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Sangwoo Lee, Ronald Davis, Lawrence W. Judge, Young-Hoo Kwon, Kihoon Han, Jemin Kim, Jaewoong Kim and Jaehwa Kim

The purpose of this study was to investigate the relationships among release factors (speed, height, and angle) and distance thrown in Paralympic seated shot put. Fortyeight trials performed by 11 men and 5 women during the 2012 US Paralympic trials in track and field were analyzed. With both genders combined, release speed (r = .95, p < .01) and angle (r = .51, p < .01) showed significant correlations to distance thrown. Release speed (r = .94, p < .01) in men and all release factors (r = .60–.98, p < .02) in women showed significant correlations to distance. Release speed and angle were identified as important predictors of the distance, explaining over 89–96% of the variance in distance thrown. Unlike athletes without disability, seated shotputters exhibited significant positive speed–angle correlations (combined: r = .37, p < .01; women: r = .57, p = .03). Application of these results should address a focus in training on generating speed through the release point with a consistent release angle.

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David S. Haydon, Ross A. Pinder, Paul N. Grimshaw and William S.P. Robertson

Wheelchair-propulsion kinematics have been investigated across a range of activities including wheelchair basketball, 1 wheelchair racing, 2 and daily living. 3 Variables such as contact and release angles, as well as stroke and recovery times, have been used to assess variations across athlete

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Paul G. Taylor, Raul Landeo and Jennifer Coogan

The purpose of this study was to explore movement variability of throwing arm and ball release parameters during the water polo shot and to compare variability between successful (hit) and unsuccessful (miss) outcomes. Seven injury free, subelite, females completed 10 trials of the 5 m water polo penalty shot. Intraindividual coefficient of variation percentage (CV%) values were calculated for elbow and wrist angular displacement, wrist linear velocity and ball release parameters (height, angle and velocity). Coordination variability (elbow/wrist angular displacement) was calculated as the CV% of the mean cross-correlation coefficient. Elbow and wrist displacement variability decreased to 80% of throwing time then increased toward release. Wrist linear velocity variability reduced toward release. Individual CV% values ranged between 1.6% and 23.5% (all trials), 0.4% and 20.6% (hit), and 0.4% and 27.1% (miss). Ball release height and velocity variability were low (< 12%; all trials) whereas release angle variability was high (>27%; all trials). Cross-correlation results were inconclusive. Roles of the elbow and wrist in production of stable ball release height and velocity and control of the highly variable release angle in the water polo shot are discussed and suggested for further study. Optimal levels of variability warrant future investigation.

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Brianne N. Schwark, Sasho J. Mackenzie and Eric J. Sprigings

The primary purpose of this study was to determine the optimal release conditions and corresponding arm movement pattern for the free throw for players classified as 3 to 4.5 on the international player classification system in wheelchair basketball. A 2-D, three-segment simulation model was used to investigate this problem. The computational process involved a two-step optimization scheme in which an outer computational loop was used to optimize the magnitude and timing of the muscle torques that generate the arm's motion, and an inner computational loop was used to determine the optimal angle and speed of the ball at the moment of release. The inner optimization loop revealed that Brancazio's (1981) and Hay's (1993) approaches to determining the optimal release angle produced identical results. The lowered seated height of the wheelchair basketball player required that the ball be released at a steeper angle with greater vertical velocity, and hence the need for greater shoulder torque. For the wheelchair player, the peak shoulder flexion torque generated by the model was reduced by approximately 43% when the upper arm was initially positioned at an angle approximately 40° below the horizontal, as compared to being positioned at an angle of 10° above the horizontal. For the wheelchair player, the optimal release angle and speed for a ball released at a horizontal distance of 4.09 m from the center of the basket, and 1.30 m below the rim, was computed to be 53.8° and 7.4 m/s, respectively.

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Shinji Sakurai, Bruce Elliott and J. Robert Grove

Three-dimensional (3-D) high speed photography was used to record the overarm throwing actions of five open-age, four 18-year-old, six 16-year- old, and six 14-year-old high-performance baseball catchers. The direct linear transformation method was used for 3-D space reconstruction from 2-D images of the catchers throwing from home plate to second base recorded using two phase-locked cameras operating at a nominal rate of 200 Hz. Selected physical capacity measures were also recorded and correlated with ball release speed. In general, anthropometric and strength measures significantly increased through the 14-year-old to open-age classifications, while a range of correlation coefficients from .50 to .84 was recorded between these physical capacities and ball speed at release. While many aspects of the kinematic data at release were similar, the key factors of release angle and release speed varied for the different age groups.

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Mont Hubbard and LeRoy W. Alaways

Changes in the rules for construction of the men's javelin have dramatically altered the pitching moment profile as a function of angle of attack. Thus the optimal release conditions are different for the new javelin. Optimal release conditions are presented for nominal release velocities in the range 20 < vn < 35 m/s. Although the optimal release angle remains roughly constant near 30° over this speed range, the optimal angle of attack and pitching angular velocity change substantially with speed. The main effects of the rule change have been (a) to decrease the achievable range at a nominal velocity vn = 30 m/s by about 10% by making it impossible to take advantage of the javelin's potentially large aerodynamic lift forces, and (b) to make the flight much less sensitive to initial conditions.

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David Sherwood, Keith Lohse and Alice Healy

Many research studies have shown the advantage of directing the focus of attention (FOA) externally as opposed to internally. However, it is not clear how the availability of concurrent visual feedback might impact attentional processes as the FOA is shifted between internal, external, relevant, and irrelevant sources of attention. The current experiment varied the FOA by asking the participants to judge joint angles (internal-relevant), respiration (internal-irrelevant), dart release angle (external-relevant), and tone loudness (external-irrelevant) at dart release in which task-intrinsic concurrent visual feedback was available or not. Spatial errors and trial-to-trial variability in the outcome were reduced when vision was available. Spatial errors were greater during internal judgments compared with external judgments particularly when vision was not available and when making judgments about task-relevant factors. A focus on irrelevant factors generally did not affect performance compared with relevant factors. These findings suggest that availability of concurrent visual feedback modulates focus of attention effects in motor control.

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Mark G.L. Sayers and Stephen Bishop

release velocities. Importantly, the MBP-P protocol presented here has the advantage of enabling the standardization of throwing technique and ball release angle, both factors that are acknowledged weaknesses of research in this area. 22 , 23 A key additional advantage of using a vertical ball throw

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Bryan L. Riemann and George J. Davies

not significantly influence terminal release angles nor heights, 1 possibly explaining the association similarities between the 2 tests in this study across the 2 ball masses. Nonetheless, despite small and statistically insignificant differences between the dominant and nondominant limbs with regard