USE OF '2D-DLT' FOR THE ANALYSIS OF LONGSWINGS ON HIGH BAR

The purpose of this study was to establish how closely a 2D DLT analysis compared with a normal 3D analysis during a longswing on the high bar. Repeated digitisations from two orthogonal camera views were averaged to produce 3D criterion data. Comparisons between 2D reconstructions from the left, right and from an additional perpendicular (2DP) camera view were made. Root mean squared differences (RMSD) for hip and shoulder angles (θH, θS) and angular velocities (ωH, ωS) were determined. Max RMSD was found to be θS= 0.06 rad viewed from the left camera and ωS = 0.60 rad.s-1 from 2DP view. It is therefore recommended that 2D DLT can be used to analyse this skill and that added accuracy can be obtained using left or right camera views during ascending and descending phases respectively. This has direct implications for future research of this type of skill

BIOMECHANICS AND GYMNASTICS

The applied session at the 28th The second theme presented by Dr Marianne Gittoes and Professor Peter Brüggemann examines the effects of gymnastic performance on the loading of the biological structures of the gymnast. These two talks will explore impact loading and the resultant physical demand on performers. Examples will include landing in gymnastics. One fundamental topic will be an examination of the ability of the gymnast to voluntarily i.e. consciously modify technique. Investigating what the gymnast can do and what is inherent in predisposing them to high loads therefore how does the gymnast interact technique changes with inherent mechanisms of load attenuation. International Society of Biomechanics in Sport Conference focuses on two major themes of research; the Coaching-Biomechanics Interface and Injury and biological loading. These two interrelated themes underpin the understanding and knowledge needed to provide a safe and effective environment for the development of gymnastics skills and for the well being of performers. Ecological validity permeates these research approaches ensuring that meaningful information for coaches, scientists and clinicians is provided. The four presentations will use examples from evidenced based research on these themes. Two will focus on the coaching-biomechanics interface; one from an experimental perspective (Dr Gareth Irwin) and the other from a theoretical/modelling one (Dr Mike Hiley). The coaching-biomechanics interface is a term used to conceptualise how coaching can be informed from a biomechanical perspective. The process involved here is a continuous one, with each cycle starting and ending with the athlete. The process is based on a coach’s tacit knowledge in relation to the practices that are routinely used to develop athletes’ skills. Integral to this process, is the communication between the biomechanist and the coach and athlete. This cycle of extracting, processing and imparting new scientifically grounded knowledge and understanding represents the coaching-biomechanics interface. Sometimes this new knowledge may simply reinforce existing practices or it can provide new insights which inform future skill development. The overall purpose of developing the coaching-biomechanics interface is to bridge the gap between biomechanical science and sport practice. The interface aims to make training more effective and efficient for athletes who are already working near to their physiological limits. Presenters are: 1. Dr Gareth Irwin (Wales): Coaching Biomechanics Interface: Competition and training 2. Dr Mike Hiley (England): Coaching Biomechanics Interface: Simulation modelling 3. Dr Marianne Gittoes (Wales): Variability and performance: implications for injury in gymnastics 4. Prof Dr Peter Brüggemann (Germany): Biological load and injury in gymnastic

MUSCULOSKELETAL WORK PRECEDING THE TKACHEV ON UNEVEN BARS

The purpose of this study was to identify the mechanics of traditional outward facing (O) and newer inward facing (I) Tkachev on uneven bars. Images of ten straddle Tkachevs (O=5, I=5) performed at the Sydney Olympic Games, 2000 were recorded with twin video cameras (50Hz). Manual digitising and 3D DLT reconstruction techniques were combined with inertia modelling to develop customised profiles for the ten gymnasts. Inverse dynamics analyses were used to quantify hip and shoulder joint kinetics, and segmental and bar energy exchanges from the horizontal position on the downswing to bar release. There was evidence that more energy was stored in and recovered from the bar in the inward technique. The role of the hips remained similar for both skills, but a large shoulder flexion rather than extension occurred in the inward technique close to release

COACHING BIOMECHANICS INTERFACE: COMPETITION AND TRAINING

Bridging the gap between the underlying biomechanical parameters that determine successful gymnastics performance, and the provision of meaningful information for coaches has been the challenge for sports biomechanists for decades. Conceptualising this fundamental relationship through the coaching-biomechanics interface draws on the cognitive processes of learning and understanding, combined with grounded scientific concepts, which help explain and increase understanding of gymnastic performance. As such the coaching-biomechanics interface begins with an examination of coaches’ implicit knowledge highlighted through the conceptual models of skill learning and development (Irwin et al., 2005). Central to this model is the development of a mind set, a conceptual understanding of how a skill works. Coaches develop an understanding of how the skill works then aim to replicate the spatial and temporal characteristics of the final skill in the physical preparations, progressions and preparatory skills used in training

