault type is dominant in the stress field. The maximum horizontal direction changes clockwise from E–W to NW–SE from the northern to the southern regions and counterclockwise from NW–SE to E–W from the Japan Sea to the inland area. In the Tohoku inland area, the estimated direction of the maximum horizontal axis changed after the 2011 Tohoku-Oki earthquake, from E–W to WNW–ESE. ST values were calculated for seven events in the EMJS area. To avoid the influence of the Tohoku-Oki earthquake, only stress field data prior to the 2011 Tohoku-Oki earthquake were used to determine ST values for four of the events in the Tohoku inland area. The results showed eastward-dipping fault planes with low dip angles (approximately 30°–45°) and large ST values (approximately > 0.7). The large ST values indicate that the stress field fault is favorable to slip and the results were consistent with the actual fault plane in the EMJS area. However, in the Tohoku inland area and the southern part of fault model of the 1993 Hokkaido Nansei-Oki earthquake, fault planes with large ST values were found to be inconsistent with the slipped fault plane, thus indicating that slipping was unfavorable. The regional differences are consistent with the volcano distribution and thus, the fluid supply from volcanic activity may have helped the fault slip under difficult stress conditions.Graphical

Associations between biological maturation, physical performance, postural control, and mathematical achievement in youth soccer players.

This investigation explored relationships between biological maturation, physical and academic performance in young male soccer players. Thirty-eight players (age: 9.79 ± 1.21 years; body mass index (BMI): 20.4 ± 2.39 kg/m2; body fat: 16.8 ± 2.21%) participated. Measures of anthropometry used for body mass, body fat percentage (%BF), and BMI as well. Postural control, 15 m sprint, squat jumps and counter-movement jumps (SJ, CMJ), and T-half test for change-of-direction (CoD) were parameters of physical performance. The grade point average (GPA) of mathematics determined academic attainment. Moore's equations were used to estimate their maturity status (PHV). Biological maturation was highly correlated with most (not 15 m sprint) physical and academic performance parameters, especially CMJ (r = -0.812) and mathematics (r = -0.781). Academic performance showed the largest relations to the jumping performance (CMJ: r = 0.771; SJ: r = 0.723). In contrast, anthropometric and fatness parameters were not relevantly (r ≥ 0.5) correlated with any other parameters. The largest correlations were calculated for sitting height vs. SJ (r = -0.408), sitting height vs. postural control (r = -0.355), leg length vs. postural control (r = -0.339). As a result, it is essential to take biological maturation inconsideration while assessing the physical and academic achievement of young soccer players. In consequence, soccer coaches and physical education (PE) teachers should be cognizant of the impact of biological maturity on physical and academic performance to assist fair and equal opportunities for achievement in young players.

Thermodynamic bifurcation in anoxic heart: A far-from-equilibrium dissipative structure.

Thermodynamic consequences of a three-hour long anoxia were investigated on the isolated mammalian rat myocardium. The anoxic heart operated in a far-from-equilibrium manner as attested by the non-linearity between the thermodynamic force and the thermodynamic flow. When subjected to slight fluctuations due to anoxia, the open far-from-equilibrium cardiac system presented a thermodynamic bifurcation at ~ 60 minutes of anoxia. The bifurcation was characterized by a sudden change of direction in the bifurcation diagram of a one-dimensional nonlinear differential equation with one parameter and occurred at a non-hyperbolic fixed point at which moment the heart lost its thermodynamic stability. The parameter of the differential equation was the single force of the myosin molecular motor. These results helped to reflect a self-organized process and the occurrence of a dissipative structure. This offers valuable insights into our understanding of myocardial protection and could be of considerable interest, especially for heart transplants where the recipient must benefit from the donor's heart in the shortest possible time.

