Sadie's mom was a former collegiate gymnast, so she decided to enroll Sadie into gymnastics for fun at the age of three. Sadie could climb the rope by four years old and got invited to join the gymnastics team. At the beginning of Sadie's gymnastics career, she trained at Atlanta School of Gymnastics in Tucker, GA. Sadie was the 2016 Level 3 GA State All-Around Champion, 2017 Level 4 GA State Uneven Bars Bronze Medalist, 2018 Level 5 GA State Balance Beam Champion, 2019 Level 6 GA State Uneven Bars Silver Medalist and 2019 Level 6 Regional Qualifier.

Sadie skipped level 7 and quickly moved up to level 8 for the 2020 season. She was unable to compete at the State Championships due to COVID-19 pandemic. In 2021, Sadie only competed in-house with the Atlanta School of Gymnastics, due to the continued COVID-19 pandemic impacting Atlanta, GA. As a level 9 gymnast in 2022, Sadie placed in the top eight on uneven bars and in the all-around at the State Championships. In April of 2022, Sadie moved to the Gymnastics Academy of Atlanta. In 2023, she finished fifth in the all-around, first on vault and third on uneven bars. She qualified to the Level 9 Eastern Nationals after finishing sixth in the all-around with a 37.500 and fifth on balance beam at the Region 8 Championships. At the Nationals, Sadie placed seventh on floor exercise and 11th overall.

In 2024 as a first-year level 10 gymnast, Sadie placed fourth in the all-around and third on vault and floor exercise at the State Championships. At the Region 8 Championships, she placed fourth in the all-around and fourth on balance beam and floor exercise. Sadie qualified to the Level 10 Nationals in Daytona Beach, FL where she placed 16th on floor exercise out of 57 gymnasts. In 2025, Sadie placed third on balance beam and fifth on vault at the State Championships. She qualified to the Region 8 Championships, finishing eighth on balance beam with a 9.450.

When Sadie is not busy training 20 hours each week in the gym, she enjoys reading, playing the fiddle/violin, doing puzzles, following sports, baking and journaling. She is the daughter of Julie and Jon Witten and she has a sister, Nora, and a dog named Birdie. Currently, Sadie is an honor student at Midtown High School and she will graduate in 2026. She is on Principal's list and was invited to National Society of High School Scholars. Sadie plays violin on her high school orchestra.