http://www.sarugbymag.co.za/how-tough-tackle-sanctions-impact-the-game/
Article says much more, but here's a snapshot...
THE RESEARCH STUDY
World Rugby's research team, led by Tucker, studied 611 incidents that resulted in HIAs and compared them to more than 3,500 tackles that didn't cause head injuries.
The most significant discovery was that 335 HIA injuries occurred while making a tackle and 129 while being tackled.
'That was surprising and challenging from a legal perspective, because the law is almost exclusively written to protect the ball-carrier, who is on the receiving end of most instances of foul play,' says Tucker.
The research team then looked at why the tackler is 2.6 times more at risk of a head injury than the ball-carrier, with every analysed tackle scored according to 20 or so factors, including the following:
• Relative speed of players: Backline players are twice as likely to get injured while making a tackle than forwards, probably because backs tend to engage in higher speed tackles. High-speed tackles are more dangerous than medium-speed tackles, which are more dangerous than static tackles.
• Nature of the head contact in the tackle: Was it head to head, head to shoulder, head to hip, head to knee, etc? Head to head contact is six times more risky than head to hip contact. The ideal target for the tackler is between the sternum and the waist of the ball-carrier. Overall, the risk of injury is 4.3 times higher for legal tackles with higher contact (shoulder and head to head) than legal tackles with lower contact (below the shoulder).
• Body position of the ball-carrier and tackler: Were they upright, bent at the waist or diving/falling? As either of the players can be in one of three positions, there are nine possible combinations. The most injuries occur when both players are upright. The lowest risk for the ball-carrier is when he is bent at the waist, no matter what the tackler does. For the tackler, the risk is lowest when diving and highest when upright. 'The key message here was that an upright tackler is the situation we want to avoid, because it is higher risk and happens quite often,' says Tucker. 'The safest tackle is one where the tackler is bent at the waist or diving.'
• Type of tackle: Was it an active or passive shoulder or a smother tackle? The research team then produced a spectrum of risk, and worked out which type of tackles were more and less likely to cause a head injury. 'Once we knew that, we could look at substituting high-risk tackles with low-risk tackles,' says Tucker. 'One way to eliminate high-risk tackles would be to ban tackling, but obviously that's not an option. That would be like banning cars to prevent car accidents. Instead, we wanted to look at ways to shift behaviour away from high risk towards low risk. That meant, for instance, getting tacklers lower and bent at the waist, lowering the speed of the tackle, or having fewer front- on tackles. Of course, some of these are feasible, others are not, and our challenge was to identify where a difference could realistically be made. That's where the expert multidisciplinary working group came in.'
www.bbc.co.uk
