Stride Pattern of the Lower Extremities Among Stride Types in Baseball Pitching

The present study investigated the differences in the stride pattern of the lower extremities among different stride types in baseball pitchers with the aim of evaluating stride movement and skills to improve training effectiveness. Thirty elite male college baseball pitchers volunteered to pitch on an indoor-mound-like force plate, where motion data of their fastest strike trials were collected using an eight-camera motion analysis system at a 200–250 Hz sampling rate. Pelvis center trajectories of each participant were calculated and further categorized into three groups: tall-and-fall (TF), dip-and-drive (DD), and mixed (MX) pitchers. Motion analysis revealed that DD pitchers initiated pivot–knee extension and pivot–hip adduction earlier than TF pitchers and accelerated their bodies sooner than TF pitchers. In addition, TF pitchers accelerated their bodies forward by pivoting their legs until the middle of the arm-cocking and acceleration phases. The movement patterns of MX pitchers were similar to those of DD pitchers in terms of pivot leg, although this occurred a little later in the stride. Our findings are useful in developing training strategies for coaches, players, and trainers to better meet the demands of different pitching styles.

ANALYSIS OF TRUNK POWER AND JOINT STRESSES BETWEEN PROFESSIONAL AND COLLEGIATE PITCHERS

The dynamic motion of a baseball pitch generates high elbow and shoulder torques that can result in injury. Previous research has noted the importance of properly transferring energy from the lower extremities through the throwing arm to decrease joint stress. The goal of this study was to compare segmental powers between two levels of pitchers at various moments throughout the pitching cycle and observe their influence on upper extremity torques. Thirteen professional and thirteen collegiate pitchers participated in this study. Forty-seven reflective markers were attached to the subjects at specific landmarks. An 8-camera motion analysis system was set up surrounding an artificial pitching mound, where participants threw 10 fastballs. Data were exported and processed using Visual 3D software. Welch’s T-tests compared the means between groups with a significance set at p < 0.05. Professional pitchers were found to have significantly greater torso power at foot contact, maximum shoulder external rotation, ball release, and overall peak torso power. They also demonstrated significantly greater pitch velocity. Professional pitchers generated similar elbow varus torque and shoulder internal rotation torque compared to collegiate pitchers. These findings suggest professional pitchers more effectively use torso power to help increase pitch speed without increasing overall joint torques.

Impact of Engaging the Nonthrowing Arm on Maximal Ball Velocity From an Overhand Throw With Both the Dominant and Nondominant Arms: A Pilot Study

The overhand throw is a complex whole-body motor skill that is fundamental to many sports and activities. When throwing properly, the momentum generated to complete the movement begins in the lower body and transfers through the trunk to the throwing arm. This proof-of-concept study’s primary purpose was to evaluate the impact of the nonthrowing arm on the ball speed during an overhand throw with both the dominant and nondominant arms. Eighteen participants (age: 20.20 ± 2.90 years, nine women) were divided into two intervention groups: a pulling group taught to engage the nonthrowing arm through a pull toward the body and a nonpulling group taught the overhand throw using a component-based physical education curriculum. Each participant completed 12 total throws, six for each side (dominant and nondominant arm). Ball speed and kinematic data were collected using an eight-camera motion analysis system and were assessed using a pre–post study design. The two groups showed significant improvements pre–post when throwing with both the dominant and nondominant arms. Based on effect size comparisons, engaging the nonthrowing arm makes a meaningful difference in maximal ball velocity.

