Insights from a Nine-Segment Biomechanical Model and Its Simulation for Anthropometrical Influence on Individualized Planche Learning and Training in Gymnastics.

The Planche is a challenging, the most required, and a highly valued gymnastic skill. Yet, it is understudied biomechanically. This article aims to explore the anthropometric variations that could affect the quality of balancing control in the Planche and to identify the body types that have an advantage in learning and training. To achieve this goal, a 9-segment rigid-body model is designed to simulate the skill performance by using 80 different body types. The results demonstrate that body type is a critical factor in determining an individual's innate ability to perform the Planche. The innate ability is affected by body mass, height, gender, and race. The findings reveal that a personalized training plan based on an individual's body type is necessary for optimal learning and training. A one-size-fits-all approach may not be effective since each individual's body type varies. Additionally, this study emphasizes the importance of considering segmental and/or limb characteristics in designing effective training plans. This study concludes that, for a given height, individuals with relatively longer legs and a shorter trunk (the characteristics of Europeans in comparison to Asians) could be better suited to perform the Planche. This suggests that European body types are naturally more advanced than Asian body types when it comes to performing the Planche. The practical implications of the current study are that practitioners can use biomechanical modeling and simulation techniques to identify body types that are most suited for the Planche and design training programs that are tailored to individual body types for optimizing their learning and training.

Soccer Scoring Techniques-A Biomechanical Re-Conception of Time and Space for Innovations in Soccer Research and Coaching.

BACKGROUND: Scientifically, both temporal and spatial variables must be examined when developing programs for training various soccer scoring techniques (SSTs). Unfortunately, previous studies on soccer goals have overwhelmingly focused on the development of goal-scoring opportunities or game analysis in elite soccer, leaving the consideration of player-centered temporal-spatial aspects of SSTs mostly neglected. Consequently, there is a scientific gap in the current scoring-opportunity identification and a dearth of scientific concepts for developing SST training in elite soccer. OBJECTIVES: This study aims to bridge the gap by introducing effective/proprioceptive shooting volume and a temporal aspect linked to this volume. METHOD: the SSTs found in FIFA Puskás Award (132 nominated goals between 2009 and 2021) were quantified by using biomechanical modeling and anthropometry. RESULTS: This study found that players' effective/proprioceptive shooting volume could be sevenfold that of normal practice in current coaching. CONCLUSION: The overlooked SSTs in research and training practice are commonly airborne and/or acrobatic, which are perceived as high-risk and low-reward. Relying on athletes' talent to improvise on these complex skills can hardly be considered a viable learning/training strategy. Future research should focus on developing player-centered temporal-spatial SST training to help demystify the effectiveness of proprioceptive shooting volume and increase scoring opportunities in soccer.

An Examination of Trunk and Right-Hand Coordination in Piano Performance: A Case Comparison of Three Pianists.

Playing the piano at expert levels typically involves significant levels of trial-and-error learning since the majority of practice occurs in isolation. To better optimize musical outcomes, pianists might be well served by emulating some of the practices found in sports, where motor learning strategies are grounded in biomechanics and ergonomics in order to improve performance and reduce risk of performance-related injuries. The purpose of the current study is to examine trunk-hand coordination and preparatory movement strategization in piano performance, while considering the influence of anthropometry, skill level of the performer, and musical context. Using a ten-camera motion capture system, movement of C7 and right-hand distal phalanges was tracked at three different playing speeds during performance of an excerpt from Beethoven's "Appassionata" Sonata. There were three participants: two males and one female of differing anthropometric characteristics and skill levels. Motor strategization was examined. Expertise influenced starting trunk position: Initiation intervals and trunk range of motion (ROM) both suggested anthropometry to be a performance factor. For the shortest performer, trunk movement appeared to be used as an efficiency measure to compensate for a shorter arm reach. Skill level was revealed by examining right-hand velocity at the fastest tempo. The current study hypothesizes that an examination of proximal-to-distal preparatory strategies in terms of anthropometry and skill level can help to optimize motor learning for pianists. To realize piano performance as a whole-body skill and encourage healthy practice, pedagogy needs to educate learners regarding fundamental biomechanical and ergonomic principles, movement optimization, and movement strategization in the service of artful performance.

