The application of functional data analysis to force signatures in on-water single sculling

Biomechanics as a discipline of sports science has played an important role in on-water rowing over the last 150 years. Substantial focus has been placed on understanding kinetic variables acting around the oar-boat-rower system, and how these variables interact to change boat velocity. Of these variables, propulsive force applied at the oar has received considerable attention, and rowing instrumentation systems capable of measuring propulsive force have enabled coaches and sport scientists the ability to assess and descriptively understand characteristics of rowing technique and performance. Propulsive force is observed through different continuous graphs (i.e. force-time graphs, force-oar angle graphs, etc.), with the shapes on these graphs often referred to as force profiles. Large variations are present between athletes in the shape characteristics of force profiles, and subsequently these differences have led to propulsive force patterns being referred to as a rower’s ‘signature’. The overarching aim of this thesis was to provide content that would build a more thorough understanding of differences in force profiles between rowers, using novel statistical approaches from the area of functional data analysis (FDA). Following a review of the literature, two separate FDA techniques, functional principal components analysis (fPCA) and bivariate fPCA (bfPCA) were explored as potential statistical approaches for application with force profiles. Subsequently, an experimental study applied bfPCA to force-angle profiles of highly skilled male and female sculling rowers. This demonstrated that differences in the patterns of force-angle profiles could be attributed to both rower gender and boat-side. A following experimental study controlled for gender and boat-side, and used bfPCA to explore differences between rowers relative to performance measures such as competition level and boat velocity. Different force profile patterns were attributed to each measure of performance. A final experimental chapter explored whether patterns of continuous force asymmetry were associated with better rowing performance (assessed using rower competition level). This study demonstrated that international level rowers perform the skill with what appear to be deliberate and intentional asymmetries. Biomechanics as a discipline of sports science has played an important role in on-water rowing over the last 150 years. Substantial focus has been placed on understanding kinetic variables acting around the oar-boat-rower system, and how these variables interact to change boat velocity. Of these variables, propulsive force applied at the oar has received considerable attention, and rowing instrumentation systems capable of measuring propulsive force have enabled coaches and sport scientists the ability to assess and descriptively understand characteristics of rowing technique and performance. Propulsive force is observed through different continuous graphs (i.e. force-time graphs, force-oar angle graphs, etc.), with the shapes on these graphs often referred to as force profiles. Large variations are present between athletes in the shape characteristics of force profiles, and subsequently these differences have led to propulsive force patterns being referred to as a rower’s ‘signature’. The overarching aim of this thesis was to provide content that would build a more thorough understanding of differences in force profiles between rowers, using novel statistical approaches from the area of functional data analysis (FDA). Following a review of the literature, two separate FDA techniques, functional principal components analysis (fPCA) and bivariate fPCA (bfPCA) were explored as potential statistical approaches for application with force profiles. Subsequently, an experimental study applied bfPCA to force-angle profiles of highly skilled male and female sculling rowers. This demonstrated that differences in the patterns of force-angle profiles could be attributed to both rower gender and boat-side. A following experimental study controlled for gender and boat-side, and used bfPCA to explore differences between rowers relative to performance measures such as competition level and boat velocity. Different force profile patterns were attributed to each measure of performance. A final experimental chapter explored whether patterns of continuous force asymmetry were associated with better rowing performance (assessed using rower competition level). This study demonstrated that international level rowers perform the skill with what appear to be deliberate and intentional asymmetries. Biomechanics as a discipline of sports science has played an important role in on-water rowing over the last 150 years. Substantial focus has been placed on understanding kinetic variables acting around the oar-boat-rower system, and how these variables interact to change boat velocity. Of these variables, propulsive force applied at the oar has received considerable attention, and rowing instrumentation systems capable of measuring propulsive force have enabled coaches and sport scientists the ability to assess and descriptively understand characteristics of rowing technique and performance. Propulsive force is observed through different continuous graphs (i.e. force-time graphs, force-oar angle graphs, etc.), with the shapes on these graphs often referred to as force profiles. Large variations are present between athletes in the shape characteristics of force profiles, and subsequently these differences have led to propulsive force patterns being referred to as a rower’s ‘signature’. The overarching aim of this thesis was to provide content that would build a more thorough understanding of differences in force profiles between rowers, using novel statistical approaches from the area of functional data analysis (FDA). Following a review of the literature, two separate FDA techniques, functional principal components analysis (fPCA) and bivariate fPCA (bfPCA) were explored as potential statistical approaches for application with force profiles. Subsequently, an experimental study applied bfPCA to force-angle profiles of highly skilled male and female sculling rowers. This demonstrated that differences in the patterns of force-angle profiles could be attributed to both rower gender and boat-side. A following experimental study controlled for gender and boat-side, and used bfPCA to explore differences between rowers relative to performance measures such as competition level and boat velocity. Different force profile patterns were attributed to each measure of performance. A final experimental chapter explored whether patterns of continuous force asymmetry were associated with better rowing performance (assessed using rower competition level). This study demonstrated that international level rowers perform the skill with what appear to be deliberate and intentional asymmetries

