Jennifer Sey Calls Out Nike for Allegedly Funding Study on Transgender Youth in Sports

Jennifer Sey, founder of XX-XY Athletics, has taken a public stand against Nike, blasting the sportswear giant for its alleged financial support of research into puberty blockers for children—and how these interventions might impact athletic performance.

The research reportedly aims to determine what level of medical intervention would be needed for a male athlete to "fairly" compete in girls’ and women’s sports. The issue first came to light in a recent New York Times piece focused on Blaire Fleming, a transgender female volleyball player at San Jose State who’s become a flashpoint in college athletics.

A key figure in the study is Joanna Harper, a trans woman and researcher, who is said to be overseeing an ambitious, years-long project tracking trans adolescents’ performance on a 10-step fitness test before and after starting hormone therapy. The project is set to run every six months for five years. According to Harper, funding isn’t the problem—Nike is footing the bill. The real challenge, she says, comes from recent political pushes to restrict gender-affirming care for minors, making it difficult to recruit participants.

Nike, for its part, has not responded publicly to requests for comment or offered clarification on their role in the study.

Sey didn’t mince words when discussing the situation in a recent interview. She denounced the research, questioning why a shoe company is involved in such a controversial and sensitive topic. Sey argued that framing the issue as a question of "retained male advantage" is degrading to women and girls in sports, saying, "We are not impaired boys. It’s so degrading to think of us that way." She went on to use a vivid analogy, asking, "Would we do a study that says, ‘How many fingers can we cut off of a boy to make it OK for him to compete in tennis with a girl?’ That’s what we’re doing here."

Sey speculated that the initial decision to fund the study may have happened deep within Nike’s organization, possibly escaping the notice of senior executives. She suspects the company is now scrambling to handle the backlash.

Ultimately, Sey called for Nike to apologize and withdraw its support from the study, labeling it as incentivizing medical experimentation on youth.