[9] Ruck is the all-time leading medallist at the FINA World Junior Swimming Championships having won nine gold, two silver, and two bronze over the course of the 2015 and 2017 editions.

Ruck competed with Penny Oleksiak, Chantal van Landeghem, Sandrine Mainville, and Michelle Williams and swam to a bronze medal, behind Australia and the United States.

[14] She became the first athlete born in the 2000s to win an Olympic medal along with fellow Canadian swimmer and relay partner Penny Oleksiak.

She last competed in the 4×100 metres medley, swimming the anchor leg in the trials before being replaced for the finals, where the Canadian team placed fifth.

[13] To end the 2016 season, Ruck and her teammates won a gold medal in the FINA short-course world swimming championships 4 × 200 m freestyle relay.

For the 2017 season, Ruck relocated back to Canada to train at the High Performance Centre – Ontario led by Ben Titley.

[17] There she began training with teammates Oleksiak, Toro, Van Landegham, Rebecca Smith, Sandrine Mainville, Kayla Sanchez, and Richard Funk.

[21][22] The first day of competition in the Gold Coast was in fact a golden one when Ruck out-swam Ariarne Titmus and Emma McKeon to win the 200m freestyle in a Commonwealth Games record 1:54.81.

Later that night she added to her total with a silver in the 4×100 m freestyle relay together with Penny Oleksiak, Kayla Sanchez, and Alexia Zevnik.

She then beat American star and fellow Stanford swimmer Katie Ledecky in the 200 m freestyle, leading from start to finish.

CBC commentator Byron MacDonald said of Ruck's race and form that "anytime you beat the best female swimmer in the world… it's a huge step forward.

[28] Ruck took a year off from Stanford to train in Toronto with the Canadian national team under Ben Titley in anticipation of the 2020 Summer Olympics in Tokyo.

The effects of these were aggravated by the onset of the COVID-19 pandemic, which resulted in the Olympics being delayed by a full year, as well as the city of Toronto being largely locked down, leading to greatly increased isolation.

[41] Ruck swam the third leg for the Canadian team in the heats of the 4×100 m mixed freestyle relay, helping them qualify to the event final in second place.

[44] She had initially intended to compete at the national swimming trials a few weeks later, but after resuming training in Toronto she determined that she had a "need to unplug for a little while, so I can come back refreshed and ready to be at my best in the pool.

[49] In advance of the Olympic season, Ruck moved to train at Arizona State University, and announced that she would forego participation in NCAA competition while preparing.

[50] While many of Canada's top swimmers opted to skip the 2024 World Aquatics Championships in Doha, Ruck was named to the team.

[51] On the first day of swimming finals, Ruck participated in the 4×100 m freestyle relay, recording a 53.26 split on the anchor leg and leading the Canadian team to a bronze medal.

She does not hold American citizenship and continues to spend time in Canada while visiting family in Kelowna, Winnipeg, and Vancouver.