Mechanics of the giant circle on high bar

In Men's Artistic Gymnastics the accelerated backward giant circle on high bar is used to generate the rotation required for the subsequent skill. When used prior to a dismount at the end of a high bar routine the gymnast performs a number of backward giant circles in order to generate sufficient rotation to perform the dismount. The most common dismounts from high bar require the gymnast to perform two backward somersaults in the layout position. Of all the dismounts performed by elite male gymnasts it is the double layout somersault dismount which requires the most rotation. Observations of elite gymnasts have shown that two different techniques may be adopted in the accelerated giant circle performed before release. Since gymnasts are able to perform the dismount from both types the question arises: What is the best technique for increasing rotation using accelerated backward giant circles? [Continues.

OPTIMISATION TO IMPROVE CONSISTENCY IN THE TKATCHEV ON HIGH BAR

The purpose of this study was to improve the consistency of performance of the Tkatchev release and re-grasp on high bar. A simulation model (Hiley & Yeadon, 2003) was used to optimise the technique in the giant circle leading up to release in order to maximise the size of the window within which the gymnast could release and successfully re-grasp the bar. The optimal simulation resulted in a release window considerably larger (93 ms) than the gymnast’s actual performances (mean 29 ms). However, when the technique was required to be robust to small errors in timing the size of the release window was smaller. Performing the final hip and shoulder flexion and extension actions earlier and over a larger angle range than in the actual performances lead to the increase in size of release window

OPTIMISATION OF THE BACKWARD GIANT CIRCLE ON ASYMMETRIC BARS

The purpose of this study was to optimise the release window in the backward giant circle performed prior to release for a double layout somersault dismount from the asymmetric bars. An additional aim was to investigate the effect of requiring the optimal technique to be robust to perturbations in timing of the changes in joint angles. A planar computer simulation model was used to maximise the release window (Hiley and Yeadon, 2005) of a female gymnast by manipulating the joint angle time histories during the giant circle prior to release. Optimisations were performed where the timing of the joint actions at the shoulder and hip were perturbed in order to obtain solutions that were robust to such perturbations. Joint angle time histories were limited by muscle data scaled from a male gymnast. Although introducing the requirement for robustness into the optimised giant circle technique reduced the size of the release windows more consistent performances were achieved

WEIGHT TRANSFER CHANGES DURING GOLF SHOTS FROM DIFFERENT LIES

The aim of the present study was to examine changes in weight transfer during golf shots from flat, uphill, and downhill lies. Twelve male amateur golfers with a mean handicap of 1.6 ± 2.4 hit a total of 30 golf shots from flat, downhill, and uphill lies. A computer assisted rehabilitation environment (CAREN) was used to collect 3D kinematics and kinetics and a Foresight GC2 launch monitor was used to measure performance outcomes (ball speed, launch angle, azimuth, side spin, and offline displacement). The mean position of the centre of pressure moved approximately 9.4% closer to the front foot for downhill lies and approximately 8.9% closer to the back foot for uphill lies. The speed of the ball was not significantly affected by the lie, but the distance the ball travelled was. An uphill lie encourages spin of the ball to the left, and may increase the risk of playing a hook shot

FACTORS INFLUENCING VARIATION IN DIVE HEIGHT IN 1M SPRINGBOARD DIVING

The aim of this study was to determine the factors contributing to variation in dive height in performing a 1m springboard dive. 15 performances of a forward dive pike by an international diver were recorded using high speed video (250 Hz) and were digitised manually. The relationships between variables at hurdle landing, during board contact and dive height were determined. Hip extension during board contact accounted for 77% of the variance in dive height

ADJUSTMENT IN THE FLIGHT PHASE OF 1M SPRINGBOARD FORWARD PIKE DIVES

The aim of this study was to investigate the variability in 1m springboard forward pike dives (101B). Variability of body orientation angle at takeoff and water entry together with joint angle time histories of 15 forward pike dives, performed by an international diver, were determined using video analysis. A computer simulation model was used to investigate the effects of initial conditions variability and flight phase configuration variability on outcome (orientation at entry) variability. It was found that the variation in the simulated orientation at entry arising from variability in the initial conditions was greater than the actual variation. This indicates that the diver used feedback correction to make adjustments during flight to reduce the variability of his entry angle

The effect of uphill and downhill slopes on weight transfer, alignment and shot outcome in golf

The aim of the study was to examine changes in weight transfer, alignment and shot outcome during golf shots from flat, uphill, and downhill slopes. Twelve elite male golfers hit 30 shots with a six-iron from a computer assisted rehabilitation environment (CAREN) used to create 5° slopes while collecting 3D kinematics and kinetics of the swing. A launch monitor measured performance outcomes. A shift in the centre of pressure was found throughout the swing when performed on a slope, with the mean position moving approximately 9% closer to the lower foot. The golfers attempted to remain perpendicular to the slope, resulting in the weight transfer towards the lower foot. The golfers adopted a wider stance in the sloped conditions and moved the ball towards the higher foot at address. Ball speed was not significantly affected by the slope, but launch angle and ball spin were. As predicted by the coaching literature, golfers were more likely to hit shots to the left from an uphill slope and to the right for a downhill slope. No consistent compensatory adjustments in alignment at address or azimuth were found, with the change in final shot dispersion due to the lateral spin of the ball

ADJUSTMENT IN THE TAKEOFF PHASE OF 1-M SPRINGBOARD FORWARD DIVES

The aim of this study was to investigate whether any adjustment is made during the board contact phase of 1-m springboard forward dives. Variability of body orientation angle at landing from hurdle (touchdown) and at takeoff together with joint angle time histories of 15 forward pike dive takeoffs, performed by an international diver, were determined using video analysis. A computer simulation model of a diver and springboard was used to determine the effects of perturbations of initial conditions on takeoff variability. The variation at takeoff obtained in the simulation outcome was much greater than in the actual performance, indicating that the diver made adjustments during the board contact phase. The diver varied his body configuration during the board recoil phase to adjust his body orientation, leading to low variability at takeoff