Table of contents

[**14 Anthropometry and biomechanics**
14-1](#anthropometry-and-biomechanics)

[14.1 General application of anthropometric and biomechanic data
14-2](#general-application-of-anthropometric-and-biomechanic-data)

[14.1.1 User population 14-2](#user-population)

[14.1.2 Using design limits 14-4](#using-design-limits)

[14.1.3 Avoiding pitfalls in applying anthropometric data
14-6](#avoiding-pitfalls-in-applying-anthropometric-data)

[14.1.4 Solving a complex sequence of design problems
14-7](#solving-a-complex-sequence-of-design-problems)

[14.1.5 Use of distribution and correlation data
14-11](#use-of-distribution-and-correlation-data)

[14.2 Anthropometric variability factors
14-13](#anthropometric-variability-factors)

[14.3 Anthropometric and biomechanics data
14-13](#anthropometric-and-biomechanics-data)

[14.3.1 Data usage 14-13](#data-usage)

[14.3.2 Static body characteristics 14-14](#static-body-characteristics)

[14.3.3 Dynamic (mobile) body characteristics
14-28](#dynamic-mobile-body-characteristics)

[14.3.3.1 Range of whole body motion 14-28](#range-of-whole-body-motion)

[14.3.3.2 Joint motion 14-29](#joint-motion)

[14.4 Reach 14-35](#reach)

[14.5 Human strength and handling capacity
14-42](#human-strength-and-handling-capacity)

[14.5.1 Muscle strength factors 14-42](#muscle-strength-factors)

[14.5.2 Exerted forces 14-43](#exerted-forces)

[14.5.3 Push and pull forces 14-47](#push-and-pull-forces)

[14.5.4 Lifting and carrying 14-52](#lifting-and-carrying)

[14.6 Wheelchair anthropometrics 14-52](#wheelchair-anthropometrics)

[Glossary 14-55](#__RefHeading___Toc31426353)

[References 14-57](#__RefHeading___Toc31426354)

[Index 14-58](#__RefHeading___Toc31426355)

**List of exhibits**

[Exhibit 14.1.4.4 Additive effects of clothing on anthropometric
measures 14-9](#__RefHeading___Toc31762886)

[Exhibit 14.1.4.4 (continued) Additive effects of clothing on
anthropometric measures 14-10](#__RefHeading___Toc31762887)

[Exhibit 14.1.5.1 Percentile values 14-11](#__RefHeading___Toc31762888)

[Exhibit 14.3.2.1 Static human physical characteristics (head)
14-15](#__RefHeading___Toc31762889)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(head) 14-16](#__RefHeading___Toc31762890)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(head) 14-17](#__RefHeading___Toc31762891)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(head) 14-18](#__RefHeading___Toc31762892)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(seated) 14-19](#__RefHeading___Toc31762893)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(seated) 14-20](#__RefHeading___Toc31762894)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(seated) 14-21](#__RefHeading___Toc31762895)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(seated) 14-22](#__RefHeading___Toc31762896)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(standing) 14-23](#__RefHeading___Toc31762897)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(standing) 14-24](#__RefHeading___Toc31762898)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(standing) 14-25](#__RefHeading___Toc31762899)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(hand) 14-26](#__RefHeading___Toc31762900)

[Exhibit 14.3.2.1 (continued) Static human physical characteristics
(standing position) 14-27](#__RefHeading___Toc31762901)

[Exhibit 14.3.3.2.1 Joint movement ranges
14-30](#__RefHeading___Toc31762902)

[Exhibit 14.3.3.2.1 (continued) Joint movement ranges
14-31](#__RefHeading___Toc31762903)

[Exhibit 14.3.3.2.1 (continued) Joint movement ranges
14-32](#__RefHeading___Toc31762904)

[Exhibit 14.3.3.2.2 Change in range of joint movement with movement in
an adjacent joint 14-34](#__RefHeading___Toc31762905)

[Exhibit 14.4.2 Reach envelopes in vertical and horizontal planes
14-36](#__RefHeading___Toc31762906)

[Exhibit 14.4.3 (a) Touch, grip, and grasp functions
14-37](#__RefHeading___Toc31762907)

[Exhibit 14.4.3 (a) (continued) Touch, grip, and grasp functions
14-38](#__RefHeading___Toc31762908)

[Exhibit 14.4.3 (b) Thumb and forefinger grasp boundary data for females
in the 46 cm and 61 cm horizontal planes
14-39](#__RefHeading___Toc31762909)

[Exhibit 14.4.3 (c) Thumb and forefinger grasp boundary data for females
in the 0 and -15 cm vertical planes 14-40](#__RefHeading___Toc31762910)

[Exhibit 14.5.2.1 Male muscle strength of the arm, hand, and thumb for
control forces (5th percentile values)
14-44](#__RefHeading___Toc31762911)

[Exhibit 14.5.2.1 (continued) Design criteria for male muscle strength
of the arm, hand, and thumb for control forces (5th percentile values)
14-45](#__RefHeading___Toc31762912)

[Exhibit 14.5.3.1 Horizontal push and pull forces that can be exerted
14-47](#__RefHeading___Toc31762913)

[Exhibit 14.5.3.2 Static muscle strength data for vertical pull
exertions 14-49](#__RefHeading___Toc31762914)

[Exhibit 14.5.3.2 (continued) Static muscle strength data for vertical
pull exertions 14-50](#__RefHeading___Toc31762915)

[Exhibit 14.5.3.2 (continued) Static muscle strength data for vertical
pull exertions 14-51](#__RefHeading___Toc31762916)

[Exhibit 14.6.1 Forward reach from a wheelchair.
14-52](#__RefHeading___Toc31762917)

[Exhibit 14.6.1 (continued) Forward reach from a wheelchair
14-53](#__RefHeading___Toc31762918)

[Exhibit 14.6.4 Side reach from a wheelchair.
14-53](#__RefHeading___Toc31762919)

[Exhibit 14.6.6 Wheelchair dimensions.
14-54](#__RefHeading___Toc31762920)

#  Anthropometry and biomechanics

Designers and human factors specialists incorporate scientific data on
human physical capabilities into the design of systems and equipment.
Human physical characteristics, unlike those of machines, cannot be
designed. However, failure to take into account human physical
characteristics when designing systems or equipment can place
unnecessary demands and restrictions upon user personnel.

**Definitions. Anthropometry** is the scientific measurement and
collection of data about human physical characteristics and the
application (engineering anthropometry) of these data in the design and
evaluation of systems, equipment, manufactured products, human- made
environments, and facilities. **Biomechanics** describes the mechanical
characteristics of biological systems, in this case the human body, in
terms of physical measures and mechanical models. This field is
interdisciplinary (mainly anthropometry, mechanics, physiology, and
engineering). Its applications address mechanical structure, strength,
and mobility of humans for engineering purposes.

