I’ve seen many male soccer players – specially famous players who play for well-known teams – wear a piece of clothing that looks like a sports bra. They’re usually worn during practice, and a few other times I’ve seen them worn under the jersey during the games. I’m guessing it has some training benefits, but what is the bra looking thing? What’s the purpose of wearing it?
They are performance trackers. They track a player’s vital statistics (heart rate, etc) as well as their movement. Their average speed, their distance covered, etc. As for the “bra-like” design, it would appear to just be the result of needing a small and unencumbered design that allows for minimal interruption, maximum body contact, and full range of motion.
Link to the manufacturer of Zlatan’s bra