Thread by @KirstiMiller30

Tucker, Hilton etc cite Q angle, lung size, bone density & height in XX women – confer a performance advantage for XY trans women, but there is NO support in the literature that these factors confer any such advantage.

link.medium.com/WZuukFsdiob

The Q angle – defined as the angle between a line drawn from the anterior superior iliac spine (ASIS) to the center of the Patella & a second line from the Patella to the Tibial Tubercle & has often been assumed to play a role in generating power during acceleration

and efficiency of a running stride. However, under investigation there appears to be no performance advantage conferred in sport as a result of Q angle, further increased risk of injury attributed to Q angle can be entirely removed with training

(Bruton et al., 2013; Kernozek & Greer, 1993; Thomas et al., 1998; Nguyen et al., 2009; Sigward & Powers, 2006; Hertel & Braham, 2004).

Arguments based on bone density derive from systematically racist arguments first introduced in the 1920’s while attempting to ignore this background, black women and women of color have higher bone density than white men (Leslie, 2012)

removing any potential for bone density to be considered a factor for unfairness in trans athletes.

Lung size is also commonly attributed as performance enhancing; however, it is never adjusted for height (taller individuals naturally have larger lungs on average) nor is it a good predictor of sport performance (Hopkins et al., 2018; Degens et al., 2019; Åstrand et al., 1964).

To clarify, on the topic of Maximum Breathing Capacity (MBC) “MBC is not likely to be an adequate physiological measure of the competence of the respiratory system in strenuous work and

should be regarded rather as the biomechanical limit of the possibilities of the ventilatory apparatus” (Breslav et al., 2000, pp. 485) and “After differences in lung volume are accounted for there is no intrinsic sex difference in the DLco, Vc, or Dm response to exercise …

together, these data suggest that the pulmonary capillary blood volume response is proportional to lung size & is adequate to meet individual oxygen demand during exercise” (Bouwsema et al., 2017).

As such, lung size should not be used as a proxy for an individual’s endurance capacity.

Beyond using misleading physiological traits, studies often use measurement techniques with poor accuracy and generalizability.

Hand grip strength, for example, is often used for broad population level analysis, however handgrip strength should not be used as a proxy for overall muscle strength (Yeung et al., 2018).

In fact, due to ease of gripping the testing device, grip strength is largely correlated with hand size and therefore height (Alahmari et al., 2019).

Additionally, some studies do not include cis female control groups, which leads to poor accuracy and confounding attributions.

One example of this can be found in Wiik et al., (2020)’s essay, in which the authors’ results ignore that ciswomen are also able to maintain or increase muscle mass while undergoing intense training cycles &

that untrained females have a high capacity to build muscle mass, particularly upper body strength (Roberts et al., 2020).

Without a cis women comparison group, the results are misleading. Moreover, many strength studies ignore that untrained individuals can quickly gain strength independent of muscle gain due to neural mechanisms (Chilibeck et al., 1997).

This ability to quickly gain muscle is in addition to higher performance on strength tests that can be attributed to comfort and familiarity with testing devices after repeated use.

As such, sedentary adults should not be used as a proxy for elite athletes when determining the ability to gain or retain muscle mass.

Additional studies need to be made which appropriately control for these factors. This requires studies to use appropriate control groups of height adjusted elite athletes and measure muscle and strength from appropriate tests which can be used as a proxy for overall strength and

adequately control for artifacts such as training familiarity and neural adaptations which give inaccurate measurement results.

Having lived & breathed these changes as an elite athlete & by examining the available literature, we I have significant confidence with the following statements:

1. There is no clear scientific evidence that high levels of naturally produced serum testosterone was predictive of athletic performance among cis women or cis men.

2. Female participation in elite athletics is significantly lower than male participation. This leads to a significant statistical artifact in performance data where statistical sampling results in a larger gap in performance than would otherwise exist if participation rates

between sexes were equal. This issue is compounded by training advantage conferred by additional resources typically given to male programs over female programs.

3. The higher levels of red blood cell count experienced by cis men is removed within the first four months of testosterone suppression. This suggests a rapid decrease in athletic performance particularly in sports with an endurance requirement.

4. There is no basis for athletic advantage conferred by bone size or density, other than advantages achieved through height. Elite athletes tend to have higher than average height across genders,

and this is not currently considered an athletic advantage.

5. Trans women who are pre-testosterone suppression still have lower Lean Body Mass (LBM), Cross Section Area (CSA), and strength than cis males. This indicates that the performance benefit experienced by these individuals cannot be generalized by examining cis male athletes.

6. Non-athletic trans women experience significant reduction in LBM, CSA, and strength loss within 12 months of hormonal suppression. It is important to note that this 12-month threshold is arbitrarily defined,

and no significant studies examine the rate of LBM, CSA or strength reduction over time.

7. When adjusting for height and fat mass, LBM, CSA & strength after 12 months of T suppression, trans women still retained statistically higher levels than sedentary cis-women.

However, this difference is well within the normal distribution of LBM, CSA and strength for cis-women (Jassen et al., 2000)

8. LBM, CSA and strength loss continues after the 12-month initial T suppression.

9.Evidence directly examining the effect of T suppression as it directly affected trans women’s athletic performance showed no athletic advantage exists after one year of T suppression (Harper, 2015, 2021).

10. Despite unavailability of the exact prevalence of trans women in the population, we can reliably conclude trans women are systematically underrepresented in elite athletics both in terms of participation and results.

11. Post gonadal removal, many trans women experience testosterone levels far below that of pre-menopausal cis-women.

12. That the literature largely ignores areas where cis-women have an athletic advantage over cis-men.

13. Estradiol likely plays a role in athletic performance as trans women undergoing HRT increase their average body fat percentage (Handelsman et al., 2018). This in turn reduces performance through increasing body mass for the equivalent LBM.
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