Thread by @KirstiMiller30

The airforce study even though it had many flaws actually confirms the reduction in athletic performance. The reduction doesn't stop after two years eventually HRT takes you completely out of sports. Post operative it's an immediate loss.

https://twitter.com/KirstiMiller30/status/1493166909722075139

This study from the U.S. Air Force looked at trans men and trans women in three fitness tests before and after their transition. The tests were a 1.5-mile run and the number of situps and pushups that can be done in a minute.

After 2 years of hormone therapy, the trans men matched the cis men in the 1.5-mile run and in the number of pushups per minute, and they exceeded the cis men in the number of situps per minute.

Prior to gender affirming hormones, transwomen performed 31% more push-ups and 15% more sit-ups in 1 min and ran 1.5 miles 21% faster than their female counterparts (gender gap at 1.5 is 11%. The trans women & cis women were not matched for height. 5ft4 cis to 5ft 9 trans.

After 2 years of taking feminising hormones, the push-up and sit-up differences disappeared completely meaning the trans women lost 31% of push-ups & 15% sit-ups, but transwomen were still 12% faster over 1.5 miles meaning this group of trans women lost 11% the exact gender gap.

Prior to gender affirming hormones, transmen performed 43% fewer push-ups and ran 1.5 miles 15% slower than their male counterparts. After 1 year of taking masculinising hormones, there was no longer a difference in push-ups or run times, and

the number of sit-ups performed in 1 min by transmen exceeded the average performance of their male counterparts.

The 15–31% athletic advantage that transwomen displayed over their female counterparts prior to starting gender affirming hormones completely declined with feminising therapy. The trans women still ran 9% faster but they were 21% faster prior to commencing HRT.

Meaning the trans women actually lost more than the gender gap of 11% over 1.5 miles in just 12 months. They lost 12 % on their run speed after the 1 year period of testosterone suppression that is recommended by World Athletics for inclusion in women’s events.

Gooren found that during the first 12 months muscle mass (area) was decreased by 9.4% & hemoglobin levels by 14% in 20 transwomen (M2F trans) treated with an estrogen-based regimen that reduced circulating T concentrations from the male range to the female range.

Conversely, in 17 transmen (F2M transgender) treated for the first time with testosterone for 12 months (which increased circulating testosterone levels to a mean of 31 nmol/L), muscle mass increased by 19.2% and hemoglobin by 15%.
pubmed.ncbi.nlm.nih.gov/9950792/?

The muscle mass findings remained stable between 1 and 3 years after initiation of treatment, although fat mass continued to change between 1 and 3 years of testosterone treatment.
pubmed.ncbi.nlm.nih.gov/9215270/?

although with disproportionately greater effect on muscle strength than on muscle mass. This study did not report muscle strength, but other studies of T dose-response relationships for muscle mass and strength show consistently positively correlation,

Hence, the muscle mass estimates in these prospective treatment initiation studies in trans individuals likely underestimate the muscle strength gains from...

elevated T levels where the circulating T markedly exceeds female range to be within the male range as occurs in severe hyperandrogenism of DSD females, poorly controlled transwomen (M2F transgender),..

or transmen (F2M transgender). These effects are also the biological basis of the ergogenic efficacy of androgen doping in women.

In both intersex/DSD and trans individuals, the developmental effects of adult male circulating T concentrations will have established the sex difference in muscle, hemoglobin, & bone, some of which is fixed & irreversible (bone size)....

& some of which is maintained by the male circulating testosterone concentrations (muscle, hemoglobin, bone mineral density over 200 daily functions in the XY physiology ).

The limited available prospective evidence from initiation of trans cross-sex hormone treatment suggests that the advantageous increases in muscle & hemoglobin due to male circulating T concentrations....

are induced or reversed during the first 12mths further declines in strength after 36 months occur, and a recent small study out of Brazil suggests that the entire strength advantage goes away.

But they just looked at grip strength in eight trans women, compared with eight cis women matched for BMI.

dx.doi.org/10.1210%2Fjend…

This time course is much faster than the somatic effects of male puberty, which evolve over years and for some variables (e.g., peak bone mass) are not complete for up to a decade after the start of puberty.

However, the abrupt hormonal changes induced by medical treatment in intersex/DSD or transgender individuals is telescoped compared with male puberty where circulating testosterone concentrations increase irregularly and incompletely for some years.

Additional data are available from the unique investigative model of men undergoing castration for prostate cancer. Just as androgen sensitivity to testosterone may differ between tissues...

ncbi.nlm.nih.gov/pmc/articles/P…?

The time course of offset of androgen effects following withdrawal of male testosterone concentrations may also differ between the major androgen-responsive tissues.

For example, circulating hemoglobin shows a progressive fall for 6 months reaching a nadir and plateau at 12 to 16 months in six studies involving 534 men undergoing medical castration for prostate cancer. 
pubmed.ncbi.nlm.nih.gov/8876707/?

