Skull meets muscle and bone with the momentary force of a high-speed car crash. The player gets to his feet, shakes it off, his attention back to the game.
Hits of this magnitude are common enough on any rugby field in New Zealand. In most instances, they are fleeting, and quickly forgotten.
Sometimes a confused, stumbling player is forced to leave the field.
Occasionally, as with Hurricanes captain Conrad Smith's misplaced tackle last weekend, they are carried from the field, knocked out cold. In extremely rare instances, a life is cut short out on the grass.
Concussion in rugby is coming under increasing scrutiny, with claims that repeated head trauma is leaving some players with lasting brain damage.
In the United States, similar claims from former American football players have boiled over into a series of massive lawsuits that could end up costing the NFL billions.
Evidence of a severe brain trauma, known as chronic traumatic encephalopathy, has been found in the autopsies of former NFL players, boxers and ice hockey players. All are collision sports, like rugby.
So should we be worried?
The New Zealand Rugby Union's answer is probably not, or at least "We don't know yet". Its public relations man caught wind of this article and quickly phoned to make the union's position clear: "Rugby is not NFL."
But the question remains. Are New Zealand's more than 145,000 rugby players, not to mention those in rugby league, playing it safe?
Doug King's interest in concussion began 15 years ago with a young rugby league player convulsing on an Upper Hutt field. Mr King, a trained nurse, was on the sidelines that day and rushed out to Leonardo Va'a in a desperate attempt to resuscitate him.
The 26-year-old died the next day, leaving behind a partner with a 7-year- old son and 6-month-old baby.
A coroner's report into his death, and that of another league player the next year, revealed he had suffered an ongoing battle with concussion and had been advised five years earlier to stop playing.
On the day he played his last game, he took the field against medical advice, telling the team manager he had been cleared to play.
"That experience really knocked me, made me question myself," Mr King says.
Two years ago, he again watched in horror as another young rugby player collapsed before him after a big tackle; his teeth clenched, convulsing on the grass.
"I just thought, 'Oh no, not again'."
The player survived. Mr King later learned he had been concussed the previous week and cleared to play by his doctor. It was his fifth concussion in the past year. "He shouldn't have been playing."
Mr King has written a PhD paper on concussion in rugby league and is now midway through a second, on union.
He juggles his study on top of working fulltime as a nurse at Lower Hutt Hospital's emergency department, where he often sees the sharp end of on-field collisions.
"We've seen quite a few concussed players in just the last week. A lot of them get back on the field less than a week later."
While attitudes are improving, the "harden-up" approach to concussion is still far too prevalent in club rugby, he says. "I've seen players that have got concussion being told by coaches, 'It's fine, just tough it out and get it done.' There needs to be a complete culture shift."
Those who know Mr King have described him as a crusader, with strong views on players' health. His abrupt, uncompromising style has rubbed more than a few people the wrong way. One rugby union club banned him for life after a heated argument over whether a concussed player should be taken off the field.
The key to his latest study is measuring the impact on players of repeated hits, and linking it back to reported concussion.
In a New Zealand first, he has fitted the Hutt Old Boys' Marist premier team with microchipped mouthguards that can record the velocity of hits to the head.
The study is only seven rounds in, and he has yet to crunch the numbers. However, results so far show the average player takes about 100 knocks to the head per game. Most of these are minor, about five times the force of gravity, or roughly equivalent to what the body feels during a rollercoaster ride.
But a handful are above 100 g-force, similar to the jolt experienced in a high-speed car crash. If big hits like this are common at a club level, what is the impact of a solid tackle from a front-row All Black?
Mr King says the trouble comes from more than one big hit - it is the cumulative battering of the head.
"I'm not having a go at rugby. I love rugby, but there does need to be an attitude shift."
He has spoken to former rugby players who are depressed and even suicidal, a condition he believes can be linked back to repeated concussion. Many are suffering in silence, he says. "But that awareness is changing. I think over the next two or three years we are going to see these people coming out of the woodwork."
While he waits on definitive proof, he says there is still enough evidence to warrant a more conservative approach, from the New Zealand Rugby Union management down.
This could include strictly enforced stand-down periods for concussed players, and more thorough sideline tests.
Even at a professional level, concussed players are often allowed to play again the following week. "We see the likes of Conrad Smith after his first concussion back playing after a week. The question I then face is why can't I put Joe Bloggs back on the field a week later?"
