Duke University Twichell swam for
Duke University from 2007-2011 under Head Coach Dan Colella, who specialized in backstroke at Sewanee, and served as Head Coach at Duke from 2002-2020. As a Junior at Duke, she captured 19 first and four second place finishes, and as a distance swimming specialist, was an honorable mention All-American in the 1650 free. As a Sophomore, Twichell was the first Duke University woman swimmer to go under the 16-minute mark in the mile swim, and broke the University records for the 500, 1000, and 1650 freestyle events.
2011 Twichell earned the first international medals of her career at the
2011 World Aquatics Championships in Shanghai, China, winning gold in the 5 km team and bronze in the 5 km open water events. Later in 2011, she earned a silver medal in the 800-meter freestyle at the
2011 Pan American Games. Duke University Assistant Coach Dan Kane introduced Twichell to Hall of Fame Head Coach
Bill Rose of the Mission Viejo Nadadores. Twichell moved to Mission Viejo in the summer of 2011 after graduating Duke, helping her to qualify for her first international team.
2012 At the
2012 U.S. Olympic Trials, she placed 10th in the 800-meter freestyle and 18th in the 400-meter freestyle, missing the Olympic team.
2013 In 2013, Twichell won gold in the 10 km open water event at the
2013 Summer Universiade in Kazan, Russia.
2016 World Swimming Championships Twichell competed at the
2016 World Swimming Championships held in
Windsor,
Canada in December 2016. She won the silver medal in the
800-meter freestyle with a time of 8:11.95, finishing only behind
Leah Smith.
2017 World Aquatics Championships At the
2017 World Aquatics Championships in July 2017 in
Budapest,
Hungary Twichell won two medals. The first medal she won was a gold medal with a time of 59:07.0 in the
women's 5 kilometer open water swim. With her win, Twichell became the oldest American swimmer to win a world title in open water swimming as well as the oldest female swimmer for the United States since 2003 to win an international swimming title in an individual event. The day after winning a gold medal in an individual event, Twichell won a silver medal in the
5 kilometer mixed team relay event.
2019 World Aquatics Championships In July 2019 at the
2019 World Aquatics Championships in
Gwangju,
South Korea, Twichell qualified for her first
Olympic Games. Her sixth place finish in the
10 kilometer open water swim secured her spot on the
U.S. Olympic Team in the
marathon 10 kilometer swim for the
2020 Summer Olympics. Twichell and her teammate Haley Anderson, who also competed in the race and finished in the top ten, were the first athletes qualifying to represent the United States at the 2020 Summer Olympics in any sport.
2020 After months of pool closures and a lack of swim meets to compete in due to the
COVID-19 pandemic, Twichell returned to racing in the pool in November 2020 at the
2020 U.S. Open Swimming Championships. At the Championships, she won a silver medal in the 1500-meter freestyle with a time of 16:18.11, finishing less than fourteen seconds behind gold medalist
Bella Sims.
2021 2021 US Open Water National Championships In April 2021, Twichell competed in the 5 kilometer and 10 kilometer open water swims at the 2021 US Open Water National Championships in
Fort Myers Beach, Florida. She finished second with a time of 2:03:01 in the women's 10 kilometer open water swim. In the women's 5 kilometer open water swim, Twichell finished first with a time of 1:01:31, winning the national title in the event.
2020 US Olympic Trials At the
2020 USA Swimming Olympic Trials (held in June 2021 due to the COVID-19 pandemic) Twichell competed in two individual events, the 400-meter freestyle and the 1500-meter freestyle. In the 400-meter freestyle Twichell placed eighth with a time of 4:10.51 in the prelims heats and decided not to swim in the final even though she qualified. In the 1500-meter freestyle she finished fifth in the final with a time of 16:01.62, not qualifying to swim the
event at the 2020 Summer Olympics.
2020 Summer Olympics Twichell was 32 years old heading into the
2020 Summer Olympics in
Tokyo, making her the oldest first-time American swimmer at an Olympic Games in over 100 years. Specifically, she was the oldest American swimmer at Olympic debut since
James Green debuted at age 32 in 1908. In the swimming community, only one female U.S. swimmer at the Olympic Games had been older,
Dara Torres who was 41 years old at the
2008 Summer Olympics. ==Awards and honors==