In an equation of physics and physiology, collisions plus big, fast, athletic bodies equals concussions. But while the risk can’t be eliminated, it can be lowered. With that common goal, a group of international sport representatives – including the NFL, World Rugby, NHL and AFL – gathered at the Collision Sports Conference this October. The meeting gave the various sports leagues the opportunity to share research and collaborate on improving player health and safety. High on that list was research into concussion.

Pads or no pads, like the NFL, rugby is in the process of understanding how concussions occur, and from that, how to prevent them. Rugby hasn’t taken that assignment lightly. Research from the conference, presented by Dr Ross Tucker, a sports science researcher for World Rugby, detailed the study of video from 611 head injuries. “We have the responsibility to make the game safer,” said Dr Martin Raftery, chief medical officer for World Rugby and part of the research team. “Since we have control over the rules of the sport.”

The study found, not surprisingly, that tackles are the most numerous and highest risk events for concussion. What was surprising were numbers that showed the tackler had a head injury risk almost three times larger than the ball carrier.

So, how do you save tacklers from hurting themselves? The simple answer to the question was this: find the tackler’s head and you find the risk. Head to head tackles were 6.6 times more likely to cause head injury than head-to-hip contacts, and 22 times more likely than head to upper body.

“We found that any tackle in which the tackler’s head was in the another’s ‘airspace’ was a high-risk tackle,” said Tucker, “And that risk was highest when the tackler is upright, so that’s the situation to avoid.

Science is straightforward, the politics of change are not. So, how do you change the game without changing the game? For the NFL, that’s walking a tightrope between changing a popular on-field product and reducing the risk of short- and long-term health consequences. For rugby, it’s a similar situation, with critics arguing that changing the game to make it safer makes it “too soft”.

“The tricky thing with any change,” emphasizes Tucker, “is that when you change a behavior from x to y, you have to be mindful of what risk the behavior will create.”

World Rugby first began by enforcing existing rules more harshly. Officials hoped that more penalties and yellow cards would mean fewer high tackles, presumably leading to a lower number of concussions. In the carrot and stick analogy, this was the stick. But, while there was a 64% increase in penalties for high tackles, and a 41% increase in yellow cards for high tackles, neither seemed frequent enough to seriously dissuade risky tackles and prevent head injuries.

Based on post-match video review, Phase 2 is exploring punishment off the field. Players may receive High Tackle Warnings for tackles deemed risky (not illegal) – those that were upright and with clear head contact – educating them and their coaches on unsafe tackling.

Confronted by a similar problem, the continued rise in concussions, the NFL utilized a very similar process. In addition to learning about the relative safety of helmet models, the NFL’s medical and engineering advisors recognized a trend in injury biomechanics – lowering the head to align the neck and spine before initiating contact with the helmet was associated with a disproportionate number of concussions. A more detailed analysis of that subset revealed that, like rugby, the tackler had the greater risk of head injury.

Crunching the numbers was only part of the process. The researchers determined risky on-field actions, but it was up to the Competition Committee to determine what, if any, rules were to be changed. After discussing the issue – in this case helmet to helmet contact – the Committee elected to more strictly enforce rules against helmet to helmet contact.

Like rugby, new rules and penalties might only have a limited effect on changing unsafe behavior. According to the NFL, nine use of helmet penalties were called through week 11 of the season (by comparison, offensive holding, the most common penalty, has been called over 400 times). Like rugby, enforcement of the penalty alone is unlikely to have a meaningful impact on concussions. However, 96 other players have been later disciplined through fines. Further, like rugby’s high tackle warning, letters have gone out to players, letting them know that officials have identified techniques that put themselves and their opponents at unnecessary risk.

What might have the greatest effect, in both leagues, is the education of players and coaches on unsafe tackling. In that effort, both football and rugby are attempting to eliminate unsafe on-field actions which many believe are relatively new to the game.

“In deciding to enforce the rules against initiating contact with the head,” said Jeff Miller, the NFL’s executive vice president for health and safety, “The Competition Committee believed that they were eliminating a behavior that had ‘crept into the game’.”

According to Tucker, a similar belief emerged from rugby’s research, that the high tackle was a new way for the tackler to both stop the opposing player and prevent him from passing the ball to a teammate.

In fact, the NFL’s emphasis on proper tackling technique – knees bent, pads down, hands first, head up and out of the way – closely mirrors the rugby-style of tackling already adopted by several NFL teams.

After learning rugby-style tackling offered both effectiveness and a lower risk of injury, Pete Carroll’s Seattle Seahawks assistants began teaching the style to defensive players. Coaches were soon impressed. “Rugby has the same type of violent collisions, but they’re just wearing shorts and t-shirt,” said Rocky Seto, former Seahawks assistant head coach, “and they just get up and jog away.”

Seto believes that Carroll’s greatest contribution to the game of football won’t be his Super Bowl title, but his championing of a safer, and more effective, style of tackling. “The rugby style tackling technique isn’t new,” adds Seto. “A couple of generations before us, players like Dick Butkus, tackled in that manner. It’s taking football back to the way the game was played in the past.”

While early returns for the NFL – a 13% decrease in pre-season concussions – are promising, Miller acknowledges that change is unlikely to happen overnight. That will likely require behavior change across all levels of football, not just the NFL.

Tucker believes the largest challenge for rugby will be a cultural one. “We need the safety initiatives to become part of the normal fabric of the sport, so that every fan understands them rather than reject them as external interference.”

Real acceptance, by experts and fans alike, will come with the understanding that rule changes are meant for player health, not to “soften” the game.