Dancers’ Joint Strategies for Achieving Turnout in Low and High Friction Conditions

BACKGROUND: Dancing with legs externally rotated (turnout) is a fundamental element of ballet technique. A reliance on floor friction to achieve turnout may contribute toward the high injury rate in dancers. Joint strategies used by dancers in high and low friction turnout conditions are not well understood. OBJECTIVES: To quantify the lower limb and lumbar spine joint strategies used by female pre-professional dancers to achieve turnout in low-friction (rotation discs) and high-friction (functional and forced) conditions. METHODS: Twenty-three pre-professional female dancers participated in the study. A 12-camera motion analysis system collected hip and knee external rotation (ER), ankle abduction, and lumbar extension angles in three turnout conditions and passive hip ER range of motion angles. Repeated measures ANOVA analysed the differences between joint angles, maximum turnout angle (foot relative to pelvis), and available hip ER. RESULTS: Dancers demonstrated lower knee ER (18.5±4.8°) and ankle abduction (6.0±7.7°) angles during low-friction turnout compared to higher friction conditions (p<0.05). Dancers utilised between 70–83% of available hip ER within all conditions. Low-friction turnout demonstrated greater hip ER contribution within maximum turnout (43%) compared to higher friction conditions. Dancers demonstrated greater lumbar extension angles in low-friction turnout compared to higher friction conditions (p<0.05). CONCLUSIONS: Further hip ER strength training is required to promote greater hip ER range within the position. Rotation discs may be a valuable training tool as dancers demonstrated greater hip ER utilisation with less knee ER and ankle abduction; however, this position did promote undesirable lumbar extension.

EVALUATION AND PREDICTION OF HUMAN GAIT PARAMETERS USING UNIVARIATE, MULTIVARIATE AND STEPWISE STATISTICAL METHODS

This research was carried out to establish the relationship between human anthropometric data and corresponding gait variables. A group comprising 35 participants (18 male and 17 female) was selected for the current study. The study consisted of trials in which each participant was asked to walk the length of the instrumented walkway (Kistler’s force platform inset) at a self-selected speed. Using a four-camera motion analysis system, the kinematic and kinetic parameters of each trial were calculated. The peak values obtained from the data curves were used to generate the necessary regression fits. In order to establish the correlation between the anthropometric data of human and the gait parameters, the univariate, multivariate and stepwise fits were generated. Further, the statistical methods were employed to evaluate the [Formula: see text], [Formula: see text] and [Formula: see text]-values for each fit. The current multivariate study indicates an increasing trend in [Formula: see text] values and decreasing trend for [Formula: see text]-values when compared with the univariate fits and the results follow the expected line.

Influence of cross-fit footwear on patellofemoral kinetics during running activities

The aim of this work was to examine the effects of barefoot, cross-fit, minimalist and conventional footwear on patellofemoral loading during running. Twelve cross-fit athletes ran at 4.0 m/s in each of the four footwear conditions. Lower limb kinematics were collected using an 8 camera motion analysis system and patellofemoral loading was estimated using a mathematical modelling approach. Differences between footwear were examined using one-way repeated measures ANOVA. The results showed the peak patellofemoral force and stress were significantly reduced when running barefoot (force = 3.42 BW & stress = 10.71 MPa) and in minimalist footwear (force = 3.73 BW & stress = 11.64 MPa) compared to conventional (force = 4.12 BW & stress = 12.69 MPa) and cross-fit (force = 3.97 BW & stress = 12.30 MPa) footwear. In addition, the findings also showed that patellofemoral impulse was significantly reduced when running barefoot (0.35 BW·s) and in minimalist footwear (0.36 BW·s) compared to conventional (0.42 BW·s) and cross-fit (0.38 BW·s) footwear. Given the proposed association between patellofemoral loading and patellofemoral disorders, the outcomes from the current investigation suggest that cross-fit athletes who select barefoot and minimalist footwear for their running activities may be at reduced risk from patellofemoral joint pathology in comparison to conventional and cross-fit footwear conditions.

