Table 1

Characteristics of the tackle analysed in this study

Tackle type
Active shoulder tackle	First contact is with the tackler’s shoulder, and the tackler drives or attempts to drive the ball carrier (BC) backwards.
Passive shoulder tackle	First contact is with the tackler’s shoulder and the tackler does not drive or attempt to drive the BC back.
Smother tackle	Tackler uses the chest and attempts to wrap both arms around the ball carrier.
Tap tackle	Tackler trips the BC with a hand on the lower limb below the knee.
Lift tackle	Tackler lifts the BC’s hips above the BC head.
No arm tackle	Tackler impedes the BC without use of their arms.
High tackle	Tackler makes contact above the BC shoulders, as adjudicated by the on-field referee.
Tackle direction
Front-on	Tackler makes contact on the front of the BC.
On angle	Tackler makes contact with the BC on an angle.
Side-on	Tackler makes contact with the side of the BC.
Back	Tackler makes contact with the BC from behind.
Accelerating player
Tackler	Only the tackler accelerates into contact.
Ball carrier	Only the BC accelerates into contact.
Both	Both tackler and BC accelerate into the contact.
Neither	Neither player accelerates into contact.
Tackler and BC speed
High	Running or sprinting
Low	Walking or jogging
Stationary	Standing still or moving minimally
Tackler and BC body positions
Upright	The player is standing in an upright position, with the knees only slightly bent and with minimal hip flexion.
Bent at the waist	The player is bent at the waist or crouched.
Falling/diving	The player is in the process of diving or falling to ground at the point of contact.