The Cognitive Function and Taekwondo-Specific Kick Performance of Taekwondo Athletes at Different Hydration Statuses.

PURPOSE: Successful participation in taekwondo (TKD) requires athletes to possess quick decision-making abilities and demonstrate technical proficiency during competition. Dehydration, occurring during both training and competition, is widely recognized to have various negative effects. METHODS: This study investigated the impact of different levels of dehydration on cognitive function, as measured by the Vienna Test System, and the specific performance of kicking techniques among TKD athletes. Using a randomized crossover design, 12 participants were involved in the study. Before and after 1 hour of training at 80% of maximal heart rate, participants were weighed and provided urine samples. All participants were randomly assigned to 3 different hydration conditions: the euhydrated (EUH) group had unrestricted access to fluid consumption, while the hypohydrated (HYP) and severely HYP (S-HYP) groups experienced reductions of 2.0% and 4.0% of their initial body weight, respectively. RESULTS: The EUH group exhibited better reaction speed in reaction-time test-form S1 than the HYP and S-HYP groups. Notably, the EUH group demonstrated a significantly higher success rate in the front-side kick (EUH 98%, HYP 90%, S-HYP 88%; P < .05). However, the success rates of back roundhouse kick and free head kick were similar among the 3 statuses. Furthermore, postexercise heart rates were found to be significantly higher in the HYP and S-HYP groups compared with the EUH group. CONCLUSIONS: This study provides insight into the negative effects of dehydration on cognitive function and TKD-specific performance. It is recommended that TKD athletes maintain optimal hydration levels during training and competition to ensure optimal performance.

Influence of Torsional Stiffness in Badminton Footwear on Lower Limb Biomechanics.

Torsional stiffness of athletic footwear plays a crucial role in preventing injury and improving sports performance. Yet, there is a lack of research focused on the biomechanical effect of torsional stiffness in badminton shoes. This study aimed to comprehensively investigate the influence of three different levels of torsional stiffness in badminton shoes on biomechanical characteristics, sports performance, and injury risk in badminton players. Fifteen male players, aged 22.8 ± 1.96 years, participated in the study, performing badminton-specific tasks, including forehand clear stroke [left foot (FCL) and right foot (FCR)], 45-degree sidestep cutting (45C), and consecutive vertical jumps (CVJ). The tasks were conducted wearing badminton shoes of torsional stiffness measured with Shore D hardness 50, 60, and 70 (referred to as 50D, 60D, and 70D, respectively). The primary biomechanical parameters included ankle, knee, and MTP joint kinematics, ankle and knee joint moments, peak ground reaction forces, joint range of motion (ROM), and stance time. A one-way repeated measures ANOVA was employed for normally distributed data and Friedman tests for non-normally distributed data. The 70D shoe exhibited the highest ankle dorsiflexion and lowest ankle inversion peak angles during 45C task. The 60D shoe showed significantly lower knee abduction angle and coronal motions compared to the 50D and 70D shoes. Increased torsional stiffness reduced stance time in the FCR task. No significant differences were observed in anterior-posterior and medial-lateral ground reaction forces (GRF). However, the 70D shoe demonstrated higher vertical GRF than the 50D shoe while performing the FCR task, particularly during 70% - 75% of stance. Findings from this study revealed the significant role of torsional stiffness in reducing injury risk and optimizing performance during badminton tasks, indicating that shoes with an intermediate level of stiffness (60D) could provide a beneficial balance between flexibility and stability. These findings may provide practical references in guiding future badminton shoe research and development. Further research is necessary to explore the long-term effects of altering stiffness, considering factors such as athletic levels and foot morphology, to understand of the influence of torsional stiffness on motion biomechanics and injury prevalence in badminton-specific tasks.

Improving Special Ability Performance of Badminton Players through a Visual Reaction Training System.

