title: Velocity and acceleration before contact in the tackle during rugby union matches.
abstract: The velocity and acceleration at which the ball-carrier or tackler enters the tackle may contribute to winning the contest and prevailing injury free. Velocity and acceleration have been quantified in controlled settings, whereas in match-play it has been subjectively described. The purpose of this study was to determine the velocity and acceleration of the ball-carrier and tackler before contact during match-play in three competitions (Super 14, Varsity Cup, and Under-19 Currie Cup). Using a two-dimensional scaled version of the field, the velocity and acceleration of the ball-carrier and tackler were measured at every 0.1 s to contact for 0.5 s. For front-on tackles, a significant difference (P < 0.05) between the ball-carrier (4.6 ± 1 m · s⁻¹) and tackler (7.1 ± 3.5 m · s⁻¹) was found at the 0.5 s time to contact interval in the Varsity Cup. For side-on tackles, differences between the two opposing players were found at 0.5 s (ball-carrier: 4.6 ± 1.7 m · s⁻¹; tackler: 3.1 ± 1.2 m · s⁻¹) and 0.4 s (ball-carrier: 6.3 ± 2.3 m · s⁻¹; tackler: 3.7 ± 1.6 m · s⁻¹) at Under-19 level. After 0.4 s, no significant differences (P > 0.05) were evident. Also, the ball-carrier's velocity over the 0.5 s was relatively stable compared with that of the tackler. Results suggest that tacklers adjust their velocity to reach a suitable relative velocity before making contact with the ball-carrier.
authors.affiliation: UCT/MRC Research Unit for Exercise and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Newlands, South Africa. sharief.hendricks@uct.ac.za
authors.forename: Sharief
authors.initials: S
authors.lastname: Hendricks
authors.forename: David
authors.initials: D
authors.lastname: Karpul
authors.forename: Fred
authors.initials: F
authors.lastname: Nicolls
authors.forename: Michael
authors.initials: M
authors.lastname: Lambert
mesh_terms: D000054:Acceleration; D001265:Athletic Injuries; D054874:Athletic Performance; D003163:Competitive Behavior; D005538:Football / Q000293:injuries; D006801:Humans; D012307:Risk Factors; D013647:Task Performance and Analysis