[5] She was coached by Trish Cazeau Brown and Sergei Telenkov from 1998 to 2008, by Maria Jeżak-Athey in 2008–2009, and by Vadim Naumov and Evgenia Shishkova from 2010 to 2011.

[7] In October, Scimeca/Knierim won the gold medal in their first-ever international event, the 2012 Coupe Internationale de Nice.

[8] After several withdrawals by other teams, they received a Grand Prix assignment, the 2012 NHK Trophy in November, where they placed fourth.

[14] Scimeca/Knierim began their season at 2015 Nebelhorn Trophy, where they won the silver medal behind reigning Olympic champions Tatiana Volosozhar / Maxim Trankov.

Scimeca/Knierim went on to win the bronze medal at 2015 NHK Trophy, which helped qualify them for the 2015–16 Grand Prix Final in Barcelona, where they placed seventh.

She was properly diagnosed with a rare, life-threatening gastrointestinal condition in August and underwent two abdominal surgeries that month.

[18] Alexa Knierim's illness involved regular episodes of vomiting, debilitating pain, difficulties with sleeping, eating, or drinking, and significant weight loss.

In February, the Knierims made a strong return to competition at the 2017 Four Continents Championships, where they placed sixth in a deep field of Chinese and Canadian pairs.

The Knierims began their season at the 2017 U.S. International Classic, where they won the silver medal and were narrowly edged by Canadians Kirsten Moore-Towers and Michael Marinaro.

They placed a strong 4th in the short program with a season's best score, defeating top pairs from China, France, and Italy.

[31] In early November, the Knierims won the bronze medal at their second Grand Prix event, 2018 NHK Trophy, ahead of Canadians Kirsten Moore-Towers and Michael Marinaro.

In early December, they won the silver medal at 2018 Golden Spin of Zagreb, placing 1st in the free skate and finishing one point from 1st overall.

It was revealed after the competition that Chris Knierim had been suffering from a torn wrist ligament that required surgery to repair.

[36][37] At their second Grand Prix event, 2019 NHK Trophy, they placed fifth in the short program with a fall and a completely invalidated death spiral.

[39] After leaving some points on the table in an otherwise strong free skate performance, they placed second in that segment and first overall after having a nearly ten-point lead over silver medalists Calalang/Johnson from the short program.

"[4] On April 1, Alexa Knierim announced that she was teaming up with Brandon Frazier, who had split with his former partner, Haven Denney.

They began training in Irvine, California, at Great Park Ice, with coaches Todd Sand, Jenni Meno, Rafael Arutunian, Chris Knierim, and Christine Binder.

This event was attended by skaters training in the United States due to travel restrictions caused by the COVID-19 pandemic.

[51] Knierim/Frazier skated strongly at the Cranberry Cup International, where they won the silver medal behind Russian pair Evgenia Tarasova and Vladimir Morozov.

In September, they won the gold medal at the John Nicks Pairs Challenge, an ISU international competition in New York City.

[53] In their first Grand Prix event of the season, 2021 Skate America, Knierim/Frazier placed fourth and narrowly missed the podium, just 2.56 points behind reigning World bronze medalists Boikova/Kozlovskii.

After arriving at the competition, Frazier began to feel unwell, and he tested positive for COVID-19 on January 5, the day before the short program.

[57] The pair was forced to withdraw from the competition, and Frazier shared an emotional video message in which he expressed his devastation over not being able to compete.

However following a positive doping test of Russia's gold medalist Kamila Valieva, the team members were not awarded their medals, pending an investigation.

As those countries' athletes comprised the entirety of the top five pairs at the Olympics, this had a big impact on the field for Worlds, and Knierim/Frazier entered the event as medal favorites.

[73] Knierim/Frazier won the gold medal at their second Grand Prix event, 2022 MK John Wilson Trophy, by a dominant 21.66-point margin.

They earned all-new season's best scores and won both segments of the competition with a strong short program and some errors in the free skate.

In the short program, they skated cleanly except for a hand down by Frazier on their side-by-side jump, and earned a new personal best score of 77.65 to place second, only 0.43 points behind Miura/Kihara.

[79] At the 2023 U.S. Championships, Knierim/Frazier won their second national title by a dominant 31.11 points, the largest margin of victory in history, which surpassed their own previous record set in 2021.

[84] The leadup to the 2023 World Championships was a difficult time for the team, after their coach Todd Sand had a heart attack on March 2 and was hospitalized for an extended period.