A CONCUSSION sub will be introduced into the AFL this season after the AFL Commission approved the change on Tuesday.

The rule change will allow teams to use its substitute as an interchange player for a 20-minute period while a concussion assessment is taking place.

However, if the player being assessed returns to the field inside that 20-minute period, it will be considered a major interchange breach and a free kick and 50m penalty will be awarded to the opposition.

Under the new guidelines, the SCAT3 assessment (a tool used to determine whether or not a player is suffering concussion) will not begin until a minimum of 10 minutes after the on-field incident.

Club doctors will review video footage as well as orientation, balance and cognitive function as part of their assessment.

Once the temporary sub is activated, an AFL interchange official will notify a club interchange official after about 17 minutes of the assessment period so he can be removed from the field.

If that player does not leave the field before the 20 minutes expires, the sub will be declared activated and the player who has undergone the concussion test will be subbed out of the game.

Most notably for clubs, if their sub has already been activated in a game, he cannot be re-used for concussion? assessment.

The temporary sub is considered a key change to support conservative new concussion guidelines that will be introduced this season.

The rule change will ease pressure on doctors as they make assessments and is consistent with the recommendations from the Consensus Statement of Concussion released last Tuesday.

That statement, which arose from the International Conference on Concussion in November, said sports should consider rule changes to ensure the assessment of players suspected of suffering head knocks could occur "without affecting the flow of the game or unduly penalising the injured player’s team".

The AFL Medical Officers Association recommended the rule change and it had club support.

Clubs will be required to submit the completed SCAT3 form for any concussion assessment conducted on match day to AFL medical director Dr Peter Harcourt and Dr Harry Unglik by Monday following the match. ?

That statement, which arose from the International Conference on Concussion in November, said sports should consider rule changes to ensure the assessment of players suspected of suffering head knocks can occur "without affecting the flow of the game or unduly penalising the injured player’s team".

The AFL Medical Officers Association recommended the rule change and it had club support.