KINEMATIC CHANGES DURING LEARNING THE LONGSWING ON HIGH BAR

Understanding technique development during complex skill learning provides information that can be used to influence feedback and skill development. The purpose of this study was to investigate changes in longswing technique during an 8 week period of learning. Fourteen male participants with no previous high bar experience took part in the training study. Data were collected using a CODA motion analysis system (200 Hz) during weekly testing sessions. There was a significant increase in swing amplitude for the group between week 1 and all subsequent weeks (p < .05). Based on initial swing amplitude three patterns of learning were displayed; each having distinctive functional phase characteristics. This study highlights the importance of quantifying changes in technique throughout learning on an intra-individual basis, to understand how technique changes

THE INFLUENCE OF EXPERIENCE ON FUNCTIONAL PHASE KINEMATICS OF THE LONGSWING

The biomechanics of successful longswings are well understood, however, the influence of experience on execution is not well defined. This study aims to explore functional phase (FP) kinematics during repeated longswings performed by an experienced (E), inexperienced (I) and novice (N) participant. METHODS: Three participants performed five sets of five longswings on a high bar. Data were collected using an automated motion analysis system (CODA CX-1), sampling at 200Hz. Circle angle (&#952;C) was defined by the mass centre to bar vector with respect to the horizontal. Kinematics ofFP’s, defined by maximum shoulder flexion to extension (&#952;CS) and hip extension to flexion (&#952;CH), were analysed duringswing three and four in each set

PREPARATORY LONGSWING TECHNIQUES FOR DISMOUNTS ON UNEVEN BARS

The purpose of this study was to quantify the biomechanical differences between two methods of performing the preparatory longswing preceding the double layout dismount. Video images of 6 female Olympic level gymnasts performing the double layout dismount (3 = straddle preparatory longswing, 3 = dished preparatory longswing) were recorded using two synchronised 50 Hz digital cameras. 3D DLT reconstructed coordinates were combined with inertia values to define discrete release variables including vertical and horizontal velocity of the mass centre, release angle and angular momentum about the gymnast’s mass centre. Joint angular kinematics at the hips and shoulders were contrasted with particular reference to the hip functional phase. Based on the reported release parameters the straddle longswing could be considered preferential

JOINT KINEMATIC VARIABILITY IN THE AERIAL AND LANDING PHASES OF BACKWARD ROTATING DISMOUNTS FROM BEAM

This study aimed to develop insight into the joint kinematic variability in backward rotating dismounts from beam. Two-dimensional lower-body coordinate data were obtained for ten backward piked (BP) and tucked (BT) dismounts performed by four gymnasts (N = 80 trials). The within-gymnast coefficient of variation (CV%) in the joint angle profiles was lower in the aerial-landing phase transition than the remaining dismount element. The CV% was consistently larger in the initial joint configurations of the BP aerial and landing phases than the more basic BT skill. Initial ankle and hip joint landing configurations produced the largest CV% difference between skills (ankle: 9.4 %, hip: 9.4 %). The development of complex dismounts from beam requires a pre-programmed control strategy allowing joint kinematic modulations at the onset of aerial and landing phases

LANDING STRATEGY MODULATION IN BACKWARD ROTATING PIKED AND TUCKED SOMERSAULT DISMOUNTS FROM BEAM

The aim of this study was to develop understanding of the landing strategy modifications made when performing backward rotating piked (BP) and tucked (BT) dismounts from beam. Sagittal plane lower-body joint angular kinematic profiles were determined for four female gymnasts during the landing phase of BP and BT somersaulting dismounts. A common hip-biased landing strategy was employed by the four gymnasts in the dismounting skills. The more complex BP task was distinguished by the use of a more extended (3.7º) and flexed (5.0º) initial knee and hip joint configuration, respectively compared to the basic BT skill performed. Effective skill developments of backward rotating dismounts from beam may require modulation to the individual joint patterns defining the lower-body landing strategy

PREPARATORY LONGSWINGS PRECEDING TKACHEVS ON UNEVEN BARS

The preparatory longswing on uneven bars is fundamental to the development of more complex skills in women’s gymnastics. The preceding longswing governs the release parameters that in turn determine the success of the straddle Tkachev (Arampatzis & Brüggemann, 2001). Of the many longswing variations currently in use in women’s gymnastics, this study aims to investigate differences in the biomechanics of three distinctive preparatory longswings used in performing the straddle Tkachev. The long term purpose is to increase understanding of these skills and potentially improve the effectiveness of coaching