Pressure is mounting on the AFL to overhaul its interchange system to ensure teams aren't crippled by injuries or the careers of superstars cut short.

In wake of a brutal weekend of injuries in Round 3, the increased ferocity and speed of the modern game has sparked coaches, players and medical experts to call for change to the current four-man bench and review the number of interchange rotations.

Suggestions include a cap on rotations, a six-man bench with unlimited rotations or the introduction of a substitute who is only used when an injured teammate cannot return to the field.

The increasing number of player rotations - the average of 92 per team last year could be as high as 130 this year - means teams that lose players to injury are disadvantaged more than ever by a lack of fresh legs.

The Adelaide Crows had four injured players - one in hospital and three on the bench - by the end of their loss to Melbourne on Sunday.

The Western Bulldogs and Hawthorn each had only one fit man to turn to by the time their robust battle was over, prompting Dogs' coach Rodney Eade and Crows' counterpart Neil Craig to lobby for change.

Hawthorn enforcer Campbell Brown endorsed these calls on Monday, claiming teams almost had no chance of winning if they were hampered by game-ending injuries.

St Kilda was another club restricted by injury when it had only two fit men on the bench at one stage of its controversial win over Collingwood after skipper Nick Riewoldt tore his hamstring in the shadows of half-time and Sam Fisher was carried off in the third term.

The feverish use of rotations, leaving players fresher and stronger for longer, has also prompted the AFL this year to ask game analysis manager Andrew McKay to investigate whether there was any correlation between interchanges and more high-impact injuries.

Former Essendon High-performance sports manager John Quinn, now a consultant to Carlton, said the game had dramatically increased in tempo in the past decade and greater discussion was needed not only on the interchange system but the number of rotations.

"Do we actually want to take the intensity out of the game with a cap on rotations because it makes it an exciting spectacle when teams are firing right through to the last bit of the game?" he told backpagelead.com.au.

"But you can't have it both ways. If you want to keep your best players on the ground and manage them well, and with these high level of rotations, is it going to become inevitable for players once they hit 30 that they can't keep up with the on-going intensity and speed of the game?

"Are we going to see more injuries like we saw with Nick Riewoldt? He is an explosive, dynamic player but the intensity of the game now goes over two hours rather than it being an endurance- based game.

"The whole nature of the game over the last 10 years has moved from being an aerobic power sport to a repetitive speed sport."

That change was also acknowledged recently by AFL legend Leigh Matthews, who noted there was now a sustained attack at the contest and "that there was nowhere to hide in the game now".

Quinn said if a link between the number of interchanges and high-impact injuries was proven, there would be a "good case" to cap rotations but this could spark more problems.

"If you limit the interchange to 80 a game, then I ask the question who is going to police that?" he said.

"We did that in the NAB Cup and the reality of keeping track of the number of rotations that a team is going through is a logistical nightmare, not just for the team, but for the officials.

"Perhaps we could have a six-man bench and unlimited rotations."

Eade reiterated today a cut in rotations could put more strain on players. He said his men would still be expected to maintain their current tempo and this could lead to more soft-tissue injuries as a result of fatigue.

AFL Medical Association executive Dr Hugh Seward said the merits of an extended interchange and the introduction of substitutes was regularly discussed but officials were no closer to a decision.

But he did admit game-ending injuries now hampered teams more than ever.

"There is more pressure than ever before to rotate players," he said.

Quinn said a substitute - separate to the four-man bench - who could replace a teammate unable to return to the field deserved consideration.

"I think that's got merit but it also opens you to people not using that in a sportsman-like manner," he said.

He said the chief concern would be players, under instructions from a coach, feigning injury in a bid to bring a fresh teammate on.

Clubs have been allowed to use substitutes simply to limit game time for players in the past two NAB Cup campaigns.

The AFL Players Association said it was awaiting a review of this before deciding whether to endorse any regular-season move.

Club officials have also questioned how the substitute would keep fit if he couldn't break into the best 22 but wasn't used for weeks on end if there were no injuries.

Then there is the issue of match payments and what a substitute - who doesn't play - should be entitled to.

"A substitute would have to receive a match payment but we don't believe this will be the determining factor as to whether such a concept would ever be introduced," the AFLPA spokesman said.