This chapter of the HFDS provides additional anthropometric and
biomechanics data beyond that used in other chapters. Previous data are
cross-referenced, where appropriate. Unlike the other sections, this
section provides more guidance about the nature of the data, its
selection, and its proper use. It provides rules for applying the vast
amount of human form data available to specific design fit, function,
and human task performance.

The section also covers application principles and their resulting
rules, human body measurement data (static and dynamic), range of motion
and strength data, as well as comfort information.

## 14.1 General application of anthropometric and biomechanic data

In this document, body size, strength, and mobility data are presented.
In the future, this population will include a wider range of ethnic
backgrounds. Minorities and females are expected to increase. The
average age is expected to decrease. These changes will be important for
future systems design.

In this general section, design criteria and rules are given for: (1)
ascertaining user population data, (2) using the design limits approach,
(3) avoiding pitfalls in applying the data, (4) using distribution and
correlation data, (5) solving design problems, and (6) using models.

### 14.1.1 User population

Anthropometric data are most appropriate when they are derived from a
survey of the existing worker population of interest. Since the
sub-population associated with the FAA has not been surveyed,
information from substitute sources is used as a basis for design.

-   **14.1.1.1** **Use of data.** Anthropometric and biomechanics data
    shall be used in the design of systems, equipment (including
    personal protection equipment), clothing, workplaces, passageways,
    controls, access openings, and tools. \[Source: National Aeronautics
    and Space Administration (NASA-STD-3000A), 1989\]

    **Discussion.** The human\'s interface with other system components
    needs to be treated as objectively and systematically as are other
    interface and hardware component designs. It is not acceptable to
    guess about human physical characteristics or to use the designer\'s
    own measurements or the measurements of associates. Application of
    appropriate anthropometric and biomechanics data is expected.

-   **14.1.1.2** **Data to be used.** Designers and human factors
    specialists shall use the anthropometric and biomechanics data
    provided in this document. If additional data are needed, they shall
    use the more complete data given in DOD-HDBK-743A. If other
    reference or new data collections are considered, the contractor
    shall obtain the approval of the acquisition program office.
    \[Source: NASA-STD-3000A, 1989; Department of Defense
    (DOD-HDBK-743A), 1991\]

    **Discussion.** If this document does not present data needed for
    the problem at hand, the designer will have to select appropriate
    sample information from DOD-HDBK-743A. In that handbook, the 1988
    military male and female survey distributions can be used to
    represent the FAA user population when needed, as it represents the
    most comprehensive samples available. Note that civilian working
    populations could be expected to have a larger range of sizes and
    ages than the military. Samples with comprehensive measures are not
    available.

-   **14.1.1.3** **Using population extremes.** Designers and human
    factors specialists shall draw upon the extremes of the larger male
    population distribution and the extremes of the smaller female
    population distributions to represent the upper and lower range
    values, respectively, to apply to anthropometric and biomechanics
    design problems. \[Source: NASA-STD-3000A, 1989\]

**Discussion.** The use of separate male and female population data is a
conservative approach that results in more inclusive design dimensions
than the same percentiles would from a composite population.

### 14.1.2 Using design limits

Initial rules in this section address the design limits approach. To
understand this approach, it is helpful to consider the overall steps
and choices that one makes in applying anthropometric and biomechanics
data. The design limits approach entails selecting the most appropriate
percentile values in population distributions and applying the
appropriate associated data in a design solution. These steps are listed
in this introductory material and are explained in detail in the initial
three rules of this subsection. If the reader has applied the design
limit approach and understands it, the reader can skip the rest of this
introductory material as well as the explanations associated with the
first three rules. However the reader should not skip the rules.

**Definition.** **The design limits approach** is a method of applying
population or sample statistics and data about human physical
characteristics to a design so that a desired portion of the user
population is accommodated by the design. The range of users
accommodated is a function of limits used in setting the population
portion.

To understand the design limits approach, it is helpful to consider step
by step the choices that design personnel make in applying these human
physical data.

a.  Select the correct human physical characteristic and its applicable
    measurement characteristic (description) for the design problem at
    hand.

b.  Select the appropriate population, representative sample, or rule
    information on the selected human physical characteristic and
    measurement description to apply to the design problem.

c.  Determine the appropriate statistical point(s), usually percentile
    points from rule information or from the sample distribution(s) in
    order to accommodate a desired range of the human characteristic
    within the distribution of the user population.

d.  Read directly or determine statistically the measurement value(s)
    that corresponds to the selected statistical point(s) relevant to
    the population distribution.

e.  Incorporate the measurement value as a criterion for the design
    dimension, or in the case of biomechanics data, for the movement or
    force solution in the design problem.

-   **14.1.2.1** **Clearance dimension at the 95th percentile.** Design
    clearance dimensions that must accommodate or allow passage of the
    body or parts of the body shall be based upon the 95th percentile of
    the male distribution data. \[Source: Department of Defense
    (MIL-STD-1472D), 1989\]

-   **14.1.2.2** **Limiting dimension at the 5th percentile.** Limiting
    design dimensions, such as reach distances, control movements,
    display and control locations, test point locations, and handrail
    positions, that restrict or are limited by body or body part size,
    shall be based upon the 5th percentile of female data for applicable
    body dimensions. \[Source: MIL-STD-1472D, 1989\]

    **Discussion.** For example, the maximum height from floor level to
    an accessible part of any piece of equipment needs to be within
    reach of the 5th percentile female user, which will ensure that at
    least 95 percent of the user population can access this part of the
    equipment.

-   **14.1.2.3 Adjustable dimensions.** Any equipment dimensions that
    need to be adjusted for the comfort or performance of the individual
    user shall be adjustable over the range of the 5th to 95th
    percentiles. \[Source: MIL-STD-1472D, 1989\]

-   **14.1.2.4 Sizing determinations.** Clothing and certain personal
    equipment dimensions that need to conform closely to the contour of
    the body or body parts shall be designed and sized to accommodate at
    least the 5th through the 95th percentile range. If necessary, this
    range shall be accommodated by creating a number of unique sizes,
    where each size accommodates a segment of the population
    distribution. Each segment can be bounded by a small range of
    percentile values. \[Source: MIL-STD-1472D, 1989\]

-   **14.1.2.5** **Critical life support equipment.** Dimensions or
    sizes of critical life support equipment shall accommodate, at
    least, the range defined by the 1st through the 99th percentiles of
    the distribution. \[Source: MIL-STD-1472D, 1989\]

### 14.1.3 Avoiding pitfalls in applying anthropometric data

There are several common errors to be avoided by designers when they
apply anthropometric data to design. These are: (1) designing to the
midpoint (50th percentile) or average, (2) the misperception of the
typical sized person, (3) generalizing across human characteristics, and
(4) summing of measurement values for like percentile points across
adjacent body parts.