WHAT IS CONCUSSION?
Concussion, also known as a mild traumatic brain injury, occurs when the skull either accelerates or decelerates rapidly, after being slammed into the ground or struck with a blunt object.
This causes the brain to move out-of-kilter with the skull, tearing or stretching the nerve fibres and upper brain stem.
A torn brain stem can cause immediate disorientation, confusion and loss of memory. It usually results in a complete loss of consciousness.
For months afterwards the person can continue to feel sleepy, experience slow thinking, blurred vision and headaches. The symptomshave been likened to post-traumatic stress disorder.
If a person still recovering from a concussion is hit again it can cause acute brain swelling, with potentially disastrous consequences.
Repeated concussions have been linked to dementia later in life, particularly among ex-boxers, but not yet in rugby.
While concussion is the most common brain injury, "traumatic migraines" are often misdiagnosed as a concussion, particularly among young rugby players.
A traumatic migraine starts with a tingling soon after a heavy blow and the person often has trouble speaking. After about 15 minutes, the person develops a throbbing headache and starts vomiting. This can last for up to four hours, at which stage the person quickly recovers.
Unlike concussion, there is no ongoing or compounding damage caused by traumatic migraines.
Other, more unusual problems associated with even a mild concussion can include permanent loss of smell and a spinning dizziness caused by damage to the inner ear.
Former All Black Steve Devine needs Botox every few months. He doesn't do it to keep his face youthful, he does it to stop the pain. The halfback's rugby career ended in 2007 after a decade playing for Auckland, the Blues and 10 caps with the All Blacks.
His head troubles started five years earlier while playing for the All Blacks against England at Twickenham, where he was knocked out twice in the first half. In 2003, he was knocked out again in the Super 12 semifinal, missing the Blues' win in the final.
After that, the knocks kept coming, culminating in an enforced six-month break in 2006 after he played a game against the Reds in Brisbane while essentially asleep on his feet.
The final blow came in the opening NPC game against Counties-Manukau in 2007, when he caught a swinging arm at the back of a scrum. His playing days, the doctors said, were over.
The next morning he woke with a splitting headache, which stayed with him for the next 3 1/2 years.
"For a while, it was pretty tough for me. It wasn't only struggling with the fatigue and the headaches. It was my career that I had lost."
Devine tried dozens of drugs, most of which left him feeling worse, before giving the more unconventional treatment - Botox - a go.
"It was like my life was turned upside down. Within a week, I was able to live and function again."
Botox is now a part of his life, relieving pressure on his nerves and keeping the pain at bay. He still has to be careful about knocks. He doesn't ski and is cautious riding his bike. "The next whack might turn my 3 1/2 years into eight."
After coming out publicly about his battle with concussion, Devine says he is often called by people recovering from head injuries, including rugby players, looking for advice. "I think you just need to keep asking questions."
He still loves rugby and believes the dangers are far outweighed by its benefits. But he also worries about the risks. Not to the professionals, but to the kids and "weekend warriors".
"Within 10 seconds, Conrad would have had a doctor with him. That doesn't always happen at the lower levels."
At 25, Taranaki prop Shane Cleaver is on the other side of his rugby career. But he, too, has battled with concussion. His first season for the Chiefs was wiped out last year after one knock too many in the first game of the season, against the Blues in March.
"I was taking the ball into contact and I don't remember much else. I just remember I kept losing my feet."
He has since watched himself on the match replay, stumbling about on the field for 15 minutes until the final whistle.
He tried playing again the following week, but lasted only a few minutes before being taken off.
The final knock that sidelined him was the fourth in a year. After each successive concussion, it took less and less to make him dizzy.
He says not playing for a year has been "horrible", a frustrating procession of false starts, headaches and fatigue. "It felt like I was talking through a hazy fog, like I was looking into the room through a third person."
Even when the fog subsided, heavy strain at training left him dizzy and weak.
When Cleaver was finally cleared to play in February, it was a huge relief. He is already training with the Chiefs as injury cover and has signed a two-year contract with Taranaki.
After the enforced break, he is confident his head is back to normal and ready for collision. "The next knock would have to be a big one."
But how many knocks is too many? The short answer is nobody knows. Even if we had an answer, it would be complex, depending on the individual's history and physiology.
Some argue it's not even clear that too many knocks have anything to do with lasting brain injuries.
