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Understand
that our walk is very efficient. The ability to pendulum swing each leg ...
balancing on the other leg ... allows for a minimal amount of energy spent at
toe push off to assure forward momentum for the swing leg to 'step' forward. The
energy (other muscle activities) added to the walk (outside of the toe push)
will dictate balance (due to terrain/body position), gait/pace (speed and
stopping), and navigation (turning). The muscles that we call on can be from our
back and gluts on down each leg.
The tightening or the dominance of muscles (dominant leg?) will effect the foot
placement and/or the toe push.
With the ground being level and clear of debris ... the legs/feet left on their
own ... the pendulum will be true with each step. Each RL step will be the same
as the next RL step and conversely the LR step will be the same as the next LR
step. Therefore each total stride (either LRL or RLR) will be equal to each
other. Giving us NO TURN.
Still wondering. Check out this URL http://www.uni-essen.de/~qpd800/ANIMP1.GIF
the toe push off is only slightly more energy than the heel strike.
To see a Quicktime Movie of a human walk ... http://www.univie.ac.at/cga/simulation.mov
or http://www.univie.ac.at/cga/skeleton.mov
OR a .MPG ... http://www.univie.ac.at/cga/7link.mpg
The dominant limb 'curve' must be coming from a muscle source that is placing
our foot off-line a little with each step. Might it show in the 'pitch'?
I
know that you all don't carry protractors ... but get one and see if there isn't
a greater pitch on your dominant limb. It may be as small as 1/2 to 1 degree,
but this would be enough to curve your LOT over the length of a football field.
I
believe (unless someone can provide more information
outside of TB's Books or classes) that direction of travel
(even blindfolded) is a complex assortment of balance
control which is dictated by the bodies COG (center of
gravity), terrain features, routes of easy travel, footwear,
lower body aches/pains/ailments, and mental maps that we use
when we travel... corrected by visual "dead reckoning"
toward landmarks or intentional steering (twisted turns)
around obstacles
That's easy enough to agree with, Del, although you haven't begun to include all
the likely factors. Jeez, if anyone is telling you that virtually anything a
living body does is "simple" or unidimensional, you know something's
wrong...
It is not controlled by a "dominant" leg
even over a long haul, the farther your subject travels the
more variables are introduced that are not dominant limb
related. Lost people do not always travel in circles until
they die, this has been proven by record keeping of actual
cases. . The concept that people will always turn to a
dominate side is fallacy and has led to many searches for
these lost people to be driven in the wrong direction. This
is what I have seen to be true.
Who's going around saying that lost people "always" travel in circles,
or "always" turn to the dominant side? Hang along any path or street
and watch people walking around trashcans, bushes, other people, etc., and (in
my experience) you will see that a person will favor circumnavigating to one
side or the other. That is, a person passing to the right of the first obstacle
will typically, but not always, pass to the
right of others. I've not seen people claiming "always" in this
context.
Animals
and people almost always circle. Unless there are geologic features to guide
them in a particular direction. I don't hunt anymore but in the distant past I
hunted extensively with dogs. Animals almost uniformly circle back to the point
where they were first jumped by the dogs. The larger the animal the larger the
circle. (Usually). Very rarely an animal will beeline out of the area.
Don't know the reason animals do this? Just know that they do!
As for humans:
I can only speak from personal experience.
While hunting in an area of several square miles of flooded timber in
Arkansas (no guiding geologic features), I misplaced my boat.
Fortunately I came across another person and asked directions. He sent me
on my way and it began snowing making directions even more difficult. No compass
of course. I walked for about an hour and decided he had given me wrong
directions. But thank goodness there was another person just ahead. When I got
up to the person I discovered, much to my embarrassment, that it was the same
person who had previously given me directions. I had made a big circle!
First
I'll say that I am not a student of Biomechanics, my interest in you world is
peripheral in nature. I am a volunteer in a Search and Rescue group that
specializes in tracking humans.
Within another List, that I receive, there has been many heated discussions
about limb dominance and how it will relate to the navigation of a traveling
human.
Questions for this List:
Is limb dominance the same as 'footedness'?
Is there a way to test for a limb dominance?
