The AFL's use of the NAB Cup as a tool of experimentation will continue this year with the league trialling restrictions on the use of the interchange bench.

A cap of 16 interchange rotations per quarter, and 64 per match, per club will be introduced for this year's pre-season tournament.

As a result, due to the potential for hotter weather in February and March, the amount of interchange players that teams are allowed has inreased from six to eight.

"The number of interchanges has risen substantially in recent years, jumping from 17 per team in 2000 to an average of 58 per team in 2007," AFL general manager of football operations Adrian Anderson said.

"With players on the ground for less time and covering less distance, but travelling at significantly faster speeds, there is a concern about the potential increase in collision injuries and also the impact of player congestion caused by players being able to get to more contests."

In addition to the interchange limitations, the AFL has also announced that a 'no-go' zone will be added to the centre of the ground.

Players won't be allowed to enter the designated area at any stage during an umpire's bouncing process.

The two-metre zone, which extends six-and-a-half metres out from the centre of the centre circle, will aim to protect umpires from when they prepare to bounce the ball to re-start the match until they leave the thick of the action after the bounce is completed.

The rule changes continue a long history of pre-season experimention by the AFL that has included the trialling of nine-point super goals, the prohibition of marking from a backwards kick in the defensive half and the use of four goal umpires.