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STRIDE STRATEGY ON FASTBALL PERFORMANCE IN COLLEGIATE BASEBALL PITCHERS
Get PDFOur study aimed to determine if a baseball pitcher’s stride strategy impacts pitching performance. Two global strategies are used by pitchers when striding down the mound. One strategy consists of dropping their center of mass (COM) and propelling forward the other consists of maintaining a higher COM when striding out. The effects of the stride phase on pitching velocity are not firmly established. In contrast to prior work, vertical COM displacement during the stride phase was used as a continuous variable to determine if the stride strategy impacted pitching velocity. Pitch velocity prediction models were improved by max negative COM displacement (lowest position) and max positive COM displacement (highest position) and timing of max positive COM displacement. Regardless of strategy, increasing vertical COM displacement in either direction increased performance
INCREASED FOREFOOT ENERGY RETURN OF FOOTWEAR IMPROVES METABOLIC ENERGY EXPENDITURE
Get PDFThe purpose of this study was to determine how systematically increasing the energy return in the forefoot of running footwear impacts energy expenditure of running. For this, 13 participants ran on a treadmill at a submaximal speed, in three shoe conditions differing only in their mechanical properties of the midsole foam, allowing an energy return of 11 J, 12 J, and 13 J, respectively. Running with a 13 J energy return improved energy expenditure compared to the condition with 11 J (2.03%; p = 0.026). The 12 J condition did not significantly differ from the others. These findings suggest that a 2 J increase in forefoot energy return from footwear improves energy expenditure of running, potentially contributing to recent world records in long-distance running
PREDICTIVE MODELING OF KNEE ANTERIOR SHEAR FORCES USING INERTIAL MEASUREMENT UNIT DATA AND MACHINE LEARNING
Get PDFThis study presents a non-invasive approach using machine learning to predict proximal tibial anterior shear force (ASF), a surrogate for anterior cruciate ligament (ACL) loads from inertial measurement unit (IMU) data, providing a practical alternative to direct force measurement. Employing XGBoost, the research analysed IMU data from drop jump tasks performed by 22 female participants and validated on an additional participant. The model underwent optimization through feature reduction and signal filtering. The results demonstrate an XGBoost model using IMU data to estimate ASF showed improved prediction accuracy after feature reduction and a low-pass filter. The model was able to predict ASF with a root mean squared error of 41.59±13.18N, a mean absolute error of 35.18±11.97N, and an R² value of 0.84±0.0
STANDING LONG JUMP POWER ESTIMATION FROM SMARTPHONE IMUS
Get PDFThe purpose of this study was to provide athletes/coaches with an easy-to-implement estimate of the power of standing long jump (SLJ), recognized as an indicator of the ability of lower limbs of exert power. To this aim, inertial sensors embedded in smartphones were used. A sample group of 150 trained young participants was recruited and asked to perform the SLJ task while holding the smartphone. A set of features was identified, based on biomechanical knowledge and literature, and then selected through Lasso regression to be feed as input of three different optimized machine learning architectures to estimate the SLJ power. A Multi-Layer Perceptron Regressor was selected as best performing model and showed, in the test phase, a RMSE of 0.37 W/kg. This smartphone-based estimate, if compared to an average power of 1.8 W/kg, represents a reasonable approximation
BODY ROTATION AFFECTS KNEE MECHANICS DURING SIDESTEP CUTTING... EVEN WHEN CONTROLLING FOR CHANGE OF DIRECTION ANGLE
Get PDFThe effect of cutting technique on knee joint loading during change of direction (CoD) manoeuvres has been widely studied in the context of anterior cruciate ligament (ACL) injury. However, experimental inter-technique variation in the actual CoD angle achieved during the CoD step may affect results and influence conclusions. The purpose of this study was to compare cutting techniques with different amounts of torso rotation whilst experimentally controlling for CoD angle. Seven participants competed a 45° CoD task under three different cue conditions while ground reaction force and optical motion capture data were collected simultaneously. When CoD angle was controlled, techniques with greater body rotation in the direction of travel were generally associated with knee kinetics and kinematics that have been previously linked to lower ACL loading
INDIVIDUAL RESPONSES TO RUNNING SHOES: AN INVESTIGATION USING UNSUPERVISED MACHINE LEARNING
