A LOOK AT GLIDING AND UNDERWATER KICKING IN THE SWIM TURN

A series of studies were conducted to examine hydrodynamic drag throughout the gliding and stroke preparation phases of the freestyle tumble turn. The first study examined the effects of velocity and depth on the passive drag forces and demonstrated that significant drag reduction benefits were found with the swimmers performing glides underwater when compared to gliding at the water surface. The second study sought to establish the appropriate velocity for initiating underwater kicking, as well as the most efficient gliding position and kicking technique. The results indicate that swimmers should initiate underwater kicking at between 1.9 and 2.2 ms-1. No significant differences were found between two streamline glide positions, and similarly, between three underwater kicking styles. The results of these studies present strategies for reducing the drag forces experienced by swimmers throughout the freestyle turn

THE USE OF COMPUTATIONAL FLUIDS DYNAMICS TO OPTIMISE UNDERWATER KICKING PERFORMANCE

Elite swimmers use a variety of underwater kicking patterns in current competition with little scientific information used in their selection. The current study sought to discriminate between 2 different patterns of underwater dolphin kick (large amplitude, slow kicks versus small amplitude, fast kicks) using computational fluid dynamics (CFD). Inputs into the CFD model included an accurate 3D mapping of an elite swimmer and detailed kinematic information of the underwater kicking from a 2D analysis. Initial results of the static CFD model were in agreement with previous empirical testing of passive drag. Results of the dynamic CFD modelling and comparisons are still to be finalised

QUANTIFYING THE HAND-CURVE AND OARLOCK FORCES FOR DETERMINING THE DIFFERENCE BETWEEN EXPERIENCED AND ELITE MALE SWEEP ROWERS

Rowing lends itself well to biomechanical research given that it is a closed, cyclic skill that is technically demanding. While a relatively large number of papers have been published on the force profile of the rowing stroke and its effect on performance (DalMonte and Komor, 1989; Millward, 1987), very little research has been conducted into describing specific technical points which may lead to undesirable force characteristics. To allow a more knowledgeable feedback to an athlete's technique, such that improved performances result, it is necessary to isolate the critical factors that can discriminate between performance levels. Angst (1980) prepared a paper in which he subjectively described a relationship between the path that the handle of the oar described (hand-curve) and the shape of the force profile. The hand-curve is one method that could be used as a more direct feedback to the rower, with observable adjustments in technique having direct implications to the force applied. The current project involves determining those hand-curve and force profile variables that can be used to effectively differentiate between performance levels in sweep rowing

DIFFERENTIATION OF THE ENERGETIC PARAMETERS BETWEEN MALE AND FEMALE ELITE POLE VAULTERS

This study aimed to examine whether differences were evident in the average energetic waveforms and energy summary results between four male and four female elite pole vaulters. Full body DXA scans and 3D body surface scans were conducted for each of the athletes to allow subject specific body segment inertial parameters to be calculated. A total of 67 vaults were recorded across the 8 vaulters, with a 3D kinematic analysis being performed on each vault. Translational and rotational kinetic energy; and gravitational potential energy were derived from this analysis and used to calculate total vaulter energy. Average summary energy values and energetic waveforms were compared between the male and female vaulters. Significant differences were found in some of the initial energy values as well as variables related to the pole extension phase

AN ANALYSIS OF DIFFERENT POLE VAULTING POLE LOAD-DEFORMATION TESTING REGIMES

This study aimed to determine whether differences in the pole elastic energy characterisation were evident between quasi-static and dynamic load-deformation testing on pole vault poles. A total of 12 pole vault poles were tested from three different manufacturers, who each utilise different materials within their pole construction processes. A quasi-static and a dynamic pole bending test was performed on each pole utilising a custom built rig. A 3D load cell was positioned in series with the rig to obtain the forces required to develop a load-deformation curve for each trial. The results of the bending trials demonstrate a noticeable difference in the load-deformation curves obtained via the two methods, most notably regarding the degree of hysteresis between the loading and unloading phases and the resultant elastic potential energy calculations

FORCE DEVELOPMENT PROFILE OF THE LOWER LIMBS IN THE GRAB AND TRACK START IN SWIMMING

Left and right ground reaction forces of 9 male and 7 female national and international level swimmers were measured during grab and track starts. Analysis of temporal, kinetic and velocity measures indicated that while swimmers left the block faster in the track start, grab starts enabled swimmers to generate greater vertical impulses and take-off velocities. No significant differences were found in the horizontal impulses and the time to 6m between the two starts. Left and right force profiles were examined qualitatively to identify key points related to force development strategies and lateral asymmetr

