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In this work, we are concerned with the order preservation problem for multidimensional neutral type stochastic differential equations of infinite delay with jumps under non-Lipschitz conditions. By using a truncated Euler-Maruyama scheme and adopting an approximation argument, we have developed the well-posedness of solutions for a class of stochastic functional differential equations which allow the length of memory to be infinite, and the coefficients to be non-Lipschitz and even unbounded. Moreover, we have extended some existing conclusions on order preservation for stochastic systems to a more general case. A pair of examples have been constructed to demonstrate that the order preservation need not hold whenever the diffusion term contains a delay term, although the jump-diffusion coefficient could contain a delay term. [ABSTRACT FROM AUTHOR]

Background Verbal and tactile cues can increase muscle activity, force production, and kinematics. Several studies demonstrate the effects of verbal and tactile cues on upper extremity muscles, while relatively few examined lower extremity muscles, specifically the gluteals. Studies that observed changes in gluteal function from verbal and tactile cues examined muscle activity via electromyography rather than force production or functional activities such as jumping. Purpose The purpose of this study was to measure the effects of verbal and tactile cues on gluteal force production and broad jump distance. Study Design Cross-Sectional cohort Methods Gluteus maximus force production and broad jump distance were tested in forty-two healthy male and female university students at baseline and after verbal and tactile cues given in random order. Gluteus maximus force was measured using handheld dynamometry and reported in kilograms. Verbal cues included "push, push, push" before both tests. The examiner provided tactile cues to the gluteus maximus before force production testing, and the participant provided tactile cues to both gluteus maximus muscles before performing the broad jump. Performance on the broad jump was measured in centimeters. Descriptive statistics and test-retest reliability via Pearson correlation coefficients were calculated, differences in performance between sexes were analyzed with an independent t-test, and changes in force production and jump distance from baseline were analyzed using a one-way ANOVA. Results Mean gluteus maximus force production following verbal cues significantly increased (p = 0.000) by 13.48% (3.83 kg) compared to the control condition, while gluteal force production following the tactile cues was not significantly different. Broad jump distance following the verbal cues significantly increased (p = 0.000) 3.99% (7.71 cm) compared to the control condition and significantly increased (p = 0.000) by 2.95% (5.71 cm) following the tactile cues. There were no significant differences in performances between males and females. The test-retest reliability of all measurements was 0.97-0.99. Conclusion Verbal cues significantly increased gluteus maximus force production and broad jump distance. Tactile cues significantly increased broad jump distance but had no significant effect on gluteus maximus force. These results have implications for clinical testing and athletic performance when gluteus maximus force and jump distance are concerned. Level of Evidence 3 [ABSTRACT FROM AUTHOR]

Jumping performance is considered an overall indicator of gymnastics ability. Acrobatic Gymnastics involves base and top gymnasts, considering the type of training that is performed and the distinct anthropometric traits of each gymnast. This work aims to investigate a hierarchy of variables that influence the force–velocity (F-V) profile of top and base acrobatic gymnasts through a deep artificial neural network model. Twenty-eight first division and elite acrobatic gymnasts (eleven tops and seventeen bases) performed two evaluations to assess the F-V profile during the Countermovement Jump and its mechanical variables, using My Jump 2 (a total of 56 evaluations). A training background survey and anthropometric assessments were conducted. The final model (R = 0.97) showed that the F-V imbalance (F-Vimb) increases with higher force and decreases with higher maximal power, fat percentage, velocity, and height. Coaches should prioritize the development of force, followed by maximal power, and velocity for the optimization of gymnasts' F-Vimb. For training planning, the influences of body mass and push-off height are higher for the bases, and the influences of years of practice and competition level are higher for the tops. [ABSTRACT FROM AUTHOR]

This study evaluated the differences in training and match volume per set by season phase in female high school volleyball. Twelve athletes wore a device to measure total jumps (TJ) and high jumps (HJ), movements per minute (MPM), kinetic energy expended, and stress percent throughout the season phases: preseason, tournament, and district. In matches, athletes jumped less and had lower MPM in preseason (4.4 ± 2.3 TJ/set, 1.9 ± 0.5 MPM/set) compared with tournament (13.2 ± 8.1 TJ/set, 6.4 ± 1.7 MPM/set) and district (16.5 ± 9.9 TJ/set, 6.7 ± 1.8 MPM/set; p ≤.001 for all) phases. District registered more HJ/set (2.6 ± 2.2 HJ/set) than preseason (0.7 ± 0.7 HJ/set, p =.007) and tournament phases (292 ± 172 J/lb/set, p <.001), and more kinetic energy expended/set (488 ± 174 J/lb/set) than preseason (201 ± 94 J/lb/set, p =.001). The highest training volume occurred during preseason with more TJ (preseason: 70.9 ± 26.0; tournament: 44.3 ± 19.3, p <.001; district: 34.7 ± 3.4, p =.004) and kinetic energy expended (preseason: 1,645 ± 547 J/lb; tournament: 980 ± 506 J/lb, p =.018; district: 1,108 ± 362, p =.016). Preseason training had higher stress percent (16.6 ± 3.0%) than tournament (19.4 ± 3.7%, p =.004) and more HJ (7.7 ± 6.3%) than district (3.1 ± 2.9%, p =.012). Match volume was unbalanced across the season phases, with preseason showing the lowest volume and district having the highest volume. This was counterbalanced with a higher training volume during the preseason compared with the other phases. [ABSTRACT FROM AUTHOR]

Understanding the reliability of jump testing is essential to determine the neuromuscular progress of athletes and make informed decisions. This study aimed to assess the reliability of several countermovement jump (CMJ) and drop jump (DJ) test metrics in female volleyball players. Sixteen (n = 16) semi-professional female volleyball players participated in this test-retest study. Intrasession and intersession reliability of CMJ and DJ metrics were evaluated using a randomized cross-over design. A dual force platform was used to collect CMJ and DJ data, and several dependent variables were calculated using forward dynamics. Intraclass correlation coefficients (ICC), coefficients of variation (CV), and minimum difference (MD) were calculated to assess intra- and interday reliability. During the same testing, the third attempt consistently yielded the highest values for both tests in jump height but presented excellent reliability (CMJ: ICC [95%CI] = 0.97 [0.93–0.99]; CV [95%CI] = 4.1% [1.2–7.0]; MD95 = 3.5 cm; MD90 = 2.9 cm; DJ: ICC [95%CI] = 0.91 [0.77–0.97]; CV [95%CI] = 6.7% [1.9–11.5]; MD95 = 6.0 cm; MD90 = 5.0 cm). CMJ height exhibited excellent reliability between sessions (ICC [95%CI] = 0.93 [0.81–0.97]; CV [95%CI] = 3.8% [1.1–6.4]; MD95 = 3.5 cm; MD90 = 3.0 cm), whereas DJ height demonstrated slightly lower but still acceptable intersession reliability (ICC [95%CI] = 0.81 [0.55–0.93]; CV [95%CI] = 6.1% [1.7–10.4]; MD95 = 5.2 cm; MD90 = 4.4 cm). Intersession reliability for CMJ kinetics and kinematics was excellent for 13 of the 24 metrics assessed. For DJ, only concentric (ICC [95%CI] = 0.91 [0.76–0.97]; CV [95%CI] = 3.0% [0.9–5.2]; MD95 = 15 Ns; MD90 = 12.6 Ns) and eccentric impulses (ICC [95%CI] = 0.99 [0.96–0.99]; CV [95%CI] = 1.7% [0.5–2.9]; MD95 = 9.2 Ns; MD90 = 7.7 Ns) demonstrated excellent intersession reliability. Most CMJ variables showed excellent reliability within sessions, while DJ had lower reliability in most metrics. These findings provide valuable information to physical trainers to select the metrics to assess athletes' performance as well as to identify a minimum cut-off value that serves as a reference for each of the metrics reported in both tests. [ABSTRACT FROM AUTHOR]

