AFL FOOTBALL, HAMSTRING INJURY and GPS
Hamstring Injury is on the rise again it seems in the AFL. Yet we are seeing the AFL gloat about how the rules have changed the game and made it less dangerous for contact injury and link this to the rule changes. An article by Damian Barret quoted the decrease in high intensity running in the GPS report.
“THE AFL’S GPS data from the 2008 season has revealed a fourth consecutive increase in “playing intensity”.
Among results that delight AFL football operations manager Adrian Anderson, who has introduced a raft of rule changes, the 2008 season saw players spend less time at “high-end speeds” and more time at “steady-state running speeds”.
The report quoted Adrian Anderson noting the decrease in collision injuries since 2004 but of course we also have had far more stringet tribunal decsions with head high contact cases for example. So one has to be a little wary of making rash conclusions with this GPS research. Also the report said that ball in play had increased over 10% since the 2001/2002 season but of course one must remember that extensive GPS use was not occuring then.
“Anderson said there were strong warnings at the end of 2004 that the game had moved too far to a stop-start style and, as a result, players were suffering serious collision injuries because when the ball was in play, they found themselves playing at a higher speed”
So why have Hamstring and Groin injuries increased?
The attention to detail in the area of soft tissue management is pristine these days in the AFL. What this report totally misses and what GPS really struggles with is that there is a maximal instantaneous muscular effort occuring time and time agan in a game. So whilst players are fatigued due to less rest thay are still contracting at maximal effort close to the ball increasing the risk of soft tissue injury. GPS does have accelerometers that measure impact forces but again this is not measuring the maximal contraction of a fatigued muscle.
And added to this problem is the massive interchange numbers which means a fresh player comes on a totally fatigued player and adds to the need to maximally accelerate at an instantaneous moment. WHACK more injury. Fatigue causes loss of efficiency in movement apart from other problems that expose soft tissue to injury.
So whilst a player may be cruising at a slightly lower speed they still have to bend and crank 100% effort many times over and in a more fatigued state. Just not something a GPS can measure. That is, the massive instantaneous eccentric contractions that occur at maximal intensity compounded by the fight or flight response.
So again we see the flawed use of statistics and technology. GPS was fantastic to allow sports scientists a clearer picture of game loads and variations from training to games for example. Coupled with HR data and subjective data and linked to video one can really analyze general game loads for AFL players.
Reality all that may have happened is that the rule changes have changed work/rest ratios and meant that coaches have to select slightly more “aerobically” biased teams with a result that players are running around slightly more fatgued than in the past. So yes it may nicer to watch but one can see where soft tissue is strainign even more now. And also one would have to look at the rule changes with collision injuries to judge whether that has been the main reason for less contact injuries.
It is the old story. One can use statistics to justify most scenarios. And also as in the grand final one will see a lot more euse of tactics that will again change many variables.
loris bertolacci 