Why are male World Cup players wearing… sports bras?

We don’t know Victoria’s secret, but we might’ve figured out Vini Jr.’s.

People on social media have been pointing out that World Cup soccer players seem to be rocking some extra support underneath their jerseys — or out on their own.

“Their matching sports bras are sooooo cute,” reads one TikTok caption. “This is peak girlhood.”

“I love their little sports bras,” wrote another user.

While the undergarments certainly evoke the iconic image of Brandi Chastain at the 1999 Women’s World Cup, these star athletes are actually wearing GPS vests that track and measure performance during training and matches.

A majority of the World Cup players, including the entire Brazil national men’s team, wear the vests, which are made by sports technology companies like Sports Performance Tracking (SPT), Catapult and STATSports.

“Because the vests are tight and cropped, many viewers think male athletes are wearing sports bras for chest support,” Thomas Borchert, an account executive at SPT, told the Post.

“The crop-top design is purely functional. It keeps the GPS pod securely anchored between the shoulder blades. This is the optimal anatomical position for satellite signal reception, minimal body movement interference and player safety during collisions.”

The goal? To help teams better understand each player’s individual output and make smarter decisions about training and recovery, giving coaches and staff the data they need to push players to their limits while protecting them from injury.

Yes, it’s the same GPS technology used in navigation apps and trackers. They’re also part of the same family of sports wearables as biometric fitness devices like Oura rings, Apple Watches and Whoop bands.

How these high-tech crop tops change the game

Unlike runners following a predictable route, soccer players and other field-based athletes sprint, cut, collide and constantly change direction. That means the sophisticated GPS technology inside these vests is built to collect and store data throughout practices and matches, capturing the random, explosive movement unique to field sports.

Rather than prescribing the same workload for an entire squad, teams can create customized training plans for each player. Coaches can analyze how fast a player is running, whether they’re getting quicker, how much ground they’re covering, whether fatigue is setting in or if a specific body part — such as a recovering hamstring — needs extra attention.

Athletes, coaches, performance staff and medical teams then use specialized software to turn that data into better decisions about training, conditioning, recovery and treatment. Instead of relying on guesswork, workloads can be adjusted based on what each player’s body is actually doing.

“An athlete might ‘feel’ 100% ready to return, but GPS data reveals they are only reaching 80% of their maximum pre-injury sprint speed or favoring one leg during high-speed decels,” explained Borchert.

“Keeping them in rehab until their high-speed metrics match baseline data prevents immediate re-injury.”

More numbers, more nuance

A 2023 study published in BMC Sports Science, Medicine and Rehabilitation found sports wearable technologies, including GPS trackers, provide critical information for assessing fatigue, guiding recovery and supporting injury rehabilitation strategies.

Researchers found the devices are especially valuable for monitoring stress patterns and fatigue indicators that can help reduce the risk of overuse injuries and ligament strains — particularly in sports like soccer, where knee and ankle injuries are common.

But as is the case with wearables, more data doesn’t automatically mean easier decisions.

Carlo Ancelotti, head coach of Brazil’s national men’s team, recalled an instance in which one player appeared to be underperforming based solely on his GPS numbers. He was covering about 3.7 miles per match, roughly half the distance of his teammates.

Turns out, he was simply always right where he needed to be.

“This specific player was always in the right spot in the perfect tactical position,” Passos told the BBC. “He was a very efficient player.”

This goes to show that while GPS trackers can measure nearly every physiological movement, they still can’t quantify some of soccer’s most valuable skills like decision-making, positioning, vision and leadership.

At least, not yet.