Performance Alteration Induced by Weight Cutting in Mixed Martial Arts-A Biomechanical Pilot Investigation.

Currently, there are pros and cons of research results related to weight cutting in combat sports, resulting in inconclusive results regarding the effects of weight-cut on athletes' performance, and biomechanical investigations are hardly seen. Therefore, this pilot study tried to fill the gap by initiating an exploration in real-life competitions. It is our hope to add biomechanical insights (advantages/disadvantages) that would discern the impact of weight cutting on competitive performance and help to structure hypotheses in future research. The method consisted of 3D motion capture, EMG measurement and biomechanical modeling. Through the synchronized data, striking power, striking accuracy and reaction time were quantitatively determined. Pre- and post-test design was used to test common strikes before weight cutting and 24 h after weigh-in. Seven male athletes from local clubs were tested during regional competitions. Results were characterized by using descriptive statistics (means and standard deviations) and T-tests were performed to contrast differences between the pre- and post-tests. This pilot study has revealed that there is actually weight-regain instead of weight-loss. The weight-regain would speed up the perceptional and total reaction, slow down the limbs' movement, worsen the striking accuracy and, possibly, decrease the strike power. The preliminary results are inconclusive regarding the competitive advantages/disadvantages induced by weight cutting. Further biomechanical studies are needed to deal with the controversial subject more objectively and scientifically.

The Proper Motor Control Model Revealed by Wheelchair Curling Quantification of Elite Athletes.

BACKGROUND: Wheelchair users are disadvantaged when it comes to accruing the benefits of physical activities. Hence, promoting various sports is crucial for keeping this population healthy. Since wheelchair curling can be played by individuals from a wide range of ages, strengths, and endurance levels, it has potential to improve wheelchair users' well-being. Yet, hardly any motion studies exist. This study aimed to facilitate understanding of optimized control of wheelchair curling for promoting wheelchair users' participation. METHODS: Using motion capture technology, nine national-level athletes were tested. Kinematic parameters related to segment/joint control and their coordination were quantified for both slow and fast curling. Descriptive statistics (means and standard deviations) and correlation analysis were applied for characterizing the skill. RESULTS: (1) Curling control consists of an acceleration phase and a stabilizing delivery phase; (2) the control of trunk, shoulder, and wrist are responsible for accelerating the rock; (3) elbow control is accountable for the accurate delivery of the rock; and (4) during the slow curling, a synchronized effort of trunk, shoulder, and wrist is used for accelerating the rock, while a sequential control among the segment/joints is applied in fast curling. CONCLUSIONS: The results supply valuable motor learning markers that could have a significant positive impact on the teaching and learning of wheelchair curling, as such, the findings have great potential for the health promotion of wheelchair users.

A Wearable-Sensor System with AI Technology for Real-Time Biomechanical Feedback Training in Hammer Throw.

Developing real-time biomechanical feedback systems for in-field applications will transfer human motor skills' learning/training from subjective (experience-based) to objective (science-based). The translation will greatly improve the efficiency of human motor skills' learning and training. Such a translation is especially indispensable for the hammer-throw training which still relies on coaches' experience/observation and has not seen a new world record since 1986. Therefore, we developed a wearable wireless sensor system combining with artificial intelligence for real-time biomechanical feedback training in hammer throw. A framework was devised for developing such practical wearable systems. A printed circuit board was designed to miniaturize the size of the wearable device, where an Arduino microcontroller, an XBee wireless communication module, an embedded load cell and two micro inertial measurement units (IMUs) could be inserted/connected onto the board. The load cell was for measuring the wire tension, while the two IMUs were for determining the vertical displacements of the wrists and the hip. After calibration, the device returned a mean relative error of 0.87% for the load cell and the accuracy of 6% for the IMUs. Further, two deep neural network models were built to estimate selected joint angles of upper and lower limbs related to limb coordination based on the IMUs' measurements. The estimation errors for both models were within an acceptable range, i.e., approximately ±12° and ±4°, respectively, demonstrating strong correlation existed between the limb coordination and the IMUs' measurements. The results of the current study suggest a remarkable novelty: the difficulty-to-measure human motor skills, especially in those sports involving high speed and complex motor skills, can be tracked by wearable sensors with neglect movement constraints to the athletes. Therefore, the application of artificial intelligence in a wearable system has shown great potential of establishing real-time biomechanical feedback training in various sports. To our best knowledge, this is the first practical research of combing wearables and machine learning to provide biomechanical feedback in hammer throw. Hopefully, more wearable biomechanical feedback systems integrating artificial intelligence would be developed in the future.