-   **14.1.3.1 Misuse of the 50th percentile or of the average.** The
    50th percentile or mean shall not be used as design criteria as it
    accommodates only half of the users. \[Source:NASA-STD-3000A, 1989\]

    **Discussion.** When the population distribution is Gaussian
    (normal), the use of either the 50th percentile or the average for a
    clearance would, at best, accommodate half the population.

-   **14.1.3.2** **Misperception of the typically sized person.**
    Designers or human factors specialists shall not use the concept of
    a typically sized person where the same percentiles values are
    expected across many dimensions. A person at the 95 percentile in
    height is unlikely to measure at the 95th percentile in reach or
    other dimensions. A percentile value and its measurement value that
    pertains to a particular body part shall be used exclusively for
    functions that relate to that body part. \[Source: Department of the
    Air Force (AFSC DH 1-3), 1980; NASA-STD-3000A, 1989\]

    **Discussion.** When the middle 30 percent of a population of 4000
    men was measured on 10 dimensions, only one-fourth of them were
    \"average\" in a single dimension (height), and less than 1 percent
    were average in five dimensions (height, chest circumference, arm
    length, crotch height, and torso circumference). Keeping in mind
    that there is not an \"average person,\" one also must realize that
    there is not a \"5th percentile person\" nor a \"95th percentile\"
    person. Different body part dimensions are not necessarily highly
    correlated. An implication is that one can not choose a person who
    is 95 percentile in stature as a test subject for meeting 95
    percentile requirements in reach or other dimensions.

-   **14.1.3.3** **Summation of segment dimensions.** Summation of like
    percentile values for body components shall not be used to represent
    any human physical characteristic that appears to be a composite of
    component characteristics. \[Source: NASA-STD-3000A, 1989\]

**Discussion.** The 95th percentile arm length, for instance, is not the
addition of the 95th percentile shoulder-to-elbow length plus the 95th
percentile elbow-to-hand length. The actual 95th percentile arm length
will be somewhat less than the erroneous summation. To determine the
95th percentile arm length, one must use a distribution of arm length
rather than component part distributions.

### 14.1.4 Solving a complex sequence of design problems

In this section, rules are presented for approaching complex design
problems that require the consideration of a sequence of relevant design
reference locations (such as seat reference points and eye reference
zones), human physical characteristics, statistical points, and
measures. The recommended approach involves identifying the necessary
human activities and positions and establishing reference points and
envelopes for the necessary activities. These envelopes impact the
location and design of controls and displays, as well as the placement
of work surfaces, equipment, and seating accommodations. The effects of
clothing or carried equipment are then used to expand the dimensions.

-   **14.1.4.1** **Design to body positions and motions of the tasks.**
    Design personnel shall base the necessary operator and user body
    positions and motions on personnel tasks to be performed during
    normal, degraded, and emergency modes of operations and maintenance.
    \[Source: NASA-STD-3000A, 1989\]

-   **14.1.4.2** **Construction or collection of unique position data.**
    If the common and mobile working positions data in Chapter 10 of
    this document do not represent the unique working positions
    associated with a design, then design personnel shall construct the
    applicable human physical characteristics and measures from the
    static and dynamic data provided later in Sections 14.3.2 and 14.3.3
    or in DOD-HDBK-743A. If no applicable data can be found or
    calculated for important design measures, then, with the prior
    approval of the acquisition program office, sample measures shall be
    taken on appropriate personnel for the unique working positions.
    \[Source: DOD-HDBK-743A, 1991; Roebuck, Kroemer, & Thomson, 1975\]

    **Discussion.** Anthropometric measurement needs to be done by
    professionals because there are many complexities and potential
    interactions among positions of body segments, as well as many
    technical points and pitfalls to avoid in measurement practice.
    Sample measurement methods can be found in Roebuck, Kroemer, and
    Thomson, 1975.

```{=html}
<!-- -->
```
-   **14.1.4.3** **Building and using reach envelopes.** If reach data
    provided in this document (see Section 14.4) do not apply to a
    specific design problem, then reach design dimensions or envelopes
    for design use should be constructed considering:

a.  one-handed or two-handed operation,

b.  grasp requirements which may affect the functional reach envelope,

c.  positional relationship of a shoulder reference point or arm
    rotation point to the seat back, seat reference point, or other
    posture reference or design reference points, and

d.  the appropriate samples and anthropometric measurements from the
    data provided in this document or in DOD-HDBK-743A, 1991 (see
    Paragraph 14.1.1.2). \[Source: DOD-HDBK-743A, 1991\]

-   **14.1.4.4** **Effects of clothing.** Because most anthropometric
    data presented in this document and in other data sources represent
    nude body measurements (unless otherwise indicated), suitable
    allowances shall be made for light, medium, or heavy clothing and
    for any special protective equipment that is worn. Exhibit 14.1.4.4
    illustrates the additive effects of clothing on static body
    dimensions and shows the 95th percentile gloved hand measures. If
    special items of protective clothing or equipment are involved, the
    effects shall be measured in positions required by the users\'
    tasks. The effects on the extremes of the population distribution
    shall be determined. \[Source: Department of Defense
    (MIL-HDBK-759B), 1992; Johnson, 1984\]

    **Discussion.** Nude dimension and light clothing can be regarded as
    synonymous for practical purposes. Additional information on the
    changes in anthropometric measurement values imposed by different
    clothing ensembles is found in Johnson, 1984.

    ![](media/image1.png){width="4.8in" height="5.383333333333334in"}

> []{#__RefHeading___Toc31762886 .anchor}**Exhibit 14.1.4.4** Additive
> effects of clothing on anthropometric measures

[]{#__RefHeading___Toc31762887 .anchor}**Exhibit 14.1.4.4 (continued)**
Additive effects of clothing on anthropometric measures

![](media/image2.png){width="5.965972222222222in"
height="2.036111111111111in"}

a.  

### 14.1.5 Use of distribution and correlation data

Complex uses of statistical data concerning human physical dimensions or
capabilities are introduced in this section. Data and distribution
information on a single physical characteristic and its measures
provides no information about that characteristic\'s composite
relationship with any other characteristic and its measures. For design,
the relationship between two or more characteristics and how their
measures vary together is important. Consider sizing clothing and
designing seats. Bivariate distributions and correlation statistics can
be used by knowledgeable professionals to determine design criteria.

