Velocity and acceleration before contact in the tackle during rugby union matches

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.