In this paper, we present BilevelJuMP.jl, a new Julia package to support bilevel optimization within the JuMP framework. The package is a Julia library that enables the user to describe both upper and lower-level optimization problems using the JuMP algebraic syntax. Because of the generality and flexibility that our library inherits from JuMP's syntax, our package allows users to model bilevel optimization problems with conic constraints in the lower level and all constraints supported by JuMP in the upper level including conic, quadratic, and nonlinear constraints. Moreover, the models defined with the syntax from BilevelJuMP.jl can be solved by multiple techniques that are based on reformulations as mathematical programs with equilibrium constraints (MPEC). Manipulations on the original problem data are possible due to MathOptInterface.jl's structures and Dualization.jl features. Hence, the proposed package allows quick modeling, deployment, and thereby experimenting with bilevel models based on off-the-shelf mixed-integer linear programming and nonlinear solvers. History: Accepted by Ted Ralphs, Area Editor for Software Tools. Funding: The authors were partially supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. The work of A. Street was also partially supported by Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). The work was partially funded by the project P&D ANEEL PD-00403-0050/2020 sponsored by ENGIE BRASIL ENERGIA S.A. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information (https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2022.0135) as well as from the IJOC GitHub software repository (https://github.com/INFORMSJoC/2022.0135). The complete IJOC Software and Data Repository is available at https://informsjoc.github.io/. [ABSTRACT FROM AUTHOR]

BACKGROUND: Foot arch dynamics play an important role in dynamic postural control. Association between foot arch dynamics and postural control among adolescent athletes remains poorly explored. OBJECTIVE: To examine the relationship between foot arch dynamics, intrinsic foot muscle (IFM) morphology, and toe flexor strength and dynamic postural stability after jump landing and repetitive rebound jump performance in competitive adolescent athletes. METHODS: Based on foot arch dynamics, evaluated from relative change in the foot arch height in sitting and standing positions, 50 adolescent athletes were classified as stiff, normal, or flexible. IFM morphology was evaluated by ultrasonography. Dynamic postural stability index (DPSI) was measured as participants jumped and landed with the right leg onto a force plate, whereas repetitive rebound jumping performance was assessed using the jump height and reactive jump index. RESULTS: The stiff group had a significantly worse DPSI and vertical stability index than the normal group (p = 0.26, p = 0.44, respectively), and worse anteroposterior stability index (APSI) values than the flexible group (p = 0.005). Multivariate regression models of the relationship between the APSI and foot arch dynamics showed adequate power (probability of error = 0.912). CONCLUSIONS: Increased foot arch stiffness negatively affects dynamic balance during jump-landing, which may deteriorate their performance. [ABSTRACT FROM AUTHOR]

This study examined seasonal variation and the effect of the transition period on physical fitness parameters in female youth soccer players. Twenty-four players (13–17 years old) were assessed through field and laboratory testing. They completed laboratory testing three times: (1) at the beginning of the season (post-preseason), (2) at the end of the regular season (postseason), and (3) following the transition period (preseason). Field testing was conducted post-preseason and postseason. Results indicated that weight and body fat significantly increased from post-preseason to postseason and following the transition period. A paired samples T-test revealed that the players performed significantly better in the vertical jump and 30 m sprint test (all p < 0.01) postseason compared to post-preseason. Also, it was indicated that torque production for the right quadriceps, left quadriceps, and right hamstring (all p < 0.01) was significantly reduced after the transition period by 10%, 11.8%, and 10.5%, respectively. Cardiorespiratory measurements demonstrated that performance on an incremental cardiopulmonary treadmill test, maximal oxygen consumption, velocity at the first ventilatory threshold, velocity at the second ventilatory threshold, and velocity at maximal oxygen consumption (all p < 0.01) were significantly reduced postseason and following the transition period. Based on the results, coaches and trainers should primarily focus on maintaining the aerobic capacity of the players during the season, as it has been indicated to be reduced from the beginning to the end of the competitive period (VO2max reduced by 3.3%). In addition, they should focus on maintaining lower body strength and aerobic capacity during the transition period. [ABSTRACT FROM AUTHOR]

Background: Vertical jumps are commonly prescribed in literature as a method to enhance speed performance, yet the impact of puberty on this relationship remains unclear. Purpose: This study aimed to investigate whether pubertal stage affects the correlation between jump performance and sprinting ability in young futsal players. Methods: Seventy-six male players were categorized into pre-pubertal, pubertal, and post-pubertal stages. The pubertal stage was evaluated by the peak height velocity (PHV) in which it differentiated the players in prepubescent (pre-PHV), pubescent (mid-PHV) and post-pubertal (post-PHV). All of them performed the squat jump (SJ) and countermovement jump (CMJ), straight-line sprint (SLS-20 m) and sprint with change of direction (COD-25 m). The Shapiro-Wilk normality test was used and when comparing the morphological and performance variables between the stages, the ANOVA one way with Tukey post hoc was used. To analyze the correlations between performance of sprints and jumps, the Pearson correlation test was used and in all analyzes a significance level of p < 0.05 was adopted. Parents and players signed specific terms for the inclusion of athletes in the survey. Results: A significant correlation only being found in the pre-PHV stage for SJ vs SLS (r = - 0.63) and COD (r = - 0.50); CMJ vs SLS (r = - 0.56) and COD (r = - 0.48) compared to mid-PHV and the post-PHV for the same correlations. Conclusions: The results demonstrate that the pubertal stage influences the level correlation between vertical jumps and sprint performance. Training to improve muscle strength through jumps to develop speed, to the detriment of specific training in this capacity, in players in mid- and post-PHV stages needs to be used with caution. [ABSTRACT FROM AUTHOR]

