EXPLAINER: The tech behind Tokyo Olympics' fast track

Marie-Josee Ta Lou, of Ivory Coast, wins a women's 100-meter semifinal at the 2020 Summer Olympics, Saturday, July 31, 2021, in Tokyo. (AP Photo/Petr David Josek)

Javianne Oliver, of United States, prepares to start in her heat of the women's 100-meters at the 2020 Summer Olympics, Friday, July 30, 2021, in Tokyo. (AP Photo/Matthias Schrader)

Competitors start in their heat of the men's 100-meters with empty seats as a backdrop in the Olympic Stadium at the 2020 Summer Olympics, Saturday, July 31, 2021, in Tokyo. (AP Photo/Jae C. Hong)

Alex Rose, of Samoa, and Diane Van Es, of Netherlands, colapse after competing during the first round of the women's 5,000-meter at the 2020 Summer Olympics, Friday, July 30, 2021, in Tokyo. (AP Photo/Morry Gash)