Career
She trains at East London Gymnastics under Lorraine Atkinson
2012
Mattis" first big elite meet was at the British Gymnastics Championships at the Echo Arena in Liverpool. 2013
Mattis competed for Great Britain at the Australian Youth Olympic Festival in Sydney earlier in January. The team placed 2nd behind China.
In March, she then went to Liverpool for the British Championships.
She placed 1st, 2nd and 3rd in Vault, Beam and Floor finals. Her final meet was the European Youth Olympic Festival in Utrecht.
She got a team silver, 2 bronzes in the all-around and Vault and managed 5th on Bars. Whilst she was there, she competed a Silivas on floor in the all-around competition and became Britain"s first women ever to compete lieutenant
2014
In March 2014, she traveled to Wigan to compete in the English Championships.
She placed 1st in the all-around. However, an injury forced her to take the rest of the 2014 season off from competition. 2015
Mattis made her senior debut in 2015 at the English Championships in Loughborough, where she earned a silver medal on the uneven bars, while only competing bars and balance beam.