Context: Lower-extremity loading patterns change after anterior cruciate ligament reconstruction (ACLR). However, there is limited research regarding energy absorption contribution (EAC) of athletes following ACLR who reinjure their ACL and those who do not. EAC can be utilized as a measure of joint loading during tasks. Design: Cross-sectional study. Methods: Three groups of individuals (13 in each group) with matched age, sex, height. weight, and sports were enrolled. Data were collected at time of return-to-sport testing for the 2 ACLR groups. An 8-camera 3D motion capture system with a sampling rate of 120 Hz and 2 force plates capturing at 1200 Hz were used to capture joint motions in all 3 planes during a double-limb jump landing. Results: Participants in the ACLR no reinjury and ACLR reinjury groups had significantly greater hip EAC (55.8 [21.5] and 56.7 [21.2]) compared with healthy controls (19.5 [11.1]), P<.00\ and P < .001, respectively. The ACLR no reinjury and ACLR reinjury groups had significantly lower knee EAC (24.6 [22.7] and 27.4 [20.8]) compared with healthy controls (57.0 [12.2]), P < .001 and P < .001, respectively. However, the ACLR reinjury group had significantly lower ankle EAC (15.9 [4.6]) than healthy controls (23.5 [6.6]), whereas there was no statistical difference between the ACLR no reinjury group (19.7 [7.8]) and healthy controls. Conclusions: Athletes who had a second ACL injury after ACLR, and those without second ACL injury, appear to have similar hip, knee, and ankle joint loading of the surgical limb at return-to-sport testing. Nevertheless, joint loading patterns were significantly different from healthy controls. The study suggests that EAC as a measure of joint loading during a double-limb jump landing at time of return to sport may not be a strong predictor for second injury following ACLR. [ABSTRACT FROM AUTHOR]

Research on the evolution of performance throughout a season in team sports is scarce and mainly focused on men's teams. Our aim in this study was to examine the seasonal variations in relevant indices of physical performance in female football players. Twenty-seven female football players were assessed at week 2 of the season (preseason, PS), week 7 (end of preseason, EP), week 24 (half-season, HS), and week 38 (end of season, ES). Similar to the most common used conditioning tests in football, testing sessions consisted of (1) vertical countermovement jump (CMJ); (2) 20 m running sprint (T20); (3) 25 m side-step cutting maneuver test (V-CUT); and (4) progressive loading test in the full-squat exercise (V1-LOAD). Participants followed their normal football training procedure, which consisted of three weekly training sessions and an official match, without any type of intervention. No significant time effects were observed for CMJ height (p = 0.29) and T20 (p = 0.11) throughout the season. However, significant time effects were found for V-CUT (p = 0.004) and V1-LOAD (p = 0.001). V-CUT performance significantly improved from HS to ES (p = 0.001). Significant increases were observed for V1-LOAD throughout the season: PS-HS (p = 0.009); PS-ES (p < 0.001); EP-ES (p < 0.001); and HS-ES (p = 0.009). These findings suggest that, over the course of the season, female football players experience an enhancement in muscle strength and change of direction ability. However, no discernible improvements were noted in sprinting and jumping capabilities during the same period. [ABSTRACT FROM AUTHOR]

We introduce the notion of eventually uniformly weak truth table array computable (e.u.wtt-a.c.) sets. As our main result, we show that a computably enumerable (c.e.) set has this property iff it is weak truth table (wtt -) reducible to a maximal set. Moreover, in this equivalence we may replace maximal sets by quasi-maximal sets, hyperhypersimple sets or dense simple sets and we may replace wtt -reducibility by identity-bounded Turing reducibility (or any intermediate reducibility). Here, a set A is e.u.wtt-a.c. if there is an effective procedure which, for any given partial wtt -functional Φ ˆ , yields a computable approximation g (x , s) of the domain of Φ ˆ A together with a computable indicator function k (x , s) and a computable order h (x) such that, once the indicator becomes positive, i.e., k (x , s) = 1 , the number of the mind changes of the approximation g on x after stage s is bounded by h (x) where, for total Φ ˆ A , the indicator eventually becomes positive on almost all arguments x of Φ ˆ A . In addition to our main result, we show several properties of the computably enumerable e.u.wtt-a.c. sets. For instance, the class of these sets is closed downwards under wtt -reductions and closed under join. Moreover, we relate this class to – and separate it from – well known classes in the literature. On the one hand, the class of the wtt -degrees of the c.e. e.u.wtt-a.c. sets is strictly contained in the class of the array computable c.e. wtt -degrees. On the other hand, every bounded low set is e.u.wtt-a.c. but there are e.u.wtt-a.c. c.e. sets which are not bounded low. Here a set A is bounded low if A † ⩽ wtt ∅ † , i.e., if A † is ω-c.a., where A † is the wtt -jump of A (Anderson, Csima and Lange (Archive for Mathematical Logic56(5–6) (2017) 507–521)). Finally, we prove that there is a strict hierarchy within the class of the bounded low c.e. sets A depending on the order h that bounds the number of mind changes of a computable approximation of A † , and we show that there exists a Turing complete set A such that A † is h-c.a. for any computable order h with h (0) > 0. [ABSTRACT FROM AUTHOR]

Many grasshopper species produce conspicuous sounds while escaping from approaching predators; however, they occasionally escape without producing sounds. The Chinese grasshopper, Acrida cinerea, often exhibits noisy escape behavior. Therefore, a field experiment was conducted using A. cinerea to identify factors related to the production of sound during escape. This study utilized a predator model with an investigator approaching A. cinerea three times. We examined the relationship between the production of sound during escape and the following factors: ambient temperature and relative humidity as environmental factors; sex, body length, body weight, and limb autotomy as prey traits; and the repeated approach as a predator trait. The relationships between noisy escape and flight initiation distance (i.e., predator-prey distance when the prey initiates the escape), distance fled (i.e., distance the prey covered during the escape), and the mode of locomotion during escape (i.e., flying or jumping) were also examined. Noisy escape was observed only in males that escaped by flying, whereas the females and males that escaped by jumping invariably escaped silently. Among males that flew, noisy escape was related to ambient temperature, limb autotomy, and distance fled. The proportion that produced sound increased in parallel with the ambient temperature and distance fled. This proportion was lower among individuals that had autotomized one of their hind legs. These results indicate that noisy escape behavior is most frequent in healthy male A. cinerea under warm conditions. [ABSTRACT FROM AUTHOR]

Copyright of Online Turkish Journal of Health Sciences (OTJHS) / Online Türk Sağlık Bilimleri Dergisi is the property of Oguz KARABAY and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Gümüshane Üniversitesi Saglik Bilimleri Dergisi is the property of Gumushane University, Faculty of Health Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The intensity, hardness, and extent of catastrophic accidents in recent decades have led insurance companies to seek resources to raise the capital to deal with the caused damage by these accidents. One of the most effective tools to cover the risk of catastrophic events such as earthquakes, floods, etc., which is widely used in the world, is catastrophic bonds. The purpose of this study is to provide a model for the pricing of catastrophic bonds. Because earthquake catastrophic damage causes major changes to corporate assets as well as investment trends, a jump sentence is added to the study model to indicate the severity and probability of damage. To produce the time discretization, the suggested methodology employs a one-order correct expression in the first process. To generate the full-discretization in the second level, the spectral collocation method approach that relies on the Chebyshev basis of the second kind is presented. Adding the jump sentence causes the original model to become an integral differential model, which approximates using the spectral method. Also, based on the derivatives in the obtained model, we approximated the derivative operator by using this type of base. The numerical investigation confirms the temporal discretized formulation's stability and convergence. We also approximated the integral sentence using the expansion of Gauss-Laguerre quadrature and presented numerical results. [ABSTRACT FROM AUTHOR]

