Mechanics of Walking

AuthorCharles E. Turnbow
Mechanics of Walking
§400 Introduction
§410 Human Walking
§411 Bipedal Motion
§412 Cyclic Pattern of Movement
Illustration: Cyclic Pattern of Movement
§413 Ground Reaction Forces
§413.1 Traction Demand and Utilized Coefficient of Friction
§414 Typical Questions and Answers on Normal Walking Forces Generated During
Normal Stride
§415 Phases of the Stride
Illustration: Phases of Walking
§416 Stair Gait
Illustration: Phases of the Stride
§420 Gait Analysis
Illustration: Posterior View of Ankle on Heel Contact
§421 Medial or Lateral Body Shifting
Figure 4.1: Lateral Movement of the Foot During the Stride
Figure 4.2: Stringer Elevated Above the Plane of Tread
§422 Speed of Walking
§423 Angle of Impact
Figure 4.3: Moments of Force During Heel Strike
§424 The Effect of Aging and Physical Impairment
§425 Arm Function
§430 Experiments and Ergonomic Studies on Slipping
§440 Walking Surfaces
§441 Level Surfaces
Picture: Uneven Stepping Stones
§442 Ramps
Table: Static Coefficient of Friction for Level Surfaces and Various Gradients
§442.1 Side Slopes
§443 Stairways
Picture: No Slip Stripes
§444 Curbs and Risers
§445 Wheel Stops
Figure 4.4: Tire Stop and Standard Parking Stall Dimensions
Picture: Badly Placed Tire Stop
Picture: Asphalt in Bad Repair
Figure 4.5: Handicapped Parking Space
§446 Speed Bumps
Picture: Speed Bumps With Solid Painting
Picture: Proper Marking and Delineation
§447 Rough and Uneven Work Surfaces
§450 Balance and Perception
§451 Cone of Vision
§452 Visual Cues or Flags
Figure 4.6: Contrasts Against Background
Figure 4.7: NIOSH Contrast Visibility Chart
§452.1 Color Contrast
Picture: Lack of Contrast
§452.2 Lighting and Illumination
§453 Determining Visibility or Visual Acuity
§453.1 Glare
§454 Spatial Vision and Pattern Perception
§454.1 Defining an Object
§454.2 Visual Acuity and Contrast Sensitivity Function (CSF)
§454.3 Primary Factors That Determine the Visibility of Objects
§454.4 Orientation Edges
§455 Distractions
Picture: Floor Pattern Hiding Riser
Picture: Riser Hidden By Tile Pattern and Color
§455.1 Orientation Edges
§455.2 Geometric Patterns
§455.3 Vehicular and Pedestrian Traffic
§455.4 Point-of-Purchase Displays
§460 Checklist: Evaluating a Walkway
Picture: Repaired Walkway
Picture: Uplifting Tree Roots
§400 Introduction
The slip and fall practitioner should understand the mechan-
ics of walking and the forces that are generated during the
stride. Scientists have been measuring and studying these
forces for over half a century. Herbert Elftman and his
coworkers at New York University were early pioneers in
the development of the scientific concepts of human loco-
motion, writing a series of papers widely published from
1934 to 1939 on pressure distribution during the stride and
the forces generated by various muscles.
Post-war studies used improved instrumentation to measure
ground reaction forces, cadence and other parameters con-
cerned with gait analysis. Some of the most extensive work
was done at the University of California in the late 1940s.
In 1948, J.P. Frankel and B. Bressler presented a paper to
the American Society of Mechanical Engineers (ASME)
in which they reported the results of their research into the
Forces and Movements of the Leg During Walking. This
work was part of a grant by the National Research Council to
establish the groundwork for a project entitled Fundamental
Studies of Human Locomotion. In this country, the study
of human locomotion was continued under the guidance
of Verne Inman, M.D., and Henry Ralson, Ph.D., at the
Biomechanics Laboratory at the University of California
at San Francisco and Berkeley. A compendium of their
work was first published in 1981 under the title, Human
Walking, by Williams & Wilkins. The work is now in its
second edition by Rose and Gamble (1993). More recent
research in both ground reaction forces and traction demand
has been published in an American Society for Testing and
Material STP 1424, Metrology of Pedestrian Locomotion
and Slip Resistance (2002). Other publications which will
be helpful to a more technical understanding of human
walking and behavioral sciences associated with pedestrian
safety are: Introduction to Ergonomics by R. S. Bridger,
Taylor & Francis (2003); Measuring Slipperiness, Chang
and Courtney, editors, Taylor & Francis (2003); Pedestrian
Slip Resistance, 2nd Edition, Wm. English, Inc. (2003);
Perception, Sekuler and Blake, 3rd Edition, McGraw-Hill
(1994); Essential Clinical Anatomy, 2nd Edition, K. Moore
and A. Agur, Lippencott-Williams & Wilson (2002); Joint
Structure and Function, 4th Edition, P. Levangie and C.
Norkin, F.A. Davis Co. (2005).
§410 Human Walking
Studies in ambulation were first extensively conducted in
the nineteenth century. As science and technology increase
the understanding of human locomotion and the effect
to the physical world on the pedestrian’s ability to move
around the earth, many of the earlier notions of motion
and perception have been revised. The causes and preven-
tion of pedestrian fall accidents are closely related to our
understanding of how people walk and perceive the world
around them.
§411 Bipedal Motion
Quadruped animals gain stability walking on four feet,
because in most cases there are three feet on the ground at
all times. Such a walking mode requires little training and
comes naturally even to human infants. Bipedal human
walking is a learned activity that requires a combination of
instinct and learning. Each individual walks a little differ-
ently, but most of the ground reaction forces, cadence and
balance, and perception ability are in a general range that
can be studied and quantified.
§412 Cyclic Pattern of Movement
Walking is a nonspecific term that generally refers to a cyclic
pattern of movement that is repeated step after step, over and
over. Because of this cyclic pattern, most of the mechanics of
walking can be studied and described by looking at a single
cycle. Walking is the process in which the erect human body
is supported on one leg then the other. The center of body
mass moves forward and in doing so passes over the support-
ing leg, as the opposite leg starts to swing forward in prepa-
ration for repeating the cycle. As the foot leaves the ground
and swings forward, the support of the body transfers to the
opposing leg. The support is transferred back to the swinging
leg when it impacts the walkway surface and the body weight
shifts forward to be centered over the leg again. During this
phase of the stride, both feet are in contact with the ground;
during the rest of the stride only one foot is in contact at any
given time. Olney characterizes this as double support time
when both feet are on the ground during one gait cycle. The
percentage of the gait cycle spent in double support may
be increased in the elderly persons and those with balance
problems. The cycle percentage of double support decreases
as the speed of walking increases. (Olney, S., Joint Structure
and Function, 4th Ed., P. Levangie and C. Norkin, Editors.
F.A. Davis Co. (Chapter 4, Gait, page 522) (2005).)

To continue reading

Request your trial

VLEX uses login cookies to provide you with a better browsing experience. If you click on 'Accept' or continue browsing this site we consider that you accept our cookie policy. ACCEPT