Wrist Internal Loading and Tempo-Dependent, Effort-Reducing Motor Behaviour Strategies for Two Elite Pianists.

One of the greatest challenges in reducing high rates of performance injuries among musicians is in providing them usable tools to address playing-related musculoskeletal problems (PRMP) before they become disorders. Studies in biomechanics have the potential to provide such tools. In order to better understand the mechanisms through which PRMP manifest in pianists, especially in the distal segments of the upper limbs, the current study quantifies wrist internal loading (WIL) and wrist impact loading frequency. It does so while discussing pianists' motor behaviours and observed effort-reduction strategies in the wrists as a function of anthropometry. This concept has great utility for performers. A VICON 3D motion capture system documented two expert pianists performing a B major scale, hands together, at 4, 6, 8, 9, and 10 notes/sec. Biomechanical modeling quantified WIL. Changes in motor behaviour were observed at 8 notes/sec. Individualized anthropometry influenced the range of motor strategies available to each pianist. The pianist with the larger hand span employed a flexion/extension wrist strategy as a compensatory means for effort reduction, while the pianist with the smaller hand span employed a radial/ ulnar deviation strategy. The current study provides a new perspective in addressing PRMP among pianists by rationalizing anthropometric potentials in terms of ergonomic parameters and documenting the availability and utility of effort-reduction strategies in the wrists during piano performance as performers consider PRMP risk and avoidance.

Pursuing Artful Movement Science in Music Performance: Single Subject Motor Analysis With Two Elite Pianists.

Piano performance motor learning research requires more "artful" methodologies if it is to meaningfully address music performance as a corporeal art. To date, research has been sparse and it has typically constrained multiple performance variables in order to isolate specific phenomena. This approach has denied the fundamental ethos of music performance which, for elite performers, is an act of interpretation, not mere reproduction. Piano performances are intentionally manipulated for artistic expression. We documented motor movements in the complex task of performance of the first six measures of Chopin's "Revolutionary" Etude by two anthropometrically different elite pianists. We then discussed their motor strategy selections as influenced by anthropometry and the composer's musical directives. To quantify the joint angles of the trunk, shoulders, elbows, and wrists, we used a VICON 3 D motion capture system and biomechanical modeling. A Kistler force plate (1 N, Swiss) quantified center of gravity (COG) shifts. Changes in COG and trunk angles had considerable influence on the distal segments of the upper limbs. The shorter pianist used an anticipatory strategy, employing larger shifts in COG and trunk angles to produce dynamic stability as compensation for a smaller stature. Both pianists took advantage of low inertial left shoulder internal rotation and adduction to accommodate large leaps in the music. For the right arm, motor strategizing was confounded by rests in the music. These two cases illustrated, in principle, that expert pianists' individualized motor behaviors can be explained as compensatory efforts to accommodate both musical goals and anthropometric constraints. Motor learning among piano students can benefit from systematic attention to motor strategies that consider both of these factors.

Relationships between Risk Events, Personality Traits, and Risk Perception of Adolescent Athletes in Sports Training.