Clinical characteristics and efficacy of vocal fold epidermoid cysts coexisting with sulcus vocalis

Objective: To investigate the clinical characteristics and voice outcomes after laryngeal microsurgery for vocal fold epidermoid cysts coexisting with sulcus vocalis. Methods: The clinical data of 115 vocal fold epidermoid cysts coexisting with sulcus vocalis patients in Shandong provincial ENT hospital, were retrospectively analyzed, including 49 males and 66 females, aged 17-70 years old, and the duration of hoarseness ranged from 6 months to 30 years. All patients underwent surgery through suspension laryngoscope and microscope under general anestgesia. Ninety-four patients were treated with microflap excision of sulcus vocalis, cyst wall, and contents.And 21 patients that occulted with mucosal bridges were applied mucosal bridges resection (2 cases) and mucosal bridges reconstruction (19 cases) respectively. Videolaryngoscopy, subjective voice evaluation (GRBAS), objective voice evaluation, and Voice Handicap Index(VHI) were performed before and after surgery. All patients underwent histopathologic examination and follow-up after the procedure. The preoperative acoustic parameters of patients with vocal fold epidermoid cysts coexisting with sulcus vocalis were compared with those of vocal fold mucus retention cysts and simple vocal fold epidermoid cysts by independent samples t-test. The patients were compared by paired t-test for preoperative and postoperative parameters. Results: Significant reduction or lack of mucosal waves were shown via videolaryngostroboscopy in all 115 cases.In addition, vascular changes including dilation, tortuousness, increased branches, and abrupt direction change were shown on the cystic area. Eighty-one patients were detected cysts and/or sulcus vocalis by preoperative laryngoscopy, and intraoperative microscopic findings in the remaining 34 patients. The intraoperative microscopic examination revealed a focal pouch-like deficit plunging into the vocal ligament or muscle. The deep surface of the mucosal bridges was sulcus vocalis, and that in 89 cysts was lined with caseous content. Histopathology demonstrated a cystic cavity structure lined with squamous epithelium and caseous keratin desquamation inside the cystic cavity. Four of 115 patients were lost at follow-up and excluded from the analysis of voice outcomes after surgery. There was no significant mucosal wave and the voice quality in all but 14 patients 1month after surgery. Except for the fundamental frequency and noise harmonic ratio, all other voice parameters[ G, R, B, A, VHI-10, jitter, shimmer, maximum phonatory time (MPT) ]showed a significant improvement 3 months after surgery(t=15.82, 20.82, 17.61, 7.30, 38.88, 7.84, 5.88, -6.26, respectively, P<0.05). Then mucosal waves and the voice quality were gradually improved and became steady in 6 months after surgery. The subjective and objective voice parameters[G, R, B, A, VHI-10, jitter, shimmer, noise to harmonic ratio(NHR), MPT], except for the fundamental frequency, were all significantly improved(t=23.47, 25.79, 18.37, 9.84, 54.45, 10.68, 8.07, 3.24, -9.08, respectively, P<0.05). In addition, there were 2 patients with no significant improvement after the operation. Steady function with no complications was observed during the 12 months (up to 3 years in 34 patients) follow-up period in 111 patients. Conclusion: Ruptured vocal fold epidermoid cysts can result in sulcus vocalis and mucosal bridges. Characteristics changes in preoperative videolaryngoscopy are effective diagnostic tools. The complete excision of the cyst wall and repair of the lamina propria can lead to satisfactory long-term effects.

Identifying the ideal weekly training load for in-game performance in an elite Brazilian soccer team.