MORPHOLOGY AND HYDRODYNAMIC RESISTANCE IN YOUNG SWIMMERS

Morphology and hydrodynamic drag were measured of 6 males and 6 females, from each of the 9, 11 and 13 yr age groups. Net forces were examined when towing swimmers while prone streamlined gliding and flutter kicking at 1.3 to 2.5 ms-1. The passive drag force at 1.9, 2.2 and 2.5 ms-1 increased with age and anthropometry, but no changes were found at 1.3 and 1.6 ms-1. Stepwise regression revealed passive drag best predicted net active drag at velocities of 1.3, 1.9, 2.2 and 2.5 ms-1. Results supported the Froude number theory that increased height will reduce wave-making drag

OPTIMISING KINETICS IN THE FREESTYLE FLIP TURN PUSH-OFF

INTRODUCTION: Turning technique is an important component in swimming performance with turn times positively correlating with final event time. However, little is known about the mechanics of an effective turn. This study sought to provide an exploratory analysis of how various kinetic and hydrodynamic variables during wall push-off are related to the wall exit velocity. METHODS: Thirty experienced male swimmers with body types of within one SD of the mean for selected anthropometric parameters reported for elite male adult swimmers (Mazza et al., 1994) were recruited for the study. During three freestyle flip turns, selected kinetic, hydrodynamic and kinematic variables of the wall pushoff were recorded. The wall push-off phase was measured from the point of maximum knee flexion during wall contact until the feet left the wall. Kinetics were recorded via a 2D vertically mounted forceplate which recorded peak push-off force and total impulse. The acceleration of each swimmer’s centre of gravity (CG) and wall exit velocity of the CG were calculated from underwater videography. Hydrodynamic peak drag force and drag impulse were calculated from the kinetic and kinematic data using a derivative of Newton’s second law. RESULTS: A stepwise regression was performed with wall exit velocity as the criterion variable and push-off time, peak propulsive force, total propulsive impulse, peak drag force, and total drag impulse as the independent variables. The stepwise regression yielded peak drag force, peak propulsive force and push-off time in the equation, with beta values indicating that the peak drag force carried the highest weighting of the three variables. CONCLUSIONS: The results of the stepwise regression indicated that an optimal combination of a low peak drag force, high peak propulsive force and increased wall time produced the fastest wall exit velocity. The inclusion of the peak drag force in the regression equation as the most important predictor of wall exit velocity highlights the importance of drag in turning technique. Factors such as very high push-off forces and exaggerated movements during wall push-off may lead to higher peak drag forces which, in turn, could be detrimental to the overall turning performance

FREESTYLE SWIMMING: AN INSIGHT INTO PROPULSIVE AND RESISTIVE MECHANISMS

The mechanisms behind propulsion and drag generation in swimming have proven difficult to accurately and comprehensively measure. With fluid effects being the major contributing factor for swimming performance, the ability to accurately determine these effects is of great importance. Computational Fluid Dynamics (CFD) modelling provides a solution to this problem. CFD can not only quantify the net effect of the forces acting on a swimmer, but also that observed at each individual segment. CFD modelling allows complex fluid flow regimes and geometry to be simulated. The results of a CFD analysis allowed for the distribution of the forces across the body throughout the freestyle stroke to be examined. The results of this analysis include an increased level of foundational knowledge with applied outcomes that may be used to improve swimming performance

The Roles of Estrogen, Nitric Oxide, and Dopamine in the Generation of Hyperkinetic Motor Behaviors in Embryonic Zebrafish (Danio rerio)

Both estrogen (E2) and nitric oxide (NO) have been shown to affect motor function, in part, through regulation of dopamine (DA) release, transporter function, and the elicitation of neuroprotection/neurodegeneration of healthy neurons, as well as in neurodegenerative conditions such as Parkinson’s disease (PD). Currently, the “gold standard” treatment for PD is the use of levodopa (l-DOPA). However, patients who experience long-term l-DOPA and a monamine oxidase inhibitor (MAOI) treatment may develop unwanted side effects such as hyperkinesia which can be exacerbated by female Parkinsonian patients also on E2 replacement therapy. The current study was designed to determine whether embryonic zebrafish treated with either E2 or l-DOPA/MAOI develop a de novo-induced hyperkinetic movement disorder that relies on the NO pathway to elicit this hyperkinetic phenotype. Results from this study indicate that 5 days post-fertilization (dpf), fish treated with an l-DOPA + MAOI co-treatment or E2 elicited the development of a de novo hyperkinetic phenotype. In addition, the de novo l-DOPA + MAOI- and E2-induced hyperkinetic phenotypes are dependent on NO and E2 for its initiation and recovery. In conclusion, these findings point to the central role both NO and E2 play in the facilitation of de novo hyperkinesia