Dressed in a tracksuit.

plural of tracksuit

A garment, usually consisting of a top and trousers (commonly known as tracksuit bottoms) worn as an outer layer by participants in sporting events such as athletics. The tracksuit is usually designed to be easily removed or replaced, before or after competing. Tracksuits have also been adopted in some cultures as leisurewear.

(Britain) A type of soft, lightweight trousers used for sports or informal occasions, (US) sweatpants.