The Cheetah man: A new perspective on Cross Crawl and neurologic patterning.

A few months ago we wrote a piece about Uner Tan Syndrome.  Here was a key point from that blog post (blog post link) and it links beautifully to our most recent controversial blog post on the “Bird Dog” rehab exercise (link here):

[In the video presented in that blog post, and in our “Bird Dog” post photo] there is ipsilateral interference between the foot and hand in this quadrupedal gait. In this diagonal quadrupedal locomotion (QL) the forward moving lower limb is impaired from further forward progression by the posting up (contact) hand of the same side. This would not occur if the QL gait was non-diagonal (ie. unilateral), the forward progression of the lower limb would be met with same time forward progression of the upper limb, allowing a larger striding out of both limbs.  This would enable faster locomotion without increasing cadence (which would be the only way of speeding up in the diagonal QL), at the possible limitation of necessitating greater unilateral truncal postural control (which is a typical problem in some of these Uner Tan Syndrome individuals who typically have profound truncal ataxia).  

So, why are we showing you the video above today ?  If you do not know, go read those 2 blog posts again and look more closely at the video above. At exactly 0:21 seconds into the video, at the slow motion section, you can see what we were talking about in the Bird Dog post last week, that being that the quadrupedal pattern that is neurologically substantiated is that when the right lower limb is in flexion, so is the left upper limb. (we will show these 2 photos in tomorrows post).  Where as, “Bird Dog” shows the opposite, that the contralateral upper limb will be in the opposite phase of the contralateral lower limb.

Who cares right ?  Well, it matters.  In the video above, this could be a problem because if the right leg is in flexion that means that the right arm will be moving into extension. This means that the knee and the hand will be running into each other (look at the baby photo here). As we discussed in the Uner Tan article this will impair faster quadrupedal locomotion. It is also one of the theories as to what may have pushed us to become bipedal and allow faster ambulation (there are many theories of course).  So, how then does this guy in the video move like a cheetah ? How is he going so fast with the quadrupedal pattern we have clearly outlined here ?

Within days a blog reader (Micheal L, thanks Michael) messaged us and said this:

  • As a person who likes what’s going on at MoveNat, this type of quadrupedal movement is referred to by them as contralateral movement and is how they teach people to crawl at their seminars. In CrossFit workouts, we also do bear crawls as an exercise, and I always try to maintain a contralateral gait. i.e. Right arm moves forward as left foot comes forwards and vice versa. 
    So, in other words, in the Uner Tan Syndrome (UTS) the gait is cumbersome and inefficient. In the video above and at MoveNat seminars, it’s a technique/skill.
    Did you guys intend for this comparison, or am I out in the cornfield on this?
    Here was Dr. Uner Tan  himself chiming in on the dialogue:
  • Üner Tan It is not the same type of locomotion, i.e., not “the diagonal-sequence quadrupedal locomotion”, which is also used by non-human primates.. .
    Michael: The guy runs so fast it’s hard for me to see it well. Okay, so with UTS the lower limb runs into the upper limb. In this video, his upper limb quickly gets out of the way, giving room for the lower limb (to further flex forward increasing swing phase forward step length). It’s just really hard to see it without slow motion. Thank you for clarifying.

As we said in last weeks post on all of this:
“Think about gait. Your right leg and left arm flex until about midstance, when they start to extend; the left leg and right arm are doing the opposite. At no point are the arm and opposite leg opposing one another. 
If you look at it neurologically, it is a crossed extensor reflex.  It is very similar to a protective reflex called the “flexor reflex” or “flexor reflex afferent”. 

In this video case today, it appeared on the surface because of the speed of this fella, that all that we have been talking about had been left in the dust. But, after looking at things closer and more slowly, the principles remain intact.  For now.
Just a little open thinking digging today. Hope you enjoyed.
Shawn and Ivo,
The gait guys

The hand walkers: The family that walks on all fours. Part 1

Quadrupedalism and its commentary on human gait.  To understand your athlete, your patient, your client, whatever your profession, you need to have a good understanding of neurodevelopment.  If your client has some functional movement pattern flaws it could be from a delayed or expedited neurodevelopmental window. Generalized training and rehab will not correct an early or late window issue; often your work must be more specific.

     When we began our journey into our daily writings on “The Gait Guys blog” we had no idea of the never ending tangents our writing would take pertaining to gait, human movement and locomotion. It has become plainly obvious over time that this blog will likely exist as long as we choose to continue it. 

