Kammala wannan jumla: A 2012 U.S. Olympic Trials a Omaha, Nebraska, Amurka ta cancanta don gasar Olympics ta 2012, Gemmell ya shiga tawagar Olympics ta Amurka a karo na farko ta hanyar kammala na farko a cikin mita 1,500 tare da lokaci na 14:52.19. A Wasannin Olympics na 2012 a Landan, ya kasance na tara a cikin zafin farko na
1500 mita freestyle tare da lokacin 14:59.05, kuma bai ci gaba a cikin manyan takwas zuwa wasan karshe na taron ba.