Step width alters iliotibial band strain during running.

More substantiation that “the cross over gait” is a pathologic process.

Did you get to hear podcast #23 yet ?  Here is the link (iTunes).  In podcast #23 we talked at length about the effects of step width in runners.  Reducing ones step width will result in a progression into what we have been referring to for years as “the cross over gait”.  We have been reducing this phenomenon in our runners, and many walkers, for over a decade now to reduce many of the lower limb pathologic processes that ensue when the cross over is left unchecked and worse yet, strength and endurance is loaded upon the faulty pattern.  Everyone’s gait in this realm will differ because of pelvis width, femoral and tibial torsion, genu posturing (knee valgum, varum)  and foot structure and type. All of these factors must be taken into account when deciding upon the degree of step width correction.  Ultimately the goal in a perfect world would be to have the foot and knee stack pristinely under the centrated hip joint proper, but we all know that ideal biomechanics are the unicorn when it comes to humans. Anatomic variation is the known norm and this must not be forgotten, this was pounded into all of our heads in medical school.
As this article from the Nov 2012 J. of Sports Biomechanics clearly states, iliotibial band strain and strain rate is significantly greater in narrow based gait scenarios and that increasing step width during running, particularly in those who tend towards the lazier narrower step width, may be beneficial in not only the treatment but the prevention of future lateral hip and knee biomechanical syndromes such as IT band syndrome.  So, if you are a slave to your foam roller and need your IT band foam roller fix daily, you might want to look a little deeper at your biomechanics and make some changes.  Our videos here will be helpful to you and our writings on the Cross Over gait  and link here will be helpful as well.
In  summary, there is just so much more to good running form than just following the mantra “let my feet fall under my body mass and everything will be just fine”.  We wish it was this easy, but it is not. Unfortunately, too many of the sources on the internet are maintaining that good running form is mostly just that simple. Sadly, we find it our mission to bring the bitter tasting truth to the web when it comes to these things.  One just cannot ignore the factors of pelvis
width, femoral and tibial version and torsion, genu posturing (knee valgum, varum) and foot structure and foot type (and we mean so much more than are you a pronator or supinator).  These factors will alter lower limb biomechanics and may drive even the runner with heightened awareness of foot strike and running form into less than optimal foot strike positioning and loading response. Furthermore, one needs to be acutely aware that merely taking the cooked down under-toned postulation of this journal article, that being increasing step width will resolve their IT band problems, may not resolve their problem. In fact, without taking the issues of pelvis width, torsion, version, foot type and the like into account, making these changes could bring about more problems.  Seeking the advise of a knowledgeable physician in this complicated field of human locomotion is paramount to solve your chronic issues.
There is more to clean running than just a
midfoot-forefoot strike under the body mass, a good forward lean and high cadence. And we are here to bring those other issues to light, for the sake of every injured and frustrated runner.  Remember, uninjured does not always mean efficient. And efficient does not always mean uninjured.

Shawn and Ivo, The Gait Guys

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Sports Biomech.
2012 Nov;11(4):464-72.Meardon SA, Campbell S, Derrick TR.

Step width alters iliotibial band strain during running.

Abstract
excerpted:

“Greater ITB strain and strain rate were found in the narrower step width condition (p < 0.001, p = 0.040). ITB strain was significantly (p < 0.001) greater in the narrow condition than the preferred and wide conditions and it was greater in the preferred condition than the wide condition. ITB strain rate was significantly greater in the narrow condition than the wide condition (p = 0.020). Polynomial contrasts revealed a linear increase in both ITB strain and strain rate with decreasing step width. We conclude that relatively small decreases in step width can substantially increase ITB strain as well as strain rates. Increasing step width during running, especially in persons whose running style is characterized by a narrow step width, may be beneficial in the treatment and prevention of running-related ITB syndrome.”