Sports Biomechanics

Vertical and horizontal rhythms are crucial aspects of a dynamic golf swing, and the two-step swing drills (TSSD) were specifically designed to promote rhythmic unloading and loading of the legs. The purpose of this study was to evaluate the effects of a TSSD training session on the swing rhythm and clubhead speed (CHS) among competitive junior golfers (3.1 ± 4.4 hcp). The driver swings (7 swings each) of 10 competitive junior golfers (aged 15-18) were captured before and after a TSSD session consisting of four stages (lasting less than 45 minutes)...

Shoulder injuries are common in baseball pitchers and primarily involve the glenohumeral joint. Past analyses have examined shoulder biomechanics during different pitch types simply as the motion of the upper arm relative to the thorax. In this study, glenohumeral and scapulothoracic kinematics were compared between fastballs and curveballs at key timepoints throughout a pitch. Upper extremity kinematics of thirteen collegiate pitchers were collected during fastball and curveball pitches with motion capture...

Greater impulse is a key performance indicator of success in short track speed skating. The main objective of this study was to develop a method to measure skating strokes using a single IMU. Eight elite or world-class speed skaters had one IMU placed against their skin on the lower back, and a camera setup was positioned to capture the test. A maximal speed trial was then executed by each participant, and the data were analysed to estimate agreement between the camera and IMU estimates of skate stroke events...

Portable data collection devices and machine learning (ML) have been combined in autonomous movement analysis models for resistance training (RT) movements. However, input features for these models were mostly extracted empirically and subsequent models demonstrated limited interpretability and generalisability to real-world settings. This study aimed to investigate the utility of interpretable and generalisable modelling techniques and several data-driven feature extraction (FE) methods. This was achieved by developing machine learning movement analysis models for the barbell back squat and deadlift using markerless motion capture...

Biomechanical measurements of accidental ankle sprain injuries are rare but make important contributions to a more detailed understanding of the injury mechanism. In this case study, we present the kinematics and kinetics of a lateral ankle sprain of a female athlete performing handball-specific fake-and-cut manoeuvres. Three-dimensional kinematics and kinetics were recorded and six previously performed trials were used as reference. Plantarflexion, inversion, and internal rotation angles were substantially larger than the reference trials and peaked between 190 and 200 ms after initial ground contact...

The purpose of this study was to analyse the differences on the shooting score and shooting technical parameters with 50 m rifle three positions, and to find the key technical factors of shooting performance in international-level 50 m rifle shooters. A SCATT MX-02 optoelectronic shooting test system was used to collect shooting score and shooting technical variables. There was a significant effect of shooting position in shooting performance, aiming accuracy, stability of hold, stability of triggering (ANOVA, position, p  < 0...

Scapular dyskinesis (SD) indicates dysfunction of the scapular muscle activity during the arm elevation, resulting in altered scapular kinematics. This study examined whether SD alters scapular muscle activity and kinematics during swim stroke motion. Seventeen swimmers (mean age: 13 ± 1 years) were divided into SD ( n  = 8) and control ( n = 9) groups. Scapular muscle activity (the upper, middle, and lower trapezius and the serratus anterior muscle) and kinematics data were collected and time-normalised (0-100%) during swim stroke motion by swim-bench on land...

Gait velocity, or walking speed, has been referred to as the sixth vital sign, and research suggests that it is highly sensitive to change. Previous research has demonstrated the utility of cycling to improve gait parameters and in particular gait velocity in a variety of populations. However, it is unclear if the benefits from cycling to gait velocity stem from increased cadence, increased work rate, or the interaction between them. Therefore, the objective of the current research was to explicitly test the relationship between cycling work rate, cycling cadence, and gait velocity...

This study aimed to investigate the effect of different initial speeds on the performance during underwater undulatory swimming (UUS). The study included 13 female swimmers. Each participant was asked to perform a 15-m maximum UUS, starting with four different push-off speeds. The experiment was recorded using three underwater cameras; subsequently, a two-dimensional motion analysis was conducted. Statistical parametric mapping (SPM) was employed to identify the position where the UUS velocity stabilised. The findings revealed a significant difference in the average swimming velocities during the first cycle of UUS, which was attributed to the variation in initial speed ( p  < 0...

Bodyweight squat is one of the basic sports training exercises. Automatic classification of aberrant squat movements can guide safe and effective bodyweight squat exercise in sports training. This study presents a novel gated long-short term memory with transformer network (GLTN) model for the classification of bodyweight squat movements. Twenty-two healthy young male participants were involved in an experimental study, where they were instructed to perform bodyweight squat in nine different movement patterns, including one acceptable movement defined according to the National Strength and Conditioning Association and eight aberrant movements...