The aim of this study was to verify post-activation performance enhancement (PAPE) in jumping and sprinting after two endurance volume-equated running protocols with different intensities, in runners vs. active individuals. Nine recreational runners (age: 34.5 ± 9.3 years, body mass: 73.1 ± 11.9 kg, body height: 1.76 ± 0.06 m, 17.4 ± 4.4 %body fat; maximum aerobic speed [MAS]: 16.4 ± 1.0 km·h-1), and 9 active individuals (age: 34.1 ± 9.4 years; body mass: 83.2 ± 7.7 kg; body height: 1.79 ± 0.06 m; 25.6 ± 5.4 %body fat; MAS: 13.3 ± 1.2 km·h-1) volunteered for participation. The evaluations were performed over three days as follows: 1) anthropometric measures, physical fitness tests, and the University of Montreal Track Test (UMTT) to determine MAS and the distance to be covered in the running protocols; 2 and 3) the countermovement jump (CMJ) and the flying 20-m sprint (SPRINT) were assessed pre- and post-running at 70% of MAS or a time trial race (TTR), equated by volume and completed in random order. A three-way ANOVA (time*group*running) was performed to analyze the PAPE effects. The results showed a time effect (F = 10 .716; p < 0.01) and a group*running interaction (F = 12.094; p < 0.01) for the CMJ, indicating that active individuals demonstrated PAPE after running at 70% of MAS, while for runners both running interventions (70% of MAS and TTR) induced PAPE in CMJ performances. For the SPRINT, a time*group interaction (F = 4.790; p = 0.044) and a group effect were observed, with runners showing greater SPRINT performances than active individuals. From the current results, it can be suggested that training background and intensity can modulate PAPE responses in jumping and sprinting after volume-equated running protocols at different intensities. [ABSTRACT FROM AUTHOR]

Asset price jumps are very common in financial markets, and they are essential to accurately predict volatility. This article focuses on 50 randomly selected stocks from the Chinese stock market, utilising high-frequency data to construct two jump models, the heterogeneous autoregressive quarticity jump model (HARQ-J) and the full heterogeneous autoregressive quarticity jump model (HARQ-F-J), which take into account jump variables based on existing models (HARQ and HARQ-F). To further enhance the accuracy of our volatility forecasts, the study combines the newly constructed models with the machine learning (ML) to form a hybrid model. Finally, the empirical research shows that the new hybrid model performs better than existing traditional prediction methods. In particular, the long- and short-term memory (LSTM) function is significantly better than other machine learning functions. Among all the LSTM models tested by the model confidence set (MCS), the HARQ-F-J-LSTM model has the highest prediction accuracy, followed by the HARQ-J-LSTM model. [ABSTRACT FROM AUTHOR]

An increased jumping performance is key for gymnastics competition routines. Rhythmic gymnasts (RGs) use the jump as one of the main body elements. In Acrobatic Gymnastics (ACRO), top gymnasts must coordinate their jumps with the impulse provided by base gymnast(s). It is expected that the gymnasts' discipline and role played impact their jumping skill. This work aims to investigate how the jumping performance differs between ACRO gymnasts and RGs, focusing on the Force–Velocity (F-V) profile mechanical variables. Gymnasts were divided in three groups: ACRO tops (n = 10, 13.89 (3.62) median (interquartile interval) years old), ACRO bases (n = 18, 18.24 (4.41) years old) and RGs (n = 15, 12.00 (3.00) years old). The F-V profile during countermovement jump and its mechanical variables were evaluated using MyJump2. A training background survey and anthropometric assessments were conducted. The significance level was set at p ≤ 0.05. Group comparisons showed that ACRO bases jump higher than ACRO tops and RGs, present a higher maximal force than RGs and a more balanced F-V profile, while RGs present high force deficits. Coaches can use this data to develop interventions that optimize the training stimulus to different gymnastics disciplines considering the individual characteristics and adaptability of each gymnast. [ABSTRACT FROM AUTHOR]

In the context of the Poisson censored δ-shock model, this paper derives the system reliability by directly calculating probabilities, which is different from the existing literature. When the time is equal to δ, an explicit result that the reliability has a jump is verified. Based on the system reliability, we obtain the expectation of the lifetime of the system. Finally, one application of the model is shown in relationship marketing. The conclusions imply that managers should make a tradeoff between the expected return and variance of return before making decisions. [ABSTRACT FROM AUTHOR]

Copyright of Revija Šport is the property of Sport: Revija Za Teoreticna in Praticna Vprasanja Sporta and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the context of the Poisson censored δ-shock model, this paper derives the system reliability by directly calculating probabilities, which is different from the existing literature. When the time is equal to δ, an explicit result that the reliability has a jump is verified. Based on the system reliability, we obtain the expectation of the lifetime of the system. Finally, one application of the model is shown in relationship marketing. The conclusions imply that managers should make a tradeoff between the expected return and variance of return before making decisions. [ABSTRACT FROM AUTHOR]

An approach to the calculation of complex chemical equilibrium using the open-source optimization package Ipopt and the open-source package JuMP is proposed. The code of two procedures written in the open-source Julia programming language for calculating the equilibrium composition and properties of multicomponent heterogeneous thermodynamic systems is presented. The results of the test calculations showed a good performance of the code and a relatively high speed of calculations. Due to the compactness and simplicity of the code, it can be easily integrated into other applications, or used in combination with more complex models. [ABSTRACT FROM AUTHOR]

Background: The objective of this study was to assess the effectiveness of neuromuscular training on the performance of highly trainer junior tennis players. Methods: Twelve male tennis players (age: 13.4 ± 0.36 years; weight: 50.2 ± 6.29 kg; height: 163 ± 4.41 cm) participated and were randomly divided into two groups. The experimental group (EG) performed neuromuscular training that included exercises for speed, strength, throws, agility, jumps and coordination twice a week for a duration of 10 weeks. Performance was evaluated using various variables, including bilateral and unilateral countermovement jump, 30 cm drop jump and horizontal jump, 505 change of direction test conducted with both the right and left legs, 20-m sprint, and overhead 3 kg medicine ball throw. Asymmetries were also evaluated during the unilateral tests. The impact of the training was assessed through the utilization of ANCOVA tests and effect size measurements. Results: The results indicated a significant enhancement in the EG, specifically in bilateral vertical jump and horizontal jump, as well as explosive strength and speed. Conversely, the control group (CG) did not display similar advancements. Furthermore, there was no increase in asymmetries. Conclusion: This suggests that the implementation of a neuromuscular training program could prove to be an effective approach in enhancing explosive power in the lower limbs among young competitive tennis players. Finally, this training program could contribute to the enhancement of their physical attributes in lower body of young tennis players.