In 2006 we saw a documentary documentary entitled The Family That Walks On All Fours and the video clip above was from the documentary. It was a fascinating documentary and with our backgrounds in neurology, neurobiology, neuroscience, biomechanics and orthopedics we had more questions than the documentary touched upon. The documentary opened up many thoughts of neuro-development since we all start with a quadrupedal gait. But there had to be more to it than just this aspect because people eventually move through that neurologic window of development into bipedial gait.  This has been in the back of our minds for many years now.  Today we will touch upon this family and their challenges in moving through life, today we talk about Uner Tan syndrome, Unertan syndrome or UTS.

The original story is about the Ulas family of nineteen from rural southern Turkey. Tan described five members as walking with a quadrupedal gait using their feet and the palms of their hands as seen in this video.  The affected family members were also severely mentally retarded and displayed very primitive speech and communication. Since his initial discovery several other families from other remote Turkish villages have also been discovered.  In all the affected individuals dynamic balance was impaired during upright walking, and they habitually chose walking on all four extremities. Tan proposed that these are symptoms of Uner Tan syndrome.

UTS is a syndrome proposed by the Turkish evolutionary biologist Uner Tan. Persons affected by this syndrome walk with a quadrupedal locomotion and are afflicted with primitive speech, habitual quadrupedalism, impaired intelligence. Tan postulated that this is a plausible example of “backward evolution”. MRI brain scans showed changes in cerebellar development which you should know after a year of our blog reading means that balance and motor programming might be thus impaired.  PET scans showed a decreased glucose metabolic activity in the cerebellum, vermis and, to a lesser extent the cerebral cortex in the majority of the patients. All of the families assessed had consanguineous marriages in their lineage suggesting autosomal recessive transmission. The syndrome was genetically heterogeneous.  Since the initial discoveries more cases have been found, and these exhibit facultative quadrupedal locomotion, and in one case, late childhood onset. It has been suggested that the human quadrupedalism may, at least, be a phenotypic example of reverse evolution.

Neurodevelopment of Children:

Children typically go through predictable windows of neurodevelopment. Within a set time frame they should move from supine to rolling over. Then from prone they should learn to press up into a push up type posturing which sets up the spine, core and lower limbs to initiate the leg movements for crawling. Once crawling ensues then eventual standing and cruising follow.  In some children, it is rare yet still not neurodevelopmentally abnormal, they move into a “bear crawl” type of locomotion where weight is born on the hands and feet (just as in our video today of UTS).  Sometimes this window comes before bipedalism and sometimes afterwards but it should remain a short lived window that is progressed through as bipedalism becomes more skilled. 

In studying Uner Tan Syndrome, Nicholas Humphrey, John Skoyles, and Roger Keynes have argued that their gait is due to two rare phenomena coming together.

“First, instead of initially crawling as infants on their knees, they started off learning to move around with a “bear crawl” on their feet.Second, due to their congenital brain impairment, they found balancing on two legs difficult.Because of this, their motor development was channeled into turning their bear crawl into a substitute for bipedalism.”

According to Tan in Open Neurol, 2010

It has been suggested that the human quadrupedalism may, at least, be a phenotypic example of reverse evolution. From the viewpoint of dynamic systems theory, it was concluded there may not be a single factor that predetermines human quadrupedalism in Uner Tan syndrome, but that it may involve self-organization, brain plasticity, and rewiring, from the many decentralized and local interactions among neuronal, genetic, and environmental subsystems.

There is much more we want to talk about on this mysterious syndrome and the tangents and ideas that come from it. We will do so in the coming weeks as we return to this case.  We will talk about other aspects of neurodevelopment which should be interesting to you all since most our readers either are having children, will have them, or are watching them move through these neurologic windows.  And we know that some of our readers are in the fields of therapy and medicine so this should reignite some thoughts of old and new.  In future posts we will talk about cross crawl patterning in the brain, bear crawling, the use of the extensor muscles in upright posture and gait as well as other aspects of neurodevelopment gone wrong. We are not even close to being done with this video and all of its tangents. In the weeks to come we hope you will remain interested and excited to read more about its deep implications into normal and abnormal human gait.


Open Neurol J. 2010 Jul 16;4:78-89. Uner tan syndrome: history, clinical evaluations, genetics, and the dynamics of human quadrupedalism. Tan U.Department of Physiology, Çukurova University, Medical School, 01330 Adana, Turkey. link:

Humphrey, N., Keynes, R. & Skoyles, J. R. (2005). “Hand-walkers: five siblings who never stood up” (PDF). Discussion Paper. London, UK: Centre for Philosophy of Natural and Social Science.