How will limb dominance manifest itself in the gait?
If a human is blindfolded and set on a course ... the turns that s/he takes
during the course ... are they caused by a difference in step length? unequal
stride lengths? limb strength? trunk twist? maintaining balance?
How would you rate the factors that effect navigation? step length difference?
heel strike placement? foot pitch? toe push off? others?
Thanks for indulging me on these questions.
If this is not appropriate list feel free to Email me directly.
Michael
McPartland, Ph D.
You
may also want to consider issues related mechanisms inside our head
which help us maintain balance, that is as you probably know, the
vestibular system.
Effects of simple maladies such as head colds to evolved problems such as
hypo/hyper-vestibulopathies can literally steer us in directions other than
straight ahead.
My
experience has been that
"footedness" was determined by placing a ball in front of your
subject and asking
him to kick during three separate trials. Observe which foot he
uses the majority of the time. Usually it will be the same foot each
time. You
can also ask your subject to stand straight up, and then lean forward
until he begins to fall. He will stop himself from falling by placing a
foot/leg in front. Observe which leg he uses the majority of the time.
One way that limb dominance in gait (in my limited knowledge) would
manifest itself would be which foot an individual uses to begin walking
from a stop. I once observed a gait study involving the elderly, and
several of the men were ex-military. I believe it was the left foot that
they used for their first step. After the study we talked with them about
it and they told us that in the military, you always begin marching on
the left
foot. (I might have this backwards.) Anyway, I found it
interesting
that their dominance was formed from old military habit.
Your ideas about what causes an individual to turn during blindfolded gait
are interesting. During my thesis research, I observed that many
blindfolded subjects had difficulty walking a straight path of only 10 or
15
feet. When I provided them with auditory cues, like talking to them,
they were able to do much better about walking a straight line.
Bruce
Etnyre, Ph. D., P.T
I
have studied limb dominance and hemispheric specialization for a number of years
and was interested by your questions. I can't tell you much about anything other
than the first two. Limb dominance is not always the same as footedness, but
usually right-handers have dominance on their right side (including eye and ear
preference). Left-handers much more frequently have mixed dominance
of foot, eye and ear. There are some batteries of assessments for limb
dominance which I have seen, but I don't have references for them. Some include
trick questions for people being interviewed who want to deceive the surveyor
because of the stigma some cultures put on being left-handed. For
example, asking which hand they hold the deck in when they deal cards. Someone
who answers right hand to all the other questions and answers right hand to that
one is probably not answering honestly.
We have been conducting studies recently on sit-to-stand movement and have seen
some foot preferences. We came up with a screening device to determine
footedness from other batteries of tests I've seen. We ask the participants
three questions:
Which foot do you use to kick a ball?
If you had to step up on this chair, which foot would you use?
If you had to hold a pen with your toes to write, which foot would you use?
At least two out of three is what we use to indicate foot preference.
< > >Questions
for this List:
>Is limb dominance the same as 'footedness'?
Not necessarily, can be specific to particular activities.
>Is
there a way to test for a limb dominance?
Footedness can be assessed simply by asking the subject to begin hopping.
Several trials show a pattern.
Dr
Gabor Barton MD
I
try to answer some of your questions.
>Is there a way to test for a limb dominance?
If
you stand in front of a step then you usually use your dominant leg to step on.
(I can't remember percentages, for more scientific answers do a search on
Medline.)
>If a human is blindfolded and set on a course ... the turns that s/he takes
during the course ... are they caused by a difference in step
length? unequal stride lengths? limb strength? trunk twist? maintaining
balance?
One
can walk in a straight line both with equal and with unequal step length.
Unequal stride length will result in turning.
