PADDY McCartin has the potential to be a "scary" proposition for opposition defenders, his St Kilda teammate Tim Membrey says.

McCartin, 21, has been restricted by concussion and other injuries since he was drafted with the first selection in 2014, but has impressed many at the club with his fitness recently.

Since suffering his sixth concussion since 2014 in June, McCartin has worked on his running and ran a personal best time in a 3km time trial a fortnight ago.

Membrey told reporters on Tuesday he was excited about the prospect of McCartin filling the void left by retired champion Nick Riewoldt.

"I personally am his (McCartin's) No.1 fan," Membrey said.

"I love him and think that he's going to be a superstar.

"He's clearly putting in the hard yards now and the rewards are starting to show, just in his aerobic capacity and his body now.

"I just hope that he gets a clear run at it, no injuries and I personally think he could be a bit scary."

Being anointed Riewoldt's successor is a tough assignment – the six-time best and fairest booted 718 goals in 336 games.

However, Membrey believed the improvement of a young side could make up for the former captain's absence.

"(Riewoldt's) made it pretty clear that Paddy's the one to come in and make a big stamp on this team," Membrey said.

"We're excited, we're young down there. Starting to get some experience as well, with guys like Josh Bruce and Mav Weller. It's exciting and it's fresh."

David Armitage and Jade Gresham were among a small group on slightly limited duties at training.

Armitage played just twice this year after having two groin surgeries but completed a running session on Monday, while Gresham is recovering from his own groin operation.

Paddy McCartin at Catani Gardens in St Kilda on Tuesday. Picture: AFL Photos

Tim Membrey working hard on the paddleboard. Picture: AFL Photos