Alexa's mom enrolled her in the local gym when she was five years old as a fun after school activity. She immediately fell in love with the sport and shortly thereafter joined the team program at Stars Gymnastics in Katy, TX and never looked back since. She was the 2014 Level 5 TX State Vault Champion, 2015 Level 6 TX State Vault Silver Medalist, 2016 Level 7 TX State Vault Silver Medalist and 2016 Level 7 Regional Vault Bronze Medalist. Alexa was named to America's Top 100 on vault in levels 5, 6 and 7.

In 2017, Alexa moved up to level 8. She placed third in the all-around and second on vault at the State Championships. She qualified to the Region 3 Championships where she placed sixth in the all-around and second on uneven bars. Alexa competed level 9 for the next two seasons. She placed fifth in the all-around and third on uneven bars at the 2018 State Championships, qualifying to Regionals. In 2019, Alexa finished third in the all-around with a 37.750 and second on vault at the State Championships. She qualified to the Level 9 Western Nationals in Spokane, WA after finishing third in the all-around and third on vault and balance beam at the Region 3 Championships.

As a first-year level 10 gymnast in 2020, Alexa qualified to the State Championships but was unable to compete due to COVID-19 pandemic. In 2021, Alexa placed sixth on balance beam and in the top ten in the all-around at the Level 10 State Championships, qualifying to Region 3 Championships. Alexa placed sixth on vault at the 2022 Level 10 State Championships and tenth on vault at the 2022 Region 3 Championships.

Alexa was born on September 22, 2004 in Houston, TX to Laura and Tom Shields. She has an older brother, Will and a dog named Indy. Currently, Alexa is an honor student at Memorial High School and she will graduate in 2023. She is an active member of her church and she volunteers in her community through the National Charity League.