Personality traits have close relationships with risky behaviors in various domains, including physical education, competition, and athletic training. It is yet little known about how trait personality dimensions associate with risk events and how vital factors, such as risk perception, could affect the happening of risk events in adolescent athletes. The primary purpose of this study is to investigate the prediction of risk events by regression analysis with dimensions of personality, risk perception and sports, relations between risk events, risk perception, and the facets of the personality dimensions via data collecting from 664 adolescent athletes aged 13-18 years (male 364, female 300). Secondary intent is to assess school-specific levels of training risks among sports schools, regular schools, and sports and education integrated schools. The results show that psychology events are the strongest predicted by personality traits, risk perception, and sports, followed by injury and nutrition. Emotionality has the most significant positive correlation with risk events, while other traits have a significant negative correlation with risk events, except agreeableness. The integration schools are more conducive to the healthy development of adolescent athletes' personalities. Moreover, the research indicates that sports training can strengthen the development directions of different personality characteristics.

The influence of gender, dominant lower limb and type of target on the velocity of taekwon-do front kick.

PURPOSE: The current study aimed to quantify the main influences and the interactions (joint effects) of gender, leg and type of target on the biomechanics of front kick quality. Through the quantification, we tried to identify the relevant factors related to the kick accuracy and maximum velocity for coaching practice. METHODS: A ten-camera NIR VICON MX40 motion capture system (250 Hz) was used to determine the kicking foot maximum velocity from two well-trained subject groups (8 males and 6 females). Each subject performed both left and right front kicks in a lateral standing position into the air (without a physical target), to a board, to a table tennis ball and to a training shield. The target were set on a height corresponding to a height of solar plexus of each participant. RESULTS: The results showed that all the three factors (gender, leg and type of target) have significant influences on kicking speed ( p < 0.001) and significant interaction (joint effect) was only found between gender and target ( p < 0.001). Further analysis revealed that the males' kicking maximum velocity was affected more by board, while females' one was affected by the size of the target. CONCLUSIONS: The results would seem to suggest that, for males, kick-to-a-board may be the more effective method for increasing kick quality, compared to other type of target. For females, kick-to-a-small-ball appears to be effective method for increasing kick maximum velocity.

The influence of landing mat composition on ankle injury risk during a gymnastic landing: a biomechanical quantification.

PURPOSE: About 70% injury of gymnasts happened during landing - an interaction between gymnast and landing mat. The most injured joint is the ankle. The current study examined the effect of mechanical properties of landing mat on ankle loading with aims to identify means of decreasing the risk of ankle injury. METHOD: Gymnastic skill - salto backward stretched with 3/2 twist was captured by two high-speed camcorders and digitized by using SIMI-Motion software. A subject-specific, 14-segment rigid-body model and a mechanical landing-mat model were built using BRG.LifeMODTM. The landings were simulated with varied landing-mat mechanical properties (i.e., stiffness, dampness and friction coefficients). RESULT: Real landing performance could be accurately reproduced by the model. The simulations revealed that the ankle angle was relatively sensitive to stiffness and dampness of the landing mat, the ankle loading rate increased 26% when the stiffness was increased by 30%, and the changing of dampness had notable effect on horizontal ground reaction force and foot velocity. Further, the peak joint-reaction force and joint torque were more sensitive to friction than to stiffness and dampness of landing mat. Finally, ankle muscles would dissipate about twice energy (189%) when the friction was increased by 30%. CONCLUSION: Loads to ankles during landing would increase as the stiffness and dampness of the landing mat increase. Yet, increasing friction would cause a substantial rise of the ankle internal loads. As such, the friction should be a key factor influencing the risk of injury. Unfortunately, this key factor has rarely attracted attention in practice.

The relevance of body positioning and its training effect on badminton smash.

One of the dominant skills in badminton is the forehand overhead smash, which consists of 1/5 attacks during games. Empirical evidences show that one has to adjust the body position in relation to the coming shuttlecock to produce a powerful and accurate smash. Therefore, positioning is a fundamental aspect influencing smash quality. Unfortunately, a search of literature has shown that there is a dearth/lack of study on this fundamental aspect. The goals of this study were to determine the influence of positioning and training experience on smash quality in order to discover information that could help learn/acquire the skill. Using 3D motion capture and full-body biomechanical modelling, 14 skilled and 15 novice players were analysed. Results have revealed that the body positioning has direct influence on shuttlecock release angle and clearance height of the offensive player. The results also suggest that, for training the positioning of beginners, one could conduct a self-selected comfort position towards a statically hanged shuttlecock and then step one foot back - a practical reference marker for learning. As one gains experience through repetitive training, improved limbs' coordination would increase smash quality further. We hope our findings will benefit practitioners for developing effective training programmes for beginners.