This study investigates the effects of a visual reaction training system (VRTS) in improving the footwork of badminton players. The participants comprised 20 high school male badminton players (mean age, 17.83 ± 1.57 years; mean height, 171.4 ± 11.52 cm; mean weight, 58.76 ± 9.32 kg) who first underwent a badminton footwork agility training program and subsequently, a fixed or random six-point footwork test and an agility t-test. A one-way repeated-measures analysis of variance with Bonferroni correction was performed to identify differences in terms of response time, movement time, and total shift time. The results measured at midtest and posttest after the training intervention revealed significant improvements in reaction (p ≤ 0.01) and movement (p ≤ 0.05) time for the fixed six-point footwork test (p ≤ 0.01). The total time results for the fixed or random six-point footwork test and agility t-test at midtest and posttest after the training intervention revealed significant improvement (p ≤ 0.05). Badminton footwork agility training conducted through the VRTS enhances the ability and agility of badminton players. Therefore, researchers and coaches should evaluate the footwork of badminton players by precisely measuring and quantify their ability.

External Load of Flamenco Zap-3 Footwork Test: Use of PlayerLoad Concept with Triaxial Accelerometry.

The intense footwork required in flamenco dance may result in pain and injury. This study aimed to quantify the external load of the flamenco Zapateado-3 (Zap-3) footwork via triaxial accelerometry in the form of PlayerLoad (PL), comparing the difference in external loads at the fifth lumbar vertebra (L5), the seventh cervical vertebra (C7) and the dominant ankle (DA), and to explore whether the speed, position, axis and proficiency level of the flamenco dancer affected the external load. Twelve flamenco dancers, divided into professional and amateur groups, completed a 15-s Zap-3 footwork routine at different speeds. Triaxial accelerometry sensors were positioned at the DA, L5 and C7 and were utilized to calculate the total PlayerLoad (PLTOTAL), uniaxial PlayerLoad (PLUNI) and uniaxial contributions (PL%). For both PLTOTAL and PLUNI, this study identified significant effects of speed and position (p < 0.001), as well as the interaction between speed and position (p ≤ 0.001), and at the DA, values were significantly higher (p < 0.001) than those at C7 and L5. Significant single axis and group effects (p < 0.001) and effects of the interactions between the position and a single axis and the group and speed (p ≤ 0.001) were also identified for PLUNI. Medial-lateral PL% represented a larger contribution compared with anterior-posterior PL% and vertical PL% (p < 0.001). A significant interaction effect of position and PL% (p < 0.001) also existed. In conclusion, the Zap-3 footwork produced a significant external load at different positions, and it was affected by speed, axis and the proficiency level of the flamenco dancer. Although the ankle bears the most external load when dancing the flamenco, some external load caused by significant vibrations is also borne by the lumbar and cervical vertebrae.

Understanding Sex-Based Kinematic and Kinetic Differences of Chasse-Step in Elite Table Tennis Athletes.

With the progress and innovation of table tennis technology, individualized training programs may deserve special attention. This study aimed to analyze elite table tennis athletes in chasse-step, with a particular focus on sex-based biomechanical differences. A total of 36 (18 males and 18 females) elite table tennis athletes performed topspin forehand of chasse-step. Angles and moments of hip, knee, and ankle joints were calculated using OpenSim (v4.2) with marker trajectories and ground reaction forces were measured via Vicon motion capture system and AMTI in-ground force platform. Males had greater hip and knee flexion angles during the entire motion phase and greater internal rotation angles of the hip during the forward swing phase. The joint stiffness of knee in males was greater than females in the frontal plane. Females in the forward swing phase showed greater hip flexion, adduction, and internal rotation moments than males. It was suggested that the difference may be due to the limitation of anatomical structures in sexes. Male table tennis athletes should strengthen lower extremity muscle groups to improve performance, while female table tennis athletes should focus on hip joint groups to avoid injury. The sex differences presented in this study could help coaches and athletes to develop individualized training programs for table tennis.

Lower limb kinetic comparisons between the chasse step and one step footwork during stroke play in table tennis.

