Differences Between Male and Female Pelvic Structures

by Shari

This is the second part of my response to William Broad’s assertion that women—because of their inherent flexibility—are more apt to injure their hips in a “dangerous” yoga class or perhaps during a home practice. I think it is important to understand that whether or not women are more inherently flexible than men, there are significant physiological and anatomical differences in the male and the female pelvis. Have a look at these two pictures!

Female Pelvis

Male Pelvis

As you can see here, the female pelvis is typically larger and broader than the male pelvis, which is taller narrower, more compact and stable. The female pelvis is thinner and it is more mobile partly due to hormonal changes that a woman cycles through and partly due to inherent structural attributes. There is also a difference in the size of the pelvic outlet specifically due to the reproduction capacity of the female The weight-bearing surfaces of the pelvis are larger and more irregular in the male, whereas the female pelvic joint surfaces are smaller and flatter. This structural difference is specifically important in how the sacroiliac joints “lock down” to form a stable weight bearing arch linking the legs with the torso.

The way weight is transmitted through the pelvis is different with the male pelvis having a more vertical weight-bearing loading and the female having a more posterior weight-bearing load. Of interest, male pelvises are often fused after the age of 50 in 50% of males whereas only less than 1% of women’s are fused at or after the age of 50.

The acetabula are wider apart in females than in males. In males, the acetabulum faces more laterally, while it faces more anteriorly in females. Consequently, when men walk the legs can move forwards and backwards in a single plane. In women, the legs must swing forward and inward, from where the pivoting head of the femur moves the leg back in another plane. This change in the angle of the femoral head gives the female gait its characteristic swinging of hips.

So if we really want to be anatomically correct, it becomes obvious that women need to do their standing poses differently than men specifically because of our anatomical differences in our structure. In particular, it is wise to leave room for your hips in your standing poses by changing your stance. In poses such as Triangle pose, Extended Side Angle pose, Warrior 1, 2, and 3, Revolved Triangle pose, Pyramid pose (Parsvottanasana), instead of aligning your feet as we are typically instructed to (with your front heel aligned with your back arch), try widening your stance a bit by aligning your front heel with your back heel. Otherwise, if your base of support is too narrow side to side, a lot of accommodations will occur with torqueing and twisting of various body parts that could lead to injury over time.

In addition, these differences in our morphology are important because this—not just inherent flexibility as William Broad claimed—may possibly lead to more injuries for women and therefore they need to be especially careful. A post from me on Healthy Hips, which applies both to women and men, will be coming soon.

Read More

Friday Q&A: Is Women's Flexibility a Liability in Yoga? Baxter's Response to William Broad

The Flexible Melina Meza!

Q: So, Baxter, what do you think of William Broad’s latest claim that women’s flexibility is a liability in yoga?

A: Firstly, I want to thank Shari for her level-headed look at New York Times science writer and author of The Science of Yoga William Broad’s most recent assertion that women who do yoga are at great risk of injury due to their flexibility (see Women's Flexibility is a Liability in Yoga).  Thanks, as always, Shari, for your practical experience as a physical therapist and a long-time yoga practitioner and yoga teacher. I think your insights will go a long way in helping clarify articles like these that may have an unstated agenda that colors and lessens their credibility. I’d also direct some of you to this balanced response by yoga teacher Paul Grilley to the article as well. As always, William Broad’s articles do get us thinking and talking about yoga. 

But if I read Broad’s most recent article and his latest assault on yoga accurately, am I to understand correctly that both men’s tightness and women’s flexibility are liabilities in yoga? So is yoga now safe only for animals and children? I have always encouraged men to try yoga because they seem to hold so much tightness in their bodies. And women often master the more challenging poses in yoga from a seemingly more inherent flexibility. But I also have plenty of incredibly flexible male students and an equally large number of stiff and inflexible women in my classes. 

As a yoga teacher and also a student of yoga for several decades, I find most teachers today are cautionary to their students to be mindful of the feedback their bodies give them as they approach more physically challenging yoga poses. And yet, as if to throw one more barb of accusation at yoga and its teachers, the author offers this final warning: Unfortunately, yoga teachers too often encourage students to “push through the pain.” 

With all the supposed statistics the writer offers in the article, none are offered with this statement, and I am not certain where this impression comes from. I know that this can happen in some classes and styles of yoga, but this generalization, I believe, does not represent the overall state of yoga teaching in the US today.

