Let's roll through the contenders. American football comes to mind but think of the helmets and extensive padding and the risk appears diluted. It's not hurling or Gaelic football, either, although the wince factor from the stands is pretty gruesome on a championship Sunday. Soccer maybe? OK, we'll let that one slide before someone keels over with laughter. How about Australian rules, then, a sport where a flying fist or stray elbow is taken as a given?

Nope, and it's not rugby league either, despite the attritional body-on-body contact that seems to happen, oh, every five seconds or so during the average game.

The answer, however, does lie with the sport's half-brother, rugby union, the gentleman's sport that's no longer suitable for the genteel man.

The finding comes from no less a source than the British Journal of Sports Medicine . . .

trust us, they know their stuff . . . but it's a conclusion any serious rugby watcher over the past decade would have come to themselves without a PhD for company. Since the word 'amateur' was struck from the law book back in August 1995, the game has expanded in every single way you chose to interpret the word.

For one, as you'll discover in more detail on the opposite page, rugby players have added significantly to their collective frames since the game became their full-time occupation. Back in 1991, the average international back weighed 80kgs (just under 13 stone) but the current Irish backline, who would probably be a touch lighter than others in world rugby, weighs an average of 87kgs. Up front, the big boys are getting even bigger. At the 1991 World Cup, the average forward hit the scales at 100kgs, while the current Irish eight weigh in at 107kgs, again, an average slightly below some of the bigger international packs in the world. Those extra kgs might not seem all that mindblowing but there's another factor at work here. The weight added to the average player over the past decade or so has mostly constituted lean body mass, not the lagging jacket that players of previous generations may have carried.

That's the physical side of things, but there have been other expansions since the advent of professionalism.

Thanks to a series of minor rule changes over the past decade or so, the ball spends an average of 30% more time in play per game, so in effect today's player is playing the equivalent of four pre-1995 games every three times he takes the pitch. As if that wasn't enough, there's also been a significant increase in the number of top-class games on the fixture list. The average provincial and international player back in 1995 would have played somewhere about 10 top-class games per season, today it's somewhere in the region of 25, and that's if you're lucky enough to be closeted in the relatively sane world of Irish domestic rugby. A professional in the Guinness Premiership could take the field 40 times a season.

The physical effect of all these various expansions has been significant, and we're only just beginning to see it. In Ireland, an injury surveillance system was initiated, rather belatedly, by the IRFU at the beginning of the 2005/06 season and it's unlikely that we'll see any public results from it until the end of this season at the very earliest. The only concrete statistics we have to go on at the moment come from England, and although those figures aren't directly relevant to Irish rugby, they do paint an accurate enough sketch of the situation here.

It's a signpost, at the very least.

The raw figures do shock, no question. On average each player in the Premiership spent 20% of the calendar year injured, that's 73 days per year off work for every player in the league. There can hardly be a more attritional profession in the world, no matter what kind of dangerous job you throw out there, bodyguard, bomb-disposal expert, lumberjack and the like. The overall chance of sustaining an injury in a Premiership game is 12.5%, a figure that effectively means, as RFU doctor Simon Kemp pointed out this week, that two players from each side in any Premiership game will have to leave the field injured.

If you take the Llanelli-Leinster game from last weekend, where Dwayne Peel, Guy Easterby, Luke Fitzgerald and Rob Kearney all hobbled off with one injury or another, you see that the Magners League isn't all that different.

International rugby, however, is. The chances of picking up a knock at the very highest level is 29% in any given game, a quite startling, and worrying, figure, one which proves that the higher you go up the rugby ladder, the more likely you are to pick up a serious injury.

There are a couple of positions more susceptible to injury than others, as anybody who's stood out on the wing for a couple of games will know. Hookers are the most routinely injured players on a rugby pitch, and it's not surprising when you consider that they are expected to scrummage, carry and tackle over the course of an average game. It's a small wonder they're able to throw the ball in to the line-out, or hook it back in the scrum.

Next in line on the injury frequency list, surprisingly enough, is the outside centre, where high speed collisions, both offensively and defensively, contribute to an extremely high attrition rate.

Open-side flankers, rightsided second rows and props are also frequent visitors to the physio's table, as Emmet Byrne, the recently retired Leinster front row, can attest to.