A joint study, involving the Auckland University of Technology, the New Zealand Rugby Union and the International Rugby Board, is finally trying to shed light on the long-term health risks of rugby.
The first of its kind, it is surveying 600 retired rugby players in New Zealand, both elite and amateur, and cricket players.
The results will, it is hoped, show whether rugby players are more or less likely to suffer long- term health problems, including neurological diseases. It will also help measure the risks faced by professionals compared with amateurs, and how rugby compares with other sports.
Professor Patria Hume, who heads the study at AUT, says the main driver behind it is the growing concern about the long- term impact of concussion. "But we are really starting with a blank slate. At the moment, we don't have a clear picture at all."
She had planned to complete the research by the end of May, but has had trouble attracting applicants.
Hundreds more ex-rugby players, healthy or otherwise, are needed to fill out the online survey (it can be found at sprinz.aut.ac.nz, if you are interested). If the number can't be found in New Zealand, the study may have to move to Australia.
"We don't know why we are not getting the numbers. It has been quite a surprise."
While she agrees with Mr King that a culture change is needed at club level, she believes rugby is making a huge effort to improve safety in the game.
It is often not clear who is responsible for player safety, particularly when players often cannot be relied on to make the right decisions, she says.
"People often don't think about the long term. They just think about the game in front of them."
Ian Murphy, medical director for the New Zealand Rugby Union, says the union is taking concussion seriously. He points to Rugbysmart, the coach safety education programme run in conjunction with ACC since 2001, and the five-minute test developed last year to ensure concussed players are identified quickly.
The test has led to a significant increase in the number of concussed players pulled from play, he says.
He remains adamant the links between long-term brain injuries and concussion remain unproven. "But that's not to say we are not looking."
While there are undoubtedly players who have been forced to quit because of concussion, that does not constitute hard evidence, he says. A host of pre-existing or unrelated conditions could be behind health issues experienced by some former players.
"We can't afford to make enormous decisions about this game, our national game, based on assumption and gut feelings."
The argument is similar to the one employed by the NFL. It also claims links between long-term brain problems in former players, which have included Alzheimer's and dementia, are not proven and that more research is needed.
About 4000 former players are now accusing the NFL of suppressing the evidence of that link and are fighting their case through the courts.
That is not likely to happen in New Zealand any time soon, but Mr Murphy says he will be watching the case in the United States with interest.
But while the union may be pushing safety, and many coaches are listening, a huge amount still hinges on players.
Asked if he would play through another nasty knock, Shane Cleaver initially says he wouldn't - but after a pause, he is less sure. "I hope I wouldn't."
Steve Devine still remembers the moment his career ended; the swinging arm that took out a few teeth and precious years of his life.
But even in hindsight, he admits he would make the same decisions all over again.
"Would I run out for that last game? Hell, yes - I would do it again tomorrow. It was something I loved."
About 1200 people suffer head injuries while playing rugby each year, compared with about 250 while playing league.
Last year, ACC paid out more than $2 million to care for these injured players. In union, the cost of treating head injuries has been rising for the past five years.
About two-thirds of these injuries in both codes are either concussion or brain injuries, at a rate of about 1000 a year.
The figures do not account for ongoing health problems which cannot be directly linked to rugby injuries.
In total, more than 50,000 people seek medical attention for rugby injuries each year, costing about $60 million.
A five-minute test is now being used by the Rugby Union to decide whether a player can continue.
1 What is the venue today?
2 What half is it now?
3 Who scored last?
4 What team did you play last game?
5 Did your team win that game?
6 Do you have a headache?
7 Do you have any dizziness?
8 Do you have any pressure in your head?
9 Do you feel nauseated or about to vomit?
10 Do you have blurred vision?
11 Does the light or noise worry you?
12 Do you feel as though you are slowing down?
13 Do you feel like you are in a fog?
14 Do you feel unwell?
If you answer even one question incorrectly you will be kept off the field. And if a doctor notices you appear a little more grumpy, drowsy or emotional than usual, you will be off.
If you answer all these questions correctly you will still have to complete a balance test, standing for 20 seconds with boots heel to toe, hands on hips and your eyes closed.
If you open you eyes or lose your balance more than four times you will not be allowed to play on.
Any player who is convulsing, or has blacked out, will be immediately removed from the game.
- The Dominion Post
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