“They said it had to be a white or blue dress, pinafore apron and white cap or it wouldn’t count as a record,” Ms. Anderson said in an Instagram message on Sunday.

“I didn’t want to wear that, so I chose to wear my real uniform instead because the title of the record is ‘fastest marathon in a nurse’s uniform,’” she added. “But was still aiming for the record time.”

Ms. Anderson also told the website Runner’s World on Friday: “I’m sure Guinness World Records don’t intend to cause offense, but it would be nice if they decided to revise their criteria instead of reinforcing old gender stereotypes. I get that it’s supposed to be a fun thing, but their definition is just so outdated.”

She also noted, “I’ve certainly never seen a male nurse wearing a dress to work.”

Ms. Dudgeon, the record-holder, ran the 2015 London Marathon in a nurse’s outfit that included an apron and a Red Cross cap. It is not clear whether she worked as a nurse.

That Ms. Anderson was denied credit for her feat because of what many saw as a sexist, outdated criteria spurred social media users and nurses to share pictures of real-life nurses’ uniforms on Twitter under the hashtag “What Nurses Wear.”