As rugby league star Jarryd Hayne continues to push his way into the NFL, the Brumbies have invited former Houston Texans tight end Chris Coyle to spend three months training and playing in Canberra.

Coyle was a star gridiron graduate from Arizona State University, which set up a partnership with the Brumbies when coach Stephen Larkham visited the United States in September last year.

Coyle, 24, 101kg and 191cm, has publicly stated his ambition to become a professional rugby player after being cut by the Texans when he suffered a shoulder injury midway through last year.

Leah admitted there was "a long road to be travelled yet" and predicted it would take an NFL player two years to physically adapt to the needs of Super Rugby.

But Leah said rugby was the fastest-growing sport in US high schools and more American youngsters now had a background in both football codes.

"He's not contracted, he's not going to play Super Rugby, he's coming down to train with the main squad and work with the academy to try and fast-track his development," Leah said.

"The reality is, physiologically it's going to take him two years to adapt. Each play in the NFL lasts a maximum of seven seconds. He's now got to generate that power over 80 minutes."

"But rugby is the fastest-growing sport in the US, there's 15 per cent growth in high schools annually. Guys are coming into college now, having played football and rugby. If things don't eventuate in the NFL, there's nothing else for them, so there is the opportunity for those guys who've played some rugby to cross back.

"Over the next 10 years, 100 per cent there'll be more American guys playing [professional rugby] . It will be an opportunity for American players to play not only in Super Rugby but the UK."

Coyle will spend 13 weeks training with the Brumbies and will also play with Gungahlin Eagles in the ACT competition. He has been playing in the US for the past five months as a back-rower since being cut by the Texans.

"[The ASU coach] told me there was a team in Australia that was interested in training me to become a [professional] rugby player," Coyle told The Arizona Republic.

"He explained the opportunities, that I could have a good future in rugby overseas. He said a lot of ex-football players could be doing it, but they don't take the risk and give it a shot. There are so many places you can end up, with a lot of great financial opportunities because the sport is so popular in other areas of the world.

"There's such a connection between the two sports. And at first, I just used my athleticism. I used the things I knew from football, my route running skills and my ball-carrying skills. But now, there's so many times when I'll use a technique from football for leverage in rugby, or something like that.

"The difference is, there's not a defined play like in football. It flows like soccer. It's a ton of fun, such an active game, and anybody can get the ball at any moment. And when I'm on defence, it takes me back to my high school days and I get to tackle again."

"I wouldn't say the NFL is closed for good. But it seems like my best opportunity is in rugby. And I can't wait to get to Australia and see how it goes."

The Brumbies Academy also has international links with Japan and four players are in Canberra training as part of the development scheme.