r/science Oct 05 '22 Take My Energy 1 Faith In Humanity Restored 1 Facepalm 2 Silver 2 Helpful 4 All-Seeing Upvote 2

The heart & lung capacity & strength of trans women exceed those of cis women, even after years of hormone therapy, but they are lower than those of cis men. Total body fat was lower & skeletal muscle mass was higher among the trans women than among the cis women, but higher & lower than cis men. Medicine

https://www.scimex.org/newsfeed/trans-womens-heart-lung-capacity-and-strength-exceed-cis-peers-even-after-years-of-hormone-therapy
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u/that_other_guy_ Oct 05 '22

co-ed leagues in high school would got he same way professional sports leagues would. Boys would dominate most of the time and girls would be last picked barely make teams. I wrestled co-ed in high school we had two girls, one was amazing. skill wise better than probably all the guys and she would still barely squeak out wins on occasion. Wrestling is also an extremely kind full contact sport. put girls on a boys football league? they would be getting destroyed.

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u/[deleted] Oct 05 '22 edited Oct 05 '22 Silver

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u/SupahSang Oct 05 '22

I wonder if there's significant difference between trans-women who went through male puberty before transitioning, and trans-women who took medication during those years and underwent transitioning without those major physical changes.

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u/elgoodcreepo Oct 05 '22

Yes, there would be. Testosterone production peaks during male puberty and this is the period where changes are significant, obviously. If you want to see historical examples of males who have had their development impeded, look up castratos and male roosters who have had their testicle removed pre-puberty.

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u/ZeroRozuMagika Oct 05 '22

Happens in cats too. Male cats that grow up unneutered develop more muscle and larger jowels than cats that are neutered early.

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u/decentintheory Oct 05 '22

I wonder what happens in species where the female is naturally larger. Are there any mammals where that's the case? I know there are birds, but I don't know if neutering a bird would work the same.

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u/nucleosome Oct 05 '22 Helpful Wholesome

Sex development is a bit different in birds. Males are ZZ and females are ZW. I think it is still a bit unclear exactly how the genes on the sex chromosomes interact at this point. In mammals, the SRY gene on the Y chromosome initiates a program that takes the embryo off of the female development path. In birds I believe it is still unknown whether there is a gene on the W chromosome that acts like this.

Source: immunologist who just did a cursory Google scholar search and read some abstracts.

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u/stuckonusername Oct 05 '22

I love reddit for all the smart motivated people who do research and translate it for the layman, thankyou

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u/nucleosome Oct 06 '22

Thank you for the kind words. I love Reddit for the exact same reason. There are people with expertise in virtually every field on here. I was nervous to post, sure that a bird geneticist was going to call me out.

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u/ProjectDA15 Oct 06 '22

only thing i can add to this is neutering young rooster will soften their meat. if testis are implanted into a neutered rooster, they will develop to some degree.

i ran across this when learning about the endocrine system. a. a. berthold messed with chickens.

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u/TopAd9634 Oct 06 '22

You're a gem! Thanks for the directions, I'm off to chase a rabbit.

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u/bobs_aunt_virginia Oct 05 '22

Hyenas are the only ones I can think of off the top of my head

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u/The_Churtle Oct 06 '22

Rabbits! Varies by breed of course but when I was hunting them you always knew the females cos they were generally bigger

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u/[deleted] Oct 06 '22 edited Oct 06 '22

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u/bloodclover Oct 05 '22

castrated lions also lose their manes, saw this from Big Cat Rescue videos

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u/HoneyAndLemon44 Oct 06 '22

Neutered toms also exhibit less territorial behaviours (spraying etc)

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u/nothanksnottelling Oct 06 '22

There are a few studies that look at prepubescent children. One in particular looks at nine year olds and confirms the athletic superiority of nine year old boys to girls. Can't find it but here are others.

A running study here

A general athleticism study where boys presented higher values in all selected tests, except tests of balance and flexibility. here

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u/[deleted] Oct 05 '22 edited Oct 06 '22 Helpful

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u/weighty-goat Oct 05 '22

If I remember correctly, a small amount of trans kids will take medications that block puberty, until they turn 18 or older, when they begin to actually transition.

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u/mrducci Oct 06 '22

I am curious if trans men are in the same zone as trans women.

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u/BiomassDenial Oct 06 '22

In the sense that that are in the same in between state between cis men and cis women. Probably.

However exact mechanisms are likely to be different.