Get PDFThis study aimed to investigate the movement patterns of individual subjects during running across three (standardized) shod and one barefoot condition, employing t‑distributed stochastic neighbor embedding (t-SNE) and k-means cluster analysis. The t‑SNE analysis revealed three individual response strategies to different footwear conditions: (1) maintaining consistent ground reaction force (GRF) patterns across all conditions; (2) maintaining consistent GRF patters across two or three conditions; and (3) exhibiting changes in GRF patterns across all conditions. The cluster analysis showed that subjects were more often grouped into the same cluster when footwear conditions were more similar. The results indicate that only one group of two and one group of three subjects (out of 30 subjects) exhibited similar GRF patterns across all footwear conditions
THE RELATIONSHIP BETWEEN PEAK ACCELERATION OF BAT AND HAND PAIN IN BASEBALL PLAYERS DURING BASEBALL HITTING
Get PDFThe purpose of this study was to investigate the relationship between peak acceleration of the knob of the bat and hand pain during baseball hitting. Eighteen college baseball players hit the ball on the tee with three bat locations. The players\u27 hand pain sensation and the acceleration signals of the knob of the bat were collected. Hand pain was rated on a scale of 0-10 (0 for no sensation, incrementally up to 10 for maximum pain). The absolute peak accelerations were extracted. Results showed that the absolute peak accelerations of each axis at the frequency of the second bending mode (bandpass filtering at 350-750Hz) were strongly correlated with hand pain (ρ = 0.79–0.85, p \u3c 0.05). In conclusion, the peak acceleration on the knob of the bat at the frequency of the second bending mode of the baseball bat exhibits a strong correlation with hand pain. It could be utilized as a wearable indicator to monitor baseball hitting impact in the future
MUSCULOSKELETAL ANALYSIS OF TWO BASIC LATIN AMERICAN STEPS
Get PDFThis study aimed to quantitatively define two basic Latin American steps (Basic Step and Lateral Step) through a biomechanical approach, providing the main events during each step cycle and the key kinematic features related to these movements. The participant was an instructor of the Italian Federation Sports Dance, who performed the movements in the biomechanics laboratory within the “Sport and Anatomy” center, equipped with an 8-camera Vicon IR system and two force plates. The kinematic variables were computed using two OpenSim models: the Rajagopal and the Thoraco-lumbar models. The major differences between the models were observed in the pelvic tilt, while the pelvic list and rotation were quite similar in the waveforms and range of motion during the two dance steps. In addition, the coordination pattern between the lower limbs and the lumbar spine joint angles confirmed their cyclical feature, even though they had different details between the models
PREDICTING RUNNING MOVEMENTS FROM MOTOR CONTROL PRINCIPLES
Get PDFWe aim to predict running movements from motor control principles. Specifically, the central nervous system minimizes an objective related to energy efficiency when planning movements. We replicate this minimization in optimal control problems to create running simulations that predict running movements in new situations. Here, we will introduce how we create predictive simulations using optimal control, and we show how we used these to gain insight into the effect of running shoe midsole properties on running movements. We show that we can successfully predict the change in metabolic cost between different shoe conditions, but that our outcomes are limited when balance is important. Furthermore, we show that metabolic cost changed even though the kinematic and kinetic changes were small. Finally, we discuss some future directions of this simulation approach
BIOMECHANICAL ANALYSIS OF JUDOKAS`THROWING TECHNIQUES: FOCUS ON THE PREPARATION PHASE
Get PDFThe purpose of this study was to compare the Judo throwing technique uchimata (inner thigh throw) between high and low skilled judoka during the preparation phase. Fourteen male judokas participated in this research. Kinematic data were collected using three-dimensional motion capture systems. During the analysis of the thrower\u27s (tori\u27s) angular velocity and the receiver\u27s (uke\u27s) angular momentum in the preparation phase, it was observed that high skilled judoka exhibited a strong positive correlation between the peak angular velocity of tori\u27s leg and the peak angular momentum of the uke. Additionally, the peak value of the tori\u27s centre of mass (COM) velocity in the front-back direction was significantly higher for high skilled judoka. These findings suggest that, for the effective execution of the uchimata technique, rapidly advancing towards the opponent is crucial