ADELAIDE defender Rory Laird has welcomed a rule change that makes it harder for players to draw free kicks by ducking into tackles.

Laird said the practice had become commonplace in the game and it was something that needed to be eradicated.

"There are times you get very frustrated, especially down back, when you see a blatant one where someone ducks into it or lifts their arm up," Laird told reporters on Wednesday.

"Players have got very good at finding out ways to exploit that.

"If we can miss a few of those due to people doing that, it's a good rule."

Laird said there were a "fair few" players who exploited the rule, but he didn't want to single out individuals.

The AFL Commission approved changes to the rule that simplifies the interpretation of when a player draws high contact from a tackle.

Geelong captain Joel Selwood and North Melbourne forward Lindsay Thomas were among those who came under scrutiny for getting themselves into a position to draw free kicks.

"There have been players that have maneuvered their way into getting frees in terms of lifting their arms or dropping down a bit for people who are taller than them to wrap their arms around them," Laird said.

"Credit to them, you get a free kick for it, you may as well do it.

"It will make it a bit more fair and balanced if the umpires adjudicate that as play on rather than (awarding) a free kick."

The Crows held a training session behind closed doors at Football Park on Wednesday.

Midfielders Brad Crouch (hamstring) and Scott Thompson (shoulder) remain on modified programs, but both are expected to be available for the JLT Community Series.

It's the third time Crouch has injured his hamstring, while he also missed the entire 2015 season with a persistent foot complaint.

"He's going alright and he should be fine for the JLT Series," Laird said.

"He has just had a few setbacks in terms of his body and he's been (riddled) with a few injuries over the past couple of years, so it's very frustrating for him.

"He's very diligent with what he does and his rehabilitation, so I'm pretty sure the (medical) staff are confident he can get some game time before the season starts."

Defenders Luke Brown, Kyle Cheney and Alex Keath, and winger Paul Seedsman, are also on modified training programs.