This study aims to investigate the different ground reaction force (GRF) characteristics from different stride types. This study included 30 Taiwanese elite college and professional baseball pitchers. Each pitcher was classified into one of the following stride types: tall and fall (TF), dip and drive (DD), or mixed (MX). Our findings indicated that DD pitchers pressed their bodies forward earlier than TF pitchers. In contrast, the GRF of the pivot leg of TF pitchers increased slowly in the first half of the stride phase and continued to increase even after the stride leg touched the ground...

The shaft angle to the ball-to-target line at various points in the golf swing is used by coaches as an indication of the horizontal delivery plane angle (HPA). The aim of the current study was to understand to what degree this simplified method of using the shaft orientation can predict the orientation of the HPA. Fifty-two male golfers hit 40 drives each in an indoor biomechanics laboratory. Between-subject regression models were created for the relationship between the HPA and the shaft angle to the ball-to-target line at three different swing positions...

The baseball pitch is a repetitive, full-body throwing motion that exposes the elbow to significant loads, leading to a high incidence of elbow injuries. Elbow injuries in pitching are often attributed to high external valgus torques as these are generally considered to be a good proxy for the load on the Ulnar Collateral Ligament. The aim of the study is to contribute to elbow load monitoring by developing a prediction model based on the pelvis and trunk peak angular velocities and their separation time. Eleven male youth elite baseball pitchers (age 17 ± 2...

The purpose of this study was to investigate the concordance of isokinetic bilateral strength differences of the knee extensors in single- and multi-joint movement tasks. One hundred and nineteen male athletes performed isokinetic legpresses at 0.1 m/s and 0.7 m/s as well as isokinetic knee extensions at 60°/s and 180°/s. Bilateral differences and directed bilateral differences (sign indicating the direction of the difference) were calculated for all measurements. Bland-Altman-Plots were plotted to investigate if the different conditions detect bilateral differences of the same magnitude...

This study aimed to investigate the essential role of the kicking action in front crawl. To achieve this objective, we examined the relationships of the hand propulsive force and trunk inclination with swimming velocity over a wide range of velocities from 0.75 m·s-1 to maximum effort, including the experimental conditions of arm stroke without a pull buoy. Seven male swimmers performed a 25 m front crawl at various speeds under three swimming conditions: arm stroke with a pull buoy, arm stroke without a pull buoy (AWOB) and arm stroke with a six-beat kick (SWIM)...

Rowing performance depends on the design and building materials used for competition. Recently, attempting to improve rowing performance, the Randall foil has been attached to the top edge of a rowing Big blade, making it spoon shaped. The current study aimed to analyse the differences between Big blades with and without Randall foils in force-related variables. Nineteen rowers performed two bouts of 90 s at maximal effort tethered rowing and differences were found in cycle average peak force (4.33 ± 1...

The muscle size of the hip extensors has been suggested to be important in sprint running performance; however, reported findings are partly inconsistent. Here, we hypothesised that the association between hip extensor size and sprint performance may vary by sprint phase (early-acceleration, maximal-velocity and deceleration phases). To test this hypothesis, we measured the volumes of individual hip extensors of 26 male sprinters via magnetic resonance imaging and their sprint velocities for each 10-m interval during a maximal-effort 100-m sprint...

Despite the mechanical advantage of preparatory movements on the starting block, current evidence questions the start improvements of competitive swimmers with their relay techniques. Therefore, the aim of the present study was to analyse the kinetic and kinematic parameters of a successful relay start. Twenty national- and international-level swimmers performed several relay starts ( n  = 145) with their preferred technique (short or long-step start) over an instrumented OBS11 starting platform...

In baseball pitching biomechanics, kinetic values are commonly ratio 'normalised' by dividing by mass or mass*height to allow for comparison between athletes of different sizes. However, creating a normalised ratio variable should meet certain statistical assumptions. Our purpose was to determine if elbow valgus torque predicted by pitching velocity is influenced by normalisation using regression model comparison with and without normalised torque values. Motion capture data for youth to professional pitchers ( n  = 1988) were retrospectively analysed...

The aim of this study is to determine the effect of stroke rate on performance, technique and core stability during rowing ergometer. Twenty-four high-level rowers performed maximal intensity one-minute bouts at 20, 28 and 34 spm on a RowPerfect3 ergometer. Power at the handle, legs, trunk and arms levels were determined, and core kinematics and neuromuscular activations were measured. The power at the handle was enhanced with a higher stroke rate in the first half of the drive phase due to higher segment's powers...