From the Super Mario Wiki
1500m is an Athletics event for the Challengers group in Mario & Sonic at the London 2012 Olympic Games for the Nintendo 3DS. This event is unlocked from the start. The game starts at the last 400m. The goal is to get to the finish first with help from the boost panels on the floor. However, the controls frequently change. Its game level is three stars.
Stagger to the Finish!