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The aim of this study was to test the effect that changing targets during a simple long lunge attack in fencing exerts on the temporal parameters of the reaction response, the execution speed, and the precision and the coordination of the movement pattern. Thirty fencers with more than 10 years of experience participated in this study. Two force platforms were used to record the horizontal components of the reaction forces and thereby to determine the beginning of the movement. A three-dimensional (3D) system recorded the spatial positions of the 9 markers situated on the fencer plus the epee, while a moving target was projected on a screen, enabling the control of the target change. The results indicated that when a target change is provoked the reaction time (RT), movement time (MT), and the time used in the acceleration phase of the centre of mass (CM) increases significantly with respect to the attack executed with a straight thrust. The speed and horizontal distance reached by the CM at the end of the acceleration phase (VX(CM) and SX(CM), respectively) significantly decreased, while the errors increased. However, the temporal sequence of the movement pattern did not appreciably change.

The aim of this study was to determine how much the predicted distance of a hammer throw is affected by (1) ignoring air resistance and (2) assuming that the centre of mass of the hammer coincides with the centre of the ball. Three-dimensional data from actual throws (men: 72.82 +/- 7.43 m; women: 67.78 +/- 4.02 m) were used to calculate the kinematic conditions of the hammer at release. A mathematical model of the hammer was then used to simulate the three-dimensional airborne motion of the hammer and to predict the distance of the throw. The distance predicted for vacuum conditions and using the ball centre to represent the hammer centre of mass was 4.30 +/- 2.64 m longer than the official distance of the throw for the men and 8.82 +/- 3.20 m longer for the women. Predictions using the true centre of mass of the hammer reduced the discrepancy to 2.39 +/- 2.58 m for the men and 5.28 +/- 2.88 m for the women. Predictions using air resistance and the true centre of mass of the hammer further reduced the discrepancy to -0.46 +/- 2.63 m for the men and 1.16 +/- 2.31 m for the women. Approximately half the loss of distance produced by air resistance was due to forces made on the ball and the remainder to forces made on the cable and handle. Equations were derived for calculation of the effects of air resistance and of the assumption that the centre of mass of the hammer coincides with the centre of the ball, on the distance of the throw.