Jacqui Cheer, boss of the Cleveland force, is believed to be the highest-ranking officer to flunk the bleep test – while trying to set an example to her staff.
The force admitted she scored 4.2 on the test, compared with the 5.4 her rank and file officers will need to ensure their jobs are safe when the fitness checks come in officially in 12 months’ time.
Mrs Cheer, 52, joined Essex Police in 1984 and spent 28 years in uniform. She headed the investigation into the five prostitute murders in Ipswich in 2006, for which serial killer Steve Wright was jailed.
Mrs Cheer was played by the TV and film actress Jo McInnes in Five Daughters, the television drama based on the case.
It is understood many Cleveland officers already regard the targets as a farce and their own commander failing to measure up has made them even more scornful.
One source said: “They just think the whole thing is a nonsense anyway. They think it’s a complete joke.”
Expert Prof Craig Jackson, co-author of the report Are Police Fitness Tests Accurate?, said: “This is what happens when senior management try to lead by example. It can go horribly wrong.
“People might think it was just paying lip service to the fitness test and I would be interested to know if she did any training for it. The only way she could turn this into a success was by getting fit and passing it.”
Some forces favour an assault course which mimics what front- line officers do during the working day, such as crawling and climbing.
Prof Jackson’s research suggests this obstacle course is unfair because it excludes too many female officers while letting too many podgy males through.
But the Birmingham City University expert believes the shuttle run used by forces such as Cleveland is fair to both sexes and “a fail is a fail”.
He said he was not aware of any other chief constables taking and failing the test.
A Police Federation spokesman said: “The Police Federation feels officers should be fit to perform the role they do and we need to be realistic about the fact that a chief constable is not going to be knocking down doors and arresting people in the town centre on a Saturday night.
“We do have some concerns about the fairness of national fitness testing proposals, and will continue to engage with Acpo and the College of Policing to ensure these concerns are addressed.”
Mrs Cheer joined Suffolk Constabulary in 2006 as Assistant Chief Constable. After helping snare the Suffolk Strangler, she joined Cleveland Police in 2011 when predecessor Sean Price was suspended and later sacked for misconduct.
Under the Government plans, officers have to reach level 5.4 of the bleep or “beep test”, which involves completing a series of 15-metre shuttle runs at ever increasing speed. If they succeed, they will have been able to run for 3 minutes 34 seconds.
Those who fail will be given a fitness plan and 12 months to measure up – or face dismissal for “unsatisfactory performance”.
A Cleveland Police spokeswoman said: “Over the summer, a familiarisation exercise was run so that officers could see what the tests would entail, and the Chief Constable took part in the full day as she was keen to see what tests the officers would undergo, as well as supporting her staff.
“As she does not undertake an active operational role, she is not required to take the fitness test.”
National fitness working group lead Robin Merrett said: “We will be ensuring that the fitness test does not unlawfully discriminate against gender or other protected groups.”