Cardiopulmonary capacity and muscle strength in transgender women on long-term gender-affirming hormone therapy: a cross-sectional study
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  • Published on:
    Cardiopulmonary capacity and muscle strength in transgender women on long-term gender-affirming hormone therapy: A cross-sectional study.

    I appreciate the thoughtful considerations raised. Scientific discussion is always the best way for the opportunity to review points, exchange thoughts and evolve in knowledge. Here are some additional considerations below:

    - About strength and VO2peak controlled by FFM and/or weight:
    We showed these data in the article (strength/FFM; VO2peak/FFM; VO2peak/weight) in the results and table 2. There are no statistical differences comparing all populations (TW,CM and CW).

    - TW with 637 ng/dL testosterone on the day of the tests:
    In the long-term follow-up of a cohort of individuals with daily medication use, temporary failures in the regular use of medications are not uncommon. One of the participants had a high level of testosterone at the time of the study. However, we emphasize that we were careful to assess testosterone levels in the year before the study so that we could confirm the correlation of the values obtained at the time of the study with those in the last year. In addition, the values of haemoglobin denoted testosterone supression in the past 4 months. Although one of the TW was not blocked on test day (total testosterone =637 ng/dL), her value was 79 ng/dL six months before the study. This point did not interfere with her VO2 results (supplementary figure 2).

    - Weight and height:
    Studies in sports medicine generally eliminate the height as an interfering factor in the analyses.
    Height is a consequent characteristic o...

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    Conflict of Interest:
    None declared.
  • Published on:
    High quality and relevant research needed to inform policy and help in decisions about the participation of transgender women in elite sport.
    • Richard Budgett, Director Medical and Scientific Department International Olympic Committee
    • Other Contributors:
      • Yannis P Pitsiladis, Professor of Sport and Exercise Science
      • Madeleine Pape, Postdoctoral Researcher

    Dear Editor:

    Alvares et al. [1] conducted a study to compare performance-related measures such as cardiopulmonary exercise capacity and muscle strength in non-athlete transgender women (TW) undergoing long-term gender-affirming hormone therapy to non-athlete cisgender men (CM) and non-athlete cisgender women (CW). The authors report higher absolute VO2peak (L/min) and muscle strength (kg) in TW compared to CW and lower than CM. The authors conclude that their “…findings could inform policy and help in decisions about the participation of transgender women in sporting activities”.

    However, the authors interpreted their findings on the basis of the absolute data they present and not the relative data that was controlled for body mass and fat-free mass (FFM), as would be appropriate for comparisons of such performance metrics (e.g., aerobic capacity and muscle strength). By focusing on the absolute data, the authors over-emphasise differences between comparison groups (e.g., TW and CW) that are clearly driven by differences in anthropometry. For example, when the data reported in Table 2 [1] are corrected for body mass and fat-free mass (FFM), differences in aerobic capacity and strength between TW and CW disappear. Yet, in the section “WHAT THIS STUDY ADDS” [1], which is the primary focus of many readers, the authors omit the results that control for body mass and FFM, instead leaving the reader with the misleading message that “[t]he mean strength and VO2peak...

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    Conflict of Interest:
    None declared.
  • Published on:
    No observed differences in cardiopulmonary capacity in a small cohort of transgender and cisgender women from San Paulo, Brazil when corrected for body weight
    • Tiffany Thomas, Assistant Professor Columbia University Irving Medical Center

    The topic of transgender inclusion in women’s sports is politically fraught. Sport’s governing bodies are grappling with the competing priorities of inclusivity and fairness due to any perceived competitive advantage above and beyond the large and broad continuum of biological variables found within cisgender women (e.g. height, bone mass, bone length, fiber cross-sectional diameter, etc.) associated with testosterone exposure during puberty. This active area of research is rapidly evolving due to the multitude of new studies published over the previous 5 years. In fact, there have been over a dozen primary prospective and case-control research studies published on this topic since 2018 resulting in the lowering of the maximum allowable testosterone level in transgender elite athletes (i.e., from 5.0 to 2.5nmol/L) by several sports’ governing bodies.

    The preponderance of evidence suggests that hematological differences in hematocrit, red cell number, and hemoglobin are largely normalized within 120 days of testosterone suppression, which is biologically plausible as this corresponds with the average lifespan of a red cell (~ 120 days). Since oxygen delivery to peripheral tissues is performance limiting in aerobic sports, any competitive advantage is likely largely diminished within a year of testosterone suppression. Studies evaluating changes in strength, muscle mass, and body composition are more equivocal and most likely occur over a longer time span (12-36 mon...

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    Conflict of Interest:
    None declared.