Wilkinson's Arm to Give Aussies a Kicking?

Today's quarter-final clash between England and Australia in the Rugby World Cup could well hinge on the swing of Jonny Wilkinson's arm, according to scientists who have studied his kicking technique. Their research suggests that swinging his right arm across his body during a kick is crucial to his accuracy, something that rugby coaching manuals have ignored.

England supporters and coaches alike may be concentrating on Wilkinson's feet as he steps up to kick the ball in Marseille this afternoon but the scientists believe his arm motion is crucial. It helps to counterbalance the swing of the kicking leg and keeps his hips and shoulders front on to the goal for longer, giving him more margin for error. "There's a really quite vigorous upper body motion," said Grant Trewartha, an expert in biomechanics at Bath University. "[His arm] starts way out at the side and a little bit backwards and really swings right across the body during the kicking action."

To investigate the effect of upper body motion, Dr Trewartha and his colleagues studied the technique of five university team place-kickers. The students wore reflective patches while their kicking motion was recorded on video. By tracking the movement of the reflective patches the researchers could construct a 3D representation of their movements.

Upper body movements seemed to be surprisingly important to a kicker's accuracy. "The upper body seems to go through fairly major motions and play a role in kicking technique, which is certainly something that has never found its way into the coaching literature," said Dr Trewartha. "People have tended to concentrate, perhaps unsurprisingly, on the kicking leg and the planting of the non-kicking leg."

They report in the journal Sports Biomechanics that the kickers with the most vigorous arm motion were the most accurate, particularly on longer kicks. "If you've got the kicking leg producing rotation in one direction you want to counteract that with motion in the other direction because that means that overall the body rotation is closer to zero," he added.

Wilkinson, who has so far scored 40 points in the world cup, is out-swung though by his counterpart in the Scotland team, Chris Paterson. The Scottish full-back has not missed a kick yet in his team's route to a quarter-final clash with Argentina on Sunday. When he kicks, his arm motion is extremely pronounced, said Dr Trewartha. "You can't fail to notice it because it's so exaggerated - it looks unnatural." The New Zealand number 10 Dan Carter, however, uses a minimal arm swing when he kicks.