A wireless sensor system for a biofeedback training of hammer throwers.

Hammer-throw has a long-standing history in track and field, but unlike some other sports events, men's hammer throw has not seen a new world record since 1986. One of the possible reasons for this stagnation could be the lack of real-time biomechanical feedback training. In this study, we proposed to establish scientifically described training targets and routes, which in turn required tools that could measure and quantify characteristics of an effective hammer-throw. Towards this goal, we have developed a real-time biomechanical feedback device-a wireless sensor system-to help the training of hammer-throw. The system includes two sensors-an infrared proximity sensor for tracing the hip vertical movement and a load cell for recording the wire tension during a hammer-throw. The system uses XBees for data transmission and an Arduino processor for data processing and system control. The results revealed that the wire tension measurement could supply sufficient key features for coaches to analyze hammer-throw and give real-time feedback for improving training efficiency.

Biomechanical modeling as a practical tool for predicting injury risk related to repetitive muscle lengthening during learning and training of human complex motor skills.

Previous studies have shown that muscle repetitive stress injuries (RSIs) are often related to sport trainings among young participants. As such, understanding the mechanism of RSIs is essential for injury prevention. One potential means would be to identify muscles in risk by applying biomechanical modeling. By capturing 3D movements of four typical youth sports and building the biomechanical models, the current study has identified several risk factors related to the development of RSIs. The causal factors for RSIs are the muscle over-lengthening, the impact-like (speedy increase) eccentric tension in muscles, imbalance between agonists and antagonists, muscle loading frequency and muscle strength. In general, a large range of motion of joints would lead to over-lengthening of certain small muscles; Limb's acceleration during power generation could cause imbalance between agonists and antagonists; a quick deceleration of limbs during follow-throughs would induce an impact-like eccentric tension to muscles; and even at low speed, frequent muscle over-lengthening would cause a micro-trauma accumulation which could result in RSIs in long term. Based on the results, the following measures can be applied to reduce the risk of RSIs during learning/training in youth participants: (1) stretching training of muscles at risk in order to increase lengthening ability; (2) dynamic warming-up for minimizing possible imbalance between agonists and antagonists; (3) limiting practice times of the frequency and duration of movements requiring strength and/or large range of motion to reducing micro-trauma accumulation; and (4) allowing enough repair time for recovery from micro-traumas induced by training (individual training time). Collectively, the results show that biomechanical modeling is a practical tool for predicting injury risk and provides an effective way to establish an optimization strategy to counteract the factors leading to muscle repetitive stress injuries during motor skill learning and training.

The Influence of X-Factor (Trunk Rotation) and Experience on the Quality of the Badminton Forehand Smash.

No existing studies of badminton technique have used full-body biomechanical modeling based on three-dimensional (3D) motion capture to quantify the kinematics of the sport. The purposes of the current study were to: 1) quantitatively describe kinematic characteristics of the forehand smash using a 15-segment, full-body biomechanical model, 2) examine and compare kinematic differences between novice and skilled players with a focus on trunk rotation (the X-factor), and 3) through this comparison, identify principal parameters that contributed to the quality of the skill. Together, these findings have the potential to assist coaches and players in the teaching and learning of the forehand smash. Twenty-four participants were divided into two groups (novice, n = 10 and skilled, n = 14). A 10-camera VICON MX40 motion capture system (200 frames/s) was used to quantify full-body kinematics, racket movement and the flight of the shuttlecock. Results confirmed that skilled players utilized more trunk rotation than novices. In two ways, trunk rotation (the X-factor) was shown to be vital for maximizing the release speed of the shuttlecock - an important measure of the quality of the forehand smash. First, more trunk rotation invoked greater lengthening in the pectoralis major (PM) during the preparation phase of the stroke which helped generate an explosive muscle contraction. Second, larger range of motion (ROM) induced by trunk rotation facilitated a whip-like (proximal to distal) control sequence among the body segments responsible for increasing racket speed. These results suggest that training intended to increase the efficacy of this skill needs to focus on how the X-factor is incorporated into the kinematic chain of the arm and the racket.

Unraveling mysteries of personal performance style; biomechanics of left-hand position changes (shifting) in violin performance.

Instrumental music performance ranks among the most complex of learned human behaviors, requiring development of highly nuanced powers of sensory and neural discrimination, intricate motor skills, and adaptive abilities in a temporal activity. Teaching, learning and performing on the violin generally occur within musico-cultural parameters most often transmitted through aural traditions that include both verbal instruction and performance modeling. In most parts of the world, violin is taught in a manner virtually indistinguishable from that used 200 years ago. The current study uses methods from movement science to examine the "how" and "what" of left-hand position changes (shifting), a movement skill essential during violin performance. In doing so, it begins a discussion of artistic individualization in terms of anthropometry, the performer-instrument interface, and the strategic use of motor behaviors. Results based on 540 shifting samples, a case series of 6 professional-level violinists, showed that some elements of the skill were individualized in surprising ways while others were explainable by anthropometry, ergonomics and entrainment. Remarkably, results demonstrated each violinist to have developed an individualized pacing for shifts, a feature that should influence timing effects and prove foundational to aesthetic outcomes during performance. Such results underpin the potential for scientific methodologies to unravel mysteries of performance that are associated with a performer's personal artistic style.

Target effect on the kinematics of Taekwondo Roundhouse Kick - is the presence of a physical target a stimulus, influencing muscle-power generation?

Taekwondo is famous for its powerful kicking techniques and the roundhouse kick is the most frequently used one. In earlier literature, the influence of a physical target (exiting or not) on kicking power generation has not been given much attention. Therefore, the aim of this study was to investigate the kinematics of roundhouse kick execution and its factors related to power generation. 6 ITF taekwondo practitioners voluntarily participated in this study. They were asked to perform kicks with and without a physical target. The first kick aimed at breaking a board while the second one was a kick into the air. A Smart-D motion capture system (BTS S.p.A., Italy) was used to quantitatively determine their kinematic characteristics during each kick. The main findings showed that kicks aiming at a breaking board were significantly slower than kicks without a physical target (maximal kick-foot velocities were 10.61 ± 0.86 m/s and 14.61 ± 0.67 m/s, respectively, p < 0.01), but the kicking time of the former was shorter (0.58 ± 0.01 s and 0.67 ± 0.01, respectively, p < 0.01). The results suggest that a physical target will negatively influence the kick-foot velocity, which is not necessarily a disadvantage for creating a high quality kick. Possible motor control mechanisms are discussed for the phenomenon. The study made it clear: trainings with and without physical targets would develop different motor control patterns. More studies are needed for identifying the effectiveness of different controls and efficiencies of their training.

From 2D leg kinematics to 3D full-body biomechanics-the past, present and future of scientific analysis of maximal instep kick in soccer.

Biomechanics investigation on soccer kicking has a relatively long history, yet the body of knowledge is still small. This paper reviews articles published from 1960s to 2011, summarizing relevant findings, research trends and method development. It also discusses challenges faced by the field. The main aim of the paper is to promote soccer kicking studies through discussions on problem solving in the past, method development in the present, and possible research directions for the future.

A prisoner's dilemma with asymmetrical payoffs: revealing the challenges faced by performing arts health and wellness practitioners.

In a prisoner's dilemma, constructed narratives are used to demonstrate problems within individual rationality and decision-making. Performing artists can be seen as facing a type of prisoner's dilemma in their careers: they must practice repeated movements for long periods in order to improve, yet despite the short-term perception of gained artistic benefit, the long-term consequences may be playing-related musculoskeletal disorders and injury. To help avoid such an outcome, educators and health and wellness practitioners must function as negotiators, engaging in discussions of artistry as part of establishing credibility and encouraging behaviors that keep artists in efficient, healthy behaviors. By setting practice time limits that are considerate of the intensity of each specific task, performers can improve their performance on a daily basis and become more skilled at planning their future training.