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During a 90-minute soccer match, Sweden’s Zlatan Ibrahimovic makes dozens of feints, false starts, and other fine movements in an attempt to free himself from opposing defenders. Each motion requires Ibrahimovic to accelerate, and then decelerate, his 209 -pound frame forward or backward, left or right. Each effort takes a toll on his body that Paul Balsom, the head of performance for the Swedish national team, cannot track.
“Really, football is all about those movements,” said Balsom, who is responsible for keeping Ibrahimovic on the field and out of the trainer’s room. “We’re not getting enough information.”
Soon, Balsom and other sports scientists will get the data they crave. On July 7, FIFA issued a memorandum announcing the approval of wearable electronic performance and tracking systems in matches. FIFA’s approval came two months after the International Football Association Board amended its laws to allow the use of the tracking devices, called EPTS, on principle -- on the condition that they not endanger player safety and that information is not relayed to coaches during matches. (Halftime is another matter: “What the teams do in the locker room is up to them,” said Lukas Brud, the IFBA secretary.)
With clubs and teams around the world increasingly interested in data and advanced statistics, the rule change could have wide-ranging effects on international soccer. Already, information on distance covered and total workload informs everything from training methods and player valuations to lineup decisions and substitutions. (FIFA seemed to acknowledge the value of the data in its announcement, which banned the sale or even the sharing of the information with third parties.)
Previously, players could wear devices in training but only in-stadium camera systems tracked them during games. These optical-based systems provided information including player location, speed and distance travelled, but the sampling frequency and the filtering processes prevented the gathering of more refined data or the blending of the data collected by different systems into a coherent narrative.
“You try to line it up, and you hope that it matches up pretty well, but you’re never really sure,” said Dave Tenney, the Seattle Sounders’ sports science and performance manager. Wearable systems that include accelerometers and gyroscopes in addition to GPS trackers can provide everything optical systems do as well as information on metabolic power, jumps, accelerations and more. The ability to do that in real time, or to assess a player’s performance over anything from an hour-long workout to a 90-minute game shift to an entire season could be invaluable.
“Matches were the one big hole you had in your analysis,” said Jeff Agoos, the vice president of competition at Major League Soccer. “And that’s the biggest piece of the week.”
A small group of teams have already put the technology to work. While officials from each respective association, league or competition must vote on whether to allow wearable technology in matches, seven teams at the recent Women’s World Cup -- including the victorious United States -- had devices approved for use before the tournament.
Their devices are worn at the top of the back, held in place by a compression shirt that looks a bit like a sports bra and is worn under the uniform. When the German men’s national team won the World Cup in 2014, it used a system made by Adidas.
Two other leading companies in the field are Catapult and GPSports, both based in Australia. Catapult has contracts with nearly 100 soccer teams around the world, from colleges and pro clubs to the national teams of the United States and Brazil, while GPSports’ top clients include Chelsea, Bayern Munich and Real Madrid.
The IFBA’s ruling creates the option for more widespread adoption of the technology, but so far even forward-thinking leagues have expressed caution.
“My sense is that it may be an offseason project, but things are moving very quickly,” said Will Kuntz, the director of player relations and competition for MLS, which has previously shown a willingness to be at the leading edge of technical innovations like goal-line technology.
The league’s new collective bargaining agreement did include a provision for the league to approve individual devices in consultation with the players union, but teams’ requiring players to wear the technology in matches is a separate issue. While Seattle’s Tenney gets about 95 percent compliance during training sessions, he said he anticipated it would be more difficult to convince players to wear the devices in games.
Nor are the systems foolproof. GPS-based devices like the Adidas miCoach and Catapult’s GNSS-based (for global navigation satellite system) monitors rely on satellites for tracking data. Stadiums with closed roofs or roofs that overhang playing fields can interfere with the ability to lock on to individual units.
Catapult said that it was developing a local positioning system using radio-frequency identification technology and in-stadium nodes to avoid these issues, but it costs around $50,000 to install. Barry McNeill, the company’s chief executive for Europe, the Middle East, and Africa, said that while GPS was accurate to about 20 centimeters, the local systems were accurate to 5 centimeters.
Finally, in a sporting environment where knowledge can lead to a competitive advantage, there is always the concern that rival teams will try to steal data. But for many sport scientists, including Balsom, that is not a concern. In addition to his work with Sweden, Balsom works with Leicester City of the English Premier League, and he said that while some of the bigger Premier League teams are more protective of their information, “I really don’t know what they could do with our data.”
“At Leicester, we have a very open-door policy,” he said. “We’ll share everything, because we feel that by sharing our information people can come back and ask if we’ve thought about this or that.”
MLS goes further, giving each team access to anonymous data from every other league team. Currently, that includes only optical data, but including match data from the same wearable systems that have been used in training will only increase the possibilities of finding insights.
“This has given us the tools to go out and look at a million different things,” Kuntz said. “It might turn out that most of them don’t have any correlation to success, but even if one of them does, it’s really exciting.”