-   **14.1.5.1** **Gaussian distribution of measurement values on a
    single human physical characteristic.** The relationship between the
    Gaussian distribution and the measurement value equivalent to the
    desired percentile statistic value should best be determined from a
    smoothed frequency distribution or from the formula presented in
    Exhibit 14.1.5.1 if the following conditions are met:

a.  the percentile value is not given in applicable
    Human-machine-interface data, and

b.  the population distribution for the applicable human physical
    characteristic is known to be Gaussian (normal) and the mean and
    variance are known. \[Source: Israelski, 1977\]

> []{#__RefHeading___Toc31762888
> .anchor}![](media/image3.png){width="4.458333333333333in"
> height="2.0625in"}**Exhibit 14.1.5.1** Percentile values

-   **14.1.5.2** **Using bivariate distribution data.** Bivariate data
    should be professionally applied and interpreted since knowledge of
    the population distribution characteristics are necessary to project
    and extract design limits and to apply them to design problems.
    \[Source: MIL-HDBK-759B, 1992\]

    **Discussion.** The variability of two body measurements and their
    interrelationship with each other may be presented in a graph or a
    table. Bivariate information includes the ranges of two measurements
    and the percentages or frequencies of individuals who are
    characterized by the various possible combinations of values of the
    two measurements. Knowledgeable professionals can tell about the
    relationships from the appearance and shape of the joint
    distribution of measures. Correlation statistics, when the
    relationship warrants, provide additional insight, and when
    appropriate samples are large enough, may provide predictions of
    population values.

-   **14.1.5.3** **Use of correlation and multiple correlation data.**
    When two or more human physical characteristics are applicable to a
    design problem, professionals should apply and interpret correlation
    statistics. Knowledge about distributions and intercorrelations
    among the distributions need to be factored into the use of these
    data. \[Source: MIL-HDBK-759B, 1992; Kroemer, Kroemer, &
    Kroemer-Elbert 1990\]

    **Discussion.** The relationships or correlations between specific
    body measurements are highly variable among the various human
    characteristics and may differ across samples and populations. For
    example, breadth measurements tend to be more highly correlated with
    weight than with stature. The degree of the relationship may be
    expressed by a correlation coefficient or \"r\" value.

    Although common percentile values may not be used to sum data across
    adjacent body parts, (see Paragraph 14.1.3.3), regression equations
    derived from the applicable samples can be used in constructing
    composite body measures.

    **Definition.** The **correlation coefficient or \"r\" value**
    describes the degree to which two variables vary together (positive
    correlation) or vary inversely (negative correlation). The
    correlation coefficient, \"r\", has a range of values from +1.0
    (perfect positive correlation) through -1.0 (perfect negative
    correlation). Multiple correlation involves the predictable
    relationship of two or more variables with another criterion
    variable (such as a composite measurement value). **\"R\"** is the
    **multiple** **correlation coefficient.** It is recommended that
    only correlations with strong predictive values be used (that is
    where r or R is at least or greater than \|.7\|). (Note: R^2^ is the
    square of the multiple correlation coefficient and equates to the
    proportion of the variation accounted for in the prediction. An R of
    .7 would account for about 50 percent of the variation).

## 14.2 Anthropometric variability factors

There are many factors that relate to the large variability observed in
measures of the human body. These factors include: (1) body position,
(2) age, health, and body condition, (3) sex, (4) race and national
origin, (5) occupation, and (6) evolutionary trends. These factors
affect future population sampling and encourage the use of the most
recent data on the populations of interest. If designers and human
factors specialists need to draw upon other data or accomplish some
special purpose sampling, the following rules related to data
variability may assist.

-   **14.2.1** **Foreign populations.** If a specific use of the system
    or equipment involves operation or maintenance by foreign personnel
    in locations outside the United States, sample data should be
    obtained that represents the foreign work force. \[Source:
    Israelski, 1977\]

-   **14.2.2** **Body slump.** In determining body position and eye
    position zones for seated or standing positions, a slump factor
    which accompanies relaxation should be taken into account.
    Seated-eye height measurements can be reduced by as much as 65 mm
    (2.56 in) when a person sits in a relaxed position. Body slump, when
    standing, reduces stature as much as 19 mm (.75 in) from a perfectly
    erect position. These slump factors should be considered in
    designing adjustable seats, visual envelopes, and display locations.
    \[Source: Israelski, 1977\]

## 14.3 Anthropometric and biomechanics data

This section provides general guidance for the use of specific
anthropometric and biomechanics data, static body characteristics data,
dynamic body characteristic data, including range of joint motion and
common and mobile working positions.

Dimensions of the human body which influence the design of personal and
operational equipment are of two types: (1) static dimensions, which are
measurements of the head, torso, and limbs in normal positions, and (2)
dynamic dimensions, which are measurements taken in working positions or
during movement. \[Source: AFSC DH 1-3, 1980; NASA-STD-3000A, 1989\]

### 14.3.1 Data usage

-   **14.3.1.1** **Use of anthropometric and biomechanics data.** Data
    throughout Section 14.3 are to be used for anthropometric issues
    that are not addressed in earlier sections of this document. If
    designers and human factors specialists need additional data to
    solve anthropometric design problems associated with human physical
    characteristics, they shall use the data presented in DOD-HDBK-743A
    (see also 14.1.1.2). \[Source: DOD-HDBK-743A, 1991\]

-   **14.3.1.2** **Task considerations.** Designers and human factors
    specialists shall take the following task conditions into
    consideration when using the human physical characteristic data
    presented in this section:

a.  the nature, frequency, and difficulty of the related tasks to be
    performed by the operator or user of the equipment,

b.  the position of the body during performance of operations and
    maintenance tasks,

c.  mobility and flexibility demands imposed by maintenance tasks,

d.  the touch, grasp, torque, lift, and carry requirements of the tasks,

e.  increments in the design-critical dimensions imposed by clothing or
    equipment, packages, and tools, and

f.  increments in the design-critical dimensions imposed by the need to
    compensate for obstacles and projections. \[Source: MIL-STD-1472D,
    1989; MIL-HDBK-759B, 1992\]

### 14.3.2 Static body characteristics

-   **14.3.2.1** **Static data.** Exhibit 14.3.2.1 presents static human
    physical characteristics and measurement values which should be
    used, as applicable, in design problems. Exhibit 14.3.2.1 addresses
    the following body parts: head, seated body, standing body, and
    hands. \[Source: DOD-HDBK-743A, 1991\]

