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 Japan’s 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.

Brands like Kyoto-based Phiten and Osaka-based Colan Totte are famous for producing these therapeutic patches, which many top Japanese athletes trust. Phiten calls its product Power Tape and Colan Totte sells its own under the name NS Magneban.

They are available online, but trial-size packs are also found in ¥100 shops.

Phiten’s website says the patches are commonly applied to the shoulders, lower back and knees, but can also be worn on the temple for “sporting moments that call for split-second decisions, sharp awareness and unwavering focus.” They are recommended for athletes in track and field, soccer, golf, badminton and tennis.

Japan’s Mebuki Suzuki, who finished 20th in the men’s 10,000 meters on Sept. 14, swears by the Phiten patches and made sure he wore them — around his neck and collarbone — as he made his world championships debut at National Stadium.

“I first began using Power Tape after joining university, since our team was sponsored by Phiten,” said Suzuki, a member of Toyota’s long-distance running team.

“I apply the patches all over but mostly on my neck and back. They help me breathe easier and loosen up the tension in my upper body, so I can run with a smoother stride.”

While many athletes, including Olympians and Hakone Ekiden runners, believe the patches give them an edge, not everyone is convinced. Some doctors and scientists say there’s insufficient evidence to support the brands’ claims.

Phiten insists its products, which include the braided necklaces that took MLB by storm in the 2000s, are designed to help stabilize the electrical signals nerves use to send instructions to the body.

“Phiten research on aqua titanium technology hints at stress relief and muscle relaxation, but company-led studies and limited independent verification mean there’s no scientific evidence supporting these claims,” said Shingo Nakura, a former researcher at Keio University’s Department of Neuropsychiatry.

“Perceived benefits reported by athletes wearing the Phiten Power Tape may simply result from the physical act of applying the tape. Lifting the skin slightly can boost circulation, normalize muscle function and aid recovery — effects similar to kinesiology tape — likely combined with a placebo effect.”

Nakura explained that titanium, the main component in Phiten products, is not on the World Anti-Doping Agency’s prohibited list, and therefore the products are perfectly legal. With no strong scientific evidence to label it a banned substance, he suggested that many of the benefits athletes feel are likely placebo-driven.

But while the physiology behind the patches does not hold up to scientific scrutiny, that doesn’t mean they aren’t worth a try.

“The placebo effect can be seen as a false benefit or a mind-body tool,” Nakura said. “For those who value psychological gains, these Phiten patches may be worth trying. If cost or scientific certainty matters more, cheaper alternatives like kinesiology tape would be the wiser choice.”