The recently completed World Athletics Championships in Tokyo came and went with no shortage of surprises and high drama. But for some fans, the real mystery was in the strange-looking patches on the faces and bodies of Âé¶¹´«Ã½ distance runners.

¡°Product link please,¡± one social media user wrote. Plenty of others had their own comments and questions: ¡°I thought they were nicotine patches.¡± ¡°I thought he was covering up his hickeys.¡± ¡°Looks cool.¡± ¡°Diabetic?¡± ¡°Cupping marks?¡± ¡°Science or scam?¡± ¡°Is that legal?¡±

The beige-colored adhesive discs, which contain microscopic particles of titanium or ferrite permanent magnets, are quite popular in Japan. They are marketed as a way to improve circulation, alleviate stiffness and help active people breathe easier by stimulating blood flow.