And the tone used by the author implies that he has uncovered some hidden or unknown risk to yoga practitioners, and, more pointedly, women, that some of them could be at risk of hip injuries or impingements. As far back as 2009, the International Journal of Yoga Therapy published an article by Elaine Goodall "Preventing and Healing Injuries in Yoga: Acetabular Labral Tears.” In her detailed article, Ms. Goodall notes that gymnasts and dancers may have a predisposition for these kinds of injuries as well as some in yoga. So much for breaking news! 

One of my difficulties with the statistics—if they can be called statistics—that are offered in the New York Times article to back up the assertion that women are at a significant risk of hip injuries of a very specific kind is statements like this:

“Each year, he (Dr. Kelly) said, roughly 50 to 75 of his patients who danced or did yoga underwent operations. Most, he noted, were women.” 

The author goes to the effort of interviewing a surgeon, getting a guesstimate from said doctor, and never follows up with: how many were yoga related and how many dance related, and how many were a combination (as many yoga students, men and women, danced when younger)? And how many were men? What meaningful conclusions can a yoga teacher make from such superficial exploration?

In addition, the author points to a 2008 study done in Switzerland that looks at the kind of unique arthritis/traumatic changes to the hip called Femoral Acetabular Impingement, or FAI. However, he fails to mention that the women in that study had unusual hip anatomy, considered abnormal, though subtly so. The authors of the study go on to say, “The focus of the new concept (the theory on what underlies FAI) addressed those remaining cases of hip OA (osteoarthritis) in which the deformity (FAI) was considered mild, slight or even, in the eyes of casual observers, nonexistent.” 

So women and men who develop this impingement injury to the hip (prior to starting yoga) already had an anatomical reason that movements in the hip joint could lead to injury. Interesting. Developmental abnormalities that usually arose prior to adulthood were present in most cases. And this kind of FAI occurs in men and women, not women alone. Only once does this study mention that the pincer-type of injury is to women with underlying anatomically abnormal hips. And that these women often participate in “yoga and aerobics.” The authors don’t say the yoga caused the problem. As Paul Grilley so astutely points out, correlation does not mean causation! In fact, yoga is never mentioned again in the fairly lengthy article, and not at all in the final wrap up discussion that usually highlights the facts they find most compelling. They also don’t give statistics that clearly outline what percentage of women, with hip pain that requires surgery, have this kind of injury (FAI). So, again, the practical applicability for us in-the-trenches teachers is very unclear.

And statements like this are just mystifying: “I found that hundreds of orthopedic surgeons in the Mediterranean region heard a conference presentation in 2010 that linked F.A.I. to middle-aged women who do yoga.” If this was true, why does he not cite the study or the “presentation”? What was the presentation based on? Who made the presentation? Was there any study to back up these assertions?

And quotes like this: “Michael J. Taunton, an orthopedic surgeon at the Mayo Clinic, told me that he first learned of the danger a half decade ago and now annually performs 10 to 15 hip replacements on people who do yoga. About 90 percent, he added, are women.” This again does not help me much, as I don’t know how many hip surgeries this doctor does each year (about 20-30 a month, I would guess), so this may represent a small percentage of his annual surgeries, but the way it is presented seems really worrisome, if not epidemic, if you don’t have all the facts.

I have been teaching about the risks and benefits of yoga to future yoga teachers now for over 10 years. Some sort of classroom instruction on the topic is included in many 200-hour beginning level teacher trainings. So, from my personal experience and perspective, the yoga community is aware of potential dangers of certain aspects of the physical practices of asana and is better defining and sharing that information with each passing day.

Despite the author’s initial statements on the wonderful potentials of yoga in the first paragraph, little that follows in his article supports this assertion. I reminded myself that the final chapter of The Science of Yoga does give some insight into the author’s feelings and motivations regarding yoga:

“Yoga can grow up or remain an infant—a dangerous infant with a thing for handguns.” 

And a bit later in the epilogue, when discussing his concerns for the commercialization of yoga, he seems to pushing for huge government oversight of yoga with the following:

“Imagine if Big Pharma had no Food and Drug Administration and other regulatory agencies looking over its shoulder. The marketing of fake diseases and bogus cures…would be much worse.” 

And in the time since the release of his book, the three articles Mr. Broad has published have only dealt with potential negative aspects of yoga: the two on the dangers of yoga to men and women and one on the sexual scandals of yoga teachers.

How about a story from this self described yoga practitioner on the benefits of yoga next next time instead of sensationalist fearmongering?

