Sports staff are terrified of revealing their sexuality because of prejudice.
Lesbian games teachers are forced to conceal their sexuality for fear of being labelled as perverts and a danger to children.
They are particularly worried about physical contact during sports and about supervising children in showers, in case their behaviour is considered inappropriate, according to research published in International Studies in Sociology Education.
Gill Clarke, of the University of Southampton, who carried out the research, says that the bodily culture of sport and physical education creates "a unique context for denial that might not be experienced by teachers within other subject disciplines".
One student teacher, Berni, told researchers she hated supervising children in the showers. "It's stupid but you feel really awkward about it. They'll say, 'Oh you're looking at me, Miss' and stuff like that."
Another student, Christine, said: "If people know you are gay, you are as good as guilty before you've done anything."
Ms Clarke, who interviewed 18 teachers and nine students for her research, believes that the controversial Section 28 of the Local Government Act (1988) - which prohibits LEAs from promoting homosexuality or the acceptability of homosexuality "as a pretended family relationship" - has had a serious impact on their lives, causing them to fear for their careers if their sexuality is revealed.
"Not only are they forced to suffer in silence, but also pupils are denied the opportunity for lesbian role models," she argued.
She found that lesbian PE teachers habitually steered staffroom talk away from risky topics and led double lives. Fay commented on the stress of having to live two separate lives and constantly living in fear of giving anything away that might later be used as ammunition against her.
Lesbian teachers who successfully concealed their identity encountered other problems, including attempts by colleagues to act as matchmakers with men. Some kept their "Mrs" title from a previous marriage as a screen.
Dealing with pupils could also be problematic. All the women commented on how they avoided getting "too close" to pupils so as not to place themselves at risk.
Several said they did not get as friendly as they otherwise might. It was also not uncommon to lie about having a boyfriend: one teacher was shocked when pupils asked after him - even remembering his name - a year later.
Despite all this, many of the interviewees had been verbally or physically harassed because of their lesbianism, with pupils calling them names or graffiti appearing on school buildings.
One 40-year-old teacher thought pupils were now more vocal in their knowledge of lesbians and gays.
Moral blackmail was used by one head of department who discovered a junior colleague was lesbian. "He always holds that over me," she said. "If I do something that displeases him, his opening remarks will be, 'You're damned lucky you've still got a job here'."
Another teacher recalled being terrorised by a group of "older youths" outside her home. "One day all the locks on my car had been filled in," she said. "They had put a brick through every single window. There was cash in the car but they had not tried to take anything. I thought, 'These people actually hate me, and for nothing more than my sexuality or my job'."