They were a free gift from Nike.
Nike supply them free for the athletes. The yellow theme is a ploy by their clever marketing people. I guess it works cos it's brought your attention to them!
The athletes get free shoes and clothing from different brands. The yellow shoes are Nike and are made to custom fit each individual athletes feet by Nike labs & engineering. Nike makes sponsorship deals with all types of athletes from all countries of the world. Some are really small deals that just include a few pairs of shoes and clothing for the athlete and some are large deals that include millions of dollars with shoes and clothing but most are somewhere in between. After all, the marketing department at Nike wants publicity and all the yellow shoes on 90% of the best athletes in world at the most world watched event is a pretty good way to get it!! The "yellow" on the shoes is 100% marketing!!
Nike
Steeplechase
Finishline
Nike
When Christofer was 15 he got really bad athletes foot and that made him kinda just stop wearing shoes since.
The shoes and clothing worn at the games are designed to help the people wearing them run, swim, jump, or play better. The color is just what was used by the company who made them. There is no reason they are one certain color.
cow
Gold.
Nike