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Using a GPS to monitor your performance

IT is football in the technological age. Each player takes the field with a small global positioning satellite unit strapped to his back. From the first bounce, every step, heartbeat and metre covered is recorded and beamed back to the coaches’ box, where a team of sports scientists monitor the numbers in real time.

Whenever a player starts to “red-line” on any given measure, he is brought to the bench and replaced by a team-mate with fresh legs, enabling the game to continue at maximum speed and intensity.

Whenever a player’s output slips below an acceptable level, the runner is quickly dispatched to bark instructions in his ear.

A glimpse into a distant sporting future? Hardly.

According to GP Sports, the company that provides AFL clubs with GPS units, it is technology available from July 1.

The only sticking point is whether the AFL will lift its restrictions on the use of GPS equipment; a question currently the subject of fierce debate between the league administration and the clubs. For a cost of $66,000 over three years, AFL clubs can have 22 players connected to their coaches’ box by wireless telemetry.

Just as a Ferrari mechanic monitors every component of an F1 car during a grand prix race, a footballer’s body will communicate directly with a laptop sitting in view of the senior coach. If the data proves reliable, it is a potentially revolutionary coaching tool.

For the past two seasons, AFL clubs have had access to GPS units, at a cost of $4000 per unit, which measure the distance players run, their average speed, the number of accelerations and decelerations and various units of workrate.

The use of these units is restricted to five players per team for a total of 10 games per year.

The data from these trials, used to varying degrees by the clubs, has helped fitness and conditioning staff design training regimes to replicate game demands and adjust training loads to take account of the work done throughout a season. The new technology, at a staggered cost of $1000 per unit per year over three years, will allow clubs to access the information as a match is unfolding.

The software will enable clubs to set upper and lower thresholds on each measure, so that the computer tells you when a player is showing signs of fatigue or not working hard enough.

The computer will be armed with a physiological profile of every player and relative benchmarks.

“You will be able to sit on the boundary line with a laptop computer and have a look at variables such as heart rate and distance covered in real time,” Richmond conditioning and rehabilitation coach Warren Kofoed said.

“The theory would be that when a certain player has been in a certain heart-rate zone or covered a certain amount of distance you would take them off the ground at that time.”

Fremantle conditioning coach Ben Tarbox is mindful of the teething problems inherent in any new technology.

“One thing I have learned in sport science is never buy version one,” he laughed. But Tarbox agreed the potential ramifications were enormous.

“From a physiological perspective, you can determine how hard they can run for a certain period of time and how long they need to recover,” Tarbox said.

“Based on that, you can work out how best to rotate 22 players to maximise the team output for a period of time. It has the potential to optimise our performance as a team and identify when players are at greater risk of soft-tissue injuries. It would help me get a better understanding of real game demands.”

At a GPS seminar organised by the AFL last month, all 16 clubs lobbied the league to lift its restrictions on GPS equipment. But the question of whether to give clubs unfettered access to the new technology is a vexed one for AFL football operations manager Adrian Anderson and, ultimately, the AFL commission under new chairman Mike Fitzpatrick.

On the one hand, the AFL research board would love to have access to the riches of information GPS telemetry would provide. The AFL would also appreciate the commercial appeal of select data being fed to its broadcast partners. What broadcaster wouldn’t jump at the chance to flash Chris Judd’s vital statistics across the screen as he tore down the MCG wing?

On the other hand, the AFL is concerned about the growing discrepancy in football department spending between the rich and poorer clubs and whether the latter can keep pace in a technological race. The NRL has banned the units because of risk of injury in tackles and the AFL will seek its own medical advice.

The AFL is also concerned that real-time GPS information would further increase the use of interchange; a tactic the clubs have employed to circumvent AFL rule changes intended to slow the game down. “In a way, it works to negate what they are trying to achieve,” Tarbox said.

The negligible impact of last season’s rule changes are confirmed by the latest Wisbey report, an analysis of match day GPS data gathered by the clubs throughout 2006.

While the rule changes were intended to reduce the speed of the game by making it more continuous, the Wisbey report revealed AFL midfielders were able to maintain their explosive pace by spending less time on the ground.

A sample of 113 midfielders showed that the average on-baller covered 13.2km in 2006 compared to 12.9km in 2005, ran at a higher average speed, recorded an unchanged pattern of fast accelerations and reached a similar top speed while spending two minutes less on the ground.

At the same time, interchange use dramatically increased from an average of 36 in 2005 to 46 per team. In this year’s first round the average leapt to 56, with Sydney setting a new record of 80, including 24 in the final quarter of its one-point loss to West Coast. In the same match, West Coast recorded 70, setting a combined team record total.

“Coaches are quite clever at being able to rotate their players to combat the rule changes,” Collingwood conditioning coach David Buttifant said. “The intensity of the game has gone up. The velocity has gone up. Blind Freddy can see that.”

Sydney’s elite performance manager David Misson concurred. “The game is definitely not getting any slower,” he said.

“The demands on the midfielders have probably increased slightly from a running point of view. The only way you are going to get effective output from your midfielders through a game is to give them a bit of rest.

“If you are out there for 120 minutes it is almost physically impossible to produce the type of explosive efforts that you see from people like Judd and game-breaking players.”

The Australian reported in February that AFL-commissioned research had forecast up to 100 interchanges by the 2010 season.

At last month’s meeting, AFL research board chairman Ross Smith said 80 bench rotations could be the norm this season and that a restriction on interchange was the likely response of the laws of the game committee.

Brisbane coach Leigh Matthews this week called for a return to player substitutions instead of unlimited interchange. Brisbane used its bench less than any other club in round one, making just 38 changes against Hawthorn. However, any move to limit interchange would be resisted by the majority of clubs.

“The first question to ask is why they want to reduce the intensity of the game?” Buttifant asked. “Is it going to have a significant influence in reducing injuries? You would want to be able to quantify that before intervening in the rules of the game.”

The hidden cost of the new technology is the skilled labour required to analyse the reams of data that unlimited GPS use would produce. Where some clubs, most notably Adelaide and West Coast, can afford to employ a team of sports scientists to do their number crunching, Richmond relies on a work experience kid to process its GPS information.

Another inequity associated with the technology is that it doesn’t work under the closed roof of the Telstra Dome. This puts clubs such as St Kilda, the Western Bulldogs, Essendon, Carlton and the Kangaroos, who all use Telstra Dome as a home venue, at a disadvantage.

The Bulldogs have already found a way around this problem through their partnership with the Victorian University of Technology. The VUT supplies the Bulldogs with a different brand of GPS unit which provide some real-time information without access to satellites.

Bulldogs’ head of physical performance Cameron Falloon said the club had already used the technology in training. All he needs is a green light from the AFL to introduce the units on match days.

Whatever the AFL rules, the decision on when to rest players and when to put them on the ground will remain with men rather than machines.

Computers can tell you when a player is nearing physical exhaustion but they can’t tell you if an exhausted player has a final, match-saving effort left in him; like West Coast’s Daniel Kerr last Saturday night.

“To me, the beautiful thing about football is there are so many variables on performance that need to be taken into account on the day,” Tarbox said.

“If a player is doing their job on the field, why not leave them out there?

“If we got someone who is tagging Jonathan Brown and keeping his possessions to a minimum, he is rooted and he is redlining but he is still doing the job. That is more important to us than me wanting to get him off because he is tired.”

ARTICLE BY: CHIP LE GRAND
From: The Australian, 7 April 2007 

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