Wednesday, February 6, 2013

Sensors Log an Athlete's Every Move—And Heartbeat

New tech can track not only every player's location in real time, but also his heart rate, velocity, exertion, and plenty more.
Catapult at Dallas Cowboys practice.

Dogging it while the coach looks the other way isn't an option for elite-level athletes. Coach is always watching. And now, in addition to all-seeing video cameras, he has indoor GPS to track every player's location, speed, and other factors with pinpoint accuracy during every second of a practice or game. 

Catapult Sports, based in Melbourne, Australia, already has its wearable GPS and data-tracking devices strapped to the backs of athletes in the NBA, the NFL, soccer's English Premier League, and even Australian Rules Football. Soon the company will roll out its indoor GPS system upgrade, which will supplement the devices' movement-tracking feature by providing information on acceleration/deceleration, how much force a player exerts, velocity, and more. Add in a new sensor embedded in the ball, and coaches and trainers will have real-time data for each specific athlete and the ball itself. Ever want to know much force LeBron James uses to make a crosscourt pass? Science can tell you instantly. 

"For your average strength and conditioning coach looking at speed, heart rate, and distance, the (regular) GPS is an adequate solution," Catapult co-founder Igor van de Griendt tells PM from Melbourne. "The indoor GPS really allows the club to take it to the next level, where it has a lot of value on the technical side to see positions relative to opponents or the shape of an offense and defense." 

As PM noted at the Consumer Electronics Show, indoor GPS is the next big thing in navigation. But the name is a misnomer. While the typical global positioning system relies on satellites, indoor GPS relies on a network of nodes communicating with the tracking device. Catapult arranges 6.2 x 3.7–inch nodes around a stadium, providing a continuously talking network of 10 to 20 sensors depending on the size and shape of the venue. Radio waves bounce off the mobile nodes worn by players and the fixed-position nodes at high rates of speed, and smart algorithms help crunch the data and allow coaches to view the positioning of a player to within 15 centimeters of accuracy. Catapult has agreements with various ball manufacturers to insert patented technology, weighing just 0.5 ounces, into the ball at the manufacturing stage. The sensors must be robust—balls get hit, thrown, kicked, and bounced, after all—and safely tucked inside the ball without changing its characteristics. 

Catapult can set up most systems in just a couple of hours. The system uses ultrafast GPS, at 15 Hz, although Catapult suggests a rate of 10 Hz for most team sports. Indoors, this eliminates the need for using multiple cameras to triangulate player speeds, the only way other than indoor GPS to get this data. 

While still monitoring all individual-player metrics, the indoor GPS system also grants coaches a better overall understanding of the entire team and their relation to each other and to their opponents. How the coach wants to use it is up to them, whether tweaking plays, redefining positions or working players into different roles based on speed and positioning. 

With so little difference between elite athletes, coaches are all looking for that little gold nugget in the data. "Are they lazy? Can we get them to work harder? Those are the things they get excited about," van de Griendt says. "It is the ability to measure things and put their own spin on it." 
James Hanisch, a sports scientist with the University of Oregon, who previously worked in Australian Rules Football, says the tactical applications of the indoor GPS will give him even better data on the movements of the body. For example, he wants to know how much force a lineman exerts on a particular snap and in relation to specific plays. Does the lineman work harder on running plays or passing plays? How much does he wear down over the course of a game? Now Hanisch can measure that. 

"We are looking at it over time," he says. "It is really about getting a grasp on what each player is doing and coming up with a baseline. Then, how do we push him to reach peak performance, or, if the medical staff is saying these guys are at risk of injury, how do we minimize that?" 

The Seattle Sounders of MLS have begun using the equipment to keep better tabs on whether players in certain positions are overworked, fitness coach David Tenney says. "In 2007 we were just using heart-rate-type technology and we found that it was at times giving us a false sense of where guys were," he says. "Catapult is ... a training monitoring system. That is how we are using it." 

For years now coaches have been able to track how far a player runs during a game. But by combining that knowledge with biosignatures time-stamped to any point in the game, coaches can understand how hard they are working each player and how the different positions on the field compare with one another. That information has allowed coaches to make changes in training based on the data, Tenney says. 

"By looking at some of the data we get out, we can prevent muscle-type injuries," van de Griendt says. "Sensors can measure impacts and spin rates and measure the actual force or amount of tackles and force and correlate those with injuries." 

Sounders head coach Sigi Schmid has bought into the system, which means the players are onboard, too, even if that means wearing the 3.5-ounce device. And, all along the way, coaches and trainers get to watch. No more loafing. 

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