Simone Biles and Riley Gaines traded social media barbs over the latter's recent comments advocating for the exclusion of transgender athletes in women's sports.

Simone Biles hit back at former collegiate swimmer Riley Gaines Friday after she shared a celebratory post from the Minnesota State High School League after Champlin Park High School, which includes a transgender pitcher, won the state championship.

Gaines, 25, has become one of the most outspoken critics of transgender girls and women competing in female sports in recent years.