A PRACTICAL OPEN-SOURCE COMPARISON OF DISCRETE AND CONTINUOUS BIOMECHANICAL ANALYSIS TECHNIQUES

Recent work has challenged the practice of extracting and analysing discrete summary metrics from continuous biomechanical data. This paper presents a practical comparison of candidate data analysis techniques including frequentist and Bayesian discrete analysis, frequentist and Bayesian statistical parametric mapping, and vector coding. Example 1 compares knee and hip flexion / extension angles during flywheel and barbell squats. Example 2 compares pelvis and thorax transverse rotations during badminton jump smashes by an international and a regional player. All example data and scripts are open-source. Statistical parametric mapping enables comparison of continuous biomechanical variables at time points other than discrete local optima. Combining this approach with vector coding provides information regarding differences in proximal-distal joint coordination throughout a movement. These continuous open-source methodologies can increase the validity and intuitive practical application of biomechanical conclusions

UNDERGRADUATE STUDENT EXPERIENCES OF PUBLISHING BIOMECHANICS RESEARCH

The aim of this study was to investigate student experiences of publishing undergraduate research in biomechanics. Twenty-five individuals with experience of publishing peer-reviewed undergraduate biomechanics research completed an online survey regarding their perceived benefits and their level of involvement in various aspects of the research process. Areas of the greatest and least perceived benefits and student involvement were identified. Correlations suggested numerous beneficial effects of relatively low student involvement, more likely related to the concurrent greater supervisor involvement. Staff should make informed decisions regarding their level of involvement in each aspect of the research process rather than simply focusing on the final research output

Problem based learning: a netball / basketball shooting problem for projectile motion

As a sport scientist working in a multi-sport organisation, the national netball or basketball coach approaches you with a question. They currently use defenders during shooting practice but are concerned about the extra demands this is placing on their defenders during a congested competition period. The coach wants to know whether removing the defenders from the practice environment will affect the trajectory of the shots. If so, they wonder if a mannequin defender could be used as a compromise. Problem Title: The effect of a defender on netball/ basketball shooting Course Level: Undergraduate Introductory. Learning Outcomes: Identify and define important parameters influencing projectile motion Express a real-world problem in terms of projectile motion Calculate projectile motion parameters Compare values for two or more conditions Discuss the concept of ecological validity in scientific testin

The effect of joint compliance within rigid whole-body computer simulations of impacts

In high impact human activities, much of the impact shock wave is dissipated through internal body structures, preventing excessive accelerations from reaching vital organs. Mechanisms responsible for this attenuation, including lower limb joint compression and spinal compression have been neglected in existing whole-body simulation models. Accelerometer data on one male subject during drop landings and drop jumps from four heights revealed that peak resultant acceleration tended to decrease with increasing height in the body. Power spectra contained two major components, corresponding to the active voluntary movement (2 Hz 14 Hz) and the impact shock wave (16 Hz 26 Hz). Transfer functions demonstrated progressive attenuation from the MTP joint towards the C6 vertebra within the 16 Hz 26 Hz component. This observed attenuation within the spine and lower-limb joint structures was considered within a rigid body, nine-segment planar torque-driven computer simulation model of drop jumping. Joints at the ankle, knee, hip, shoulder, and mid-trunk were modelled as non-linear spring-dampers. Wobbling masses were included at the shank, thigh, and trunk, with subject-specific biarticular torque generators for ankle plantar flexion, and knee and hip flexion and extension. The overall root mean square difference in kinetic and kinematic time-histories between the model and experimental drop jump performance was 3.7%, including ground reaction force root mean square differences of 5.1%. All viscoelastic displacements were within realistic bounds determined experimentally or from the literature. For an equivalent rigid model representative of traditional frictionless pin joint simulation models but with realistic wobbling mass and foot-ground compliance, the overall kinetic and kinematic difference was 11.0%, including ground reaction force root mean square differences of 12.1%. Thus, the incorporation of viscoelastic elements at key joints enables accurate replication of experimentally recorded ground reaction forces within realistic whole-body kinematics and removes the previous need for excessively compliant wobbling masses and/or foot-ground interfaces. This is also necessary in cases where shock wave transmission within the simulation model must be non-instantaneous

VISIBILITY AND USAGE OF ISBS PROCEEDINGS AT FORTY YEARS

This study described the visibility and usage of research published in ISBS conference proceedings articles from 1983 to 2022. The 6,688 articles were downloaded 1,955,728 times in total, and 78% were indexed by Google Scholar. In recent proceedings, the number of articles and total downloads have decreased but downloads per article per year of availability have increased steeply. Top (1%) cited articles in Google Scholar had citations and citation rates similar to articles in biomechanics journals. While visibility has grown, there is limited citation of most ISBS proceedings articles compared to journal articles

SPATIAL SPEED-ACCURACY TRADE-OFF IN INTERNATIONAL BADMINTON PLAYERS PERFORMING THE FOREHAND SMASH

Speed and accuracy of the badminton smash are critical components for successful performance. Fifty-two participants data were collected using a Vicon 3D Motion capture system (400 Hz) at the BWF Glasgow World Championships (2017). The purpose of this study was to identify and compare spatial speed-accuracy trade-off (SATO) relationships amongst international badminton players performing the forehand smash, under two conditions: maximal speed (MS) in the direction of a target; and maximal speed aiming to hit the centre of a target (TAR). Exploratory and confirmatory cluster analyses revealed three groupings: Fitts’ inverse relationship (FIR), no relationship (NR) and alternate inverse relationship (AIR). Findings indicate that for international badminton players 80–99% of maximum speed is the threshold for achieving the highest levels of spatial accuracy

Determinants of countermovement jump performance: a kinetic and kinematic analysis

This study aimed to investigate the contributions of kinetic and kinematic parameters to inter-individual variation in countermovement jump (CMJ) performance. Two-dimensional kinematic data and ground reaction forces during a CMJ were recorded for 18 males of varying jumping experience. Ten kinetic and eight kinematic parameters were determined for each performance, describing peak lower-limb joint torques and powers, concentric knee extension rate of torque development and CMJ technique. Participants also completed a series of isometric knee extensions to measure the rate of torque development and peak torque. CMJ height ranged from 0.38 to 0.73 m (mean 0.55 ± 0.09 m). CMJ peak knee power, peak ankle power and take-off shoulder angle explained 74% of this observed variation. CMJ kinematic (58%) and CMJ kinetic (57%) parameters explained a much larger proportion of the jump height variation than the isometric parameters (18%), suggesting that coachable technique factors and the joint kinetics during the jump are important determinants of CMJ performance. Technique, specifically greater ankle plantar-flexion and shoulder flexion at take-off (together explaining 58% of the CMJ height variation), likely influences the extent to which maximal muscle capabilities can be utilised during the jump

THE EFFECT OF DELIVERY METHOD ON CRICKET BATTING UPPER-BODY KINEMATICS

The aim of this study was to determine the effect of delivery method on upper-body kinematics in cricketers playing a front foot drive and a back foot pull shot. Fourteen male cricketers were played both shots against a bowler, bowling machine, and SidearmTM ball thrower. The availability of pre-release visual cues appears to affect upper-body kinematics during the pull shot but not the drive other than at the back shoulder. The SidearmTM may represent a compromise between bowler and bowling machine when training the pull shot but coaches should consider differences in upper-body proximal-distal joint dominance