"Essentially, all movement is mysterious. If we analyze walking, for instance, it soon becomes obvious that it involves a motor program that comes into action sometime immediately after we have made the initial decision to move from one spot to another. Although we "will" the initial act of walking, we have very little to do with the practical aspects of how this activity is carried out. (Richard Restak, M.D. "The Brain")
Left uninstructed, blind children develop awkward walking patterns that draw attention to their unusual gait. This "blind gait" is characterized by a flat footed, shuffling pattern. Each step is small, the feet swing outward, and the base of support is wide. The effect is almost a comic waddle.
Since most people have a dominant side (foot), this baby stepping waddle results in the blind child walking in small circles (ie. not able to move rapidly straight ahead). For this reason, a "blind gait" not only looks socially unacceptable, but it can seriously impair a blind child's ability to navigate in space.
Young sighted children observe the walking patterns of others, and to some degree model their gait on a visually determined norm (I saw a more frequent occurrence of the blind gait with congenitally blind children. The adventitiously blind students that I worked with had a more normal sighted gait.) Since blind children cannot see to model the behavior, they fall back on a gait pattern that makes sense for blind individuals; ie. a slower paced movement through space with the center of gravity back on the heels (to keep the face out of danger). When the center of gravity is shifted back the base of support widens, the step becomes shuffling, outward, and small, and the result is a "blind gait." The center of gravity is the point from which balance, posture, and spatial perception begin. It's important that blind students learn not only the importance of the position of the center of gravity, but that they can feel the center shift as they move their body.
The argument that congenitally blind children develop a blind gait because it is a logical way to avoid getting hit in the face may be superficial. In human beings, as in all animals, there is an instinctual, inherited capacity for walking that is present at birth. This automatic walking pattern is governed by the subconscious lower brain, with much of the control coming from the cerebellum. The smooth walking pattern of the sighted adult is a product of learning and observing; a motor pattern with higher brain connections.
The usual explanation for the awkward gait of congenitally blind individuals is that blind children could not observe the correct walking pattern of the sighted culture, and therefore retained vestiges of the original primitive motor pattern. A second possible explanation is that failure to receive visual feedback caused a functional impairment of the cerebellum and that the walking pattern of blind persons is typical of individuals with cerebellar damage.
The age at which sight is lost may be a primary factor in gait development, but it is also likely that physical stature is an important variable that determines gait. Heavier individuals (with larger thighs) have to spread their base of support (feet farther apart) as they walk. This results in a waddling gait pattern with the center of gravity back. Palsies, of course, alter gait, as does body tone. Low tone individuals tend toward the slower, waddling gait pattern. Strong abdominal muscles hold the trunk erect, giving a base for the head to be held upright. Weak abdominals contribute to the slumped over look that is part of the blind gait.
One of my students, Mike, was born with low muscle tone. As he grew, his blind gait became more and more obvious. He was slow, getting to classes late, and he got lost easily because he tended to circle (veer) left as he moved through space. I began by motoring him through a normal walking pattern, especially pointing out the heel down pattern of foot placement (rather than his flat footed shuffling gait). He cognitively understood what I was telling him, and he could demonstrate the heel down pattern. Unfortunately, when I wasn't around, and especially when he was not consciously trying to walk with the sighted gait, he lapsed into his shuffling pattern.
I explained to Mike what the blind gait was and how it differed from a sighted gait. More importantly, I stressed that the blind gait was inefficient and was a prime cause of his disorientation. This cognitive awareness and the heel down practice was only moderately successful. If I showed up at school when he wasn't expecting me, I would find him shuffling, head down, creeping along the hallways, late for class again.
This went on for too many years, until one day I found two answers that worked for Mike:
I took away his cane for school travel
I made him increase his stride length when he walked.
These two changes made dramatic improvements in his gait.
I am a strong advocate of cane travel. In the section on uses of the cane I list twenty one ways the cane benefits the blind traveler. Taking away a students cane is no lightweight decision. What I found was that when I took the cane away, Mike had to hold his head up to be alert for landmarks and to avoid cracking his head on doors and hallway corners. When his head went up his center of gravity shifted, he stood more upright.
With no cane and his head up, I asked Mike to take long, reaching strides as he walked. A long stride causes the center of gravity to fall in front of the body. If Mike tried to walk flat footed under these conditions he would have fallen flat on his face. Walking is sometimes described as a controlled fall (a difficult skill to learn, I think, if you are blind). Long strides force the blind traveler to experience a controlled fall, and it forces a heel down pattern. The head must also be held erect, because if it sags forward the weight adds to the fall (accelerates it). Long strides increase the speed of travel, and as the speed increases so does the tendency to go straight. Straight travel is a critical variable for route navigation. So increasing stride length is directly linked to improved navigational skills.
