Rugby is a classic contact sport, and the rules of the game are designed to largely prevent serious injuries. Concussions remain serious issue in elite rugby, but amateur and hobby players are less affected.
The Rugby World Cup being held in England and Cardiff at the moment is the third-biggest sporting event in the world after the Olympics and the Football World Cup.
Of course, football - or soccer depending on where you live - is still the world's most ubiquitous sport. A rugby match, by comparison, appears to many untrained eyes like a bunch of players running into each other a lot with an odd-shaped ball. And unlike football players, most rugby players would rather burn in the fires of hell than show signs of pain or distress, despite the fact that certain types of injuries occur more frequently in rugby.
The German Sport University in Cologne says rugby injuries requiring medical care occur at a rate of roughly 40 to 50 per 1,000 player hours. In football, it's half that figure.
But Martin Raftery, chief medical officer of the sport's world governing body, World Rugby, told DW that comparing the two sports is tricky. Football is a "semi-contact" sport. Rugby is a "full-contact sport."
The comparison with, say, American football or ice hockey makes more sense, Raftery says, with all full-contact sports having similar rates of injuries.
Managing concussions has been a major issue for these types of sport, particularly at the elite level, but it is only fairly recently that more players are acknowledging they've suffered from the effects of concussion.
In the 2013-14 season, the most commonly reported injury in the English premiership was the concussion - 12.5 percent of all match injuries - according to the latest data available from the Rugby Football Union (RFU), England's governing body. The RFU's data is widely seen as one of the most comprehensive on injuries in rugby.
Twenty or 30 years ago, "Concussion was only diagnosed when someone was knocked out," Raftery says. Now, if someone has a headache following impact, it is classified as a concussion.
"The diagnostic threshold has been lowered over the years," Raftery explains. In 2001, a global consensus statement on concussion was published, setting off the ongoing process of managing concussion across a number of sports.
In 2012, World Rugby - or the International Rugby Board as it was called then - launched a pitch-side concussion assessment process for professional rugby games that allows medics to take a player off the pitch for 10 minutes to conduct a standardized assessment.
The National Football League (NFL) in the US has also introduced concussion awareness initiatives. According to data on its website, incidents of concussions have been reduced by 35 percent since 2012.
"We're now beginning to see the long-term risks of head injuries for some people in that they may be at increased risk of dementia," said Dr. Willie Stewart, neuropathologist at Queen Elizabeth University Hospital in Glasgow. Stewart is a leading expert on brain injuries in sport and also advises World Rugby.
"The recognized level of brain injury is at a level, I think, where something must be done …We can't continue to see, every game or every second game, a player leaving the field with a brain injury," he told DW.
A 'collision sport'
The majority of all injuries in rugby occur during the tackle, when players collide to compete for the ball.
In the case of concussion, "What happens is that the skull ceases to move quite rapidly, but the brain - because it's a kind of semi-liquid - continues to move around in the skull. So the sudden acceleration of the brain in the skull causes the brain substance to be damaged," Stewart explains.
He emphasizes the level of damage is "minute," but it can cause the brain to function less efficiently, causing disorientation, dizziness, unsteadiness and possibly confusion. Only in 10 percent of cases do players lose consciousness.
It's hard to say, though, how many players have suffered long-term damage from a head injury, since in the pas, players were reluctant to report these issues.
Stewart thinks that, apart from the fact that higher awareness of concussion has led to more cases being reported, the way elite players tackle these days is also playing a role.
"It now becomes a collision sport, where players quite purposely collide with each other to try and punch a hole through the opposition defense" - a technique less likely to be seen in community rugby, for example.
Although tackling above the shoulders is against the rules, tackles in the professional game are also higher today, Stewart says. They've moved away from the "textbook" tackle that aims for the legs with the tackler's head turned to one side to avoid injury.
There are also issues in the ruck, formed when the person tackled has gone to ground and a teammate binds him or herself to that player to secure the ball, all while the opposition tries to steal it.
"But you do see players now essentially launching themselves across that ruck trying to clear the opposition players out," Stewart says. Simply enforcing the rules of the game may help.
But rugby medical officer Raftery dismisses that argument, saying that, "If the tackling style had changed, then we would expect to see an increase in other traumatic injuries. But they haven't changed."
Raftery points out that "incidents of concussion have doubled over the last two years," but that the total number of injuries hasn't changed or even gone down.
"So it's not the game that's changed, it's the awareness and diagnosis."
The governing body, he says, is still in the process of analyzing hundreds of matches to see if any changes are needed.
Elite v. grassroots rugby
Head injuries are far less common at amateur or grassroots level rugby. Raftery says the discrepancy is mainly down to speed.
"When the speed is higher, there is more chance of injury, a fact that applies to every sport, not just rugby."
At the elite level, injuries are also more likely to be reported. The data on community rugby is very patchy, so comparisons are difficult.
But don't let that put you off joining your local rugby club.
"We tend to focus on the elite, male players and tend to forget that 99.9 percent of players are at amateur and grassroots level," Stewart says, adding that the benefits of participating in a sport outweigh the risks.
Raftery concurs. A recent study from rugby-mad New Zealand has shown that there are more injuries on school playgrounds than on the rugby pitch.
"You don't take any risk when you're not playing a sport at all, but also don't go the playground either," he says.