"If you're worried about the physical side of any sport, then play chess."
Those were the words of Republic of Ireland assistant manager and legendary Manchester United midfielder Roy Keane following Kevin Doyle's retirement from football. The 34-year-old had been named in the Ireland squad for their last two World Cup qualifying group games, but cut his career short due to ongoing concussion and headache problems.
Doyle hung up his boots, preparing for the next stage of his life now that medical advice has warned him to give up playing football. Keane continued on with his life, preparing for the Boys in Green's games against Moldova and Wales.
A week after he made those comments, it seemed that Keane and Ireland manager Martin O'Neill had learned nothing from Doyle's forced retirement. Ireland recorded two wins, defeating Wales in Cardiff to reach the playoffs with the extremely physical match setting a record (58) for the most aerial duels contested in a single UEFA qualifier.
Ignoring the problem of concussion and brain injury in football is not a new phenomenon, but with former U.S. international Taylor Twellman and now Doyle leading the way as the two biggest names to retire due to repeated head injury, it will become more difficult to ignore a threat that endangers the future of football.
Dr Bennet Omalu was the first to diagnose chronic traumatic encephalopathy (CTE) in the brain of American football center Mike Webster in 2002, who suffered amnesia, dementia and depression before his death at age 50. The NFL has been accused of ignoring, rejecting and refuting Omalu's research until the avalanche of evidence was overwhelming, and did not make any substantial concessions for player safety until 2007.
Having already exposed the dangers of American football, with Omalu also played on screen by Will Smith in the Hollywood movie Concussion, he is worried that more and more footballers will follow Doyle into early retirement, and that the sport as a whole is in danger if it continues to treat brain injury with the same dismissive attitude shown by Keane.
"Keane's claim is a very irresponsible statement to make," Omalu told Goal. "If you notice the industries and corporations that are doing very well in today's global economy are the information technology corporations. What is the denominator across these successful corporations? They are businesses that speak the truth, that elevate the truth, that provide human beings a platform to think and identify the truth.
"So when I see industries that intentionally deny or reject the truth, it's a very dangerous strategy. It's a dangerous strategy that could undermine the long-term sustainability of that industry. The soccer industry should stop denying the truth. They should say: soccer is not a high impact, high contact sport, but you could suffer brain injury in sports. You need to be aware of that. You need to play safe, like removing heading from play.
"We need to place the life of the player above the revenue streams. This boils down to money. It's all about money. We should not place money above the value of life — even the life of one single player. The life of one single soccer player is worth more than the billions of dollars the soccer industry makes. Life should come first. I have never vouched for the ban of soccer.
"We need to make soccer compatible with 21st century knowledge. The soccer industry should embrace the future and stop living in the past. If they fail to do that, soccer will not be as successful as it is. People will develop healthier, more brain friendly types of sports. People may not want to believe that.
"We need to be progressive, we need to be intelligent. We cannot continue to play soccer the way we played it in 1970. If we continue to play soccer the way we did in 1970, then society will move ahead and leave soccer behind."
Since Omalu's initial studies into the subject, more and more research has emerged showing the dangers of not just American football but other contact sports. In July, the Journal of the American Medical Association released an updated study showing that out of 111 brains of deceased former NFL players studied, 110 of them had CTE.
While concussions can be easier to spot in players, with FIFA and the FA both providing guidelines and protocols along the lines of 'If in doubt, sit it out', the damage done to players comes not just from large one-off contact injuries, but from repeatedly heading the ball throughout their development as children into adults. Omalu believes that in its current form, football is a danger to players and a danger to itself.
"Science has shown over the centuries that whenever the human head is exposed to repeated blows, there is a 100 per cent risk of brain damage," he continued.
"Knowing what we know today, there is no reason why a child today should be jumping up and slamming his head to try to stop a ball travelling at a high velocity. That is silly. No matter how much we may be in love with soccer, the question we need to ask ourselves is: which is more important, the life of a child or the excitement of soccer?
"Which do we value more? Life or the fleeting moments of ecstasy? Obviously there is no question about it: life comes first.
"Children under the age of 18 should not be heading the ball. Children under the ages of 12 to 14 should not be playing soccer as we play it today because their brains are not sufficiently developed to handle soccer. They should play a new type of soccer that should be developed by the soccer leagues where there is less contact, less dribbling, less players and a bigger and lighter ball.
"If we refuse to acknowledge the truth of science, the long-term sustainability of soccer as an industry would be in doubt."
In his latest book, Truth Doesn't Have a Side, Omalu warns about the dramatic changes facing sports worldwide, with CTE becoming more and more understandable and well known due to increased studies in the area. FIFPro also believe the awareness will grow with more research in Europe, and that the health of players should be the number one priority.
"The topic has been more under scrutiny in the USA because brain injuries are by far more common in the typical USA collision sports (NFL, ice hockey) than in football," Dr Vincent Gouttebarge, FIFPro's chief medical officer, told Goal.
"But the public awareness about the potential effect of sport-related brain injury is growing in Europe and, consequently, research and support measures. FIFPro has a clear position: the health and safety of professional players both in the short and long term should prevail on any other matters."
Headway, the brain injury association in the UK, are concerned about the fate of footballers in the future, and believe that Doyle's retirement should serve as a wake-up call for the FA. They are worried about the dangers of heading footballs and feel more research needs to be done in this area to ensure the safety of players.
"Kevin's retirement, albeit at the age of 34, from football as a result of persistent headaches — which he seems to be attributing to heading footballs — is certainly of interest," Peter McCabe, chief executive of Headway told Goal. "As far as I'm aware, he is the first (or one of) footballer to do so, although an increasing number of rugby players have retired early on medical advice.
"Ultimately, we need more evidence and we do feel the authorities have been dragging their feet on this for too long. They certainly have questions to answer and Kevin Doyle's retirement should be setting off alarm bells within the FA. Whether or not we see more footballers following in Kevin Doyle's footsteps in the future is yet to be seen."
While Headway are reluctant to speculate whether more players may retire in the future, Omalu is certain that many, many more will be forced to follow Doyle's lead.
"The work I did in 2002, that autopsy I did on Mike Webster, that single event has transformed and revolutionised the sports industry as we know it," the 49-year-old said.
"Sports can never be the same any more after the Mike Webster autopsy. Knowing what we know now, and since that autopsy, science has evolved. We now know more because other researchers across the world confirmed what the Mike Webster autopsy showed us.
"Knowing what we know today, we are smarter, more intelligent, more knowledgeable, more players will begin to come forward. We now know the science better. We will now reasonably identify the symptoms. With time, maybe in another five to 10 years, we may be able to diagnose the disease in living people. More and more players will begin to retire at younger ages and less and less children will be playing. That is the trend, I guarantee you that.
"Brain damage could develop in many ways. They develop dementia in later life, many of them lose their intelligence, they become less intelligent. When they retire from soccer, they don't do so well. They cannot start new businesses. Many of them live very ordinary lives, they don't get jobs.
"Many of them become alcoholics, they become drug abusers. Many of them develop psychiatric illnesses like major depression. Many of them engage in violent behaviours and criminal behaviours. Many of them become more reclusive and introverted. We have always known this. Many of them develop memory disorders and lose the ability to acquire new information. It is not just about headaches.
"If you watch some of the players after retirement, once they retire, what happens, you don't hear about them. Knowing what we know today, we need to pay closer attention."
A lot of players who have retired are suffering from these issues thanks to the dangers inherent in heading the ball from such a young age. If football fails to adapt, playing chess may not even be an option for them.