Velocity and Acceleration before contact in the Tackle Sharief Hendricksa, David Karpula, Fred Nicollsb and Michael Lamberta aMRC/UCT Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, the University of Cape Town and the Sports Science Institute of South Africa, Cape Town, South Africa bDepartment of Electrical Engineering, University of Cape Town, Rondebosch, Cape Town 7701, South Africa . Correspondence to: Sharief Hendricks MRC/UCT Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, the University of Cape Town and the Sports Science Institute of South Africa, Cape Town, South Africa PO Box 115 Newlands 7725 Tel: + 27-21-650-4572 Fax: +27-21-686-7530 Email:
[email protected] 1. Introduction A major characteristic of Rugby Union is frequent bodily collisions between two or more players. These physical collisions are generally referred to as the tackle (Hendricks & Lambert, 2010; Gabbett & Ryan, 2009; Gabbett & Kelly, 2007).The tackle contest can be identified when an opposing player, not in possession of the ball (tackler), contacts a player in possession of the ball (ball-carrier) in an attempt to prevent further progression of the ball towards the tackler’s try-line. The tackle places a range of physiological, and to an extent, psychological demands on players (Takarada, 2003; Deutsch, Kearney, & Rehrer, 2007; Passos et al., 2009; Passos et al., 2008; Brault, Bideau, Craig, & Kulpa, 2010; Passos, Araujo, Davids, & Shuttleworth, 2011). Players’ are expected to meet these demands on average about 10 to 25 times per a match depending on playing position (Deutsch et al., 2007; Quarrie & Hopkins, 2008).