O processo de fadiga pode alterar a estratégia motora de velocidade de golpes no karate: um estudo de caso

Introdução: Devido às novas exigências nas regras competitivas com maiores pontuações, o karate vem se tornando um esporte com altas demandas da variável velocidade. Dentre diversos fatores que podem afetar a velocidade de golpes, o processo de fadiga exaustão é uma importante variável interveniente. Logo, como ocorre o controle motor para a manutenção de velocidade de golpes em situação de fatigabilidade?Objetivo: Identificar as estratégias motoras na manutenção de velocidade do gyako zuki no processo de fadiga.Métodos: Foi avaliado o atual campeão sul-americano da categoria -78 kg, sub 21 do sistema World Karate Federation (WKF). O atleta prática karate por 7 anos, é faixa preta, nível internacional, com 78 kg, 1,82m, 14,4% de gordura, VO2 máx = 55 kg.ml-1.min-1. O atleta realizou um protocolo de carga progressiva denominado Karate Specific Aerobic Test (KSAT) até a exaustão. Para o modelo biomecânico foi utilizado um sistema de análise de movimento de seis câmeras (Sistema Vicon).Resultados: As diferentes contribuições de velocidade de segmentos para a manutenção de vP (velocidade de pico) do gyako zuki ocorre uma vez que protocolos de fadiga comumente atribuem adaptações funcionais para superar o efeito da fadiga e continuar executando a ação técnica da ‘melhor’ forma possível.Conclusão: A principal estratégia motora adotada no processo de fadiga é a diminuição do deslocamento de tornozelo e joelho esquerdos à frente, o que diminui a vP do gyako zuki. O deslocamento do segmento de quadril ocorre em situação de homeostase e não necessariamente em situação de fadiga.The process of fatigue can change the motor strategy in velocities of strokes in karate: a case studyIntroduction: Because of the new requirements in the competitive rules with higher scores, karate has become a sport with high demands of speed. Among many factors that can affect the speed of strokes, the process of fatigue exhaustion is an important intervening variable. How the motor control for maintaining speed in strokes fatigability situation?Objective: Identify the motor strategies in maintaining gyako zuki speed in the fatigue process.Methods: We evaluated the current South American champion of the category -78 kg, under 21 years of age, World Karate Federation system (WKF). The karate athlete practice for 7 years, is a black belt, internationally, with 78 kg, 1.82m, 14.4% fat, VO2 max = 55 kg.ml -1 .min -1. The athlete made a progressive load protocol called Karate Specific Aerobic Test (KSAT) until exhaustion. For biomechanical model was used a six camera motion analysis system (Vicon system).Results: Different contributions segments speed to maintain Vp (peak velocity) gyako zuki occurs because fatigue protocols commonly assigned functional adaptations to overcome the effects of fatigue and continue running the technical action as 'better' as possible.Conclusion: The main motor strategy adopted in the fatigue process is the reduction of ankle dislocation and left knee forwarding, which reduces the vP of gyako zuki. The displacement of the hip segment occurs in homeostasis position and not necessarily by fatigue condition.

The Influence of Different Force and Pressure Measuring Transducers on Lower Extremity Kinematics Measured During Running

In running analyses where both kinetic and kinematic information is recorded, participants are required to make foot contact with a force and/or pressure measuring transducer. Problems arise if participants modify their gait patterns to ensure contact with the device. There is currently a paucity of research investigating the influence of different underfoot kinetic measuring devices on 3-dimensional kinematics of running. Fifteen participants ran at 4.0 m/s in four different conditions: over a floor embedded force plate, Footscan, Matscan, and with no device. Three-dimensional angular kinematic parameters were collected using an eight camera motion analysis system. Hip, knee, and ankle joint kinematics were contrasted using repeated-measures ANOVAs. Participants also rated their subjective comfort in striking each of the three force measuring devices. Significant differences from the uninhibited condition were observed using the Footscan and Matscan in all three planes of rotation, whereas participants subjectively rated the force plate significantly more comfortable than either the Footscan/Matscan devices. The findings of the current investigation therefore suggest that the disguised floor embedded force plate offers the most natural running condition. It is recommended that analyses using devices such as the Footscan/Matscan mats overlying the laboratory surface during running should be interpreted with caution.