She also broke the British Indoor 5000m record on 4 January, 14.49.12 (her second ever time running that distance)   At the 2017 European Athletics Indoor Championships in Belgrade, Muir took gold in the 1500 metres, breaking Doina Melinte's 32-year old championship record along the way, and followed it up by taking a second title in the 3000 metres with another championship record the next day. Muir finished fourth in the 1500m and sixth in the 5000m at the 2017 World Championships in London. Following the championships, she announced that she would miss the 2018 Commonwealth Games in April in order to focus on her veterinary medicine exams. She did compete in March 2018 at the World Indoor Championships in Birmingham, where she won a bronze medal in the 3000m, followed by a silver medal in the 1500m two days later. In August, she won the 1500 metres title at the 2018 European Championships in Berlin, the first British woman ever to win the European 1500m title. She followed this breakthrough by winning her second Diamond League title over 1500 metres, her second, but her first since the move to a championship format. At the 2019 European Athletics Indoor Championships Muir took gold in the 3000 metres, with another championship record, and the 1500 metres, repeating her achievements in 2017. Muir attended Kinross High School, the same school as 400m hurdler Eilidh Doyle along with her brother Rory who is two years younger than she. She studied veterinary medicine at the University of Glasgow where one of her lecturers was veterinary pathologist, distance runner and teammate at the 2014 Commonwealth Games, Hayley Haining.