David G. Kerwin

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INTRODUCTION The forces produced by an athlete during the support phase of a sprint run are a vital determinant of the outcome of the performance. The purpose of this study was to improve the understanding of sprint technique in well-trained sprinters through the comprehensive analysis of joint kinetics during the support phase of a maximum-velocity sprint.(More)
The aims of this study were to investigate which arm movements are made during trip recovery, to determine the contributions of arm movements in trip recovery and to identify differences in these contributions between younger and older adults and different recovery strategies. A group of seven older adults (65-75 years) and a group of eight younger adults(More)
This study involved a theoretical and an experimental investigation of the direct free kick in soccer. Our aim was to develop a mathematical model of the ball's flight incorporating aerodynamic lift and drag forces to explore this important 'set-play'. Trajectories derived from the model have been compared with those obtained from detailed video analysis of(More)
Resultant joint moments are an important variable with which to examine human movement, but the uncertainty with which resultant joint moments are calculated is often ignored. This paper presents a procedure for examining the uncertainty with which resultant joint moments are calculated. The uncertainty was calculated by changing the parameters and(More)
Muscle forces are often estimated during human movement using optimization procedures. The optimization procedures involve the minimization of an objective function relating to the muscle forces. In this study 15 different objective functions were evaluated by examining the analytical solutions to the objective functions and by comparing their force(More)
The purpose of this investigation was to develop and evaluate a wobbling mass model of a female performing a drop landing and to examine the influence of soft tissue properties on the impact loads experienced. A planar model comprising a foot, shank, thigh and upper body segment was developed. Spring-damper systems coupled the foot to the ground and the(More)
The aim of this study was to investigate the effect of intra-limb variability on the calculation of asymmetry with the purpose of informing future analyses. Asymmetry has previously been quantified for discrete kinematic and kinetic variables; however, intra-limb variability has not been routinely included in these analyses. Synchronized lower-limb(More)
PURPOSE The aim of this study was to investigate the step characteristics among the very best 100-m sprinters in the world to understand whether the elite athletes are individually more reliant on step frequency (SF) or step length (SL). METHODS A total of 52 male elite-level 100-m races were recorded from publicly available television broadcasts, with 11(More)
The direct linear transformation (DLT) is a common technique used to calibrate cameras and subsequently reconstruct points filmed with two or more cameras in a three-dimensional object space. The assessment of the accuracy of this technique, and of the influence of the distribution of control points on accuracy were examined. It was concluded that to obtain(More)
The optimum pre-flight characteristics of the Hecht and handspring somersault vaults were determined using a two-segment simulation model. The model consisted of an arm segment and a body segment connected by a frictionless pin joint, simulating the vault from the Reuther board take-off through to landing. During horse contact, shoulder torque was set to(More)