"There's been a massive difference in the physical side of the game over the past few years, mainly since the Celtic League was initiated, " he says, having crouched for his last scrum. "Before that, provincial players like myself were playing somewhere in the region of 10 games per season but almost overnight that shot up to 20 or 25. It was a big change and there's obviously been a knock-on effect in terms of injury, not only because of those extra games, but also because players have bulked up to deal with the extra load.

"I do think it's only been in the last one or two seasons, as injury rates have increased dramatically, that stuff like rest and recovery periods have been taken more seriously by the provinces. But all those games have an effect on the body. For example, during the off season, I was capable of doing some serious weights but as soon as the matches started, my capabilities in the gym diminished dramatically. For a prop it can take anything from three to four days to recover from a serious game of rugby and then you're looking straight into the next one. The morning after a tough match, in particular, was always difficult. There were mornings when I'd have to go down on my hands and knees to ease myself into an upright position."

But while the present might be scary enough for any player taking the field this weekend, a brief glimpse of their potential future could well frighten them into early retirement. Research compiled on retired soccer players in England over the past half a century or so has shown that 40 to 45% have suffered an osteoarthritic condition in one of their joints since hanging up the boots. Experts in the area predict that this figure could rise to 85 or 90% in the case of retired rugby players. "I don't think any professional rugby player ponders the future too much, " says Byrne, "it doesn't really enter your mind. You live for the next match and that's all you really think about. I know I never really considered how playing the game would affect me in years to come but I realise that I'm going to have a touch of arthritis in certain parts of my body in my 40s rather than later on in life, when it usually hits. That's the way things are for most athletes and we have to live with it."

Some possible ways of making the game safer are chartered in the panel (left) but it's something of a catch22 situation. Rugby, beyond anything else, is a physical game and anything that dilutes that basic premise will compromise the sport irrevocably. The maintenance of the game's physical nature needs to be balanced with the health, in both the short and long term, of its participants or else nobody will want to make a living out of it, no matter how much they love the game. The lumberjack industry may begin to look like an attractive proposition after all.

FIVE WAYS TO MAKE THE GAME SAFER 1 CHANGE THE SCRUM LAWS Around 70 players in Britain and Ireland have been rendered either tetraplegic or paraplegic because of injuries sustained in the scrum. And that's not to mention the thousands of others who've picked up numerous less serious injuries in the front row down the years. Over the past 15 years, as players have bulked up, the power exerted at scrums has almost doubled leading to a sharp rise in neck and back injuries. Possible ways of making the scrum safer include decreasing the space between the packs on engagement from three feet to one foot, or by allowing the respective front rows to engage at a lower height. An outright ban on the contested scrum is favoured by some medics but that's unlikely to happen.

2 DECREASE THE LENGTH OF THE GAME A disproportionate number of injuries occur in the final 20 minutes of games . . .

just pay special attention to the last quarter of the next rugby game you watch and you'll see the evidence.

There's an argument doing the rounds that with all the changes that have occurred in the sport over the past 10 to 15 years, rugby should be a 70-minute game, like Gaelic football and hurling, rather than the 80-plus minute game as it is now. While it would undoubtedly aid the game's top-level players, the traditionalists would fight this one tooth and nail.

3 EXAMINE THE TACKLE LAWS 51% of all rugby injuries occur in the tackle and the IRB are fully aware of that gory statistic. Last year world rugby's governing body provided funding for medical research into that particular area and when results are published in the next few years, a couple of law changes could be initiated. In the past five years, tackling has changed from a purely defensive action (ie bring the player down) to something of an offensive tactic (ie bring him down, knock him backwards and earn possession of the ball). Gang tackling is one result of this new trend but we'll have to wait for the research results for anything to change.

4 SERIOUS PUNISHMENT FOR DANGEROUS PLAY The game is hazardous enough at the moment without any foul or dangerous play involved. Therefore any dangerous play, well outside the limits of the law, should be punished severely, particularly high tackles, spear tackles, taking someone out in the air without the ball and unnecessary shoeing at ruck time. It's time to get even tougher with offenders, particularly players who appear in front of disciplinary bodies on a regular basis.

5 APPEARANCE QUOTAS Top-level rugby players should not be allowed play more than, let's say, 25 to 30 full games per season. Anything else is asking for trouble. There should be no exceptions to the rule. Clubs, provinces and even international sides will have to work this into their planning and deciding what players to rest, and when, could become as much part of coaching as line-outs and back play.