Based on my impressions from the internet. This is a very important phrase
If this means a track suit, then how does one say "a sporty suit"?
Maybe something like костюм у спортивному стилі :)
a sport suit почему-то исправлено на sports suit
The adjective is sports: sports suit, sports shoes, sports clothes etc.
What is wrong with "sportswear"?
That would be "спортивинй одяг", sports clothes in general (not necessarily a tracksuit/sports suit, any piece of clothing for sports).