MUSCULOSKELETAL WORK IN HIGH BAR PROGRESSIONS

This study explained and assessed the similarity in joint kinetic profiles between the longswing (LS) and four progressions. Video recordings of four male gymnasts performing the LS and four progressions were quantified using 2D DLT techniques on an instrumented high bar. Inverse dynamic analyses quantified the muscle moments and work done at hips and shoulders. RMSD analysis between the work during the LS and progressions was used to group the progressions based on overall level of similarity to the LS. The least similar progression was the looped bar pendulum swing, whilst the most similar was the bent knee LS. This study has identified that progressions can be classified into those that are similar in terms of physical demand or movement pattern. This study raises the question should progressions be selected based on its kinetic or kinematic similarity to the target skill

ANGULAR MOMENTUM IN THE STRAIGHT TKATCHEV ON HIGH BAR

Angular momentum in the straddle Tkatchev was reported as part of a study by Arampatzis and Brüggemann, (2001). The Tkatchev is an interesting skill as it requires the gymnast to reverse the direction of rotation between the bar circling action (the longswing) and the flight phase from release until regrasp

KINETIC ANALYSIS OF TOE-ON TKACHEV ON UNEVEN BARS

The purpose of this study was to explain the mechanics of the Toe-on Tkachev on Uneven Bars, and to identify how the release conditions were created. 3D video based data and inverse dynamics were used to analyze five different Toe-on Tkachevs recorded at the 2007 World Championships. Digitising and DLT techniques were combined with customised inertia modelling as input to standard inverse dynamics. Data were normalised to eliminate influences of height and mass. Hip action was characterised by a single large input which peaked close to the horizontal on the upswing, followed by a smaller negative shoulder power contribution as release was approached. The dominant role of positive hip extension was highlighted as a major factor contributing to the creation of the final body orientation and desirable release conditions

Contributions of twisting techniques used in backward somersaults with one twist

At the 1996 Atlanta Olympic Games, 18 single somersaults with one twist in the women’s compulsory floor exercises were recorded using two video cameras. An 11 segment computer simulation model was used to analyse the twisting techniques used. It was found that counter-rotation techniques accounted for less than one third of the twist for all gymnasts indicating that the production of twist was mainly a consequence of the angular momentum and a non-zero tilt angle. Contributions to the tilt angle reached at the mid-twist position were used as measures of the twisting potential of various techniques. Contact techniques accounted for 30% of the tilt produced, the remainder being produced using aerial techniques which primarily comprised a symmetrical lowering of the arms together with minor contributions from asymmetrical arm and hip movements. There was no evidence of a difference in technique between the highest and lowest scoring competitors

KINEMATICS AND ANGULAR MOMENTUM CONTRIBUTIONS TO THE TOE-ON TKACHEV ON UNEVEN BARS IN FEMALE GYMNASTICS

The purpose of this study was to explain the mechanics of the Toe-on Tkachev on Uneven Bars, and identify whether this variant creates the release characteristics needed to perform more complex aerial body positions (e.g. straight). Images of 5 Toe-on Tkachev’s performed at the 2007 World Championships were recorded with twin video cameras (50Hz). Digitising and 3D DLT techniques were combined with inertia modelling to develop customised profiles for the gymnasts. Greater flight time and angular momentum (L) suggest this variant may provide the gymnast with the opportunity to perform more complex aerial shapes. The dominant roll of the hip in the creation of L was highlighted

Estimation of reaction forces in high bar swinging

Reaction forces experienced by gymnasts swinging on the high bar may be determined indirectly using inverse dynamics analysis or may be measured using strain gauges. The accuracy of inverse dynamics analysis may be poor because of errors in the estimated inertia parameters and in the accelerations obtained from digitized data. On the other hand the use of strain gauges is not always possible in elite competition. This paper presents a method for estimating the reaction forces based on the linear displacements of the bar. The bar was modelled as a point mass attached to horizontal and vertical linear springs (obeying Hooke’s law) with stiffness coefficients determined from static loading. The stiffness coefficients of the bar were determined with three different tensions in the stabilizing cables of the high bar. A force and video analysis of backward giant circles was performed. Estimates for the reaction forces were obtained by multiplying the bar displacements from the video analysis by the stiffness coefficients determined from the static loadings. Comparisons were made between the estimated reaction forces and the reaction forces recorded using strain gauges attached to the high bar. Varying the tension in the stabilizing cables of the high bar did not effect the stiffness of the bar. Root mean squared differences between estimated and recorded reaction forces were on average within 99 N for three ‘regular’ and three ‘accelerated’ giant circles. This was less than 3.5% of the range of forces recorded. The bar displacement method was able to estimate the peak reaction forces to within 7% on average, which compares favourably with 24% reported by Gervais (1993) using inverse dynamics

CO-ORDINATION ANALYSIS OF LANDING STRATEGIES IN BEAM DISMOUNTS

INTRODUCTION: Landing strategies selected by female gymnasts performing somersault dismounts from the beam may be related to the availability of feedback (McNitt-Gray et al., 2001). This study aims to employ co-ordination analysis to examine how female gymnasts control dropping and landing from forward and backward somersault beam dismounts

THE CHANGES IN EFFORT DISTRIBUTION FROM NOVICE TO EXPERIENCED PERFORMERS IN THE TRIPLE JUMP

This study investigated the ratios of the three phases in triple jumping by novice (n=8) and experienced (n=5) athletes during indoor competition. Video data were analysed to determine the phase distances for 58 competitive triple jump performances. Phase ratio percentages were calculated for each of the trials. There were significant differences in the step phase percentage (

BIOMECHANICS OF LONGSWINGS PRECEDING TKACHEV ON UNEVEN BARS

Changes in the rules governing the separation of uneven bars have allowed female gymnasts to perform the Tkachev in both directions. The aim of this study was to compare the similarities in the preparatory longswing during the outward (O) and inward (I) Tkachevs. Video recordings of the Tkachevs (O=5, I=5) were collected from the 2000 Sydney Olympic Games. A 37° greater range of movement was found at the hips during the I Tkachev. In the more conventional O technique changes in the hip angle were smaller (23°) and occurred over a greater circle angle. This study has identified differences in what appear to be very similar skills. Further inter-segmental coordination and joint kinetic analyses may provide insight into the performance of these release and regrasp skills

A LONGITUDINAL CASE STUDY OF STEP CHARACTERISTICS IN A WORLD CLASS SPRINT ATHLETE

The relative importance of step length (SL) and step frequency (SF) to maximum velocity sprinting is not yet fully understood. One elite male sprinter was studied during five months of training. Step velocity, SL and SF were calculated from 50 Hz video, using manual digitization and 2D DLT, for a total of 113 steps taken from the maximum velocity phase of training sprints. Mean values were calculated for each session and tracked against training diary information gathered from the athlete's coach. Chronological information showed that as the athlete’s training progressed, a link between velocity and SF was maintained whilst mean session SL remained relatively unchanged throughout. For the athlete studied, changes in step velocity as a result of training were shown to occur as a consequence of changes mainly in SF