Increase the stride length and four things can happen:
The heel has to go down first, so the walk looks normal
Longer strides mean a faster walk
A faster walk increases the likelihood that the traveler will go straight
The center of gravity will shift improving posture, lean, and head position
Mike loves music, so I used to sing marching songs to him as we practiced gait travel. I use music to show students how fast most of the sighted world is walking (what's too fast and what's too slow). I play music (or sing with them) at different speeds as they walk to show them what too slow or too fast sounds like; until they can hear just right travel speed. I also use music as a behavior feedback system. Whenever Mike let his head droop, the music would stop. When he got his head back up the music would begin again.
Working with blind children on their gait requires that the mobility specialist address the following variables:
head position
foot placement (heel to toe pattern or flat footed)
position of the center of gravity (and it's shift with movement)
speed of travel
length of stride
base of support (distance the feet are apart)
hip flexion (whether or not the hip moves straight ahead with stride, or angles outward
gait patterns: walking, pacing, marching, running, jogging, etc.
balance: the ability to maintain or assume any body position against the force of gravity.
What I did not have over the years when I worked with blind students was a tool for teaching the heel to toe walking pattern. I tried to model the behavior by taking hold of the foot and demonstrating what the motion felt like. I also used a voice drill (eee, aaaah, oooh) to indicate to students when they were supposed to have their heel on the ground (eee), then be flat footed (aaaah), and then push off with their toes (oooh). This approach was helpful but it never did engrain a motor pattern (students went back to the blind gait when I wasn't around). A tool did develop (a PT could custom design one also) that can be purchased. It is called the HTTD (heel to toe device). Here is the information on the HTTD:
The HTTD was invented by Vance Lankford who used the system (after consultation with physical therapists) to successfully teach his own students to walk with a heel to toe pattern. It is always used with the permission of a physical therapist to make sure it is compatible with each student's physical circumstances.
The HTTD is designed to fit a specific student's shoe size, although it is adjustable. The current cost (2003) for the HTTD is $49.00.
Contact: Vance Lankford at these phone numbers: 325 659 0484 and 325 450 1384, or email him at: ekejv@juno.com
Step length is defined as the longitudinal distance between successive heel contacts of opposite feet. The measurement is made from the point from which both feet are touching to the next point at which both feet are supporting the body (ie. during double support). In the normal population, mean step length is approximately 28 inches to 34 inches, with 90% of the population following between 53 and 86 inches. Step lengths vary directly with height and inversely with age. A young, tall person would have an abnormally short step length at 21 inches.
There are exact definitions for gait cycle, stride, step, line of progression and plane of progression. Normal gait has eight phases:
Initial swing (liftoff) of the leading foot until the knee of the leading leg is flexed as much as is needed before phase two below (maximum knee flexion)
Mid-swing: from maximum knee flexion to a vertical tibial position (the leading leg is poised above the ground before the leg straightens to make heel contact; ie. the point at which the body is centrally balanced on one leg with knee bent, before the weight shift forward
From the vertical tibial position to a point just prior to ground contact (weight is shifted forward with leg extended and heel poised to touch)
Initial contact: the instant the heel contacts the ground
Loading response: immediately following initial contact until the contralateral leg begins to rise
Mid-stance: From lift of the contra-lateral leg to a position in which the body is directly over the stationary (balancing) foot (of the leading leg)
Terminal Stance: From above position to the point where the contra-lateral heel is about to touch the ground
Pre-swing: From initial contact of the contra-lateral heel to a point just prior to the lift of the leading foot in preparation for the next gait cycle
Normal gait only occurs in the absence of abnormal (retained) reflexes, and only when the following are developed: righting reaction, balance, protective mechanisms, rotation, normal muscle tone (walking, running, and climbing will fail to develop if these neurological systems are not normal). Righting reactions are important for keeping the body aligned and upright. Rotation refers to the ability to roll over, and later (developmentally) to do the hip rotation necessary for walking correctly.
Notes:
Programs for walking are in the spinal cord, not in the brain. There is no primary center for a motor program. Motor patterns involve parallel processing from widely separated areas of the brain. Walking patterns are as unique as fingerprints. A capacity for walking is present at birth, it is inherited.
We cannot get in conscious contact with motor programs. This is linked to the discussion of navigation as a subconscious activity (althought the bountry between conscious and unconscious is not clear)
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