England full-back Ben Foden is one of a number of internationals who have said they are interested in competing for Team GB when rugby sevens makes its Olympic debut in Brazil.
Foden has previous experience of playing sevens, where teams of seven normally compete over 14 minutes in a fast and open game played on a full-size rugby pitch.
But England sevens coach Ryan, favourite to be put in charge of Team GB, warned that caps, medals and tries achieved in the 15-a-side game meant little in the physically demanding, all-action shorter form of the game.
"I saw the suggestion that some XV players might try and take a sabbatical to play sevens and break into the Olympic side. It's just not the same," Ryan said.
"I've said it before - and I'm not referring to Ben as he knows where he's coming from - but when players or people suggest that a XV player should play for us or Great Britain, I find it a bit insulting."
Some eyebrows were raised when rugby was voted into the programme by the International Olympic Committee in 2009 and the sport will be under pressure to prove it deserves a place at the Games.
While supporters may hope to see the likes of New Zealand World Cup winner Sonny Bill Williams at an Olympics, current sevens players, who have lower profiles and pay packets than their 15-a-side international colleagues, are understandably guarded about the prospect.
"They are two very different sports in terms of fitness," England sevens captain Rob Vickerman said.
"You have a 15 minute high intensity training session rather than an 80 minutes raw aerobic game, where size may be a little more important than it is in sevens.
"Gone are the days where you can do both."
Ryan and Vickerman were speaking ahead of the start of the Sevens World Series in Australia on October 13, the first of nine events across the world with the campaign ending in England next May.
Despite their lower profile, Ryan said his team more than matched up to the test players.
"Have you seen our players and seen what they can do? If you put a XV player against a sevens player then I'd back my man every time," Ryan said.
"And in two or three years, we should be having a conversation about why this sevens player isn't playing for England or in the Premiership.
"I understand why people don't know sevens as it hasn't had the same exposure as XV's has had but the players we have are world class and they would stand up strongly against anyone in the XV game."
- England sevens
- Ben Foden