NORTH Melbourne ruckman Todd Goldstein says he feels "stuffed" late in games but he's determined to soldier on with minimal time spent on the interchange bench.

Goldstein has played all 15 matches for the Kangaroos in 2013 and has been rotated off the field only 20 times, which is the least of any ruckman in the competition.

But without a back-up ruckman in the side apart from key forward Drew Petrie, Goldstein says things aren't going to change too much.

That's despite North's ongoing dramas with getting run down late in games, including last week's fadeout against the Brisbane Lions at the Gabba.

"I know I don't get too many rotations. But I probably was surprised that I'd only had 20," Goldstein told SEN Radio on Thursday.

"I know that's what I'm in for each game. You are pretty tired by the end of the game.

"Whenever (ruck coach) Alex Ischenko asks me how I'm going I say, 'I'm pretty stuffed'.

"If I change out of the ruck that means Drew Petrie has to go in there and he's one of our most dangerous forwards and takes their best defender.

"So I'm not really that inclined to want to change with him too much. But we do need to try to change a bit more."

He added that he was more than happy "just to keep rucking along".

Goldstein says mental lapses have been partly to blame for North's six episodes of conceding leads late in games.

"It is a bit of a mental lapse that we go through," he said.

"It seems like we're choking. But I think it's just about sticking to the game-plan for longer.

"We really get ourselves in trouble when we don't stick to it."

Challenged on North's apparent lack of fitness, Goldstein conceded it was difficult to dismiss that criticism completely.

"It is very hard to defend that sort of point because it seems we can't really run out the games that great," he said.

"It's more getting used to playing this (up-tempo) style probably as effectively as we have this year.

"We aren't used to that level of work.

"We've just got to try to stick at it for longer."