BIOMECHANICS OF THE RUGBY UNION PLACEKICK CASE STUDY OF JONNY WILKINSON (Newcastle Falcons, Toulon, England, and the British & Irish Lions)

TECHNIQUE REVIEW Simple, repeatable, fluid, rhythmical technique Highlights literature findings Approach Support Foot Position Trunk Lean Trunk & Pelvic Rotations Use of Non-Kicking Side Arm Kicking Leg Motion Segmental Contributions to Kicking Leg Swing

APPROACH 45° Approach Angle Promotes support foot planting close to ball Keeps chest towards ball for later counter-rotation between shoulders and pelvis » No rugby study has investigated the influence of approach angle but soccer studies have identified a 45-60° angle optimises kicked ball speed [1-4] Optimal Length Generates momentum into the kicking kinetic chain Doesn’t create excessive braking forces when support foot is planted » No rugby study into length influences but soccer has identified longer approaches resulting in higher kicked ball speeds [1,5]

SUPPORT FOOT POSITION Angled approach leads to close foot placing Initial observations suggest position within suggested area for optimal kicking performances » Position 5-10cm vertical and 5-28cm horizontal distance to the ball [6] » Close foot placement results in consistent high ball launch velocities from tee [7] Position optimal for kicking style Not too close to prevent trunk and pelvic rotation contributions » As seen in kickers with straight approach to ball Not too far away to alter kicking leg swing » Wider foot placing results in extensive hip abduction and a prolonged leg swing arc [7] » Leads to more lateral leg swing – a reaching for the ball

TRUNK LEAN Trunk lean counter’s lean of support leg Maintains kickers balance by keeping centre of mass above support base » Planted support foot and bracing knee joint Keeps trunk’s axis of rotation vertical and parallel to ball to allow trunk rotation to contribute to kinetic chain Lean towards ball identified as used in the most successful kickers [8]

TRUNK/PELVIC ROTATION Pelvis opens from closed position at support foot planting » Allows kicking leg to swing through towards target » Hip abductors utilised to generate extra power in kick Trunk counter-rotation to pelvic motion » Prevents pelvis from over-opening resulting in lessened chance of excessive pelvis rotation and therefore less probability of “hooking” ball wide of posts » Helps generate torque contribution into kinetic chain of momentum into kicking foot swing

NON-KICKING SIDE ARM MOTION Arm used for balance when support foot is planted As leg swings towards ball, arm rotates across body away from ball » Pulls trunk into its counter-rotation with pelvis Starts action-reaction mechanism [8] » Most accurate kickers used more swing to greater extent [8] With trunk lean to position non-kicking-side arm and kicking foot close to base of support » Those with greater non-kicking-arm swing also reported further distances for kicked ball flight [8]

LEG SWING Kicking leg fully cocked through knee flexion and slightly hip extension » Utilises powerful thigh muscles in force generation » Longer swinging arc of kicking foot results in more momentum for kicking foot Kicking leg follows through towards target » Pushes ball directly towards target, decreases chances of ball missing target » Utilises hip flexors in force generation for struck ball velocity » Keeps body’s momentum moving towards target » Kicking leg kinematics summarised in soccer placekicking [9,10] but not as yet fully for rugby placekicking

REFERENCES 1.Isokawa & Lees (1988). Science and Football, pp ; London: E & FN Spon. 2.Barfield (1995). Journal of Human Movement Studies, 29: Barfield et al. (2002). Journal of Sports Science & Medicine, 3: Kellis et al. (2004). Medicine & Science in Sports & Exercise, 36: Opavsky (1988). Science and Football, pp ; London: E & FN Spon. 6.Hay (1985). The Biomechanics of Sports Techniques; New Jersey: Prentice-Hall. 7.Baktash et al. (2009). International Journal of Sports Science & Engineering, 3: Bezodis et al. (2007). Sports Biomechanics, 6: Lees & Nolan (1998). Journal of Sports Science, 18: Kellis & Katis (2007). Journal of Sports Science & Medicine, 6: