Major League Baseball has approved the use of a continuous biometric monitor that can be worn by players during games.

The device, made by a company called WHOOP, is the first of its kind approved by any of the major American sports leagues to be worn during competition. Teams cannot force players to wear the device, however; players get to decide.

An MLB spokesman confirmed the deal was reached but would not comment further. Major League Baseball Players Association spokesman Greg Bouris declined to comment.

The WHOOP device is meant to be worn throughout the day and night. It can be worn on various parts of the body, and it measures sleep, recovery and strain. Thanks to the 100 megabytes of data a day that is gathered, it allows a player and a team to monitor the current state of an athlete's body heading into a game.

"This is Moneyball 2.0," WHOOP founder and CEO Will Ahmed said Monday.

At the recent Major League Baseball winter meetings, WHOOP presented its findings on what was described as the most comprehensive biometric data study ever conducted by a pro sports league on athletes. A direct correlation was made between recovery and injury and hitting and pitching performance.

Use of biometric monitors, which specifically measure heart rate and track sleep, among other things, has raised privacy concerns in sports. How much of the player data can a team use? If there is something a player doesn't want the team to see, what can he or she do after agreeing to wear the device? The Health Insurance Portability and Accountability Act (HIPAA), which protects patients from having their medical information shared, does not currently apply to biometric data.

According to sources, MLB's agreement provides that the vendor has no rights to the data itself and that the player and the team can use the data equally to analyze or identify trends. Commercial or public use of the player data, such as on a television broadcast, requires consent of both the player and the team.

Ahmed says that WHOOP has 27 different privacy settings that allow a player or a team to share various pieces of information, while keeping other data private.

The news received relatively little attention, but two of Nike's recent college contracts -- Michigan and Tennessee -- gave Nike the rights to biometric player data.

The NBA's new collective bargaining agreement allows players to wear biometric monitors, but only during practice. Last season, while playing for the Cleveland Cavaliers, Matthew Dellavedova was found to have worn the WHOOP device without permission for 13 games. He was told to stop. Los Angeles Clippers center DeAndre Jordan recently was found to have been wearing a WHOOP monitor under a wristband during a game. The league is looking into the situation.

"We are going to move in conjunction with the players' association to protect everyone," NBA commissioner Adam Silver said Friday at the MIT Sloan Sports Analytics Conference.

The WHOOP device costs $1,200 per athlete per year and includes the dashboard to the analytics. The recent iteration of the device for consumers, the WHOOP 2.0, went on sale in November and costs $500.

MLB had previously approved a device made by a company called Motus that specifically monitors batting and pitching performance.