British 800m Olympic champion Keely Hodgkinson pulled out of the 400 metres final at the UK Athletics Championships in Birmingham on Sunday but said it was just a precautionary measure.
The 24-year-old was out on track for her pre-race warm-up at the Alexander Stadium before walking off in tears after stepping away from her lane.
Her team insisted that Hodgkinson was not injured but felt tightness and the withdrawal was to avoid taking any risks.
"I wasn't feeling 100 per cent standing on the start line, so I made the tough decision to step away and not race," said Hodgkinson.
"I didn't want to risk anything this summer."
Hodgkinson was laid off for 376 days with injury before returning last August to set a world-leading 800m time.
She then claimed bronze at the 2025 world championships in Tokyo having raced just twice that season before travelling to Japan.
Her stated ambition is to break the highly-criticised 43-year-old 800m record, held by Jarmila Kratochvilova, in London next month.