[1][2] She was raised as a child in her parents' home country of Tonga, living in the village of Ha’alaufuli in Vava'u,[3] but her family moved to San Francisco when Manumua was 10.

[2][4] Manumua competed at the 2018 Junior World Weightlifting Championships, representing the United States of America in the women's +90 kg category.

[1][5] Manumua's first participation representing Tonga was at the 2018 World Weightlifting Championships, where she competed in the women's +87 kg category.

[1][9] In qualifications for the 2020 Summer Olympics in the women's +87 kg category, Manumua placed in 14th, initially failing to qualify.

[10] There was controversy surrounding Manumua's exclusion, due to the fact that one of the athletes in the Oceania bracket who did qualify was Laurel Hubbard, who is a transgender female.

[2][11][12][13] The San Francisco Chronicle wrote that "Manumua’s name started showing up as a cause celebre in right wing media".

[2] Hubbard, alongside one other Oceania athlete, Iuniarra Sipaia of Samoa, all qualified in the top 8, automatically giving them both a spot at the Games.