Where sex matters | Sport


Policies which allow males to play in women’s sport are not supported by evidence. They are unfair and unsafe.

Sport is divided into male and female categories for very good reason. Men are taller, faster and stronger. They have bigger bones, longer limbs, wider hand spans, wider shoulders and a narrower pelvis than women. They have larger and denser muscles, with a higher proportion of fast twitch fibres, and larger hearts and lungs. These are the result of being born with a male body and going through male puberty.

Even from a very young age, boys perform better in tests of speed, power and strength. Each year, thousands of boys and men outperform elite females.

Female excellence, participation and safety in sport depends on sex-segregation. Female athletes at every level will lose if they have to compete with and against males.

What is the problem?

In recent years the female category has been opened up to male athletes who identify as women, on the basis of weak evidence and guidance to prioritise inclusion based on gender identity ahead of fairness and inclusion for female athletes.

National and international sport governing bodies, schools, colleges, local sport clubs and the International Olympic Committee all permit males to play in female sport. At school level, males need only declare a female gender identity to be included. For adults, policies are based on a requirement to reduce testosterone levels for 12 months.

Any male advantage carried through to the female category undermines the protections that category intends to provide, and that female athletes are losing medals and opportunities to those with such male advantage.

Dozens of studies of physical changes in males suppressing testosterone (either because of transgender identity or as part of therapeutic treatment for testosterone-related illness) show that muscle mass, strength and skeletal differences between males and females remain large. Furthermore, the small negative effect of testosterone suppression on muscle loss can be entirely mitigated by the type of moderate resistance training we would expect athletes to participate in.

World Rugby has taken this evidence on board, but other sports authorities are continuing to support male athletes playing in women’s sports.


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