—Baxter

Read More

Is Women's Flexibility a Liability in Yoga? Shari's Response to William Broad

by Shari

The latest New York Times article from William Broad Women’s Flexibility is a Liability (in Yoga) sparked a conversation between Nina and me, both whom are long-term yoga practitioners who have grappled with orthopedic injuries. Broad states that he has recently learned that women are at higher risk of hip injuries in a yoga class because of their inherent flexibility compared to men. He quotes a single yoga teacher, Michaelle Edwards, saying that “women’s elasticity became a liability when extreme bends resulted in serious wear and tear on their hips. Over time the chronic stress could develop into agonizing pain and, in some cases, the need for urgent hip repairs.” He also says of arthritis researchers:

The investigators found that extreme leg motions could cause the hip bones to repeatedly strike each other, leading over time to damaged cartilage, inflammation, pain and crippling arthritis. They called it Femoroacetabular Impingement — or F.A.I., in medical shorthand. The name spoke to a recurrence in which the neck of the thigh bone (the femur) swung so close to the hip socket (the acetabulum) that it repeatedly struck the socket’s protruding rim.

I personally can’t stand sensationalism of any type and particularly sensationalism of the fear and scare tactics kind. When I first saw this article, I groaned inwardly. But I then proceeded to read it carefully, including the related links, and then went on to do some additional research of my own. After all that, my response is: maybe.

First of all, I, as a long-term yoga practitioner, am not sure what exactly he means. We all can be overly flexible in some areas of our bodies and conversely overly tight in other areas of our bodies. The biomechanical model of structure and function is a beautiful yin and yang interplay between forces that influence our bodies, and yes, can ultimately change our structure and function. Some changes may not be as beneficial as others so we need to be consciously selective and astute to observe what changes occur with function.

I also think, as in the past, Broad is careless in his citations of his evidence and is vague about these ER records of hip injuries. However, he does cite some orthopedists and one international study that do substantiate his observation that women who put their hips into extreme ranges of motion can injure their hips. Well, this is blatantly obvious to anyone who may be neurologically intact. When a joint is taken into an extreme position there is a pain response recognized by the central nervous system that warns the person to back off. Of course, if we choose to ignore the pain response, then is it the yoga that is causing the injury or is it the person who is foolishly not listening to the feedback their body is providing?

I also think that to address William Broad’s assertion that women are more flexible than men, we need a better working definition of (biomechanical) flexibility:

Flexibility is the range of motion in a joint or group of joints, or, the ability to move joints effectively. Flexibility is related to muscle strength. Flexibility is also the ability to move through a full range of motion.

Flexibility is a conscious movement that has an intricate feedback mechanism between the muscles and the nerves innervating the muscles and the joints and the central nervous system. There are significant protective mechanisms that prevent the individual from overstretching if they PAY ATTENTION to the sensation of pain rather than ignoring it.

So are women “inherently” more flexible than men? Well, it depends who you ask. But all sports attract a body type, and if yoga is considered a “sport” then there is a body type that is drawn to yoga. We all like to do things that are “easy” and for some flexible bodies yoga is “easy.” The rub here is that this isn’t “yoga” but athleticism masquerading as yoga!

So now let us look at his assertion that yoga is the root cause of “femoracetabular impingement”. The literature that I read, including one of his references, states that the subjective symptoms are deep anterior groin pain with associated intermittent catching and locking of the hip joint. In addition, there is a significant decrease in hip internal rotation. The morphology is that there is a breakdown of the hip labrum (how the head of the femur is connected into the cup of the pelvic acetabulum) and the articular surfaces of the femur and acetabulum. There is a structural change in how the head of the femur is sitting and facing, and movement of the hip will continue to tear the tissue structures with a loosening of the integrity of the hip joint. The problem is that a lot of individuals who have this condition are pain free, asymptomatic and don’t know they have it. The concern is that this condition may be a precursor to developing hip arthritis down the road. There are four types of femoracetabular impingement and one type is more common in women and one type more common in men!

Another article that I read stated that the condition is caused by internal rotation of the hip while in 90 degrees of hip flexion. Yes, this can be Uttanasana (Standing Forward Bend)! So is the problem the combination of these two movements? I don’t know, but does that mean you need to stop doing Uttanasana? I don’t think so unless it is causing pain. And, yes, there are some pretty extreme hip positions in yoga which only some of could do when we were younger (maybe can still do them now) but the bottom line is that we need to practice with intention and attention to form, function and our own bodies' abilities and not soldier on through the pain. Yoga, as we have mentioned time and time again, can be physically and mentally challenging, but is not supposed to hurt. So don’t be scared off again by a sensational journalist who claims he is a yogi.

In a future post I would like to present some of the inherent differences between male and female pelvis and hips that might also help to put into perspective the allegation of the differences between men and women.

Read More