This is a difficult subject for me to take on, but I've had an opinion for so long I might as well put it in print.
Modesty is a form of education which inhibits movement to ensure specific cultural role conformity. That's the definition I'm choosing to work from, and for the sake of this post I'm ignoring two other behaviors which are often conflated with modesty. Namely; avoidance rooted in feelings of vulnerability, and choosing not to reveal oneself for strategic, experimental, or dispassionate reasons.
This education is intense, for example a women recently told me her mother was always asking her sarcastically, "Why do you always sit like a truck driver?" I don't think I need to go into the 'how it's done' or 'why it happens' discussions. Everyone with a pulse and a conscience has already thought about this.
Boys and girls in America do a lot of the same physical activities and get a lot of the same training. Yeah, there are more boys playing baseball, and more girls doing ballet, but for the most part both genders get a lot of opportunities to practice complex coordination with running and jumping.
And then puberty hits and young women's hips grow a lot wider. In order to maintain running and jumping skills young women have to go through a process of re-learning how to run, jump and even walk. Most don't dedicate the time and effort to make these changes, and because of this, they develop with their knees and ankles aligning not below their hips but more narrowly in-between their hips. In fact, this alignment is often thought of as normal. When men pretend to be women they often imitate this poor alignment.
One of the results of this narrower alignment is knee injuries, specifically torn ACL's (Anterior Cruciate Ligament). Girl's soccer is one giant busted knee. It doesn't have to be like this.
For martial artists the issue is very serious because body structure, integrity, force transfer, force absorption, frame and mobility are all dependent on good alignment of the legs. Unfortunately it's hard to teach because modesty education and role conformity get in the way. It can also take a long time. Even more unfortunately, many teachers just decide to ignore the problem because it's a potential emotional landmine.
I should probably make a video about this because I don't even know how to describe the slight dislocation of the hip joint that happens during complete weight shifts with momentum and it's force repercussion for the knees, ankles, and feet--or how to describe the power lost. Men, by the way, often have the same problem to a lesser degree, but I've never noticed it tied into emotional content other than humility at having to re-learn something. And let me make it clear, some women don't have this problem at all. I have good things to say about the nation's gymnastics and dance teachers! They get it. And some women figure it out for themselves, perhaps driven by athletic or artistic passions.
That's pretty much all I have to say. Now you know what is going on if your teacher tries to get you to walk like a cowboy all the time or some such thing. I sincerely hope that we can begin to talk about this openly. The barefoot running movement has been wonderful for clearing up a lot of confusion about what a human being is, but without addressing the hip-modesty-alignment issue the lessons of barefoot running will slowly get lost.
For those of you who were wondering if I'm going to talk about boobs, the answer is no. It is my hope that a female blogger will take up this tissue (oops, I meant issue), as it is in serious need of attention. This post by Rowan Johnson is a good start, and the third comment is intriguing.
I spent an hour looking for good images to demonstrate what I'm saying. Check out Zoe Bell (A+) next to Uma Thurman (C+).