A 2-DIMENSIONAL VIDEO BASED MODEL FOR USE IN ERGOMETER ROWING KINEMATICS

Motion capture of the rowing stroke using accurate 3D opto-reflective systems has been limited by the constraints of the surrounding hydrodynamic environment. As a consequence 2D lower-extremity kinematic models have been used in an attempt to counter these logistical issues (Lamb, 1989). Despite this, there is limited research supporting the accuracy of a 2D video based model (2DVBM) for motion capture of the rowing stroke. The purpose of this study was to assess the accuracy of a 2DVBM against the conventional gait model using a 3D opto-reflective system

ISBS 2021 CONFERENCE PROCEEDINGS TITLE AND FOREWARD

The ISBS is an international society totally dedicated to biomechanics in sports, whose primary purposes are: To provide a forum for the exchange of ideas for sports biomechanics researchers, coaches and teachers. To bridge the gap between researchers and practitioners. To gather and disseminate information and materials on biomechanics in sports. The conference planned for Canberra, Australia did not go ahead in a face-to-face capacity due to COVID-19. The conference was instead delivered fully online. These proceedings are the accepted papers for the online conference. Papers underwent a double blinded review process. Each paper in these proceedings has been reviewed by at least two members of the scientific committee. The scientific committee comprises the current members of the board of directors of the ISBS and the keynote speakers for the upcoming conference

THE EFFECT OF CAMERA PAN ON THE TWO-DIMENSIONAL DIRECT LINEAR TRANSFORMATION AND SCALAR RECONSTRUCTION TECHNIQUES WHEN APPLIED TO ERGOMETER ROWING

Changes in camera pan may affect reconstruction accuracy of two-dimensional (2D) kinematic data collected in on-water rowing testing. The 2D direct linear transformation (2D-DLT) may assist in improving reconstruction accuracy of rowing kinematics when a perpendicular camera changes position. Accuracy of the 2D-DLT and scalar reconstruction techniques was compared using coefficient of multiple correlations (CMCs), range of motion difference (ROMDiff) and root mean square error (RMSE). 2DDLT was found to have significantly greater accuracy (CMC and RMSE;

PROXIMAL AND DISTAL CONSTRAINTS REDUCE DIMENSIONALITY OF VERTICAL JUMPING TASKS

The purpose of this study was to examine motor control strategies employed to control the degrees of freedom when performing a lower limb task with constraints applied at the hip, knee and ankle. Thirty-five individuals performed vertical jumping tasks: hip flexed, no knee bend and plantar flexed. Joint moment data from hip, knee and ankle was analysed using principal component analysis (PCA). In all, PCA performed, a minimum of two and maximum of six principal components (PCs) were required to describe the movement. A proximal to distal reduction in variability was only observed for the hip flexed and no knee bend conditions. Collectively, the results suggest a reduction in the dimensionality of the movement occurs, despite the constraints imposed within each condition and would suggest dimensionality reduction and motor control strategies are a function of the task demands

FORCE-ANGLE CHARACTERISTICS AND LEVEL OF COMPETITIVE REPRESENTATION IN ON-WATER ROWING

The graphical presentation of the propulsive form applied by the oar to the pin, plotted against the oar horizontal angle, has been used as a diagnostic tool for rowing skill. How the pattern is related to variables such as level of competitive has not been well identified. Bivariate functional principal components analysis (bfPCA) was used on form-angle data to identify the main modes of variation in curves representing twenty seven female rowers of two different competition levels (Australian Domestic and Australian International level), rowing at 32 strokes per minute in a single scull boat. Discriminant function analysis showed strong classification of rowers using force-angle graphs across both sides of the boat, with increased rate of force development identified as an important characteristic for international rowers. Additionally for the bow-side, spending less time in the first half of the drive phase was also identified as an important feature for international rowers. The results of this demonstrate that there are potentially some common characteristics of the form-angle that are important for selection in international level sculling boats

