Thank you very much for the clear explanation, Michael !! ⭐⭐⭐⭐⭐

The "track" is the thing that athletes run round or run on, when they run races. A tracksuit is a set of loose, warm clothing - a top and a bottom, a top and trousers, a top and pants - that an athlete can use to keep warm between races. These became fashion items long ago - maybe the 1980s - as clothes worn by athletes and sportspeople were adopted more widely by joggers, runners and others. Today, I'd expect these to be called jogging bottoms, and if you search for that term you will see pictures like yours. But I'm from the UK; in America I'd expect them to be called jogging pants. ADDITION - a search online for jogging pants produces the alternative "sweatpants" as well.

..I wonder what the word *track has to do with it

I see, Thank you very much!!

Hi Anastasia, they are called 'tracksuit pants' - or in British English, 'tracksuit trousers'!