The offensive messages were purportedly sent from Senior instructor Ross Brain’s WhatsApp account to a work WhatsApp group at Edinburgh University’s Sport & Exercise club.
Bosses have launched an investigation but colleagues at the Pleasance centre are understood to feel let down at a perceived lack of action three months on.
“One of the girls is considering leaving because of it - she feels intimidated,” a source told the Evening News.
Mr Brain has been accused of sending the message shortly before Christmas to the staff messaging group set-up to arrange logistics.
The group is understood to have been discussing possible forfeits to be imposed on a woman who signed up to a six-week exercise course but failed to show that morning.
A message that appears to have been sent Mr Brain stated: “Lets rape her. Or give her the choice of 600 burpees or rape.”
When junior staff in the group, mostly female, ignored the rape jibe, a further message – again purportedly send from Mr Brain’s account – queried: “No-one up for this then?”
Concerned staff reported the messages to the university’s HR department in January but were left unaware of any action being taken.
“It’s like they’re trying to brush it under the rug. People are feeling let down,” said the source. “The university is loud and proud about its zero tolerance policies but a lot of people want action on this – they feel abandoned.”
Staff have now been left struggling on in a “toxic” environment with no faith in protocols if they report misogynistic or inappropriate behaviour, revealed the source.
Meanwhile, Mr Brain – who the Evening News has attempted to contact for a comment – is understood to have since been taken on an all expenses paid work trip to a fitness expo in Europe.
The gym source continued: “Staff were told there’d be an investigation in January and have heard no more.
“There are off-hand sexist remarks particularly working in the fitness industry that are leftover attitudes that haven’t made their way out yet.
“One senior manager apparently told female members of staff they must wear tight leggings because “it looks more professional,” added the source.
A University spokesperson said: “We take incidents such as this very seriously – the use of such language is abhorrent and has no place in this University.
“We have a zero-tolerance stance towards sexual harassment of any kind and are absolutely committed to providing an environment in which all members of the University community treat others with dignity and respect. We put significant effort into reinforcing our zero-tolerance culture including through campaigns such as ‘Don’t Cross the Line’. While we do not comment on the detail or outcome of individual cases, we can confirm that a full disciplinary investigation has taken place in this instance.”
Despite attempts to reach him, Mr Brain failed to respond to requests for a comment.