Transgender women have more muscle mass than cisgender women but less than men, according to a new study published in the British Journal of Sports Medicine.
Researchers in Sao Paolo, Brazil, examined muscle strength through hand-grip tests and tested the heart and lung capacity of 15 transgender women, 13 biological men, and 14 biological women, by having them run on a treadmill with incremental effort until exhaustion. The transgender women were, on average, age 32 and had received hormone therapy for 14 years.
Transgender women had higher mean muscle strength (35.2 ± 5.4 kg) then cisgender women (29.6 ± 3.6 kg) but lower than cisgender men (48.4 ± 6.7 kg).
Total body fat was lower among transgender women than it was among other women but higher than it was among men. Cardiopulmonary function was also greater in transgender women than it was among women.
None of the participants was an athlete.
"In this small cohort of non-athlete TW [transgender women], who were previously exposed to male pubertal development and underwent long-term oestrogen therapy, we identified higher grip strength and VO2 peak levels than in non-athlete CW [cisgender women], but these same parameters were lower compared with non-athlete CM [cisgender men]," wrote the researchers.
"These findings add new insights to the sparse information available on a highly controversial topic about the participation of TW in physical activities.
"Future studies involving transgender athletes that account for and quantify variable exposure times to pubertal development and assess muscle cell metabolism are needed to elucidate the effects of long-term GAHT [gender-affirming hormone therapy] on TW sports performance."
Several major sporting organizations have recently passed rules not allowing transgender women to compete on women's sports teams, including FINA in June after Lia Thomas became the first transgender woman to win an NCAA Division I swimming championship, putting a spotlight on the issue.
Alun Williams, professor of sport and exercise genomics at Manchester Metropolitan University, said the study doesn't "support the eligibility of trans women for the female categories of most sports."
"Studies of well-trained athletes before and during their treatment, using tests that are more accurate and more relevant to competitive sport, are required to better inform sport eligibility policies," he said.
Solange Reyner is a writer and editor for Newsmax. She has more than 15 years in the journalism industry reporting and covering news, sports and politics.
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