Jen Welter: The woman who crossed the NFL line

As I sit down to speak to Jen Welter, an NFL highlights reel is running in my head. It's fast, it's brutal, it's dramatic. And most of all, it's macho.

Indeed, the only women to be seen are the lithe, leotard-clad all-American girls waving their pom-poms. NFL is a sport that would seem unlikely to take orders from a 5ft 2in doctor of psychology, and Welter is well aware of the ground she's broken.

"For a very long time, we would all say 'football is the final frontier for women in sport,'" the 38-year-old told BBC Sport. "There was always that line and I never really saw that I would cross over it."

That line was crossed in July 2015, when Welter became the first woman to hold a coaching position in the NFL, working with the Arizona Cardinals linebackers throughout training camp and the pre-season.

"These are the best of the best in this game and I wasn't sure if I was going to be a little bit shy, but I think it took me about 2.2 seconds to jump in because it was just 'oh this is football, this is natural'. The guys were so receptive."

It's hard to believe the woman facing me could ever be shy. Welter - who has a PhD in psychology - has already been a trailblazer in American football. She spent 14 years playing professionally, making history in 2014 when she featured at running back for the Texas Revolution - a men's team.

"Sometimes I laugh and say 'God has a really good sense of humour'," said Welter. "I am the last woman in the world who should've made history in men's professional football. I'm tiny.

"I was one of very many brave women who were kind of taking on this monstrous feat in getting to play the sport that wasn't for women and I promised myself that whatever happened, as these opportunities unfold, you'll step up and do it - and that was playing with men and later coaching them."

This determined spirit brought her to the attention of Bruce Arians, the respected head coach of the Arizona Cardinals, who took her on as an intern.

"I don't know if Bruce is a betting man or not but he bet on me. His coaching staff is one of the most diverse coaching staffs in the NFL. He really believes that talent has talent no matter what the packet it comes in."

There were some who questioned the move, however.

Welter's internship came at a convenient time for the NFL, which had faced criticism over its handling of domestic violence in the league - the appointment painted the NFL in a more inclusive light.

But both Arians and Welter have rejected the idea there was an ulterior motive.

"The [Arizona Cardinals players] still text me and call me coach, and so if this is a publicity stunt, then what does that mean?"

Fans of the Arizona Cardinals hold up a sign to welcome Jen Welter during team training

Welter's stay at the franchise was temporary, and a full-time position wasn't available. She has since worked as an analyst on television and as a motivational speaker.

"That shouldn't take away from what she's achieved," said Albert Breer, reporter for league-owned cable and satellite operation NFL Network. "There's so much money in this sport and so few positions available that usually interns have to go through this process several times before they can hope to get a full-time job."

"I know a lot of people were very sad that my time with the Cardinals ended after pre-season but that's what was designed in the beginning," said Welter, who hopes to return to the game once the season has finished when another internship, or more permanent role, becomes available.

"Would I love to be still there? Of course I would. But is it realistic? Well, hopefully it will be down the road."

It's in basketball where the most progress has been made.

Nancy Lieberman was recently named assistant coach of the Sacramento Kings in the NBA, following in the footsteps of Becky Hammon at San Antonio. It seems a matter of when, not if, there will be a head coach in the NBA.

So can Welter ever see the NFL following suit?

"It is absolutely a dream and it will happen," she said. "It's just in what timeline.

"Women's basketball is more accepted because of the level they've played at and its relationship to the NBA - and it still took a very long time for Nancy Lieberman to become an assistant coach in the NBA."

Welter's own time on the touchline might have been limited, but it has been long enough to see her make a lasting impression.

"To know that any little girl can grow up and dream of seeing themselves on an NFL sideline - that's probably one of the greatest things that has come out of this," said Welter.