Medics prepare to carry away on a stretcher Connor Fields of the United States after he crashed at the first bend in the men's BMX Racing semifinals at the 2020 Summer Olympics, Friday, July 30, 2021, in Tokyo, Japan. (AP Photo/Ben Curtis)

Medics carry away on a stretcher Connor Fields of the United States after he crashed at the first bend in the men's BMX Racing semifinals at the 2020 Summer Olympics, Friday, July 30, 2021, in Tokyo, Japan. (AP Photo/Ben Curtis)

Connor Fields of the United States, center, who later crashed, is followed by Romain Mahieu of France, center-left, and Vincent Pelluard of Colombia, left, as they compete in the men's BMX Racing semifinals at the 2020 Summer Olympics, Friday, July 30, 2021, in Tokyo, Japan. (AP Photo/Ben Curtis)

Connor Fields of the United States, center, leads with Anthony Dean of Australia, above, Carlos Alberto Ramirez Yepes of Colombia, 2nd right, and Giacomo Fantoni of Italy, right, following, in the men's BMX Racing quarterfinals at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Ben Curtis)

Medics use a bag valve mask on Connor Fields of the United States before carrying him away on a stretcher after he crashed at the first bend in the men's BMX Racing semifinals at the 2020 Summer Olympics, Friday, July 30, 2021, in Tokyo, Japan. (AP Photo/Ben Curtis)

Medics prepare to carry away on a stretcher Connor Fields of the United States after he crashed at the first bend in the men's BMX Racing semifinals at the 2020 Summer Olympics, Friday, July 30, 2021, in Tokyo, Japan. (AP Photo/Ben Curtis)