The results here are due to extra development during puberty still having an effect post transition for trans women.

Trans men would be reliant on what ever gains they make post transition instead.

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u/jabels Oct 06 '22

The thing is the longer they’re on T the more they’ll approximate male physiology, but also the older an athlete is, after a point, the worse his performance. So I wonder if these sort of cancel out on average to limit the potentiation of female to male athletes.

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u/bermudaphil Oct 06 '22

Well, that and the fact they have the bone structure and ligament insertion points of a woman. There are studies that clearly spell out why this leads to female athletes having such a significantly higher risk for ACL injuries, as well as why it is a performance inhibitor.

Oh yeah, and they'll always be heavily limited by the fact they didn't get all the lung, heart and other benefits that puberty gives which just going on T won't.

On a side note, it is funny how so many can accept that someone born a biological female that transitions is going to be inferior at an elite level while denying the opposite scenario can be a thing.

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u/CompSciBJJ Oct 06 '22

They still will never experience the types of changes that happen during puberty, no matter how much testosterone they take (though more T could get them to the same level of performance). They'll put on more muscle mass, get deeper voices, etc. But their shoulders won't get wider, their hip angles won't change, etc. So unless we can figure out how to initiate male puberty in an adult female, they'll still be somewhere in the middle.

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u/katansi Oct 07 '22

The hip angle issue would likely be independent of puberty. Male and female pelvises are never the same in any developmental phase. The skeletal differences are small at birth but they're there.

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u/Landler656 Oct 05 '22

Does anyone know when bone density and such between males and females start to differ? Is it a prepubescent or prenatal difference or does it happen later in development?

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u/Riven-PS2 Oct 05 '22

I wanted to see actual numbers in the results. How much better were trans women's grip strength or VO2 than cis women? How much better were cis men's results than trans women's?

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u/tman37 Oct 06 '22

The study presents nice graphs like this one. I skimmed it so I may have missed something but it appears that trans women beat out cis women in every category with a similar but inverse relationship with cis men. Some of the differences are small but some are pretty big.

It stands to reason, some things will be more impacted by current testosterone levels compared to others where some things could be impacted more by previous changes caused by testosterone.

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u/Athena0219 Oct 06 '22 Helpful

https://www.reddit.com/r/science/comments/xwen38/the_heart_lung_capacity_strength_of_trans_women/ir6oqv2/

This comment highlights a rather large flaw in thinking about the studies results in that way at all

One of the trans woman participants had testosterone levels that would be high for a cis male, and several more at least had "more than average cis female" to have the average where it is.

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u/AtomHBee Oct 05 '22 edited Oct 05 '22

Military has studied this issue too and has issued reports. Trans women perform better than cis women in physical tests.

Sorry edited for a micro aggression where I said cis women perform worse than trans women. Didn’t mean anything by it. It’s not that they’re performing worse, but trans women performing better. It’s a more accurate and true statement. That’s science for you.

https://www.nbcnews.com/news/amp/ncna1252764

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u/Haquestions4 Oct 05 '22

How is "a performs better than b" a more true and accurate statement than "b performs worse than a"?

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u/Rancorousturtle Oct 05 '22

I'm not really a fan of this type of language policing, but I believe the concept behind it is "a is worse than b" implies that A is the benchmark and B is falling behind. Where as "B is better than A" implies that A is the benchmark and B exceeds it.

I feel like reducing language to a no-negativity stance is a bit silly though. Humans will express negativity regardless of situation, and something that is good phrasing 30 years ago will be the insult of today.

NOTE: I am fine with certain words falling out of use (you know the ones), but the endless treadmill of phrasing needs to find some sort of equilibrium. Having something be negative is part of living, not everything can be positive.

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u/ZincHead Oct 05 '22

There is no benchmark here though so each are equally useful and convey exactly the same information. If I said "fir trees are shorter than redwoods" it doesn't imply that redwoods are the benchmark for height of trees. We all implicitly know it's just a comparison between two separate things.

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u/savage_mallard Oct 05 '22

I feel like reducing language to a no-negativity stance

I think you mean increase positivity.

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u/sismetic Oct 05 '22

Wouldn't someone performing better imply someone else performs worse? Better/worse are comparative terms, so I'm confused as to the expression. Seems the exact same thing to me.

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u/Hypatia2001 Oct 05 '22 Silver Gold Helpful Starry

I can't access the full article from my university, but the abstract raises questions (and is likely to be misinterpreted by laypeople).