Day-boundary discontinuity (DBD) is an effect present in precise GNSS satellite orbit and clock products originating from the method used for orbit and clock determination. The non-Gaussian measurement noise and data processing in 24 h batches are responsible for DBDs. In the case of the clock product, DBD is a time jump in the boundary epochs of two adjacent batches of processed data and its magnitude might reach a couple of ns. This article presents the four GNSS (Global Navigation Satellite System) systems DBD analysis in terms of change over an 8 year period. For each of 118 satellites available in this period, the yearly value of DBD was subject to analysis including standard deviation and frequency of outliers. Results show that the smallest DBDs appear in the GPS system, the biggest – for the BeiDou space segment. Moreover, the phenomenon of changes in DBDs over time is clearly seen at the beginning of the analysed period when the magnitude and number of the DBDs were larger than for current, newest clock products

This study investigated the effect of external (EC) and internal coaching cues (IC), analogies with a directional component (ADC) on sprint (20 m) and vertical jump performance in academy soccer players (n = 20). A repeated-measures analysis, with post-hoc comparisons, was used to identify any differences between these cues and a neutral (control) cue. Significant differences were found for both sprint (p < 0.001) and jump (p = 0.022) comparisons among cue types. In post-hoc analyses for the 20 m sprint, significant differences were observed between the EC and the IC, favouring the EC (p < 0.01, ES = 1.27 [CI: 0.24, 2.30]), and "away" ADC and the IC, favouring the "away" ADC (p < 0.01, ES = 1.21 [CI: 0.19, 2.22]). No other cues showed significant differences. For vertical jump, there was just one significant difference between comparisons, that being for the "away" ADC vs. the neutral cue, favouring the latter (p = 0.023, ES = 0.4 [CI: −0.04 to 0.84]). It appears that ECs and ADCs are most effective when coaching sprinting performance in academy soccer players. However, simply encouraging maximal effort from a youth athlete also appears to be a reasonable cueing strategy to drive performance in youth athletes. [ABSTRACT FROM AUTHOR]

Our study aimed to compare explosive performance and underlying mechanical determinants explored through F-V profiles in jumping and sprinting among young soccer players based on their playing position. Ninety elite soccer players were categorized into the following positions: goalkeepers, central defenders, wide defenders, central midfielders, wide midfielders, and forwards. Two testing sessions were conducted to measure the 30-metre sprint time (T30) using an over-ground sprint test and jump height (Hmax) through the SJ test. Results demonstrated performance variations among positions. In sprinting, forwards showed greater T30 (4.5 ± 0.14 s) compared to other positions, with goalkeepers exhibiting the lowest T30 (4.86 ± 0.18 s). Forwards also displayed higher maximal theoretical velocity (8.8 ± 0.4 m.s−1) and power output (Pmax) (19.4 ± 2.6 W.kg−1) than other positions, while goalkeepers had the lowest Pmax (16.5 ± 2 W.kg−1). In jumping, forwards (33.2 ± 3.9 cm) and wide-midfielders (33.6 ± 3.8 cm) achieved higher Hmax compared to goalkeepers (29.2 ± 5 cm) and central-midfielders (29.2 ± 3.8 cm). Wide-midfielders (28.5 ± 4.8 W.kg−1) and forwards (27.1 ± 4.3 W.kg−1) surpassed goalkeepers (23 ± 2.8 W.kg−1) and central-midfielders (25.1 ± 3.8 W.kg−1) in Pmax. Our findings reveal substantial position-related disparities in F-V profiles among elite young soccer players, in sprinting and jumping emphasizing the need for position-specific training programmes to optimize player development and on-field performance from an early age. [ABSTRACT FROM AUTHOR]

In this paper, we propose an enhanced model for pricing vulnerable options. Specifically, our model assumes that parameters such as interest rates, jump intensity, and asset value volatility are governed by an observable continuous-time finite-state Markov chain. We take into account European vulnerable options that are exposed to both default risk and rare shocks from underlying and counterparty assets. We also consider stochastic default barriers driven by a regime-switching model and geometric Brownian motion, thus improving upon the assumption of fixed default barriers. The risky assets follow a related jump-diffusion process, whereas the default barriers are influenced by a geometric Brownian motion correlated with the risky assets. Within the framework of our model, we derive an explicit pricing formula for European vulnerable options. Furthermore, we conduct numerical simulations to examine the effects of default barriers and other related parameters on option prices. Our findings indicate that stochastic default barriers increase credit risk, resulting in a decrease in option prices. By considering the aforementioned factors, our research contributes to a better understanding of pricing vulnerable options in the context of counterparty credit risk in over-the-counter trading. [ABSTRACT FROM AUTHOR]

Background: Although the superior effectiveness of free‐weight over machine‐based training has been a traditionally widespread assumption, longitudinal studies comparing these training modalities were scarce and heterogeneous. Objective: This research used the velocity‐based method to compare the effects of free‐weight and machine‐based resistance training on athletic performance and muscle architecture. Methods: Thirty‐four resistance‐trained men participated in an 8‐week resistance training program allocated into free‐weight (n = 17) or machine‐based (n = 17) groups. Training variables (intensity, intraset fatigue, and recovery) were identical for both groups, so they only differed in the use of a barbell or specific machines to execute the full squat, bench press, prone bench pull, and shoulder press exercises. The velocity‐based method was implemented to accurately adjust the planned intensity. Analysis of covariance and effect size (ES) statistics were used to compare both training modalities on a comprehensive set of athletic and muscle architecture parameters. Results: No between‐group differences were found for any athletic (p ≥ 0.146) and muscle architecture (p ≥ 0.184) variable. Both training modalities significantly and similarly improved vertical jump (Free‐weight: ES ≥ 0.45, p ≤ 0.001; Machine‐based: ES ≥ 0.41, p ≤ 0.001) and lower limb anaerobic capacity (Free‐weight: ES ≥ 0.39, p ≤ 0.007; Machine‐based: ES ≥ 0.31, p ≤ 0.003). Additionally, the machine‐based group meaningfully enhanced upper limb anaerobic power (ES = 0.41, p = 0.021), whereas the free‐weight group significantly improved the change of direction (ES = ‐0.54, p = 0.003) and 2/6 balance conditions analyzed (p ≤ 0.012). Changes in sprint capacity (ES ≥ ‐0.13, p ≥ 0.274), fascicle length, and pennation angle (ES ≤ 0.19, p ≥ 0.129) were not significant for either training modality. Conclusion: Adaptations in athletic performance and muscle architecture would not be meaningfully influenced by the resistance modality trained. [ABSTRACT FROM AUTHOR]

