Changing step width alters lower extremity biomechanics during running.

The Cross over gait. We have been talking about this for years, our theories have been supported by the available research and years of patient care.
Here is another study that goes with our ideas, which gives it deeper clinical relevance.

Changing step width alters lower extremity biomechanics during running. Brindle RA1, Milner CE, Zhang S, Fitzhugh EC. Gait Posture. 2014

"Step width is a spatiotemporal parameter that may influence lower extremity biomechanics at the hip and knee joint. Peak hip adduction and rearfoot eversion angles decreased as step width increased from narrow to wide."
Step width influences lower extremity biomechanics in healthy runners. "When step width increased from narrow to wide, peak values of frontal plane variables decreased.

The Fredericson paper (Hip Abductor weakness in distance runners with iliotibial band syndrome) is also supportive. That paper found that increasing step width reduced the strain on the iliotibial band during running. Greater ITB strain and strain rate were found in the narrower step width condition.

We have said it, and will say it again, because someone will post here, "maybe, but all the pros when you watch then and see photos of them, they all have a very narrow step width, basically qualifying for what you guys call a Cross Over gait. So how can you make such bold statements?"
Our response would be, "every attempt at squeezing out more economy in ones gait, walking that fine line of riskier gait mechanics, is a game of playing ECONOMY vs. LIABILITY. And if you have built enough durability and conditioning into your system that you can nudge right up to that fence of RISK, you can play with those liabilities and squeeze out the economy of your gait (like the pros) with that narrower step width. Just be aware and careful, that when you are losing control, as the runs lengthen, that the LIABILITIES are increasing and thus so is the RISK for injury. Just remember, you are likely not a pro, and have not spend the time building a safe zone of durability on your system to endure narrow step width for 26 miles.

A good runner will train the frontal and rotational planes regularly as they engage in their sagittal sport of running. So that as fatigue sets in and the step width begins to narrow, they have some durability of the lower limb to sustain the risky mechanics of the narrow step width. There is a limit for everyone, when the well goes dry.

Failure to Adduct the hip in symptomatic runners with iliotibial band syndrome.

This is an interesting finding. They took symptomatic iliotibial band runners and looked at the hip adduction as they fatigued. When they found was not what one might initially expect, meaning more hip adduction because of the fatigue. Instead, they found was that when exerted, the female subjects independently modify their running gait to decrease hip adduction, potentially as a result of pain....... they compensated to protect. Not earth shattering, but support for the neuroprotective biomechanical mechanisms. This is how we all find a way to keep going, we find away around the problem. The problem here is that by the time they come to see us for care, we may be hearing of the next level of compensatory break down, and not the primary issue.

https://www.ncbi.nlm.nih.gov/pubmed/27718393

How relaxed, or shall we say “sloppy” is your gait ?

Look at this picture, the blurred left swing leg tells you this client has been photographed during gait motion. 

Now, visualize a line up from that right foot through the spine. You will see that it is clearly under the center/middle of the pelvis. But of course, it is easier to stand on one leg (as gait is merely transferring from one single leg stance to the other repeatedly) when your body mass is directly over the foot.  To do this the pelvis has to drift laterally over the stance leg side.  Sadly though, you should be able to have enough gluteal and abdominal cylinder strength to stack the foot and knee over the hip. This would mean that the pelvis plumb line should always fall between the feet, which is clearly not the case here.  This is sloppy weak lazy gait. It is likely an engrained habit in most people, but that does not make it right. It is pathology, in time something will likely have to give. 

This is the cross over gait we have beaten to a pulp here at The Gait Guys over and over … . . and over.   This gait this gait, this single photo, means this client is engaging movement into the frontal plane too much, they have drifted to the right. We call it frontal plane drift. To prevent it, it means you have to have an extra bit more of lateral line strength in the gluteus medius and lateral abdominal sling to fend off pathology. You have to be able to find functional stability in the stacked posture, and this can take some training and time.  Make no mistake, this is a faulty movement pattern, even if there is not pain, this is not efficient motor patterning and something will have to give. Whether that is lateral foot pain from more supination strategizing, more tone in the ITB perhaps causing lateral knee or hip pain, a compensation in arms swing or thoracic spine rotation or head tilt  … … something has to give, something has to compensate. 

So, how sloppy is your gait ? 

Do you kick or scuff the inside of your opposite shoe ? Can you hear your pants rub together ? Just clues. You must test the patterns, make no assumptions, please.

Shawn Allen, one of the gait guys