BACKGROUND: Biomechanical footwork research during table tennis performance has been the subject of much interest players and exercise scientists. The purpose of this study was to investigate the lower limb kinetic characteristics of the chasse step and one step footwork during stroke play using traditional discrete analysis and one-dimensional statistical parameter mapping. METHODS: Twelve national level 1 table tennis players (Height: 172 ± 3.80 cm, Weight: 69 ± 6.22 kg, Age: 22 ± 1.66 years, Experience: 11 ± 1.71 year) from Ningbo University volunteered to participate in the study. The kinetic data of the dominant leg during the chasse step and one step backward phase (BP) and forward phase (FP) was recorded by instrumented insole systems and a force platform. Paired sample T tests were used to analyze maximum plantar force, peak pressure of each plantar region, the force time integral and the pressure time integral. For SPM analysis, the plantar force time series curves were marked as a 100% process. A paired-samples T-test in MATLAB was used to analyze differences in plantar force. RESULTS: One step produced a greater plantar force than the chasse step during 6.92-11.22% BP (P = 0.039). The chasse step produced a greater plantar force than one step during 53.47-99.01% BP (P < 0.001). During the FP, the chasse step showed a greater plantar force than the one step in 21.06-84.06% (P < 0.001). The one step produced a higher maximum plantar force in the BP (P = 0.032) and a lower maximum plantar force in the FP (P = 0) compared with the chasse step. The one step produced greater peak pressure in the medial rearfoot (P = 0) , lateral rearfoot (P = 0) and lateral forefoot (P = 0.042) regions than the chasse step during BP. In FP, the chasse step showed a greater peak pressure in the Toe (P = 0) than the one step. The one step had a lower force time integral (P = 0) and greater pressure time integral (P = 0) than the chasse step in BP, and the chasse step produced a greater force time integral (P = 0) and pressure time integral (P = 0.001) than the one step in the FP. CONCLUSION: The findings indicate that athletes can enhance plantarflexion function resulting in greater weight transfer, facilitating a greater momentum during the 21.06-84.06% of FP. This is in addition to reducing the load on the dominant leg during landing by utilizing a buffering strategy. Further to this, consideration is needed to enhance the cushioning capacity of the sole heel and the stiffness of the toe area.

Biomechanical Description of Zapateado Technique in Flamenco.

The main purpose of this study was to identify a dancer's body alignment while performing flamenco footwork to provide a detailed description that could be used by flamenco practitioners: teachers, instructors and students of different levels of advancement. The zapateado technique performed by a professional flamenco dancer was analyzed. The biomechanical analysis was based on 30 cycles composed of six repeating sequences of strikes. Kinematic recordings were performed using a Vicon system, while the measurement of the ground reaction forces (GRF) was accomplished with a Kistler force plate. The following parameters were analyzed: the time of each foot strike, the maximal value of the vertical component of GRF normalized to body weight (BW) for subsequent footwork steps, the impulse of the GRF and the kinematics of pelvis and lower limb joints, and an exemplary waveform view of the sound of footwork strikes was shown. The average values of the vertical component of GRF ranged between 0.6 and 2.7 BW. The maximal anterior pelvic tilt was 29°, with a 6° range of motion (RoM). This mobility was accompanied by 20° hip RoM and by ~40° knee RoM throughout flexion. The conclusions provide practical information that a teacher and flamenco student should receive.

Verification and Evaluation of a Visual Reaction System for Badminton Training.

The two aims of this study were (1) designing and developing an affordable visual reaction system for badminton training that monitors and provides instant feedback on agility; and (2) to measure and improve the footwork and movement of badminton players and output useful reference data. Ten junior high school badminton players were invited to serve as the subjects of this study. They participated in a three-week (nine sessions) training program. Training was primarily in the form of fixed or random footwork drills. Timed tests were performed before and after each session to measure the players' agility in performing six-point and four-point footwork drills. The results were compared to the training effects calculated using dependent-sample t-tests. In addition, the long-term durability and functionality of the training system were tested. The training system was able to maintain stable and reliable training and evaluation operations for extended periods. Results showed significant improvements in the visual reaction time (p = 0.003) and agility (p = 0.001) of players. The proposed training system is an affordable option for training and monitoring, evaluating, and recording training performance. It can accurately record movement and response times and simulate competitive environments.

Feasibility of Smartphone-Based Badminton Footwork Performance Assessment System.

