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

RELATIONSHIPS BETWEEN WHOLE-BODY KINEMATICS AND BADMINTON JUMP SMASH RACKET HEAD SPEED

The purpose of this study was to identify kinematic determinants of shuttlecock speed in the badminton jump smash. Three-dimensional kinematic (400 Hz) data were collected for 18 experienced male badminton players using an 18 camera Vicon Motion Analysis System. Each participant performed 12 jump smashes. The trial with the fastest shuttlecock speed per participant was analysed using an 18-segment rigid body model. Parameters were calculated describing elements of the badminton jump smash technique. Four kinematic variables were significantly correlated with racket head speed. Greater peak wrist joint centre linear velocity, jump height, shorter acceleration phase, and greater shoulder internal rotation at shuttlecock / racket impact

RELATIONSHIPS BETWEEN HITTING TECHNIQUE AND BALL CARRY DISTANCE IN CRICKET

The aim of this study was to identify the technique parameters characterising batsmen who generate large carry distances, ball launch speeds, and bat speeds during a range hitting task in cricket. Kinematic data were collected for 20 batsmen, and a series of ball launch, impact, and technique parameters were calculated for each trial. A regression analysis found impact location relative to the sweetspot and bat speed together to explain 70% of the observed variation in ball speed. A further regression analysis found the maximum X-factor (the separation between the pelvis and thorax segments in the transverse plane), front elbow extension, and wrist uncocking during the downswing explained 66% of the observed variation in bat speed. These findings will be useful in coaching more effective hitters, and in assessing the mechanics of generating bat speed

VARIABILITY OF BALL RELEASE PROPERTIES AND PITCH LENGTH ACCURACY IN CRICKET FAST BOWLING

Accurate ball pitch length in cricket fast bowling is potentially achieved from a redundant combination of four ball release parameters. Yet, it is unknown how parameter co-variations affect pitch accuracy. This study investigates whether pitch length variance is determined by coordinated ball release parameter co-variability. Twelve fast bowlers performed 18 trials at a target length and ball kinematics were captured from an indoor 3D camera setup. Multi-linear regression analysis showed that the four release parameters accounted for 79% of pitch length variance, where vertical velocity variance accounted for the most variance. When each release parameter was independently shuffled across trials, a pitch length model showed no indication of coordinated co-variability between input parameters. Therefore, pitch length accuracy was achieved by independent control of vertical velocity

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