GEELONG skipper Joel Selwood has admitted he's "nervous" over the mid-season trading period that is likely to be introduced for 2019. 

Selwood joined his fellow captains on Thursday questioning how a player movement would look next year. 

It comes after club CEO's left Wednesday's briefing with AFL executives expecting the move to be ticked off.

"To be honest I'm a little bit nervous about it, just because there's so much unknown in it," Selwood said.

"I think that it could work but there's a lot of work to go into it."

Essendon captain Dyson Heppell joined his Geelong counterpart with more queries. 

"I'm a bit similar (unsure about it)," he told AFL.com.au. 

"I'd want to see exactly how it's going to be structured first but at the moment I'm probably not for it. 

"I think the recruiting staff put an enormous amount of time in getting their list to a healthy period where they can play the whole season, I think that'll rattle it a bit. I'm not for it at the moment."

The leaders were asked for their opinion at the annual briefing with League officials on Thursday morning.

Carlton captain Marc Murphy and North Melbourne skipper Jack Ziebell said they were personally in favour of the move, while Hawthorn's Jarryd Roughead said it was a waiting game. 

"Until you actually see what the model is you can't really say yes or no," the Hawks skipper told AFL.com.au.

"You look at the American side of things, they do some things well and some things maybe not so well. 

"So until you actually know what the model looks like you can't really say yes or no."