The data - released exclusively to AFL.com.au - reveals the substitute interchange model has cut average player speeds and may have reduced the incidence of some injuries.
According to a separate injury report, also released on Wednesday, there is evidence that having three interchange players and one substitute has contributed to a reduction in groin and hamstring strain injuries.
AFL medicos have indicated they’ll be closely analysing this season’s data, as the League considers a two-sub, two-interchange format, which could be introduced as early as 2013.
The exhaustive GPS analysis shows average player speed and time spent at the highest speeds have decreased with 20 elite midfielders recording a 29 per cent reduction in high running speeds.
"I think this data really helps inform the discussion," League football operations manager Adrian Anderson told AFL.com.au.
"The best advice available to us says that by having the players out there more and the top speeds come back that we're actually protecting the players better.
"At the end of the day we need to make decisions on the basis of what we think is in the best interests of the game."
Between 2005 and 2010 the average intensity of player exertion had increased 17 per cent. In 2011 it dropped 3.1 per cent.
The exertion index is a measure of the relationship between game load, fatigue and the total load of players. It ensures both short sharp efforts and long sustained efforts are equally analysed.
But while coaches and recruiters have been calling for a decision on the proposed 'two plus two' substitute system, the AFL is sticking to its process.
"Any decisions about changes to the rules won't be made until after the end of the season," Anderson said.
"We'll spend the year devising the topics, consulting on the topics and then making recommendations to the commission.
"It's very important that the coaches and players do have input."
The GPS report also reveals;
- A 55-second fall in the amount of time players spend running at above 18km/h from 6min 20sec in 2010 to 5min 25sec last year.
- Players spend around 70 minutes per match moving at less than 8km/h and are also spending more time between 8km/h and 12km/h.
- Across the competition, teams adapted to the substitute situation differently. Some had a dramatic drop in rotations, while others maintained similar numbers despite having just three players on the bench.
- Defenders run the most travelling an average distance of 13.5km per match, forwards run 12.89km a match and nomadic players, defined in this study as midfielders and ruckmen, run 13.46km a match.
- Midfielders spend significantly less time on the ground - 109 minutes, compared to 113 minutes for forwards and almost 117 minutes for defenders.
- The intensity from midfield players though is 16 per cent higher than a forward and 14 per cent higher than a defender.
Change of pace
| Time Zone | Speed | Change |
|---|---|---|
Below 8 km/h | 70 mins 05 secs | Up 43 secs or 5.6% |
Over 18 km/h | 5 mins 25 secs | Down 55 secs or 14% |
Position of speed
| Forward | Nomadic | Defender | |
|---|---|---|---|
| Time on ground | 113 mins 25 secs | 108 mins 52 secs | 116 mins 37 secs |
| Total distance | 12.89 km | 13.46 km | 13.50 km |
| Average speed | 6.83 km/h | 7.43 km/h | 6.97 km/h |
Subiaco versus MCG
| Subiaco | MCG | |
|---|---|---|
| Distance covered | 14.26 km | 13.04 km |
| Time | 115 mins 50 secs | 107 mins 28 secs |
| Average speed | 7.4 km/h | 7.3 km/h |
