The AFL Coaches Association says everything must be done to ensure a worrying trend of serious hamstring injuries to players is avoided but has warned against a knee-jerk reaction.

The increased speed and sustained ferocity of the game in conjunction with a skyrocketing number of rotations has been blamed for three major hamstring injuries in the past fortnight.

St Kilda superstar Nick Riewoldt, Hawk Josh Gibson and now West Coast's Daniel Kerr have all required surgery on torn hamstrings and are no guarantee of playing again this season.

The career of Richmond great Matthew Richardson was brought to an abrupt end last season when he tore his hamstring, while former Essendon skipper Matthew Lloyd was never the same after he tore the tendon off the bone in 2006.

The AFL has launched an investigation into what looms as a hamstring epidemic, with match analyst Andrew McKay seeking reaction through the season from clubs. The AFL Medical Association and club doctors will be given plenty of input, with many admitting the physical strain on players is now was greater than ever.

But the various reactions to impending change so far from the league's 16 coaches means finding a solution won't be easy.

AFL Coaches Association boss Danny Frawley, a former St Kilda captain and ex-Richmond coach, said the injuries to established stars was a concern.

"I think that's going to be a big discussion point. The AFL has done a good job speeding the game up but whether it's co-incidence or bad luck, it's a hard one to get a gauge on," he said.

"But obviously the amount of interchanges, the game is at a premium all the time. In the ‘80s, ‘90s, the intensity of the game was always there for the first 10 or 15 minutes and then it would peter out to a sustainable level.

"But obviously coaches are paid to win games of footy and rotations are a pretty important part of the game."

Blaming interchange use for the hamstring injuries has become a hot topic. Some coaches, such as the Western Bulldogs' Rodney Eade and Port Adelaide's Mark Williams, have slammed the suggestion.

There have also been calls for a cap on rotations by Brisbane's Michael Voss and West Coast's John Worsfold to help slow the speed down. Limiting rotations in recent NAB Cup competitions drew a mixed response.

Geelong's Mark Thompson, a three-time premiership player with Essendon, had this simple idea: water the grounds more.

As discussed by backpagelead.com.au last week in "Interchange system reaches breaking point", there have been calls to extend the interchange bench to six, or introduce substitutes, to ensure the speed of the game can be maintained without injuries affecting a result. League great Leigh Matthews has endorsed this move.

There have even been left-field ideas from the likes of St Kilda coach Ross Lyon. Usually averse to gifting the media a headline, Lyon said 45-minute halves, rather than the usual 120 minutes of playing time, would help avoid a "war of attrition".

"It's not my typical mode of operation to throw up ideas about the game, but in the context of the last four weeks maybe it's something we could look at," Lyon said.

"We're throwing up a lot of options, but it's the one for a long period of time I've thought. It would be explosive and electric."

The frantic number of interchanges, with teams expected to average about 130 per game this season, also has some players concerned. Some have privately complained they have no idea who their opponent is when they return to the field, while Lions skipper Jonathan Brown says the game has been robbed of great one-on-one duels because players no longer stand each other for an entire game.

AFL operations boss Adrian Anderson says he will have plenty to consider when a review is completed at the end of the season.

"There's a whole range of options you could look at with substitutes, but having a cap on the number of interchanges is something that at least one of the clubs has put forward,'' Anderson said.

''AFL injury data suggests there may be some correlation between interchange use and injuries.''

Frawley, meanwhile, has called for calm and says a clearer picture will known at the mid-season break.

"We want to make sure all the best players are out there. It's probably something that is in the forefront of most people's thinking," he said.

"Spectators obviously love it (the speed) but we don't want to put a premium on all of our star players getting injured. It's only Round 4. Let's see what the trend is after Round 11 or Round 12."