With the advent of the Global Navigation Satellite System (GNSS), the need for precise and highly accurate orbit and clock products becomes crucial in processing GNSS data. Clocks in GNSS observations form the basis of positioning. Their high quality and stability enable high accuracy and the reliability of the obtained results. The clock modelling algorithms are continuously improved; thus, the accuracy of the clock products is evolving. At present, 8 Analysis Centers (ACs) contribute to the International GNSS Service final clock products. These products are based on GNSS observations on a network of reference stations, where for a given day one of the reference station clocks is the reference clock. In this paper, the authors determined the impact of the reference clock on the quality of clock product, especially outliers, for the first time. For this purpose, the multi-GNSS final clock products provided by the Center for Orbit Determination in Europe (CODE) for the period 2014–2021 (1773–2190 GPS week, 2921 days) were analysed. Analysis shows that by applying the Median Absolute Deviation (MAD) algorithm for outlier detection, the Passive Hydrogen Maser (PHM) clock installed on board the GALILEO satellites have the lowest level of noise, whereas the Block IIR GPS satellite launched in 1999 appears to have the highest levels of noise. Furthermore, the GNSS station OHIE3, when used as a reference clock, generates an increase in the level of noise, especially noticeable on the G09 and E03 satellites. [ABSTRACT FROM AUTHOR]

This study assessed the relationship between head posture displacements and biomechanical parameters during gait and jumping. One hundred male and female students (20 ± 3 yrs) were assessed via the PostureScreen Mobile® app to quantify postural displacements of head rotations and translations including: (1) the cranio-vertebral angle (CVA) (°), (2) anterior head translation (AHT) (cm), (3) lateral head translation in the coronal plane (cm), and (4) lateral head side bending (°). Biomechanical parameters during gait and jumping were measured using the G-Walk sensor. The assessed gait spatiotemporal parameters were cadence (steps/min), speed (m/s), symmetry index, % left and right stride length (% height), and right and left propulsion index. The pelvic movement parameters were (1) tilt symmetry index, (2) tilt left and right range, (3) obliquity symmetry index, (4) obliquity left and right range, (5) rotation symmetry index, and (6) rotation left and right range. The jump parameters measured were (1) flight height (cm), (2) take off force (kN), (3) impact Force (kN), (4) take off speed (m/s), (5) peak speed (m/s), (6) average speed concentric phase (m/s), (7) maximum concentric power (kW), (8) average concentric power (kW) during the counter movement jump (CMJ), and (9) CMJ with arms thrust (CMJAT). At a significance level of p ≤ 0.001, moderate-to-high correlations (0.4 < r < 0.8) were found between CVA, AHT, lateral translation head, and all the gait and jump parameters. Weak correlations (0.2 < r < 0.4) were ascertained for lateral head bending and all the gait and jump parameters except for gait symmetry index and pelvic symmetry index, where moderate correlations were identified (0.4 < r < 0.6). The findings indicate moderate-to-high correlations between specific head posture displacements, such as CVA, lateral head translation and AHT with the various gait and jump parameters. These findings highlight the importance of considering head posture in the assessment and optimization of movement patterns during gait and jumping. Our findings contribute to the existing body of knowledge and may have implications for clinical practice and sports performance training. Further research is warranted to elucidate the underlying mechanisms and establish causality in these relationships, which could potentially lead to the development of targeted interventions for improving movement patterns and preventing injuries. [ABSTRACT FROM AUTHOR]

The vertical jump height has been widely used in sports-related studies to track athletes' development. Although many systems can measure vertical jump height, there are still problems with measuring it in real-time during sports activity. Therefore, the use of inertial measurement unit (IMU)-based systems in this area is increasing. In this study, a low-cost, small, wireless, and wearable jump meter has been designed to address the real-time measurement problem. The developed system has a high accuracy for vertical jump measurements and provides some extra parameters for performance evaluation. Fourteen volleyball players' measurements were taken simultaneously with the designed system and a jump mat to evaluate the developed system's performance (n = 350). The obtained results show that the system is highly correlated with jump mat (r2 = 0.92), and it also has a mean bias of −0.06 cm (95% limits of agreement −3.4 cm to 3.3 cm; p < 0.001). [ABSTRACT FROM AUTHOR]

This paper introduces the vitality of science and technology innovation and the ability to coordinate science and technology strength of green development, builds green innovation knowledge system, studies the new endogenous growth law driven by green innovation knowledge system under the active, conscious and autonomous practice of green low-carbon behavior has become a common form. This paper constructs a green development equilibrium model of economic system from the aspects of production, household and government intervention and discusses the relationship between economic growth and environmental quality driven by green development behavior. In the production part, the green innovation knowledge system becomes endogenous factor of production under the stimulation of vitality of science and technology innovation and integrates into the production of green low-carbon behavior goods. In the consumption part, the household utility function is given from the aspects of environmental quality, carbon emission and consumption. Through empirical analysis and research, the environmental effects which are cognitive dissonance effect and loss aversion effect can be obtained. [ABSTRACT FROM AUTHOR]

Quantifying both external and internal training loads that athletes are exposed to during training sessions is often recommended to assess multifactorial sport-specific demands. Thus, the purpose of the present study was to determine the relationship between a widely used subjective marker of internal load (rate of perceived exertion - RPE) and external load variables obtained from an innovative inertial measurement unit (IMU) device within a cohort of professional male basketball players. Twenty-one athletes competing in the firstand second-tier national basketball leagues in Europe wore an IMU device (i.e., VertTM) during their regular practice session and reported an RPE score (Borg CR-10 scale) immediately post-practice. The findings of this study reveal the presence of a strong significant relationship (r = 0.714) between Stress and RPE. However, weak non-significant relationships (r = 0.198-0.287) were observed between RPE and all jumprelated metrics (Jumps, Jumps 15+, Jumps 20+, Average Jump Height) as well as Active Minutes (r = 0.330), indicating that an increase in internal load is more dependent on the type of activity that players perform rather than the duration of the practice session. Overall, these findings may help sports scientists and strength and conditioning practitioners detect changes in training load throughout a competitive season in male basketball players and ultimately improve the acute and chronic training-adaptation monitoring process. [ABSTRACT FROM AUTHOR]

The purposes were to synthesize as much scientific evidence as possible to determine the effect of core training on balance, throwing/hitting velocity or distance, and jumping in healthy subjects, identify the possible differences between isolated and combined core training on performance and study training and sample variables related to performance. PRISMA guidelines were followed, and a systematic search was performed in the Scopus, Web of Science, Sports Discuss, and PubMed databases with no date restrictions until November 2022. The studies were considered for this meta-analysis following PICO; a) randomized control trials and randomized allocation studies with healthy subjects and > 12 years old b)isolated or combined core training programs with a minimum of 4 weeks in length; c) athletic performance outcomes for balance, throw/hit, and jump variables should be measured; d) sufficient data to calculate effect sizes. The Cochrane Collaboration Risk of Bias Tool and the Grading of Recommendations Assessment, Development, and Evaluation approach were used for assessing methodological quality. A total of 3223 studies were identified, 22 studies were included in the systematic review and 21 for the meta-analysis. We observed that core training improved balance outcomes (ES = 1.17; p < 0.0001), throwing/hitting velocity (ES = 0.30; p = 0.14), throwing/hitting distance (ES = 3.42; p = 0.03), vertical jumping (ES = 0.69; p = 0.0003), and horizontal jump (ES = 0.84; p = 0.01). Our findings indicate that core training improved different variables of performance such as balance, throw/hit, and vertical and horizontal jump. [ABSTRACT FROM AUTHOR]

