Millions of consumers work out using some kind of wearable device, and the market for these devices is growing quickly.
But now professional sports teams are finding a use for wearable workout gizmos, using the data these devices measure to better track players' health and performance.
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Major League Soccer has been an early adopter of new technology with the help of Adidas, and the San Jose Earthquakes are just one of the league's teams to give it a try. Players have small sensors made by Adidas placed into pockets in their undershirts. The sensors then send real-time data to the coaching staff's iPad.
"We get some instant feedback on the field in terms of certain metrics that we feel are important like heart rate. Working at the upper limit of our heart rate that we want to be in and also during our rest we know when they are down at a reasonable level when we can train again," said Mark Watson, head coach of the Earthquakes.
Watson said the data are helpful in gauging levels of exhaustion both in practice and during games. The data complied are particularly useful in determining when a player has adequately recovered from an injury, and is suitable to play again, he said.
The data have also forced him to rethink the team's whole process regarding practice, and have made the team and coaching staff more responsive to individual health circumstances.
The Earthquakes and Adidas aren't the only ones utilizing these devices.
Australian company Catapult is also emerging as a player in this new game. The company measures more than 100 fields of data via a device worn under the athletes' jerseys. Nearly 4,000 professional teams utilize the technology, and it's already attracted some big-name investors such as Dallas Mavericks owner Mark Cuban.
But all of the data raise concerns about player privacy: Medical information is private, after all.
Some also worry that the data could be used as a tool for negotiating player salaries down the line. But like it or not, it appears wearable technology is going to be a game changer when it comes to professional sports.
—By CNBC's Mark Berniker and Josh Lipton