Somadeepti N. Chengalur and Roger M. Bartlett
Carl Payton, Vasilios Baltzopoulos and Roger Bartlett
The purpose of this study was to present a method of determining the contributions made by rotations of the trunk and upper extremity to hand velocity during the front crawl pull, and to illustrate this with an example. Six male swimmers performed front crawl trials at their middle distance pace (1.52 ± 0.12 m.s−1). Their underwater arm stroke was recorded from the front and side using video cameras suspended over periscope systems. Recordings were digitized at 50 Hz and the 3-D coordinates of the upper extremity were obtained using a DLT algorithm. Shoulder kinematics (flexion/extension, transverse abduction/adduction, internal/external rotation) and elbow kinematics (flexion/extension) were then calculated. Trunk roll kinematics were obtained by digitizing above-water video recordings of a fin attached to each swimmer’s back. The contribution of each body segment rotation to hand velocity was computed using |ɷ × r| cos ϕ, where ɷ was the segment’s angular velocity, r was the position vector of the hand from the segment’s axis of rotation, and ϕ was the angle between hand velocity v hand/pool and v (where v = ɷ × r). Analysis revealed that shoulder extension was the joint motion primarily responsible for producing hand velocity during the insweep (relative contribution: min 66% to max 118%). This was due to the angular velocities and hand-to-joint axis distances for shoulder extension being greater than those of the other joint motions analyzed. The other rotations at the shoulder also contributed to hand velocity during the insweep, but to a lesser extent (transverse adduction: 13% to 49%; internal rotation: −1% to +40%). On average, elbow flexion accounted for 25% of the hand velocity in the middle of the insweep. Trunk roll did not make a positive contribution to hand velocity during the insweep phase (–3% to –48%), contradicting the findings of previous studies.
Russell J. Best, Roger M. Bartlett and Richard A. Sawyer
This paper reports a study of the optimal release of men's and women's new and old rule javelins involving modeling, simulation, optimization (including sensitivity analysis), and simulation evaluation. Because of the lack of repro-ducibility in earlier results of two-dimensional flight simulation research, the paper presents a continuation of the two-dimensional model used previously. As expected, each javelin was found to have a different optimal release for a given individual, and the optimal release varied with the thrower's nominal release speed. A limited degree of simulation evaluation was achieved by comparison of the model and simulation results with measured throws. Within the constraints of measurement error, this tended to support both the adequacy of the two-dimensional model and the results of the simulations for such high standard throws. However, further experimental studies to quantify the angle of yaw (sideslip) in measured wind conditions are recommended to assess any changes needed to the two-dimensional model of javelin throwing and to determine the advisability of including this three-dimensional aspect of javelin release in future simulations.
Roger Bartlett, Erich Müller, Christian Raschner, Stefan Lindinger and Caroline Jordan
The aim of this study was to compare the plantar pressures and forces recorded from both feet of two groups of javelin throwers of different performance levels, in order to investigate differences between skill levels. The study was carried out using an EMED insole system on a Tartan javelin runway at the University of Innsbruck, Austria. Most of the differences (at p < .01) between the two groups were found in the two foot contacts during the delivery stride. Higher maximum total forces (forces on the whole foot) and maximum pressures were recorded for the more skilled or club throwers during the right foot contact at the beginning of this stride. For the left foot landing before release, the club throwers exhibited higher overall maximum forces and overall pressures (the largest forces and pressures recorded on any of the different foot regions) than the novices. The differences between the groups in the medial forefoot region contributed significantly to this result.
Roger Bartlett, Erich Müller, Stefan Lindinger, Fritz Brunner and Calvin Morriss
This study compared three-dimensional release parameters and important features of the throwing technique for male javelin throwers of three different skill levels (elite, club, novice), recorded using three-dimensional cine or video. As expected, significant differences (p < .01) in throw distances and release speeds were found between all three groups. The only other release parameter for which a significant difference was found (between club and novice groups) was the yaw angle. The increase in release speed with increasing skill across the groups may be attributable in part to greater run-up speeds. Also important were significantly greater peak speeds of the throwing shoulder, elbow, and hand during the delivery stride for the elite group compared to the other groups. Significantly longer acceleration paths at the start of the delivery stride and a delay in elbow flexion until after final foot strike for the elite throwers were also important in generating greater release speeds.