Footwork is the most fundamental skill in badminton, involving the ability of acceleration or deceleration and changing directions on the court, which is related to accurate shots and better game performance. The footwork performance in-field is commonly assessed using the total finished time, but does not provide any information in each direction. With the higher usage of the smartphones, utilizing their built-in inertial sensors to assess footwork performance in-field might be possible by providing information about body acceleration in each direction. Therefore, the purpose of this study was to evaluate the feasibility of a smartphone-based measurement system on badminton six-point footwork. The body acceleration during the six-point footwork was recorded using a smartphone fixed at the belly button and a self-developed application in thirty badminton players. The mean and maximum of the acceleration resultant for each direction of the footwork were calculated. The participants were classified into either the faster or slower group based on the finished duration of footwork. Badminton players who finished the footwork faster demonstrated a greater mean and maximum acceleration compared to those who finished slower in most directions except for the frontcourt directions. The current study found that using a smartphone's built-in accelerometer to evaluate badminton footwork is feasible.

The Applications of Landing Strategies in Badminton Footwork Training on a Backhand Side Lateral Jump Smash.

Previous research in badminton has associated unilateral landings following overhead strokes with the occurrence of knee injuries. Smashing involves tensing the abdomen muscles while swinging the racket rapidly and maintaining one's balance while performing coordinated movements and steps; this process puts stress on the player's lower limbs. However, few studies have compared the effects of different stroke training while performing various types of badminton strokes. This study investigated the influence of different stroke training on the smash action of badminton players. Three stroke training conditions were considered: shadow, target striking, and smashing. Sixteen male experienced badminton players were recruited for this study. One-way repeated-measures ANOVA with Bonferroni correction was used to identify the differences. At the initial contact with the ground, the knee flexion and knee valgus angles under the smash condition were significantly higher than target and shadow conditions. Under the smash condition, hip abduction was significantly higher than under the target and shadow conditions. Moreover, the hip abduction under the target condition was significantly higher than under the shadow condition. At the maximum knee flexion, the hip abduction under the smash and target conditions was significantly higher than under the shadow condition. Regarding the time from the moment of initial contact to the peak of vertical ground reaction force it was shorter under the smash condition than the target and shadow conditions. The vertical ground reaction force was higher under the smash condition than under the target and shadow conditions. The 50 ms impulse was higher under the smash condition than under the target and shadow conditions. The main findings of this study are that under the smash condition, the motion in the frontal plane increased, which produced higher loads on the joints in the lower limbs. Player performed the same footwork under the three conditions, but the landing strategies differed because of unique swing motions and techniques. The condition under which a player hits a shot to a target area can affect the landing. The results of this study suggest that target practice is more effective for improving the landing technique employed during actual shots than shadow practice.

Influences of Lateral Jump Smash Actions in Different Situations on the Lower Extremity Load of Badminton Players.

Badminton atypical actions and hitting movements often occur during the game; therefore, many special footwork methods have been developed to facilitate the rapid movements required to hit the shuttlecock, including quick turning and jumping and quick directional change movements. Studies have shown that the majority of badminton sport injuries occur in the lower extremity joints of athletes. The purpose of this study was to investigate the influences of hitting motion and unanticipated hitting direction on landing mechanics after backhand lateral jump smashing and landing to analyze joint stiffness and torque changes in three lower extremity joints. Recruited sixteen badminton athletes.The capture frequency of the Vicon Motion System (300Hz), Kistler force platform (1500Hz) and Vicon Nexus Version 1.8.5 software were used simultaneously to capture the kinematic and kinetic parameter of backhand side lateral jump smash footwork. The swing actions were divided into two situations, shadow (footwork and racket swinging practice without targets) and hitting (footwork and stroke shuttlecock) actions, whereas the directions were divided into directional and non-directional. Two-way repeated measures ANOVA with the LSD correction was used to compare the differences among the four conditions. The significance level was set to a = 0.05. Results shown that, at the peak of torque, the ankle plantar flexion of the non-directional shadow (p < 0.05) were greater than that of directional shadow (p < 0.05); meantime, ankle torque change of non-directional shadow (p < 0.05) and directional hitting (p < 0.05) was lower than that of non-directional hitting, but the non-directional hitting was larger compared to non-directional shadow (p < 0.05) at the maximum vertical GRF. The hip extension at peak of torque of directional hitting were larger than that of non-directional shadow (p < 0.05). The shadow actions hip flexion angle was larger than that of directional hitting at initial contact, but the non-directional hitting hip abduction was has the significant difference among all the conditioning. The hip flexion angle of non-directional shadow was larger than that of directional hitting (p < 0.05), the hip abduction angle of the non-directional hitting was greater than that of non-directional shadow (p < 0.05) at the peak VGRF. Elite badminton players execute different training movements; the joint stiffness was in the same state. In the hitting actions has greater ankle and hip joint torque than shadow actions. The badminton player was change joint range of motion to adjust lower limbs stiffness.

