I Won Olympic Gold. Now a Word From My Sponsor.

American Olympians could find it easier to promote products and sponsors during the Games after the United States Olympic and Paralympic Committee loosened some of its strict marketing rules on Tuesday.

For years, athletes have chafed about one such guideline, Rule 40 of the Olympic Charter, which sharply restricts what they can say and do with their sponsors immediately before and during the Games. Many athletes call it a “gag rule” that curtails their freedom of speech and unfairly sidelines the sponsors who bankrolled and supported their training, sometimes for years, at the moment of highest visibility. Olympic officials have long argued that the rule was necessary to protect the interests of the smaller group of official partners who spend millions of dollars to be associated with the Games.

While the International Olympic Committee created Rule 40, it left interpretation of it to the national committees. In recent years, a German government body weakened the I.O.C.’s authority when it declared Rule 40 was “too far-reaching” and said German athletes no longer had to abide by it. But many national Olympic committees, including the one in the United States, had stuck by a strict reading in the face of ambush marketing campaigns and protests by its own athletes.

At least one, the two-time Olympian Nick Symmonds, even cited the restrictions as a motivation for taking an early retirement.

On Tuesday, though, the U.S.O.P.C. updated its guidelines. Beginning at next year’s Tokyo Games, American athletes will allowed to thank their sponsors at the Games, the U.S.O.P.C. said. And the sponsors can also congratulate their athletes.

Restrictions remain. Athletes will be limited to seven thank you messages during the Games, and the content of such messages will be scrutinized. A post like “Thank you for supporting my journey” is acceptable, but terms like “Tokyo 2020” and “Team USA” and Olympic imagery are forbidden. Athletes also cannot promote unofficial products directly with phrases like “Your product is the best.”

Likewise, the congratulatory messages of companies without official sponsorships must steer clear of Olympics terms and imagery. Brands promoting athletes also may not increase the frequency of their advertisements during the Games.

“We worked to create a guidance that increases athlete marketing opportunities and, importantly, respects Rule 40 and affirms our commitment to providing value to our partners,” the U.S.O.P.C.’s chief executive, Sarah Hirshland, said.

For next summer’s Tokyo Games, the period in which athletes will be limited by Rule 40 is July 14 to Aug. 11.