Mitzi Alejandra Unda-Sosa was born on July 17, 1994 in Oaxaca, Mexico to Jorge Unda and Reyna Sosa. She has two siblings, Frida and Luis and two dogs. Currently, she is in 12th grade at Spring Creek Academy. During her spare time, she likes reading, listening to music, watching TV and shopping.
At the age of seven in 2001, Mitzi asked her mom to put her into gymnastics so her mom took her to the gym one day and she loved it ever since!
Mitzi represented Mexico at several international competitions in 2010 and 2011. She finished 14th in the all-around at the 2010 Pacific Rim Championships in Australia. At the 2010 World Championships, she helped the Mexico team to place 21st. In 2011, Mitzi finished sixth in the all-around during the first day of the Brazilian International. During the event finals, she earned a silver medal on uneven bars and a bronze medal on balance beam. She then traveled to Belgium for the Ghent World Cup and competed on uneven bars and balance beam. Mitzi was the alternate for the Mexician team at the World Championships.
Mitzi decided to drop back to level 10 for the 2012 season. She started her season at the WOGA Classic, finishing seventh in the all-around and fourth on uneven bars. At the Houston National Invitational, she placed first on uneven bars and sixth on balance beam. She did well at the Level 10 State Championships, finishing sixth in the all-around with a 37.975 and second on uneven bars scoring a 9.700. At the Level 10 Regionals, she finished second in the all-around and first on uneven bars. This qualified Mitzi to the Junior Olympic Nationals where she placed 16th in the all-around.
Mitzi is a level 10 gymnast training at World Olympic Gymnastics Academy (WOGA) in Plano, Texas under coaches Laurent Landi and Cecile Canqueteau-Landi. She was a member of the Senior Mexican National Team between 2009-2011. She would like to earn a college scholarship to a Division 1 school.