> []{#__RefHeading___Toc31762889
> .anchor}![](media/image4.png){width="6.5in"
> height="8.541666666666666in"}**Exhibit 14.3.2.1** Static human
> physical characteristics (head)
>
> []{#__RefHeading___Toc31762890
> .anchor}![](media/image5.png){width="6.520833333333333in"
> height="8.677083333333334in"} Static human physical characteristics
> (head)
>
> []{#__RefHeading___Toc31762891
> .anchor}![](media/image6.png){width="6.520833333333333in"
> height="8.61875in"}**Exhibit 14.3.2.1 (continued)** Static human
> physical characteristics (head)

[]{#__RefHeading___Toc31762892
.anchor}![](media/image7.png){width="6.520833333333333in"
height="8.61875in"}**Exhibit 14.3.2.1 (continued)** Static human
physical characteristics (head)

> []{#__RefHeading___Toc31762893
> .anchor}![](media/image8.png){width="6.520833333333333in"
> height="8.677083333333334in"} Static human physical characteristics
> (seated)
>
> []{#__RefHeading___Toc31762894
> .anchor}![](media/image9.png){width="6.5in" height="8.53125in"} Static
> human physical characteristics (seated)

[]{#__RefHeading___Toc31762895
.anchor}![](media/image10.png){width="6.520833333333333in"
height="8.65625in"}**Exhibit 14.3.2.1 (continued)** Static human
physical characteristics (seated)

> []{#__RefHeading___Toc31762896
> .anchor}![](media/image11.png){width="6.520833333333333in"
> height="8.5in"}**Exhibit 14.3.2.1 (continued)** Static human physical
> characteristics (seated)
>
> []{#__RefHeading___Toc31762897
> .anchor}![](media/image12.png){width="6.520833333333333in"
> height="8.65625in"}**Exhibit 14.3.2.1 (continued)** Static human
> physical characteristics (standing)
>
> []{#__RefHeading___Toc31762898 .anchor}**Exhibit 14.3.2.1
> (continued)** Static human physical characteristics (standing)

![](media/image13.jpeg){width="6.5in" height="8.622916666666667in"}

[]{#__RefHeading___Toc31762899
.anchor}![](media/image14.png){width="6.520833333333333in"
height="8.65625in"}**Exhibit 14.3.2.1 (continued)** Static human
physical characteristics (standing)

[]{#__RefHeading___Toc31762900
.anchor}![](media/image15.png){width="6.520833333333333in"
height="7.510416666666667in"} Static human physical characteristics
(hand)

[]{#__RefHeading___Toc31762901
.anchor}![](media/image16.png){width="6.520833333333333in"
height="4.489583333333333in"}**Exhibit 14.3.2.1 (continued)** Static
human physical characteristics (standing position)

### 14.3.3 Dynamic (mobile) body characteristics

This section presents: (1) information concerning the range of whole
body motion characteristics, and (2) design rules and data on joint and
body motion. Where such data are in other sections with application
topics such as design for use and workplace design, cross references are
provided.

#### 14.3.3.1 Range of whole body motion

Efficiency and accuracy of task performance can be maintained only if
required body movements are within safe and comfortable limits. Human
variability in range of body and joint movement is attributable to many
factors, including the following:

a.  Age becomes a factor after age 60, at which time mobility has
    decreased 10 percent from youth.

b.  Sex differences favor greater range in females at all joints except
    the knee.

c.  Body build is a significant factor. Joint mobility decreases
    significantly as body build ranges from the very slender, through
    the muscular, to the obese.

d.  Exercise increases movement range. Weight training, jogging, and the
    like may tend to shorten certain muscle groups or increase their
    bulk so movement is restricted.

e.  Fatigue, disease, body position, clothing, and environment are other
    factors affecting mobility. \[Source: NASA-STD-3000A, 1989; AFSC DH
    1-3, 1980; Israelski, 1977\]

This section provides introductory definitions related to the angular
motion of skeletal joints. Knowledge of the range of joint motion helps
the designer determine the placement and allowable movement of controls,
tools, and equipment.

-   **14.3.3.1.1** **Trunk movement.** Workplace designs based upon
    design-driven body positions shall allow enough space to move the
    trunk of the body. The design shall be based upon:

a.  the required tasks and human functions,

b.  the need for optimal positions for applying forces, and

c.  the need for comfortable body adjustments and movements. \[Source:
    MIL-HDBK-759B, 1992\]

-   **14.3.3.1.2** **Whole body movement.** If large forces that are
    greater than 13.6 kg (29.98 lb) or large control displacements that
    are more than 380 mm (14.96 in) in a fore-aft direction are
    required, the user shall be given enough space to move his or her
    entire body. \[Source: MIL-HDBK-759B, 1992\]

#### 14.3.3.2 Joint motion

Joint motion capabilities make body movements possible. Joint movement
is measured at the angle formed by the long axes of two adjoining body
segments or at the angle formed by a body segment and a vertical or
horizontal plane. The total range of motion is measured between the two
extreme positions of the joint. The types of movement are defined below
and are illustrated in Exhibits which follow.

**Definitions.** **Abduction** is movement away from the midline of the
body. **Adduction** is movement toward the midline. **Circumduction** is
a continuous circular movement of a limb. **Depression** is the lowering
of a body member from its normal position. **Elevation** is the raising
of a body member from a normal position. **Extension** is the
straightening of a limb or an increase in the angle between parts of the
body. **Flexion** is the process of bending a limb or decreasing the
angle between parts of the body. **Lateral rotation** is turning away
from the midline of the body, while **medial rotation** is turning
toward the midline of the body. **Pronation** is the downward turning of
the palm, or lying face down. **Supination** is the upward turning of
the palm, or lying face up.

-   **14.3.3.2.1** **Single joint movements.** Designers and human
    factors specialists shall use the data in Exhibit 14.3.3.2.1 for
    design problems involving the movement of a single joint. This
    Exhibit presents single joint movement ranges for males and females.
    \[Source: NASA-STD-3000A, 1989; MIL-HDBK-759B, 1992; Department of
    Defense (MIL-STD-1800A), 1990\]

> []{#__RefHeading___Toc31762902
> .anchor}![](media/image17.png){width="6.489583333333333in"
> height="8.583333333333334in"}Joint movement ranges
>
> []{#__RefHeading___Toc31762903
> .anchor}![](media/image18.png){width="6.520833333333333in"
> height="8.71875in"} Joint movement ranges

[]{#__RefHeading___Toc31762904
.anchor}![](media/image19.png){width="6.520833333333333in"
height="7.0in"}**Exhibit 14.3.3.2.1 (continued)** Joint movement ranges

-   **14.3.3.2.2** **Range of motion for two joints.** Exhibit
    14.3.3.2.2 shall be used for design problems involving the motion of
    two joints. Designers shall avoid using single joint movement data
    for adjacent joints because they are usually not additive. \[Source:
    NASA-STD-3000A, 1989; MIL-HDBK-759B, 1992; MIL-STD-1800A, 1990\]

    **Discussion.** The range of joint movement is drastically reduced
    by movement of the adjacent joint. Exhibit 14.3.3.2.2 defines the
    change in range of motion of a given joint when complemented by
    movement of the adjacent joint.

