Rugby sevens will appear at the Olympics for the first time in the 2016 Games in Rio de Janeiro, and Woodward claims that it would be like picking a Lions squad.
However, Ryan believes that different fitness levels and issues means that integrating 15-a-side players into the team is unlikely.
"It would be a really hard ask for them to come in," Ryan told BBC Radio Five Live. "As far as the way our leagues are set up in the UK and how the game is played and structured, it has taken our players a long time to get to the conditioning levels you want.
"You never say never because there may be somebody that has played sevens in the past and is above everyone else's fitness levels in the Premiership or international rugby and they really want to give it a go.
"But for the general population that are playing 15s at club or international level, it would be really hard. That is backed up by our fitness statistics, which are a level above first XVs."
Woodward led England to World Cup glory in 2003.