A new angle on throwing

Copyright @ 2006 Institute of physic

Optimum projection angle for attaining maximum distance in a rugby place kick

This article has been made available through the Brunel Open Access Publishing Fund.This study investigated the effect of projection angle on the distance attained in a rugby place kick. A male rugby player performed 49 maximum-effort kicks using projection angles of between 20 and 50°. The kicks were recorded by a video camera at 50 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity and projection angle of the ball. The player's optimum projection angle was calculated by substituting a mathematical expression for the relationship between projection velocity and projection angle into the equations for the aerodynamic flight of a rugby ball. We found that the player's calculated optimum projection angle (30.6°, 95% confidence limits ± 1.9°) was in close agreement with his preferred projection angle (mean value 30.8°, 95% confidence limits ± 2.1°). The player's calculated optimum projection angle was also similar to projection angles previously reported for skilled rugby players. The optimum projection angle in a rugby place kick is considerably less than 45° because the projection velocity that a player can produce decreases substantially as projection angle is increased. Aerodynamic forces and the requirement to clear the crossbar have little effect on the optimum projection angle

Release angle for attaining maximum distance in the soccer throw-in

We investigated the release angle that maximises the distance attained in a long soccer throw-in. One male soccer player performed maximum-effort throws using release angles of between 10 and 60º, and the throws were analysed using two-dimensional videography. The player’s optimum release angle was calculated by substituting mathematical expressions for the measured relationships between release speed, release height and release angle into the equations for the flight of a spherical projectile. We found that the musculoskeletal structure of the player’s body had a strong influence on the optimum release angle. When using low release angles the player released the ball with a greater release speed and, because the range of a projectile is strongly dependent on the release speed, this bias toward low release angles reduced the optimum release angle to about 30°. Calculations showed that the distance of a throw may be increased by a few metres by launching the ball with a fast backspin, but the ball must be launched at a slightly lower release angle

Effects of run-up velocity on performance, kinematics, and energy exchanges in the pole vault

Copyright @ 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and 85 reproduction in any medium, provided the original author and source are credited. The article was made available through the Brunel University Open Access Publishing Fund.This study examined the effect of run-up velocity on the peak height achieved by the athlete in the pole vault and on the corresponding changes in the athlete's kinematics and energy exchanges. Seventeen jumps by an experienced male pole vaulter were video recorded in the sagittal plane and a wide range of run-up velocities (4.5-8.5 m/s) was obtained by setting the length of the athlete's run-up (2-16 steps). A selection of performance variables, kinematic variables, energy variables, and pole variables were calculated from the digitized video data. We found that the athlete's peak height increased linearly at a rate of 0.54 m per 1 m/s increase in run-up velocity and this increase was achieved through a combination of a greater grip height and a greater push height. At the athlete's competition run-up velocity (8.4 m/s) about one third of the rate of increase in peak height arose from an increase in grip height and about two thirds arose from an increase in push height. Across the range of run-up velocities examined here the athlete always performed the basic actions of running, planting, jumping, and inverting on the pole. However, he made minor systematic changes to his jumping kinematics, vaulting kinematics, and selection of pole characteristics as the run-up velocity increased. The increase in run-up velocity and changes in the athlete's vaulting kinematics resulted in substantial changes to the magnitudes of the energy exchanges during the vault. A faster run-up produced a greater loss of energy during the take-off, but this loss was not sufficient to negate the increase in run-up velocity and the increase in work done by the athlete during the pole support phase. The athlete therefore always had a net energy gain during the vault. However, the magnitude of this gain decreased slightly as run-up velocity increased

Optimum projection angle for attaining maximum distance in a soccer punt kick

Copyright @ Journal of Sports Science and Medicine 2011.This article has been made available through the Brunel Open Access Publishing Fund.To produce the greatest horizontal distance in a punt kick the ball must be projected at an appropriate angle. Here, we investigated the optimum projection angle that maximises the distance attained in a punt kick by a soccer goalkeeper. Two male players performed many maximum-effort kicks using projection angles of between 10 degrees and 90 degrees. The kicks were recorded by a video camera at 100 Hz and a 2-D biomechanical analysis was conducted to obtain measures of the projection velocity, projection angle, projection height, ball spin rate, and foot velocity at impact. The player's optimum projection angle was calculated by substituting mathematical equations for the relationships between the projection variables into the equations for the aerodynamic flight of a soccer ball. The calculated optimum projection angles were in agreement with the player's preferred projection angles (40 degrees and 44 degrees). In projectile sports even a small dependence of projection velocity on projection angle is sufficient to produce a substantial shift in the optimum projection angle away from 45 degrees. In the punt kicks studied here, the optimum projection angle was close to 45 degrees because the projection velocity of the ball remained almost constant across all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle and so the optimum projection angle is well below 45 degrees.This article is made available through the Brunel University Open Access Publishing Fund

Changes in long jump take-off technique with increasing run-up speed

The aim of this study was to determine the influence of run-up speed on take-off technique in the long jump. Seventy-one jumps by an elite male long jumper were recorded in the sagittal plane by a high-speed video camera. A wide range of run-up speeds was obtained using direct intervention to set the length of the athlete's run-up. As the athlete's run-up speed increased, the jump distance and take-off speed increased, the leg angle at touchdown remained almost unchanged, and the take-off angle and take-off duration steadily decreased. The predictions of two previously published mathematical models of the long jump take-off are in reasonable agreement with the experimental data

Effects of a sand running surface on the kinematics of sprinting at maximum velocity

Performing sprints on a sand surface is a common training method for improving sprint-specific strength. For maximum specificity of training the athlete’s movement patterns during the training exercise should closely resemble those used when performing the sport. The aim of this study was to compare the kinematics of sprinting at maximum velocity on a dry sand surface to the kinematics of sprinting on an athletics track. Five men and five women participated in the study, and flying sprints over 30 m were recorded by video and digitized using biomechanical analysis software. We found that sprinting on a sand surface was substantially different to sprinting on an athletics track. When sprinting on sand the athletes tended to ‘sit’ during the ground contact phase of the stride. This action was characterized by a lower center of mass, a greater forward lean in the trunk, and an incomplete extension of the hip joint at take-off. We conclude that sprinting on a dry sand surface may not be an appropriate method for training the maximum velocity phase in sprinting. Although this training method exerts a substantial overload on the athlete, as indicated by reductions in running velocity and stride length, it also induces detrimental changes to the athlete’s running technique which may transfer to competition sprinting

Effect of altitude on 100-m sprint times: An analysis of race times from the finals at major championships

The aim of this study was to determine the effect of altitude on 100-m sprint times. A nonlinear regression analysis was conducted using competition data from the finals at major championships. The results indicate that the time advantage of competing at an altitude of 2250 m is about 0.19 ± 0.10 s for men and 0.23 ± 0.13 s for women. This is a substantial performance advantage and so the altitude of the competition venue should be taken into consideration when recognizing record performances

Effect of the timing of the pole plant on energy loss in the pole vault take-off

Some leading pole vault coaches recommend a late planting of the pole, at close to the instant of take-off. This technique is believed to reduce the energy lost during the take-off and produce a higher vault. The present study re-analysed data from a previous study in which male pole vaulters manipulated the timing of the pole plant. An individual analysis showed that the timing of the pole plant did not clearly affect the change in the total energy of the athlete/pole system during the take-off. This result suggests there might be no advantage in using a late pole plant. An individual analysis can sometimes be more likely to yield a true interpretation of experimental data than a group analysis