Empirical studies suggest that asset price fluctuations exhibit "long memory", "volatility smile", "volatility clustering" and asset prices present "jump". To fit the above empirical characteristics of the market, this paper proposes a fractional stochastic volatility jump-diffusion model by combining two fractional stochastic volatilities with mixed-exponential jumps. The characteristic function of the log-return is expressed in terms of the solution of two-dimensional fractional Riccati equations of which closed-form solution does not exist. To obtain the explicit characteristic function, we approximate the pricing model by a semimartingale and convert fractional Riccati equations into a classic PDE. By the multi-dimensional Feynman-Kac theorem and the affine structure of the approximate model, we obtain the solution of the PDE with which the explicit characteristic function and its cumulants are derived. Based on the derived characteristic function and Fourier cosine series expansion, we obtain approximate European options prices. By differential evolution algorithm, we calibrate our approximate model and its two nested models to S&P 500 index options and obtain optimal parameter estimates of these models. Numerical results demonstrate the pricing method is fast and accurate. Empirical results demonstrate our approximate model fits the market best among the three models. [ABSTRACT FROM AUTHOR]

This article considers clustering stationary scalar time series using their marginal properties and a hierarchical method. Two major issues involved are to detect the existence of clusters and to determine their number. We propose a new test statistic for detecting whether a data set consists of multiple clusters and a new procedure to determine the number of clusters. The proposed method is based on the jumps, that is, the increments, in the heights of the dendrogram when a hierarchical clustering is applied to the data. We use autoregressive sieve bootstrap to obtain a reference distribution of the test statistics and propose an iterative procedure to find the number of clusters. The clusters found are internally homogeneous according to the test statistics used in the analysis. The performance of the proposed procedure in finite samples is investigated by Monte Carlo simulations and illustrated by some empirical examples. Comparisons with some existing methods for selecting the number of clusters are also investigated. [ABSTRACT FROM AUTHOR]

Given the multidirectional nature of the sport, handball athletes must frequently perform high-intensity decelerations to avoid defenders, generate space, or perform directional changes. The aim of the present study was twofold: (i) to investigate different kinematic measures of horizontal deceleration performance by comparing the acceleration-deceleration assessment (ADA) with the 5-0-5 test and (ii) to investigate relationships between force-time characteristics derived from the countermovement vertical jump (CVJ) and measures of horizontal deceleration performance. Eleven female handball players competing in the first-tier professional league in Europe performed three CVJs while standing on a uni-axial force plate system sampling at 1000 Hz, followed by two ADAs (i.e., maximal-effort acceleration over a 10 m distance, followed by rapid deceleration) and 5-0-5 test trials. Tripod-mounted radar sampling at 47 Hz, placed 5 m behind the start line, was used to record horizontal velocity data. Each test was separated by a 5–7 min rest interval to minimize the influence of fatigue. No statistically significant differences were found in horizontal deceleration performance parameters between ADA and the 5-0-5 test. However, athletes with a higher CVJ height and reactive strength index-modified showed better performance in terms of horizontal deceleration measures such as maximal approach velocity and average and maximal deceleration. Overall, these results may be of interest to practitioners working with multidirectional sport athletes such as handball players as they provide critical insight for the selection of assessments and training strategies targeted toward optimizing on-court athlete performance. [ABSTRACT FROM AUTHOR]

JuMP is an algebraic modeling language embedded in the Julia programming language. JuMP allows users to model optimization problems of a variety of kinds, including linear programming, integer programming, conic optimization, semidefinite programming, and nonlinear programming, and handles the low-level details of communicating with solvers. After nearly 10 years in development, JuMP 1.0 was released in March, 2022. In this short communication, we highlight the improvements to JuMP from recent releases up to and including 1.0. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the effects of high-intensity plyometric training (HIPT) on some parameters in elite soccer players in the U17. Volunteer soccer players were randomly divided into two groups according to their positions: the regular training (RT) group (age: 16.71 ± 0.47 years; stature: 163.46 ± 3.31 cm; body weight: 61.04 ± 1.59 kg) and the HIPT group (age: 16.64 ± 0.50 years; stature: 165.60 ± 3.03 cm; body weight: 59.76 ± 1.92 kg), and each group included five defenders, five midfielders, and four attackers. While the RT group did only routine soccer training, the HIPT group performed high-intensity plyometric training three days a week in addition to routine soccer training. In the study, body weight, stature, sprint (10 m, 30 m, and 40 m), jump (standing long jump, right and left-limb triple hop) and 5-0-5 change of direction speed test measurements of the soccer players were taken. Skewness and Kurtosis values obtained from the pre-test and post-test measurements were calculated to test whether the normality assumption of the study was met. A mixed measure two-way ANOVA test was used to determine the difference between the pre-test and post-test. The significance was set as p

Asset price jumps are very common in financial markets, and they are essential to accurately predict volatility. This article focuses on 50 randomly selected stocks from the Chinese stock market, utilising high-frequency data to construct two jump models, the heterogeneous autoregressive quarticity jump model (HARQ-J) and the full heterogeneous autoregressive quarticity jump model (HARQ-F-J), which take into account jump variables based on existing models (HARQ and HARQ-F). To further enhance the accuracy of our volatility forecasts, the study combines the newly constructed models with the machine learning (ML) to form a hybrid model. Finally, the empirical research shows that the new hybrid model performs better than existing traditional prediction methods. In particular, the long- and short-term memory (LSTM) function is significantly better than other machine learning functions. Among all the LSTM models tested by the model confidence set (MCS), the HARQ-F-J-LSTM model has the highest prediction accuracy, followed by the HARQ-J-LSTM model.