How do professional tennis players move? The perceptions of coaches and strength and conditioning experts.

The purpose of this study was to explore the processes associated with successful on-court movement in professional tennis. To date, research has only provided generalised insight into the physical demands of tennis movement and the requisite physical skills. Data were collected through semi-structured interviews with 15 international tennis and/or strength and conditioning coaches involved in the development of tennis-specific movement in professional men's and women's tennis. A descriptive, qualitative approach was adopted, with interviews transcribed verbatim and analysed using an inductive to deductive thematic analysis. The highlighted ideas and concepts enabled the dynamic construction of higher-order themes representative of "good" tennis movers, alongside the conceptual development of a common movement "goal" or "outcome". The established higher-order themes portrayed three "styles" of "good" movers in modern professional tennis: those who were "fast" around the court, those who "read the play" well, and those who were "efficient" in their movement. The established themes provide a framework for interpreting and categorising the movement of professional tennis players as well as its underpinning skill.

The Functional Movement Screen and modified Star Excursion Balance Test as predictors of T-test agility performance in university rugby union and netball players.

OBJECTIVES: Agility is a functional requirement of many sports, challenging stability, and commonly cited as a mechanism of injury. The Functional Movement Screen (FMS) and modified Star Excursion Balance Test (mSEBT) have equivocally been associated with agility performance. The aim of the current study was to establish a hierarchical ordering of FMS and mSEBT elements in predicting T-test agility performance. DESIGN: Cross-sectional study design. SETTING: University. PARTICIPANTS: Thirty-two female rugby players, 31 male rugby players and 39 female netballers MAIN OUTCOME MEASURES: FMS, mSEBT, T-test performance. RESULTS: The predictive potential of composite FMS and mSEBT scores were weaker than when discrete elements were considered. FMS elements were better predictors of T-test performance in rugby players, whilst mSEBT elements better predicted performance in netballers. Hierarchical modelling highlighted the in-line lunge (ILL) as the primary FMS predictor, whereas mSEBT ordering was limb and sport dependent. CONCLUSIONS: The relationship between musculoskeletal screening tools and agility performance was sport-specific. Discrete element scores are advocated over composite scores, and hierarchical ordering of tests might highlight redundancy in screening. The prominence of the ILL in hierarchical modelling might reflect the functional demands of the T-test. Sport-specificity and limb dominance influence hierarchical ordering of musculoskeletal screens.

Comfort Difference in Sports Shoes and Its Effects on Characteristics of Foot Loading in Typical Basketball Footwork / 医用生物力学

Objective To explore the relationship between shoe comfort and foot loading characteristics in two types of basketball shoe during different basketball footwork. Methods Two Kistler 3D force platforms and Medilogic insole plantar pressure system were used to collect the kinetic data of 12 healthy male basketball players wearing two types of basketball shoe (shoe L and shoe N) during three varieties of basketball footwork (side-step cutting, 90° varied-direction running, lay-up), including peak impact force, peak loading rate, and peak plantar pressure. The perception test scale was used to evaluate comfort for two types of basketball shoe during three kinds of basketball footwork. Results For the two types of basketball shoes, there was no significantly difference in the impact force during the three kinds of basketball footwork, but the plantar pressure of shoe L was significantly greater than that of shoe N during side-step cutting and lay-up. Shoe N was significantly more comfortable than shoe L, with a significant difference in preference (heel stability, heel responsiveness, forefoot cushioning, heel cushioning, and overall liking) and intensity (forefoot and heel cushioning) on a dynamic scale. Conclusions The plantar pressure and comfort show significant differences in the two types of shoes; however, none of the shoes appeared definitively superior in the two evaluations. It is suggested that the biomechanical characteristics of the shoes and the subjective evaluation of the athletes should be considered in the overall design and evaluation of specialized shoes.