    **Example.** The following illustrates how Exhibit 14.3.3.2.2 is to
    be used. The first entry is read: the average shoulder has a full
    range of extension of 59.3 degrees with the elbow in a neutral
    position (locked in hyperextension). When shoulder extension was
    measured with the elbow flexed to one third of its full joint
    movement range (these movements can be determined from illustrations
    six and seven in the previous Exhibit), the mean value of shoulder
    extension was found to increase by 1.6 degrees, or approximately 103
    percent of the base value. The results for other movements and
    adjacent joint positions are presented in a similar manner.

> []{#__RefHeading___Toc31762905 .anchor}**Exhibit 14.3.3.2.2** Change
> in range of joint movement with movement in an adjacent joint

![](media/image20.png){width="6.5in" height="5.145833333333333in"}

## 14.4 Reach

Reach limits are clearly dependent on the task, motion, and function to
be accomplished by the reach action. Limited reach data on standard
anthropometric positions are available in sources of static and dynamic
anthropometric data. Reach envelopes need to be constructed for actual
working positions and for explicit design purposes. Reach envelopes may
be related to a body reference point (such as the shoulder joint), to a
measurement apparatus point, or to a design point (such as a seat
reference point). This section provides design criteria and rules for
using reach data and constructing reach envelopes. \[Source:
NASA-STD-3000A, 1989\]

-   **14.4.1** **Task and body position effects.** The following task
    considerations shall be taken into account in order to establish
    reference points and to obtain the reach information needed to
    construct a reach envelope:

a.  the nature and requirements of the task to be performed (see also
    Paragraphs 14.3.1.2 and 14.4.3 for the nature of the reach task),

b.  body position while reaching (standing, seated, seat back and seat
    pan angles, and others),

c.  whole body movement capabilities and restraints (seat belts,
    harnesses, necessary and permitted movements of the torso),

d.  design purposes such as: to accommodate the appropriate portion of
    the population, to enhance task performance, or to avoid striking
    reachable surfaces, and

e.  equipment locations that interfere with reach, vision or
    intercommunications. \[Source: NASA-STD-3000A, 1989\]

-   **14.4.2 Reach envelope data collection.** Designers and human
    factors specialists should understand that reach envelope
    measurement data are often related to the data collection procedures
    and apparatus. Often data can be found or should be collected to
    relate the design reference point of concern to the reach
    capabilities of the actual users. Another factor in data collection
    is the amount of whole body movement allowed. For example, consider
    bending the torso forward so that one or both shoulders no longer
    touch the seat back. \[Source: Roebuck, Kroemer, & Thomson, 1975\]

    **Example.** Exhibit 14.4.2 shows an example in which reach
    measurement is related to the seat reference point from a restrained
    shoulder level. In the left graph, a side view reference plane is
    shown, and in the right graph, a top view is shown in terms of reach
    angles. All measures and dimensions are relative to the apparatus.

[]{#__RefHeading___Toc31762906 .anchor}**Exhibit 14.4.2** Reach
envelopes in vertical and horizontal planes

![](media/image21.png){width="5.7555555555555555in" height="2.65in"}

**Discussion.** An issue surrounding the application of reach data is
how to relate static anthropometric reach dimensions, shoulder joint
points, data collection procedures and apparatus reference points, and
design reference points. Most reach measurements are made relative to an
apparatus reference point. A further complication is that the apparatus
and design seat reference point may not be the same or may not reflect
the same seat configurations (back and pan angles).

**Definition. Seat reference point** is a point in the mid-sagittal
plane where the seat back and seat pan intersect.

-   **14.4.3** **Reach envelope interaction with the reach task.** Reach
    envelope data shall be collected or modified for the tasks, motions,
    or functions to be accomplished by the reach. Exhibit 14.4.3 (a)
    defines some task demands (touch, grip, and grasp) that affect reach
    characteristics and measures. \[Source: Kroemer, Kroemer, &
    Kroemer-Elbert, 1990\]

> []{#__RefHeading___Toc31762907 .anchor}**Exhibit** **14.4.3 (a)**
> Touch, grip, and grasp functions

![](media/image22.png){width="1.1965277777777779in"
height="3.2118055555555554in"}

> []{#__RefHeading___Toc31762908 .anchor}**Exhibit** **14.4.3 (a)**
> **(continued)** Touch, grip, and grasp functions
> ![](media/image23.png){width="1.2458333333333333in"
> height="7.269444444444445in"}

**Discussion.** Fingertip touch results in the largest reach dimensions
appropriate for touch controls. Other grasp functions would reduce the
reach envelope. Two-handed operations, greater precision, and frequent
or continuous operation would necessitate locating the task closer to
the body. Bulky clothing could affect reach capabilities.

**Examples.** Exhibits 14.4.3 (b) and (c) present 5th percentile female
reach envelope data as examples of one possible presentation for such
data. The data represent right hand reach for a fingertip grasp task. In
Exhibit 14.4.3 (b) horizontal contours are shown at the 46 and 61 cm
levels.

[]{#__RefHeading___Toc31762909 .anchor}**Exhibit 14.4.3 (b)** Thumb and
forefinger grasp boundary data for females in the 46 cm and 61 cm
horizontal planes![](media/image24.png){width="5.524305555555555in"
height="5.236805555555556in"}

In Exhibit 14.4.3 (c) vertical planes are shown for the 0 and -15 cm
planes. For design use, data would be presented for other horizontal and
vertical planes. For this example, shoulders were restrained against the
seat.

[]{#__RefHeading___Toc31762910 .anchor}**Exhibit** **14.4.3 (c)** Thumb
and forefinger grasp boundary data for females in the 0 and -15 cm
vertical planes![](media/image25.png){width="5.669444444444444in"
height="5.405555555555556in"}

Three factors can affect three-dimensional reach envelopes: the effects
of different hand manipulation tasks, the effects of permitting torso
and shoulder movement, and the effects of the seat back angle of the
data collection apparatus. For instance, the Exhibit shows thumb and
forefinger grasp. Not shown is that fingertip touch reach would increase
by 7.0 cm (2.8 in) and full hand grasp reach would decrease by -5.5 cm
(2.2 in) from their fingertip grasp reach values.

