1. Transwomen competing in sports may retain strength advantages over cisgender women even after 3 years of hormone therapy.
2. Transwomen have red blood cell findings equivalent to those of cis gender women after 4 months of hormone therapy, thereby reducing their endurance performance.
Evidence Level Rating: 1 (Excellent)
Presently, there is a lack of prospective studies investigating changes in athletic performance in transgender athletes after undergoing gender affirming hormone treatment (GAHT) which is known to have a feminizing effect on the body. It is also known that World Athletics requires that transgender athletes and athletes with differences of sexual development have testosterone levels ≤5 nmol/L to be eligible for the female category. As a result, the objective of this study was to systematically review the literature to determine the influence of GAHT on athletic performance.
This systematic review included 24 studies from 1999-2020. Eligible studies measured at least one of the variables of interest, included transwomen, and were written in English. The quality of the studies were examined by the Effective Public Health Practise Project (EPHPP) tool and were deemed to be moderate in quality. GAHT treatment varied based on the study, in line with the individualized approach advised by the WPATH Standards of Care. Study outcomes assessed the influence of GAHT on muscular area, lean body mass, muscular strength, and haemoglobin/hematocrit.
After taking the strength parameter data collectively, results indicated that after 12-36 months of GAHT, transwomen still retained a strength advantage over cisgender women. In contrast to these strength findings, transwomen were found to have decreased haemoglobin/hematocrit levels (impacting endurance performance) after 3-4 months of GAHT, matching that of cisgender women. One key strength of the present study included the use of the EHPP tool to account for the overall quality of the studies included. By contrast, this study was limited as only studies from Western countries were included, contributing to geographical bias. Nonetheless, this study was significant in suggesting strength may be retained after GAHT in transwomen in the first 3 years of treatment.
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