Introduction: The purpose of this study was to investigate the ideal training load to be applied during periods of fixture congestion to ensure an adequate dose-response effect for performance maintenance. Methods: Match performance data and corresponding pre-match training load sessions (both N = 498 match performance cases and training-block session cases) were collected (with the catapult system, VECTOR7) from 36 male professional soccer players (23.5 ± 5.2 years; 178 ± 4cm; 75.5 ± 6.0kg) belonging to the Brazilian First Division team during the 2022 season. The following data were collected in match and training sessions: jump, acceleration, deceleration, and change of direction (COD); running distance producing metabolic power at different intensities (>20, >20-35, >35-45, >45-55, and >55Wkg-1), total distance (m), relative distance (m/min), running distance at different speeds (>20, >25, and >30km/h), number of sprints (running >25km/h), and maximum speed (km/h). Mixed linear model (MLM), decision tree regression (DTR), and cluster K means model (SPSS v.26) approach were performed to identify the most critical variables (and their respective load) in the training sessions that could explain the athlete's match performance. Results: MLM and DTR regression show that training load significantly affects game performance in a specific way. According to the present data, an interference phenomenon can occur when a high load of two different skills (running in a straight line vs COD, deceleration, and jumping) is applied in the same training block of the week. The cluster approach, followed by a chi-squared test, identified significant associations between training load and athlete match performance in a dose-dependent manner. Discussion: The high load values described here have a beneficial effect on match performance, despite the interference between stimuli discussed above. We present a positive training load from a congested season from the Brazilian First Division team. The study suggests that an interference effect occurs when high physical training loads are applied to different specific physical skills throughout the season.

Influence of the Stick Grasping in Sprint and Change of Direction Performance in Elite Youth Rink Hockey Players

This study aimed to investigate the influence of stick grasping on the performance of elite youth rink hockey players in 10 m linear sprints and 180° change of direction (COD) tasks. Forty-nine rink hockey players (age = 18.40 ± 2.12 year; body mass = 73.52 ± 6.02 kg; height = 1.82 ± 0.07 m; BMI = 23.61 ± 1.69; sports experience = 6.42 ± 1.41 years; 4.89 ± 0.68 years’ post-peak height velocity) participated in this cross-sectional study. Measurements included 10 m sprint time and COD 180° performance with and without stick grasping. Results revealed non-significant differences when carrying a stick in the 10 m linear sprint (1.90 s ± 0.08 with stick vs. 1.89 s ± 0.08 without stick; p = 0.71; d = 0.05), neither did COD 180° for the left limb (2.75s ± 0.11 with stick vs. 2.76 s ± 0.11 without stick; p = 0.91; d = 0.02). However, for the right limb, significantly better performance in COD 180° was found when players held the stick (2.72 s ± 0.11 with stick vs. 2.75 s ± 0.09 without stick; p = 0.03; d = 0.32). These findings imply that the distinctive biomechanics and requirements of rink hockey, especially the lateral movements inherent in skating, might alleviate the negative impacts associated with implement grasping observed in other sports. This study highlights that stick grasping did not hinder COD ability and may even have a facilitating effect on certain movements, emphasizing the importance of considering sport-specific biomechanics in rink hockey performance analysis.

The Inclusion of Preplanned and Random and Unanticipated/Unexpected Events During Strength Training Improves the Ability to Repeat High-Intensity Efforts Under Uncertainty.

To compare the effects of unilateral flywheel training (FT), using a rotational conical pulley, including multidirectional movements with either preplanned or random unanticipated/unexpected executions on functional performance in football players. A total of 32 young male football players were randomly assigned to an FT program including preplanned unilateral multidirectional movements (PTG, n = 11), an FT executing the same unilateral movements through random (ie,right or left leg) unanticipated (ie,verbal or visual cue) or unexpected (ie,moment where the cue was provided) situations (UTG, n = 11), or a control group (n = 10) that followed their football training routine. FT consisted of 1 set × 5-12 repetitions of 4 exercises performed once a week for 10weeks. Intermittent endurance performance, repeated unilateral and bilateral jumping ability, change-of-direction (COD) ability, linear sprint velocity, preplanned repeated-sprint ability (RSA), and uncertainty RSA (RSA-RANDOM) were assessed preintervention and postintervention. Significant improvements were found in RSA-RANDOM performance (P < .05, effect size [ES] range: UTG [1.83-2.16], PTG [0.69-0.73]) and COD (P < .05, ES: UTG = 1.34, PTG = 0.98]) in both training groups. Furthermore, significant improvements were also found in intermittent endurance performance (P = .016, ES = 0.37) and sprinting (P = .006, ES = 0.45) in UTG. No changes in any variable were found in the control group. No significant between-groups differences (P > .05) were reported between UTG and PTG, while differences were observed to the control group in unilateral jumping ability, COD, and RSA-RANDOM for UTG, and in RSA-RANDOM for PTG. A 10-week unilateral FT improved RSA-RANDOM and COD ability in youth football players, so both preplanned and unexpected situations should be included on strength training.