A
quotation from the CGA web-site's Teach-In section (by Dr. Chris Kirtley):
--------
•"the stride length is the distance between two successive placements of
the same foot. It consists of two step lengths, left and right, each of which is
the distance by which the named foot moves forward in front of the other one. In
pathological gait, it is perfectly possible for the two step lengths to
be different. If the left foot is moved forward to take a step, and the right
one is brought up beside it, rather than in front of it, the right step length
will be zero....However, the stride length measured between successive positions
of the left foot must always be the same as that measured from the right foot,
unless the subject is walking around a curve." (Mike Whittle, Gait
Analysis)
•"stride length is the horizontal distance covered along the plane of
progression during one stride; it is the distance covered from IC to IC of the
same foot... equal to the sum of the two step lengths and will be equal for left
and right limbs if the person is walking in a straight line, even in the presence
of marked assymetry... Specific step lengths for right and left side
must be measured within the same stride. The term can also be used to specify an
average step length over many strides." (David Winter, The Biomechanics
& Motor Control of Human Gait)
--------
See the CGA list's archives at http://guardian.curtin.edu.au/cga/
for more details.
I
would say that there is a preference for certain tasks (ex. high jumping,
kicking, and due to this preference this limb might get dominant in athletes)
but in daily living there is no dominance, as this would be far too dangerous.
Turning during normal walking is for me a daily activity and I do not think that
there is any real dominance as for upper limbs. Unfortunately I do not have some
literature present, however, I know, that J.J.Collins has written about limb
dominance/ preferences. Should you need further information, let me know and I
will try to find these articles for you.
Carole
J. Zebas, P.E.D.
We
presented a paper at the International Society of Biomechanics in Sports in
1993 on "What is leg dominance?" Basically what we found is that leg
dominance is related to the type of skill performed. If you are right-handed
and perform a weight bearing skill such as a basketball layup, you would use
your left leg as the weigh bearing leg. If you are right-handed and perform a
manipulative skill such as kicking a soccer ball, you would use your right
leg. An article by Chapman, J.P.; Cahpman, L. J.; and Allen, J.J. (1986) in
Neuropsychologia 25(3):579-584 addresses the issue of measuring foot
preference. Our article appears as follows:
Spry, S., Zebas, C.J., and Visser, M.F. (1993). What is leg dominance?
BIOMECHANICS IN SPORTS XI. J. Hamill, T. R. Derrick, & E. H. Elliott
(Eds.) University of Massachusetts, Amherst, MA.
David
Hynd
The
following papers may be of some use...
Nigorikawa, T.;
A preliminary study of walking bias phenomenon which is related to
ring-wandering.
Ann. Phsiol. Anthrop. 1988; 7: 99-106
In the present study several experiments of walking bias were performed in
order to investigate the fundamental nature of ring-wandering and to examine
the relationships between various physical dominant factors and the
direction of walking bias. Subjects were 20 to 29 male and female college
students, 18 to 21 years of age.
The conclusions of the present study were summarized as follows: 1) The
repeatability of one's direction of bias was rather high if the experimental
conditions were the same for all walkings. 2) Assuming that 5 m from the center
line is the limit of acceptable deviation, the distance one can keep
correct direction to the target while blindfolded would be roughly 40 m. 3)
The relationships between walking speed and amount of walking bias were as
follows: for the whole group, the subjects who walked unconsciously with high
speed showed reletively smaller bias; and with respect to an
individual subject when he walked with consciously high speed, he tended to
register smaller walking bias than he had registered previously in walking
unconsciously. 4) There were no significant relationships between one's
direction of
walking bias and his various physical dominant factors.
--------------------------------------------------------
Uetake, T. ;
Can we really walk straight? Am. J. Phys. Anthropol. 1992; 89: 19-27
Twenty healthy men were asked to walk as straight as possible to a target 60 m
away at normal speed. A series of footprints was recorded for each subject by
having him wear socks soaked with red ink and walk on white paper fixed flat
to the floor. Fourier analysis was applied to determine whether the subjects
were able to walk straight, and the results revealed that all walked in a
sinuous line rather than a straight line. Periodicity and amplitude of the
meandering differed from subject to subject. These facts suggest that none of
us can walk in a strictly straight line; rather we meander, primarily due to a
slight structural or functional imbalance of our limbs, which produces a gait
asymmetry, and secondarily due to feedback from our sense of sight, which acts
to correct the shifted walking course.
David Hynd, Clinical Scientist, Gait Laboratory, Roehampton Rehab. Center,
Queen Mary's University Hospital, Roehampton Lane, London, SW15 5PN
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