THE APPLICATION OF FUNCTIONAL DATA ANALYSIS TECHNIQUES FOR CHARACTERIZING DIFFERENCES IN ROWING PROPULSIVE-PIN FORCE CURVES

The pattern of propulsive force (measured at the pin), represented by force-time and forceangle graphs, typically differs among rowers. How the pattern differs according to competition level and gender has not been identified. Functional data analysis (FDA) techniques were used on force-time and force-angle data to identify the main modes of variance in curves representing thirty eight rowers of different competition levels (domestic, underage international and open international) and different gender. Stepwise discriminant function analysis showed strong classification of rowers using force-time and force-angle graphs and strong classification of female rowers. Male rowers, Underage rowers and Open International rowers showed weaker classification. Despite this, FDA provided useful information for the assessment of rowing performance

Countermovement jump and squat jump force-time curve analysis in control and fatigue conditions

This study aimed to reanalyze previously published discrete force data from countermovement jumps (CMJs) and squat jumps (SJs) using statistical parametric mapping (SPM), a statistical method that enables analysis of data in its native, complete state. Statistical parametric mapping analysis of 1-dimensional (1D) force-time curves was compared with previous zero-dimensional (0D) analysis of peak force to assess sensitivity of 1D analysis. Thirty-two subjects completed CMJs and SJs at baseline, 15 minutes, 1, 24, and 48 hours following fatigue and control conditions in a pseudo random cross-over design. Absolute (CMJABS/SJABS) and time-normalized (CMJNORM/SJNORM) force-time data were analyzed using SPM 2-way repeated measures analysis of variance with significance accepted at α = 0.05. The SPM indicated a magnitude of difference between force-time data with main effects for time (p \u3c 0.001) and interaction (p \u3c 0.001) observed in CMJABS, SJABS, and SJNORM, whereas previously published 0D analysis reported no 2-way interaction in CMJ and SJ peak force. This exploratory research demonstrates the strength of SPM to identify changes between entire movement force-time curves. Continued development and use of SPM analysis techniques could present the opportunity for refined assessment of athlete fatigue and readiness with the analysis of complete force-time curves

CASE STUDY OF AN ACCIDENTAL ANKLE TWIST: A KINEMATIC ANALYSIS USING FUNCTIONAL DATA ANALYSIS

This study examined an accidental ankle twist occurring during a single-participant study of the effects of traction on ankle biomechanics. One male participant performed a series of randomly distributed side-cuts and turns. In the 11th trial, the participant twisted his ankle during a side-cut. As no injury occurred, another 24 side-cut trials were recorded. Functional Data Analysis (FDA) demonstrated that the ankle twist trial was characterised by a sudden increase in inversion and internal rotation along with rapid transition from plantarflexion to dorsiflexion. Velocities showed a two-step increase in internal rotation and inversion, exceeding a 300 °/s safety threshold. The shift to dorsiflexion is indicative of an unloading mechanism that likely prevented the injury. FDA revealed variations between the ankle twist and the control that could inform stud design to prevent injuries

MOVEMENT VARIABILITY IN ELBOW AND WRIST KINEMATICS OF NEW BALL OUTSWING BOWLING IN CRICKET FAST BOWLERS

This study investigated between-bowler movement variability of wrist and elbow kinematics during new ball swing bowling. A 3D motion analysis system captured the bowling action and ball trajectory of 11 pre-elite and elite fast bowlers delivering outswing. Kinematics were normalised to 100% of the delivery stride between back foot contact and ball release. A statistical parametric mapping approach using one-way ANOVAs investigated inter-individual movement variability. Significant differences were found in all kinematic parameters except for wrist radial/ulnar deviation angular velocity with bowlers using small amounts in either direction at the beginning of the phase. This study highlights that high-level athletic performance can be achieved using different movement variations and future research should include individual analyses of fast bowlers