Three-Dimensional Numerical Study of Hydrodynamic Interactions between Pectoral Fins and the Body of Aquatic Organisms.

Fish swimming has attracted attention as a locomotion system with excellent propulsive efficiency. They swim by moving their body, fins, and other organs simultaneously, which developed during evolution. Among their many organs, the pectoral fin plays a crucial role in swimming, such as forward-backward movement and change of direction. In order to investigate the hydrodynamic interaction between pectoral fins and fish bodies, we examined the asymmetric flapping motion of the pectoral fin concerning the body axis and investigated the effect of the pectoral fin on the propulsive performance of the body of a small swimming object by numerical simulation. In this study, the amplitude ratio, frequency ratio, and phase of the body and pectoral fin varied. Therefore, although propulsive performance increased in tandem with the frequency ratio, the amplitude ratio change had negatively affected the propulsive performance. The results revealed that the propulsive performance of the fish was high even in low-frequency ratios when the phase difference was varied. The highest propulsion efficiency increased by a factor of about 3.7 compared to the phase difference condition of 0.

Implementing Velocity-Based Training to Optimize Return to Sprint After Anterior Cruciate Ligament Reconstruction in Soccer Players: A Clinical Commentary.

After anterior cruciate ligament reconstruction (ACLR), return to sprint is poorly documented in the literature. In soccer, return to sprint is an essential component of return to play and performance after ACLR. The characteristics of running in soccer are specific (velocity differences, nonlinear, intensity). It is important to address these particularities, such as curvilinear running, acceleration, deceleration, changes of direction, and variations in velocity, in the patient's rehabilitation program. Force, velocity, and acceleration capacities are key elements to sprint performance. Velocity-based training (VBT) has gained much interest in recent years and may have a role to play in optimizing return to play and return to sprint after ACLR. Force, velocity, and acceleration can be assessed using force-velocity-power and acceleration-speed profiles, which should inform rehabilitation. The purpose of this commentary is to describe a velocity-based return to sprint program which can be used during ACLR rehabilitation.

Emergence of a Constructivist Theory on Nurses’ Caring Decisions for Patients Being Withdrawn from Ventilatory Support

This research is centered on developing a constructivist grounded theory that reflects how intensive care unit (ICU) nurses carry out their caring decisions for patients withdrawn from ventilatory support as captured from the Filipino context. To frame an exhaustive discussion, the researcher utilized Charmaz’s constructivist grounded theory approach with semi-structured interviews, observational field notes, and memos as data collection methods. Employing theoretical sampling, twenty senior ICU nurses, four doctors and ten patients’ family members provided data that formulated the theory. The formulated core category of Perspicacity in Caring Decisions is indicated by ICU nurses' ability to develop a deeper concept of wisdom and understanding gained through clinical and life experiences. This constructivist theory stands on a strong foundation built from five interlinked subcategories: Voicing Out, Establishing realities, Navigating transitions, Taking the time, and Serving a Good Death. This brings together and contextualizes what was happening throughout the processes of nurses’ end-of-life caring decisions. This research concludes that moving into a realm where death becomes an acceptable outcome, recognizing the Filipino cultural background, the patient made comfortable, and their family supported to understand the change of direction in approach are essential parts of the nurses’ caring decisions.