accommodation in MadridA U.S. Anti-Doping Agency investigation of patches worn by six Stanford swimmers at the Olympic trials last month showed no signs the athletes used banned substances, according to the American and international governing bodies for the sport.

The inquiry arose after an accusation that the patches worn by swimmers working under Stanford coach Richard Quick were laced with testosterone, according to the man whose company makes the product.

David Schmidt previously told The Chronicle that his LifeWave Energy Enhancer contained only amino acids and water-based solutions, and he called the charge "ridiculous."

Nevertheless, USA Swimming collected samples of the patch from Quick and sent them to USADA.

On Friday, USADA sent letters to USA Swimming and FINA, the sport's world governing organization, stating it had found no wrongdoing.