So there's a diary up about the two transphobic garbage bills currently being pushed in Montana.
In the comments section of that diary several (cisgender) Kossacks are showing that they've been suckered by an old and pernicious lie told by TERFs and transphobes regarding trans women in sports.
This lie is designed to "sound reasonable" to a well intentioned but uninformed person, and after they swallow it, they'll feel that trans people pushing back against it are "being unreasonable", thus alienating us trans folks from potential allies.
That lie is as follows:
"Because trans women went through male puberty they have major physical advantages over cis women and therefore it's unfair to let them compete in women's sports"
This is bullshit. Unmitigated, unscientific tripe hiding behind a veneer of "common sense" and designed to conjure up the mental image of a burly 6'4" linebacker in a wig and lipstick demanding to be on the women's rugby team.
So let's dissect this garbage, shall we?
After a short time on hormones trans women (and girls) have less testosterone than cis women do. We also have worse muscle tone, a harder time gaining muscle mass, and a higher risk of osteoporosis than cis women have once we've been on HRT for a couple years.
(Quick example in action: Trans women have been admitted to qualify for women's events in the Olympics.
So if going through "male puberty" is such a distinct advantage, then why hasn't a single trans woman qualified?
Surely that big bad male puberty should mean the entirety of the US women's teams would all be trans, right? So why aren't they? Because that advantage doesn't exist.)
Now, we'll get into a few specific counter arguments.
"Trans women are so much taller than cis women it's unfair"
Are trans women who've gone through puberty, at least on average, taller than cis women? In a word, yes. Should that disqualify us from women's sports? I mean, if you want to establish an arbitrary height limit to women's leagues and enforce it regardless of whether a woman is trans or cis, go for it, but that seems a bit silly. Height among humans is ridiculously varied. Is it "unfair" to a teen girl who loves to play basketball but is destined by her genetics to never get above 4'11" tall? I suppose so, but unless you're gonna go all Harrison Bergeron and start adding weights, masks, etc to people to make us all equal I don't see how a trans woman being a few inches taller on average is disqualifying.
This one I've seen more rarely, but it's pernicious all the same. Does a trans woman who is freshly on hormones have a slightly higher bone density than a cis woman? Sure, but as I mentioned above that rapidly dissipates once you've been on hormones for any length of time. And again, if you really want to do bone Density scans of every girl who wants to be on the volleyball team, go for it I guess, just don't single us transes out.
This one is straight garbage. We lose so much muscle so quick it's ridiculous. And as I said above it's harder for us to gain muscle than it is for cis women, as when taking HRT we have even less testosterone than they do.
So hopefully this helps clear up these insidious lies that are designed specifically to further alienate trans folks from potential allies. If you'd like to read up on the effects of HRT on things like bone density and muscle mass there's a decent amount of studies available on Google. Here's one that covers both trans men and women as an example.