Mechanics of tackling lower

[Rich_NL]

Interesting coincidence given the recent tackling trials - I have a couple of interns working in my group at work (I'm an engineer), and was chatting to their academic supervisor. He's a biomechanical engineer too, and he's been looking into rugby injuries.

He linked me to a couple of papers that look at head motion in the tackle. These were not dealing with concussion, but cognitive impairment from chronic low-grade head injuries. As found for boxers and footballers, having your head shaken about for years damages your mental performance even if you're never concussed. Old rugby players perform worse than average on things like visual memory, reaction time, motor processing and so on. Two of the main predictors of this damage is acceleration of the head, and how fast the head is spun from a contact (the rotational acceleration).

Analysing many professional tackles, they found that tackling against the upper torso (and not bending from the hip) increased the accelerations by 80-120% for the tackler, and inertial loads on the ball carrier's head (the 'whiplash' caused by a body impact moving the head) by 120-600%

It's ongoing and not definitive research, there are several angles to be explored, etc... but in terms of long-term cognitive health and youth training, it's definitely a positive step to encourage low tackling (assuming head-knee injuries aren't significantly more common than head-head, say). I wonder if someone at WR is aiming at this but using the concussion argument to simplify the case?

 

[crossref]

Did he have anything to say about the position adopted by the ball carrier

 

[Marc Wakeham]

Interesting coincidence given the recent tackling trials - I have a couple of interns working in my group at work (I'm an engineer), and was chatting to their academic supervisor. He's a biomechanical engineer too, and he's been looking into rugby injuries.

He linked me to a couple of papers that look at head motion in the tackle. These were not dealing with concussion, but cognitive impairment from chronic low-grade head injuries. As found for boxers and footballers, having your head shaken about for years damages your mental performance even if you're never concussed. Old rugby players perform worse than average on things like visual memory, reaction time, motor processing and so on. Two of the main predictors of this damage is acceleration of the head, and how fast the head is spun from a contact (the rotational acceleration).

Analysing many professional tackles, they found that tackling against the upper torso (and not bending from the hip) increased the accelerations by 80-120% for the tackler, and inertial loads on the ball carrier's head (the 'whiplash' caused by a body impact moving the head) by 120-600%

It's ongoing and not definitive research, there are several angles to be explored, etc... but in terms of long-term cognitive health and youth training, it's definitely a positive step to encourage low tackling (assuming head-knee injuries aren't significantly more common than head-head, say). I wonder if someone at WR is aiming at this but using the concussion argument to simplify the case?

Concussion can occur from shaking with no direct impact "Concussion is a temporary injury to the brain caused by a bump, blow or jolt to the head." source: https://www.nhs.uk/conditions/concussion/

So these injuries were, quite possibly, "concussion". Worryingly, from a point of monitoring, a series of very mild concussions that brought a massive cumulative effect over time. SO the player would never have realised they had suffered an injury untill far too late.

 

[Marc Wakeham]

Did he have anything to say about the position adopted by the ball carrier

You raise an important point. Concussions affect both the tackled player AND the tackler. Halfpenny is a perfct example of a "brave" tackler with a very poor technique. He is very susseptable to concussion due to his body positioning in relation to the tackled player.

 

[Rich_NL]

The study didn't cover the ball carrier. I'm sure such studies will be done in the future, though.

Concussion is symptomatically defined - if the shaking doesn't cause concussive symptoms, it's not concussion - it's called a sub-concussive event/impact. You can spend a few hours getting them with no ill effects, but over a longer period of time they have a definite effect on your cognitive functioning, and over years can cause chronic traumatic encephalopathy (CTE). This is not brought on by concussions, but repeated (smaller) physical shocks over a long period.

 

[Marc Wakeham]

Symptoms can be very difficult to spot when very mild. so it goes undiagnosed. That's just the opinion of a Brain Doctor ref within our society, of course.