Stack was a member of the U.S. Olympic Team that placed fourth at the 1988 Olympic Games in Seoul, Korea. She won the U.S. title for the uneven bars in 1988-89. Her other top finishes at the nationals include second on floor in 1989, third on floor in 1988, and tied for third on the uneven bars in 1991. Stack was fifth in the all-around at the 1988 U.S. Olympic Trials and 1989 World Championships Team Trials.
She represented the USA at the 1989 World Championships, where the team was fourth. At the 1991 Pan American Games, Stack helped the USA to the team title, as well as won the floor exercise, and was second in the all-around. Her international success also included winning vault at the 1991 USA-Romania dual meet; fourth in the all-around at the 1989 French International Competition; and winning the floor title at the 1988 American Cup, where she also was third in the all-around, vault, and balance beam.
She trained with Martha and Bela Karolyi, SCATS, and Cypress Academy. Stack attended the University of Oklahoma for two years and appeared in the Cirque du Soleil show at Walt Disney World. In addition to owning Chelle Stack’s Gymnastics in Winter Park, Fla., she has earned a brevet rating as a judge and works major USA Gymnastics competitions.