Additional data also not shown in the Exhibit reveals that if the seat
back angle were changed from 13 degrees rearward (as shown in the
Exhibits) to the vertical position, that is to 90 degrees, then reach
measures in a horizontal plane from 0 degrees (arm straight forward and
horizontal) to 90 degrees to the right increase as follows:

a.  at 0 degrees, by 1.02 cm (.40 in);

b.  at 15 degrees, by 1.27 cm (.50 in);

c.  at 45 degrees, by .94 cm (.37 in);

d.  at 60 degrees, by .66 cm (.26 in); and

e.  at 90 degrees, by .25 cm (.10 in).

-   **14.4.4** **Strength or fine manipulation.** Tasks which require
    strength or fine manipulation, as well as repetitious tasks should
    be located well within the perimeter of the reach limit envelope.
    \[Source: NASA-STD-3000A, 1989\]

**Discussion.** The strength that can be exerted varies considerably
throughout the reach envelope. As was noted in the previous example, the
reach envelope varies with the type of grasp required in defining the
envelope. This rule points out that one may need to further accommodate
the task location by the strength, fine manipulation, or repetitive
nature of the tasks to be performed. In these cases, consider the
capabilities of the small (1st or 5th percentile) female user and also
provide sufficient space and adjustability to accommodate the large
male.

## 14.5 Human strength and handling capacity

The designer and human factors specialist needs to know the limits and
ranges of human strength to create designs that are within the
capabilities of potential users. If demands on human strength are too
high, inefficient and unsafe worker performance will result. If the
designer underestimates strength, unnecessary design effort and expense
may be incurred.

This section introduces muscle strength factors and provides criteria
and rules on control forces, as well as push and pull forces. This
section also provides supplemental criteria and rules on lifting and
carrying.

### 14.5.1 Muscle strength factors

The forces delivered by the human body depend on the contractile
strength of the muscles, and the mechanical advantages of the body lever
system with the joints serving as fulcra and the long bones serving as
levers.

Knowledge of some of the many factors that relate to muscular strength
may aid design personnel in understanding human physical capabilities.
In addition to the strength capabilities of various body members, other
factors include: (1) age, (2) endurance, (3) gender, (4) body build, (5)
body position, (6) handedness, (7) exercise, (8) diet and drugs, (9)
diurnal variation, and (10) emotional and fatigue states. Gender and
handedness are discussed below while strength limit factors are
presented in the criteria and rules throughout Section 14.5. \[Source:
Israelski: 1977\]

**Discussion.** In general, females are about 35 to 85% as strong as
males with varying differentials for various muscle groups. Gender
differences favor greater range in joint motion in females at all joints
except the knee. The preferred hand and arm are approximately 10%
stronger than the non-preferred hand and arm.

**Definitions.** There are three basic categories of strength: (1)
**static strength**, also known as isometric strength, which is steady
force exerted while the limbs are in a stationary or static position,
(2) **dynamic strength**, which is a force exerted by limbs moving in a
smooth manner over time, such as while lifting an object, and (3)
**explosive strength**, which is the application of peak amounts of
strength for short periods of time, usually periodically, such as in
running or sprinting.

### 14.5.2 Exerted forces

-   **14.5.2.1** **Maximum young male force or resistance for a
    control.** The maximum amount of force or resistance designed into a
    control should be determined by the greatest amount of force that
    can be exerted by the weakest person likely to operate the control.
    Control force limits, like most strength design limits, should be
    based upon the 5th percentile (or, for critical tasks, the 1st
    percentile) of the female user population. \[Source: MIL-HDBK-759B,
    1992; AFSC DH 1-3, 1980\]

    Exhibit 14.5.2.1 represents 80% of the maximum exertion forces for
    the 5th percentile male for the arm, hand and thumb. Since the
    experimental conditions used to collect the source data yielded
    maximum possible exertion values for young men, these values are
    were too high for design purpose. For design, one does not want to
    deliberately or consistently require maximum exertions. Thus these
    source values were reduced by 20% before applying them as design
    criteria. Male data should be selected based upon the body
    components involved in the specific exertion task. To estimate
    female strength, male data should be further reduced according to
    Paragraph 14.5.2.3. Females can apply most strength when torso,
    back, and legs are major contributors. Female upper body and arm
    strength are weakest (see also comparative lifting strength
    information Paragraph 14.5.2.3).

    **Discussion.** The maximum force that can be applied will depend on
    such factors as the type of control, the body member used to operate
    it, the position of this body member during control operations, the
    general position of the body, and whether or not support is provided
    by backrests.

[]{#__RefHeading___Toc31762911 .anchor}**Exhibit 14.5.2.1** Male muscle
strength of the arm, hand, and thumb for control forces (5th percentile
values)![](media/image26.png){width="5.552083333333333in"
height="3.5493055555555557in"}

[]{#__RefHeading___Toc31762912 .anchor}**Exhibit 14.5.2.1 (continued)**
Design criteria for male muscle strength of the arm, hand, and thumb for
control forces (5th percentile
values)![](media/image27.png){width="5.194444444444445in"
height="0.9736111111111111in"}

-   **14.5.2.2** **Increasing strength values.** Strength values shall
    be slightly increased if:

a.  a lifting yoke or other special harness is to be used,

b.  the object is unusually easy to handle,

c.  the required force must be applied infrequently or only for a few
    seconds, if more than one per 30 seconds, decrease by .30 or

d.  the working body parts are provided with suitable support. \[Source:
    MIL-HDBK-759B, 1992; MIL-STD-1472D, 1989; MIL-STD-1800A, 1990; AFSC
    DH 1-3, 1980\]

-   **14.5.2.3** **Comparative strength.** Research has produced little
    insight into the strength of women relative to men. The following
    strength relationships developed by the US Army Research Institute
    of Environmental Medicine should be used until better data becomes
    available:

a.  For upper extremities, females strength is 56.5% of men.

b.  For lower extremities, female strength is 64.2% of men.

c.  For trunk extremities, female strength is 66.0% of men.