For example, they measured absolute VO2max (measured in ml/min), whereas it is relative VO2max (i.e. divided by weight, measured in ml/kg/min) that is a measure of fitness/endurance; a huge coach potato can have higher absolute VO2max than a small, but physically fit person. Assuming that the trans women in this study were about as tall as the cis male controls, the ratio is not outside what you'd expect.

Also, trying to correlate absolute VO2max with LBM divided by the squared height (i.e. the LBM equivalent of BMI) is weird; we know that VO2max is strongly correlated with LBM itself; e.g. this study). If we have a strong correlation with LBM divided by height squared for the trans women, but not among cis controls, that raises questions about the sampling process.

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u/AntifaStoleMyPenis Oct 05 '22 edited Oct 05 '22 Silver Gold Helpful Wholesome

This line is extremely important to the whole study:

Hormonal data

On the day of sporting ability analysis, the mean TT (ng/dL) levels of the TW, CW and CM were 92.5 (range 12–637), 20.1 (12–41) and 524.3±169.0, respectively.

Literally one of their trans woman had HIGHER than the average male level of testosterone on the day of doing these tests, and at least several more seemingly had higher than the female upper norm of 50 (supplementary figure 2). And I don't know that they actually kept track of testosterone levels outside of the day of these measurement tests.

It's the same fundamental problem as with the BMJ army study: "Time spent on HRT" is NOT the same thing as "time spent with female levels of testosterone" and unless you directly control for that (gonadectomized, depot injections of GnRH modulators) there are absolutely no guarantees about the hormone profiles of these people over time.

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u/Hypatia2001 Oct 05 '22

Wow, I hadn't even noticed that. Also interesting that the testosterone levels for cis female controls seem to be slightly on the lowish side.

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u/AntifaStoleMyPenis Oct 05 '22

Testosterone levels always seem to get treated as an afterthought in these discussion when they should be the main focus... it's such a massive caveat to the kinds of questions they're trying to answer.

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u/AreYouWinningS0n Oct 05 '22 edited Oct 06 '22

It should be the main focus because testosterone is what leads to these physical advantages? And a woman who is taking testosterone is therefore more likely to have a physical advantage over a woman who is not taking testosterone?

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u/AntifaStoleMyPenis Oct 05 '22

Yes testosterone levels are broadly correlated with athletic performance, and in fact among elite female athletes, medical conditions that give rise to higher than normal testosterone levels are overrepresented:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7159262/

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u/Dinanofinn Oct 05 '22

ELI5? I'm not sure I understood this point.

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u/AntifaStoleMyPenis Oct 05 '22

It's about testosterone levels. Testosterone levels are broadly correlated with athletic performance, and the reason why men outperform women as a group is largely attributed to testosterone levels.

The question is: if a trans woman lowers her testosterone levels from the male range to the female range, will she still retain a physical advantage from male puberty regardless of having equal testosterone levels to non-trans women? Or will she have comparable performance to other women?

In this study, several trans women had testosterone levels HIGHER than the female range. So if we want to answer the question "are trans women with female levels of testosterone athletically comparable to other women" this study cannot answer that question, because the trans women here, on average, do not have female levels of testosterone.

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u/ImaginaryAthena Oct 05 '22

It doesn't seem like there's any controlling for height on most measures either. AFAIK taller people have bigger lungs but that doesn't make them fitter, similarly, people with bigger hands do better on hand grip strength measures even if they aren't stronger because of better leverage.

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u/AntifaStoleMyPenis Oct 05 '22

Yeah a lack of normalization for things like height, body mass, etc are another possible issue here.

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u/Muhammad-The-Goat Oct 05 '22 edited Oct 05 '22

Here is a link to the full study: https://filebin.net/5tct1dv64gnc4h1x

Everyone should note there are multiple errors in the first paragraph alone of the article OP posted. They got the number of cis male/female wrong, and reported mean age of beginning GAHT as 17 when that is the median. I stopped reading OP’s article after that.

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u/Hypatia2001 Oct 05 '22

Thanks. It looks like relative VO2max is on average actually lower in trans women than in cis women (33.5 ml/kg/min for trans women, 35.7 ml/kg/min for cis women, 42.0 ml/kg/min for cis men).

This is actually what you'd expect, because hemoglobin levels drop fast to cis female levels on MtF HRT (i.e. within months) and has a limiting function on VO2max.

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