title: Prediction of distance in hammer throwing.
abstract: 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.
authors.affiliation: Department of Kinesiology, Indiana University, Bloomington, IN 47405, USA. dapena@indiana.edu
authors.forename: Jesús
authors.initials: J
authors.lastname: Dapena
authors.forename: Marcos
authors.initials: M
authors.lastname: Gutiérrez-Dávila
authors.forename: Víctor M
authors.initials: VM
authors.lastname: Soto
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Rojas
mesh_terms: D000054:Acceleration; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005260:Female; D006112:Gravitation; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D009716:Numerical Analysis, Computer-Assisted; D015203:Reproducibility of Results; D014142:Track and Field