Effects of footwear and barefoot on movement coordination of lower extremities and metatarsophalangeal joints during push-off in badminton footwork / 医用生物力学

Objective To explore the influence of footwear and barefoot on movement coordination of the lower extremities and metatarsophalangeal (MP) joints during push off phase in typical lunge footwork of badminton, so as to provide theoretical basis for scientific training of badminton, as well as choice and development of badminton shoes. Methods Male badminton elites were recruited and required to perform the typical push-off footwork in playing badminton under two shod conditions (commercial badminton footwear and a prototype) and the barefoot condition. A Vicon motion capture system and a high-speed video camera were simultaneously employed to collect the kinematics and coordination characteristics of the hip, knee, ankle and MP joints during the push-off stage of the lunge step. Results (1) No substantial difference was found in joint kinematics of the lower extremities during push-off stage for wearing two types of badminton shoes adopted in this study. Compared with barefoot, wearing badminton shoes could increase the angular velocity of ankle and MP joints to some extent and significantly decrease the time of peak angular velocity occurrence in each joint; (2) With respect to characteristics of movement coordination, the hip, knee, ankle and MP joints were accelerating successively in a proximal-to-distal way during push-off under three foot-shoe conditions. Conclusions Footwear can provide the dynamic source during push-off, and contribute to improve the velocity and effects of push off in order to enhance performance. The movement coordination of the lower extremities during push off in the lunge step is more inclined to be a rational combination of sequence and synchronization. Consequently, more attention should be paid to the speed/strength training of the ankle and MP joints.

A notational analysis of shot characteristics in top-level table tennis players.

This study aimed to analyse selected shot characteristics in top-level table tennis matches, with a special focus on comparing the playing style of Asian and European players. Ten men's matches played by 20 top-ranked players (14 Asians and 6 Europeans) were analysed. The indicators examined were the area of ball bouncing for serves (n =918), and the stroke type, footwork type and shot outcome for other shots (n=3692). The interrelationships between variables were analysed using chi-squared tests, log-linear modelling and multiple correspondence analysis. A strong association was found between strokes and footwork types, with most stroke types executed each after specific footwork types. Furthermore, a clear tendency to have a positive, negative or neutral outcome was observed for each stroke type. When compared to Europeans, Asians used more frequently the most aggressive strokes and footwork types, confirming anecdotal claims on their particularly offensive playing style. Asians showed also a better serving effectiveness, often sending the ball in those areas of the table from which a counterattack is difficult to make. In summary, this study gives a systematic description of highly relevant technical and tactical characteristics in top-level table tennis, thus providing valuable information for coaches and performance analysts.

EFFECTS OF PLYOMETRICS ON THE ABILITIES OF THE JUMP, FOOTWORK AND THE CHEST PASS IN COMPETITIVE BASKETBALL PLAYERS / 体力科学

The purpose of this study was to determine the effects of plyometrics on jump, footwork and chest pass ability in competitive basketball players. Ten male basketball players competing at the college level in Japan practiced plyometrics by using the drop jump and the medicine ball throw three sessions per week for seven weeks. All players had continued regular training and competition in basketball over ten years. Height and contact time of the rebound drop jump and the jump shot were tested for each player along with sprint running velocity in a straight direction and with four footwork phases for changing direction, ball velocity and contact time of hands for chest pass pre and post plyometrics. Drop jump training significantly shortened contact time but did not enhance jumping height of the jump shot with a basketball. Moreover, drop jump training significantly shortened average velocity of sprint running with four footwork phases for changing direction, but did not enhance sprint running in a straight direction. Medicine ball training significantly enhanced ball velocity and contact time of hands for the chest pass. These results suggest that plyometrics, by using the drop jump and medicine ball throw, are effective training methods for improving jump, footwork and chest pass ability in competitive basketball players.