Gemma is a former World Champion and World Record holder in the 100m backstroke. She represented Great Britain in the 2008 Summer Olympics, narrowly missing a medal in the 100m backstroke. Gemma also competed in the 2012 Olympics and earned fifth place in the 100m backstroke. She holds a doctorate in Education from the University of Florida and enjoyed a successful collegiate swimming career, winning multiple NCAA championships. After the 2012 Olympics, Gemma retired from competitive swimming. She now holds the title of Aquatic Program Director at Florida Aquatics Swimming and Training (FAST).