If you’ve been watching as many World Cup games as I have recently, you’ve probably caught a glimpse of a singular undergarment worn by players on the pitches beneath their jerseys: a sports bra. Well, it’s not exactly a sports bra, despite its looks. And it has less to do with corporeal support than it does with tracking biometric data as these world class athletes ply their trade.

These harnesses are designed to link up to GPS to track players’ movements around the pitch, both during games and in practice. By providing coaches and trainers with data on heart rate, velocity, acceleration, strain and other metrics. Trends in these data help team managers make informed decisions about when to rest, replace, or push players.

But why the tight-fitting, bra-mimicking design? Apparently, the data logger and GPS unit that fits into the upper back of the garment attains the optimal signal when positioned thusly. And to collect biometric data sensors must be worn close to the skin.

Read more: “The Unexpected Humanity of Robot Soccer”

These GPS tracker vests have been used by soccer teams for a few years now, and they’re just one bit of tech that is turning this year’s men’s World Cup into quite an advanced affair. Officials are also using semi-automated offside technology that uses 16 dedicated cameras to model exactly where players and ball are on the pitch when a pass is made for a goal-scoring opportunity. And even the balls at this year’s World Cup are equipped with a motion sensor that can deliver real-time data to help match officials determine when goal lines are crossed and when offsides calls must be made. And some teams use AI simulations to help strategize game plans based on myriad possible outcomes and combinations of players and situations.

In support of many of these technological advances all the players participating in the World Cup are 3-D scanned for about 90 seconds to create their own, unique digital avatars. How long before we won’t even need to play the actual games on grass?

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Lead image: Alicja / Adobe Stock