200,000 years ago man controlled the upright posture. Life on earth is billions of years old so this is a recent development and thus phylogenetically fragile. Human ontogenesis is “hard-wired” in our DNA to create this upright posture by 4 years of life. Unfortunately, modern lifestyle conspires with gravity to impair it.

According to Pr Janda, upright posture is defined functionally in single leg stance since gait is our most fundamental function and 85% of normal cadence gait is on a single leg. Modern lifestyle involves a preponderance of constrained, seated postures along with reduced walking volume. It is estimated that for most of our 100,000 years we have taken between 20,000-35,000 steps/day. Today the average western adult takes only between 5000-8000 steps/day.

Bohannon RW has reviewed 42 studies on average steps/day.

< 65 years old mean- 9,797

> 65 years old mean- 6,565

18,425 for Amish men






The sole of the foot evolved to not only handle a greater volume of steps/day, but also greater sensory stimulation. Pr Janda described how in modern society the foot is de-afferented due to 2 main factors. First, due to lack of stimulation from being in constrained footwear. Second,  when ambulating the surface is more often than not flat (either paved or carpeted). Therefore, we often find what we term a “dead foot”.

Ontogenetically, the birth of the higher CNS motor control occurs at the end of the 1st month of life when the head can be lifted or oriented towards the mother. The flexed, fetal cervical spine position then begins to reverse as the adult cervical lordosis starts to form. Within the 3rd or 4th month of life the lumbar kyphosis reverses and the adult lordosis forms as the infant performs the sphinx and cobra.

Is T4 a Dead Zone: The Effects of Environment?

By and age of  4 and half years old the child can balance in an upright stance on a single leg with eyes closed and full shoulder external rotation (Kolar). But, by this time the influence of couches, chairs, television, video games, and computers is already negatively influencing this pristine program for upright posture.

One-third of the population is particularly vulnerable to the effects of gravity and modern sedentary lifestyles due to a “central disturbance of coordination”. This can be seen in those children who have a pronounced cluster of the following signs:


knock kneed or genu recurvatum

anterior pelvic tilt

winged scapulae

rounded shoulders

head forward posture

A functional assessment of upright posture would include many if not all of the following tests:

Wall Angel

Overhead Squat

Single Leg Balance (eyes open & closed)

Single Leg Squat

Inline Lunge or Single Leg Bridge


Pr Janda said gait is the most important human function. Since 85% of normal cadence gait is spent in single leg stance POSTURAL ASSESSMENT should be of SINGLE LEG STANCE. Pr Janda’s assessment is shown in his chapter in my book ROS. And, also on the accompanying DVD where Misha Veverokova, PT shows his assessment.

Janda, Frank, Liebenson said, ” Pelvic movements are associated with the range of  hip extension and lateral muscular pelvic brace, which is important during one leg stance. It has to be noted that about 85% of gait cycle involves standing on one leg   A quick test to check on the lateral brace is to have the patient perform a single leg stance with his eyes open (fig. 10-30).  The clinician observes for the amount of pre-shift to the stance leg and unleveling of the pelvis and/or shoulders.  The normal pre-shift to the stance leg should not be more than 1 inch and the patient should be able to perform the single leg stance for about 15 seconds without any compensatory movements.”

The initial goal of training or rehab should  be to improve upright posture. The above tests will guide progress towards this goal. The means to the end may be any of the following direct or indirect methods –


DNS-Prone Sphinx Test showing C0-C1 hyperextension substitution for hypomobile T4-8

Foam 3 pack

T4 sphinx

Kneeling thoracic rotation


Hip mobilizations

Gluteal facilitation


Core or Pillar training in plank positions

Split stance or single leg posterior chain training

Dead Lifts


 Related Blog Posts.

Physical Exam: A Dying Art?


Progressing Patients 



Function, Function, Function – Test it, Train it, & Troubleshoot it 


Function: Assess-Correct-Reassess 


Screening Faulty Movement Patterns


Do we focus too much on the Sagittal Plane? 















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One Response to What is the Fundamental Human Function?

  1. During 15 years of practice, I found that the single leg stance (eyes open) was one of the most revealing tests I could administer. Coming from WSCC, I cut my teeth on Janda’s work (sharpened them with Liebenson’s), and it profoundly affected the way I practice. Kudo’s and thanks to both of them.

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