FOR FOUR seasons, James Polkinghorne has promised plenty but delivered only sporadically.

As a 20-year-old, he ran straight through Chris Judd to win a centre clearance in the dying stages of the Brisbane Lions' memorable 2009 elimination final win against Carlton at the Gabba.

It was just one play, but it was enough to show coach Michael Voss this promising forward could make it at the top level.

He quickly became one of Voss' favourites.

But with every glimpse of potential came patches of invisibility, as Polkinghorne drifted in and out of games.

Entering his fifth season in the AFL, the 23-year-old son of former Hawthorn player Robert and nephew of former Hawks star David realises it's time to step his game up.

Polkinghorne quietly went about playing all 22 games last year to take his career tally to 61, but said he now wanted to have more impact.

"As far as playing games, I was consistent last year," Polkinghorne said.

"There was still a bit of inconsistency [though] so over this pre-season I've definitely tried to work on the running and that gut-running you need to be in the midfield.

"I definitely think at 50 games you have to take the next step and it comes with a bit of maturity as well.

"Playing 50 senior games you have a good feel for it after that, so there's a bit of ownership on myself to step up not only with my game but more importantly for the team."

Polkinghorne is a strong overhead target for his 184cm frame, but it's an inside midfield role he craves.

He is powerful and fearless at the contest and forms the nucleus of a strong midfield alongside veteran Simon Black and young teammates Tom Rockliff, Daniel Rich and Jack Redden.

"That's definitely a focus, trying to get in and get the contested footy," he said.

"I've been working closely with Woey (midfield coach Shane Woewodin) and he works well with all of us midfielders - we have a good relationship with him.

"Every chance we get, we try and stick together to work out all the structures and patterns and how to read each other in training which correlates into games."

Polkinghorne admits he won't know the extent of his newfound fitness until he's put under the pressure of a game, but says it's so far, so good.

"It's early into game simulation stuff and the game running is a lot different to the fitness base you build early in the pre-season but so far it feels not too bad."

Michael Whiting covers Brisbane Lions news for AFL.com.au. Follow him on Twitter: @mike_whiting