Study purpose. The aim of the study was to evaluate jumping performance and lower limbs strength asymmetry in young soccer players by comparing this movement performed on both a conventional surface and a sand surface. Materials and methods. 20 young soccer players under 17 years old randomly performed a standing long jump, a single hop jump in the sagittal plane (Hop Jump Test) and a single side hop jump in the frontal plane (Side Hop Jump Test), first on a conventional surface (natural grass) and then on sand. The jump distance and strength asymmetry was calculated using the formula: (NDL / DL) x 100. Results. The values from the two different jumping conditions showed a statistically significant decrease in the Broad Jump Test (p

Abstract Background Performance in jumping and change of direction tests are good proxies to reflect the skill level during soccer-specific actions. Greater inter-leg asymmetries have been identified as a risk factor for developing acute and overuse injuries and jeopardizing soccer performance. The aim of this study was to assess the association between asymmetry in the unilateral vertical and horizontal jump tests, ankle range of motion, linear velocity, and change of direction in a sample of highly trained adult female soccer players. Methods Thirty-eight highly trained female soccer players underwent a testing protocol including ankle dorsiflexion, single leg jumps for height (CMJ), distance (HJ), 40 m sprint and 180° change of direction tests. Results Within-session reliability was acceptable (CV ≤ 7.9%), and relative reliability showed good to excellent (ICC: 0.83 to 0.99). The one-way ANOVA reported higher inter-limb differences for change of direction deficit (10.9 ± 8.04%) and single leg CMJ (5.70 ± 5.22%). Pearson correlations highlighted significant relationships between horizontal jump asymmetries and ankle dorsiflexion (r = -0.41), CMJ (r = -0.36 to -0.49) and HJ (r = -0.28 to -0.56). Conclusions Assessing inter-limb asymmetries through different methods can help scientists understand the specificity of their detrimental effects on soccer performance. Practitioners should be aware of these specificities as well as the magnitude and direction of the asymmetries when aiming to improve specific on-field skills.

The combination of strength training with complementary whole-body electromyostimulation (WB-EMS) and plyometric exercises has been shown to increase strength and jumping performance in athletes. In elite sport, however, the mesocycles of training are often organized according to block periodization. Furthermore, WB-EMS is often applied onto static strength exercises, which may hamper the transfer into more sport-specific tasks. Thus, this study aimed at investigating whether four weeks of strength training with complementary dynamic vs. static WB-EMS followed by a four-week block of plyometric training increases maximal strength and jumping performance. A total of n = 26 (13 female/13 male) trained adults (20.8 ± 2.2 years, 69.5 ± 9.5kg, 9.7 ± 6.1h of training/w) were randomly assigned to a static (STA) or volume-, load- and work-to-rest-ratio-matched dynamic training group (DYN). Before (PRE), after four weeks (three times weekly) of WB-EMS training (MID) and a subsequent four-week block (twice weekly) of plyometric training (POST), maximal voluntary contraction (MVC) at leg extension (LE), leg curl (LC) and leg press machines (LP) and jumping performance (SJ, Squat Jump; CMJ, counter-movement-jump; DJ, drop-jump) were assessed. Furthermore, perceived effort (RPE) was rated for each set and subsequently averaged for each session. MVC at LP notably increased between PRE and POST in both STA (2335 ± 539 vs. 2653 ± 659N, standardized mean difference [SMD] = 0.528) and DYN (2483 ± 714N vs. 2885 ± 843N, SMD = 0.515). Reactive strength index of DJ showed significant differences between STA and DYN at MID (162.2 ± 26.4 vs. 123.1 ± 26.5 cm·s-1, p = 0.002, SMD = 1.478) and POST (166.1 ± 28.0 vs. 136.2 ± 31.7 cm·s-1, p = 0.02, SMD = 0.997). Furthermore, there was a significant effect for RPE, with STA rating perceived effort higher than DYN (6.76 ± 0.32 vs. 6.33 ± 0.47 a.u., p = 0.013, SMD = 1.058). When employing a training block of high-density WB-EMS both static and dynamic exercises lead to similar adaptations.

Jumping performance is considered an overall indicator of gymnastics ability. Acrobatic Gymnastics involves base and top gymnasts, considering the type of training that is performed and the distinct anthropometric traits of each gymnast. This work aims to investigate a hierarchy of variables that influence the force–velocity (F-V) profile of top and base acrobatic gymnasts through a deep artificial neural network model. Twenty-eight first division and elite acrobatic gymnasts (eleven tops and seventeen bases) performed two evaluations to assess the F-V profile during the Countermovement Jump and its mechanical variables, using My Jump 2 (a total of 56 evaluations). A training background survey and anthropometric assessments were conducted. The final model (R = 0.97) showed that the F-V imbalance (F-Vimb) increases with higher force and decreases with higher maximal power, fat percentage, velocity, and height. Coaches should prioritize the development of force, followed by maximal power, and velocity for the optimization of gymnasts’ F-Vimb. For training planning, the influences of body mass and push-off height are higher for the bases, and the influences of years of practice and competition level are higher for the tops.

This study examined seasonal variation and the effect of the transition period on physical fitness parameters in female youth soccer players. Twenty-four players (13–17 years old) were assessed through field and laboratory testing. They completed laboratory testing three times: (1) at the beginning of the season (post-preseason), (2) at the end of the regular season (postseason), and (3) following the transition period (preseason). Field testing was conducted post-preseason and postseason. Results indicated that weight and body fat significantly increased from post-preseason to postseason and following the transition period. A paired samples T-test revealed that the players performed significantly better in the vertical jump and 30 m sprint test (all p < 0.01) postseason compared to post-preseason. Also, it was indicated that torque production for the right quadriceps, left quadriceps, and right hamstring (all p < 0.01) was significantly reduced after the transition period by 10%, 11.8%, and 10.5%, respectively. Cardiorespiratory measurements demonstrated that performance on an incremental cardiopulmonary treadmill test, maximal oxygen consumption, velocity at the first ventilatory threshold, velocity at the second ventilatory threshold, and velocity at maximal oxygen consumption (all p < 0.01) were significantly reduced postseason and following the transition period. Based on the results, coaches and trainers should primarily focus on maintaining the aerobic capacity of the players during the season, as it has been indicated to be reduced from the beginning to the end of the competitive period (VO2max reduced by 3.3%). In addition, they should focus on maintaining lower body strength and aerobic capacity during the transition period.

Study purpose. The aim of the study was to evaluate jumping performance and lower limbs strength asymmetry in young soccer players by comparing this movement performed on both a conventional surface and a sand surface. Materials and methods. 20 young soccer players under 17 years old randomly performed a standing long jump, a single hop jump in the sagittal plane (Hop Jump Test) and a single side hop jump in the frontal plane (Side Hop Jump Test), first on a conventional surface (natural grass) and then on sand. The jump distance and strength asymmetry was calculated using the formula: (NDL / DL) x 100. Results. The values from the two different jumping conditions showed a statistically significant decrease in the Broad Jump Test (p<0.001, ES: 3.56), Hop Jump Test left limb (p<0.001, ES: 4.99), Hop Jump Test right limb (p<0.001, ES: 3.95), Side Hop Jump Test left limb (p<0.001, ES: 4.67) and Side Hop Jump Test right limb (p<0.001, ES: 2.98) in the sand condition. The asymmetry values in the Hop Jump Test and the Side Hop Jump Test showed a statistically significant increase (+21.5%, p<0.001, ES: 3.66 and +41.1%, p<0.001, ES: 1.99, respectively) when comparing the performance on grass and sand. Conclusions. This different performance response in the two different jumping modes leads to the hypothesis that young soccer players who want to stress their explosive strength ability and joint stability should favor the use of oneleg rather than two-leg jumps. The values described in the study lead to the hypothesis that training on sand should be suggested when the young soccer player presents modest values of inter-limb asymmetry measured on a conventional surface. [ABSTRACT FROM AUTHOR]