Although these studies of older men with prostate cancer must be extrapolated with caution, age, stage of disease, race, & baseline circulating T concentration did not affect the rate or extent of decline in hemoglobin.
pubmed.ncbi.nlm.nih.gov/8876707/

pubmed.ncbi.nlm.nih.gov/12820454/

Comparable longitudinal studies of muscle loss, strength, and performance following castration for prostate cancer are well summarized,
showing progressive loss for 24 months
pubmed.ncbi.nlm.nih.gov/22367184/?

Testosterone levels drop quickly after hormone treatment. Is it true that the testosterone levels of trans women are similar to cis female levels.

90% of cisgender women have testosterone below 2 nanomoles per liter. And in a recent study of nearly 250 trans women, 94% of them had testosterone below 2 nanomoles per liter.

doi.org/10.1530/EC-19-…

The single most important physiological factor for endurance athletes is hemoglobin. In sports it’s often measured as hematocrit levels. Hematocrit is the percentage of blood that's red blood cells.

That's the reason that endurance athletes go to altitude to train, or [those who cheat] use blood doping or EPO. There are a lot of things that go into making an endurance athlete, but the single most important factor would be hemoglobin levels.

Hemoglobin levels follow the testosterone. Within weeks of starting T suppression, T levels will be within female norms, but it takes a little longer for hemoglobin to get the female norms, in the 3- to 4-month range. That's roughly the life cycle of red blood cells.

As trans women replace their red blood cells, with their new lower testosterone levels, they will have fewer red blood cells and lower hemoglobin, but it does take 3 to 4 months.

do.org/10.1136/bjspor…

One of the important things to note is that even before starting hormone therapy, the trans women in all these studies were substantially less strong than cis men.

I put it colloquially that as a population group, trans women would rather starve themselves to look like models, than put on muscle to be athletes.

Trans women have bone density lower than natal males, natal females, and FtMs, as a group, BEFORE hormone therapy even begins (sample=711, FAR larger than any of the studies Hilton uses)

asbmr.onlinelibrary.wiley.com/doi/full/10.10…

But that's the population these studies have all looked at -- they weren't looking at trans women who are active in sports. The trans women didn't lose very much strength or lean body mass because they didn't build up very much before they started hormone therapy.

How applicable that finding is to trans athletes is massively debatable. This is 3 years of muscle mass loss for me as a trans athlete.

There's absolutely no question in my mind that trans women will all eventually lose all their strength advantages over cis women after hormone therapy. That's based on my lived experience & published data, I would say there's zero doubt in my mind but it's a case by case basis.

The important question isn't, “Do trans women have advantages?” What really matters is can trans women and cis women compete against one another in meaningful competition.

There's no indication that trans women are anywhere close to taking over women's sport, it's not happening now. It's not likely to happen anytime in the future.

Are there any potential disadvantages for trans women athletes? Absolutely. Trans women our frames, which are now being powered by reduced muscle mass and reduced aerobic capacity, and that can lead to disadvantages in things like quickness, recovery endurance,

and things that might not be quite as obvious as seeing somebody bigger.
The idea that trans women only have advantages just isn't true. The analogy I've used is that it's like a big car with a small engine with bad fuel competing against a small car with a small engine.

Trans Women in Sport Testosterone & how testosterone suppression mitigates Performance.

This video debunks the bogus research of @WorldRugby &  Drs. Hilton and Lundberg, they relied on  fear and prejudice way before science.

Sports like #WorldRugby banning #transgender women on safety grounds place themselves on a slippery slope. Safety has no gender.

austlii.edu.au/au/journals/Ad…

https://twitter.com/KirstiMiller30/status/1484864829487988738?s=20&t=nYeNb5DWJOwA8qAvfIMFfQ

Banning every transgender woman from playing women’s elite contact rugby on the basis of risk outcomes of a group level aggregate of physical characteristics that any given individual belonging to this group may demonstrably not possess individually

cannot be considered reasonable, proportionate or justified.

This is before we consider the uncomfortable fact that none of the evidence presented by World Rugby involves empirical research of trans women rugby players actually playing rugby or in fact any sport. There were no injuries reported & no elite trans players.

In relation to performance advantage: there is clear evidence that increasing the acceptable period of testosterone suppression further reduce parameters thought to be associated with “meaningful” performance advantage in trans women

(which would clearly be more reasonable than banning all trans women), there is currently no definitive threshold of what this “meaningful” reduction should be anyway,

and finally there is no current scientific work demonstrating specifically what the performance advantages of men over women in rugby itself could be said to be composed of.

This means there is no current threshold of “meaningful” performance advantage reduction that any transgender woman rugby player could satisfy.

@WorldRugby and the @USASwimming policies, trans women are placed in an uncomfortable double-bind: accused of performance advantage they cannot prove they do not possess. As swimming has not done this research either.

There is no typical transgender or cisgender athlete, broad rules for transgender or cisgender athletes are not appropriate. The decision as to the appropriate accommodation must be based on the particular facts of each individual athletes case.

“IN FACT”

There is no clear biological list of features that allow us to even remotely cleanly separate men from women.

Chromosomes? NOPE

Testosterone? NOPE

Height? NOPE

Vo2 Max? NOPE

Haemoglobin? NOPE

Weight? NOPE

Bone Density? NOPE

medium.com/@kirstiphillip…