Australian athlete Joanna Wietrzyk has apologised after criticism over continuing a Hyrox indoor fitness race after soiling herself.

The 23-year-old finished the event with excrement on her legs and shoes and continued using the race mats and equipment, prompting concerns about hygiene and the potential health risk to other competitors.

In a statement on Instagram, Wietrzyk apologised to the people of China, fellow athletes, spectators and the Hyrox organisers.

She said she felt fit and healthy when the race began but admitted that, in hindsight, she should have stopped competing.

Wietrzyk, who holds a world record, has since withdrawn from the event and agreed to forfeit the points she earned from her performance.

Hyrox co-founder Moritz Furste also apologised over the incident, acknowledging that organisers should have intervened immediately.

The competition has since updated its rules to allow race directors to remove athletes on medical grounds when blood, vomit, urine or faeces creates a welfare or contamination risk to competitors.