You know your rugby sevens - a summer muckabout at school, a once-a-season bit of fun for the club, a day on the sauce at Twickenham or in Hong Kong watching the big boys dash and splash.

Some of that still stands true. A lot of it doesn't.

Sevens at international level has been becoming more serious and less circus ever since the World Series was launched at the turn of the century. But it was still, in the words of England coach Ben Ryan, a "bolt-on" - a sideshow starring young wannabes and older probably-won'ts, a slice of fun in the sun without the profile or kudos of the 15-a-side game.

What changed? The Olympics. In October 2009, the IOC accepted sevens into its programme for Rio 2016. And so was set in progress a series of events that have transformed the sport, both in how it is played and how we all might feel about it.

IRB Sevens World Series Nine tournaments in five continents across 10 months

Teams divided into pools of four teams in round-robin format

Games are two halves of seven minutes each

Top two teams in each pool advance to quarter-finals

Overall Series champions decided by total points won at all tournaments

"The England programme was on the edge of being binned," admits Ryan. "I couldn't get any players, because the EPS (Elite Player Squad) agreement meant no club in the country had to give us a player for international sevens.

"So you were working your way down. We capped 39 players that year, and we were really struggling - meeting players at the airport, limited training, players earning less than the minimum wage.

"Fast-forward a couple of years, and we have full-time players, earning a decent salary, with a career path that wasn't there 24 months ago."

Those players are fitter, faster and better prepared than ever before. The World Series external-link requires them to peak for nine tournaments in five continents across 10 months, clocking up 80,000 air miles over 32 flights to play in 84 games.

On the training ground, they must deliver - the backs able to sprint 40 metres on grass from a standing start in less than 4.9 seconds, the forwards the same in 5.05 secs. Off the pitch, they are backed up by performance analysts, nutritionists and sports scientists producing cutting-edge ideas beyond what many in the 15-a-side game are attempting.

England will be hoping home advantage can help them finish the series in style

Such is the power of the five famous rings. When Olympic medals are up for grabs, particularly in sports with limited geographical reach, funding flows. Attitudes change; teams advance.

"It used to be that you would have two easy games in your (World Series) pool and then one game to see who won and who came runner-up," says Ryan.

"Now every game is tough. Everyone is doing what we do. Opposition teams have got analysts and doctors and conditioners. They're full-time, with second teams and development pathways.

"Spain are currently bottom of the rankings, but they're very good operators. A lot could be full time in England. Portugal and Russia could beat any of us.

"A couple of seasons ago, you'd look at your opposition's kick-off, and they'd have one set play. That's all you had to deal with. Now it's five, from three kickers. All nations are close to the same fitness and speed and power levels."

2013 London Sevens draw Pool A: South Africa, USA, Australia, France

Pool B: New Zealand, Wales, Canada, Kenya

Pool C: England, Fiji, Samoa, Argentina

The consequences have been even more far-reaching in the women's game. England head coach Gary Street in effect sacrificed his side's Six Nations campaign to focus on winning June's sevens World Cup; with sevens an easier game to promote at amateur level, and the Olympic allure seeing rugby minnows like the Netherlands set up professional women's sevens squads, the shorter format may even take over from 15s as the dominant form.

Hurdles remain despite such giant strides forward. While 100,000 tickets have already been sold for this weekend's concluding London leg of the World Series, an equally significant number is the 1.2 million pints expected to be sunk.

While the sport has never been more serious for players and coaches, the majority of the spectators have yet to catch up. Quality on the pitch can still feel less important than quaffing in the stands.

"There are people who will be there who would struggle to tell you who had reached the final, because alcohol levels have risen or the fancy dress has fallen over their face," admits Ryan. "You don't want it to turn into just a beerfest for 48 hours, because the sport can stand up on its own."

Rob Vickerman in action during this year's Hong Kong Sevens

His skipper Rob Vickerman, who has witnessed first-hand sevens' evolution from part-time to professional, agrees. "In some of the stadiums we play at, it could be table-tennis on the pitch, as long as they're having a good time."

Both men are sanguine rather than exasperated. Cricket Tests are seldom cheapened by the inebriation of those watching. Beach volleyball retains its Olympic credentials while actively encouraging the party atmosphere all around. Sevens attracts an atmosphere. But it is not darts.

"The severity of the tournaments and the quality of the teams has shot up, and the crowd appreciate that," says Vickerman. "They also want to watch something that anyone can win, which now sevens has become. Spain or Portugal, the traditional minnows, can turn up and beat South Africa or Samoa."

What about the players' peers? Is sevens still viewed as something for the cast-offs and kids, even as alumni like Alex Cuthbert and Christian Wade run rings round packed defences?

"There's probably a bit of, 'Is he playing sevens because he's not playing Premiership?'" says Vickerman, who played for both Leeds and Newcastle in the top flight. "But I think it's a far harder test of your skills as a rugby player being on a sevens pitch than it is in the Premiership.

Top points scorers this season Nathan Hirayama - Canada - 229 Joji Baleviani Raqamate - Fiji - 221 Dan Norton - England - 214 Tomasi Cama - New Zealand - 211 Christian Lewis-Pratt - England - 198 Cornal Hendricks - South Africa - 180 Paul Albaladejo - France - 180 Lewis Holland - Australia - 163 Sean Duke - Canada - 160 Colin Gregor - Scotland - 157

"Everyone is deemed a specialist sevens player, even when they're not. You get a lot of sevens players who could easily translate to 15s and be pretty lethal at it. But you don't have 15s players who could transfer their skills easily into sevens, purely because it's much harder fitness-wise, and your core skills are put under much greater test.

"There's a respect they have for us as athletes. They know full well that their worst training week is usually in the middle of pre-season, while ours is like that for the whole year."

All this effort could yet count for little. While the home unions will meet later this month, there is no firm plan yet for how a prospective Great Britain team might be selected or coached, no automatic qualification as its football equivalent enjoyed in London.

The top four nations in the 2014 World Series will all go, but the British teams compete individually. Do England try to snatch GB a place? Their form this year has been patchy; Wales and Scotland have never won a World Series tournament.

Should a GB team - an Olympic version of the Lions, external-link at best - make it to Rio, neither would a medal be any sort of certainty.

"There have been five different winners of the eight tournaments so far this season," says Ryan. "Come Olympics, once you get 12 teams into that, God only knows who will win, because the top four seeds all got knocked out of the last World Cup before the quarter-finals in one surreal hour and a half. That could easily happen at the Olympics, because matches are 14 minutes long and there's a lot of moving parts."

And what of the big names and fast feet of the Test teams, the dashing wingers and flying flankers of household fame? Might they be tempted by the lure of an Olympic gold to switch late to sevens?

"They've already asked," says Ryan. "There are a number of current internationals, who would be 28 or 29 in Rio, going right, I'll run my club contract through to the end of the 2015 World Cup, and then if I'm in good shape, I'll keep my options open.

"I'm open to all of it. But they would need to dedicate a certain proportion of their season. I know how hard our lads work; three years down the track, is a Dan Norton, with 100 caps, going to be pushed out by someone who comes in six months out? I doubt it.

"You want the best team you can assemble. What you don't want is chuck in someone with no experience of international sevens. It's a tough sport, and it's getting tougher."