The time each runner spends on the ground will also be limited in a radical change designed to limit the impact of on-field officials.
AFL coaches expressed concern when the change was mooted at the laws summit held on the Gold Coast last month, worried it would impact their ability to coach effectively.
However, the AFL was worried that runners were doing too much on-field coaching. Research has shown that runners were spending inordinate amounts of time on the ground, with some clubs having runners on the ground for 90 per cent of each game.
With many runners now drawn from within club football departments, they are able to provide information relating to structures, rather than specific messages from the coaches.
The AFL is also concerned that on-field officials have been used to clog up space inside the 50m arcs.
When AFL football operations manager Mark Evans flagged the changes in Grand Final week he indicated there was some move to remove runners altogether.
"I am keen to explore whether we can reduce this impact by limiting the time frame, or the number of times, in which some of the officials are on the arena," Evans told AFL.com.au.
"Given the high number of player rotations through the interchange bench there may not be the need to have some officials on the arena during play."
The result of one runner is something coaches can live with and represents a step back in time to when teams only had one runner.
Players were expected to be upset at the decision to reduce the number of trainers permitted to enter the field from six to four. A fifth trainer will only be allowed to enter the field when a stretcher is required.
At the AFL Players' Association delegates meeting last week, players questioned the need for any reduction and expressed concern that it would impact negatively on player wellbeing.
They were worried about their ability to hydrate and receive adequate treatment if injured.
However the player wellbeing manager at the Players' Association Ian Prendergast said they were comfortable with the changes and pleased the AFL had listened to its concerns.
He said the main issue with the original proposal was a suggestion to limit trainers entering the field to only after a goal had been scored. However the AFL had taken a more practical approach and considered players' wellbeing.
"The AFL’s research suggests that the new rule change will have negligible impact on players’ intake of fluids during a match, and on this basis we are satisfied that the rule change won’t have any impact on player health and safety.
"The AFL has assured us that it will monitor the rule change throughout the year and will be flexible in certain conditions, for instance on hot or humid days."
The AFL also added that financial sanctions against clubs would be increased if medical staff were used to deliver coaching messages.