**Explanation.** These numbers may serve as a design rule until more
information becomes available.

-   **14.5.2.4** **Preventing tremor in positive control performance.**
    Tremor is important in activities in which a body member is
    maintained in a precise position or motion (tasks involving fine
    continuous control, detailed drawing, tracking, tracing, cutting, or
    painting). The following features should be designed into systems or
    equipment, where applicable, to help reduce tremor and ensure
    positive control performance of fine detailed tasks:

a.  ensure that visual reference can be used,

b.  provide support of the body and the member involved, for example,
    the hand or arm,

c.  support the hand because tremor is less if the hand is 203.2 mm (8
    in) above or below the heart level, and

d.  provide mechanical friction in the control device to add enough
    resistance to movement to partially counteract the energy of the
    vibrations of the body member. \[Source: Israelski, 1977\]

**Definition and discussion. Tremor** is the oscillation of a body
extremity which may occur along with an effort to maintain a fixed
position or direction. The degree of tremor is measured by the distance
or number of departures from the fixed path or position per unit of
time. Tremor increases when (1) effort is made not to tremble, and (2)
fatigue is present. It is greatest in vertical motion, less in
front-to-back motion, and least in side-to-side motion.

### 14.5.3 Push and pull forces 

-   **14.5.3.1** **Horizontal direction of force.** Manual horizontal
    push and pull forces that are initially necessary to set an object
    in motion, or to sustain the motion over a period of time, should
    not exceed the values given in Exhibit 14.5.3.1. For the second or
    third person applying horizontal forces, the value in the Exhibit\'s
    first column should be doubled or tripled, respectively. For each
    additional person (beyond the third) another 75 percent of the force
    value in the first column should be added. \[Source: MIL-HDBK-759B,
    1992\]

    **Explanation.** The Exhibit shows maximum push and pull forces that
    a designer would be expected to use when appropriate body positions,
    support, and traction conditions are provided. Use of the maximum
    values shown in the Exhibit is predicated upon a suitable surface
    for force exertion (vertical with rough surface approximately 400 mm
    (15.75 in) wide and between 0.51 - 1.27 m (1.673 - 4.167 ft) above
    the floor) to allow force application with the hands, shoulders, or
    back.

> []{#__RefHeading___Toc31762913
> .anchor}![](media/image28.png){width="6.476388888888889in"
> height="4.270833333333333in"}**Exhibit 14.5.3.1** Horizontal push and
> pull forces that can be exerted

-   **14.5.3.2** **Vertical direction of force.** Required manual
    vertical static lift forces should not exceed the applicable 5th
    percentile peak or mean force values given in Exhibit 14.5.3.2.
    \[Source: MIL-HDBK-759B, 1992\]

    **Explanation.** Based upon NIOSH experience, the forces found in
    the source that studied young military personnel have been reduced
    by 20 percent (Exhibit 14.5.3.2). The mean forces given represent
    force over a three second interval, beginning two seconds after it
    reached a minimum value of 45 N provided that it continued to
    exceeded this minimum. Exhibit 14.5.3.2 reflects the higher of two
    trials for each condition.

> []{#__RefHeading___Toc31762914
> .anchor}![](media/image29.png){width="6.5in"
> height="8.59375in"}**Exhibit 14.5.3.2** Static muscle strength data
> for vertical pull exertions
>
> []{#__RefHeading___Toc31762915
> .anchor}![](media/image30.png){width="6.5in"
> height="8.614583333333334in"}**Exhibit 14.5.3.2 (continued)** Static
> muscle strength data for vertical pull exertions
>
> []{#__RefHeading___Toc31762916 .anchor}**Exhibit 14.5.3.2
> (continued)** Static muscle strength data for vertical pull exertions

![](media/image31.png){width="6.5in" height="8.614583333333334in"}

### 14.5.4 Lifting and carrying

There are three major muscular components of weight-lifting: (1) the
legs, (2) the arms-back, and (3) the arms. In efficiently lifting
objects to different heights, these components are combined in different
ways. Specifically, lifting objects to about knee height involves
primarily the use of the leg component, while objects lifting to about
waist level involves a combination of leg and arm-back components.
Lifting objects to shoulder level or higher requires the use of all
three components.

-   **14.5.4.1** **Lifting and carrying limits.** Data, criteria, and
    rules in Chapter 4 shall be used to establish recommended maximum
    weights to be lifted and carried by one and two people. \[Source:
    AFSC DH 1-3, 1980; Israelski, 1977; NASA-STD-3000A, 1989\]

## 14.6 Wheelchair anthropometrics

-   **14.6.1 Maximum high forward reach in a wheelchair**. If the clear
    floor space only allows forward approach to an object, the maximum
    high forward reach allowed shall be 48 in (1220 mm)(see Exhibit
    14.6.1), unless there is an obstruction projecting 20 to 25 in (510
    to 635 mm), in which case it is 44 inches (1120mm). \[Source: UFAS,
    1988\]

-   **14.6.2 Minimum low forward reach in a wheelchair**. If the clear
    floor space only allows forward approach to an object, the minimum
    low forward reach shall be 15 in (380 mm)(See Exhibit 14.6.1).
    \[Source: UFAS, 1988\]

-   **14.6.3 Maximum reach over obstruction in a wheelchair**. The
    maximum forward reach over an obstruction with knee space below
    shall be 635 mm (25in) (see Exhibit 14.6.1). \[Source: UFAS, 1988\]

[]{#__RefHeading___Toc31762917 .anchor}**Exhibit 14.6.1** Forward reach
from a wheelchair.

![](media/image32.png){width="5.25in" height="2.34375in"}

[]{#__RefHeading___Toc31762918 .anchor}**Exhibit 14.6.1 (continued)**
Forward reach from a wheelchair

![](media/image33.png){width="4.946527777777778in"
height="3.0208333333333335in"}

-   **14.6.4 Maximum side reach in a wheelchair**. If the clear floor
    space allows only parallel approach to an object by a person in a
    wheelchair, the maximum high side reach allowed shall be 54 in (1370
    mm)(see Exhibit 14.6.4), unless there is an obstruction projecting
    20 to 25 in (510 to 635 mm), in which case it is 46 inches (1170mm).
    \[Source: UFAS, 1988\]

-   **14.6.5 Minimum side reach in a wheelchair**. If the clear floor
    space allows only parallel approach to an object by a person in a
    wheelchair, the minimum side reach allowed shall be no less than 9
    in (230 mm)(see Exhibit 14.6.4) above the floor. \[Source: UFAS,
    1988\]

[]{#__RefHeading___Toc31762919 .anchor}**Exhibit 14.6.4** Side reach
from a wheelchair.

![](media/image34.png){width="2.25in" height="2.625in"}
![](media/image35.png){width="2.852777777777778in"
height="2.7506944444444446in"}

-   **14.6.6** **Wheelchair dimensions.** Designers and human factors
    specialists shall use the data in Exhibit 14.6.6 for design problems
    involving wheelchair users. This Exhibit presents wheelchair
    dimension data. \[Source: UFAS, 1988\]

[]{#__RefHeading___Toc31762920 .anchor}**Exhibit 14.6.6** Wheelchair
dimensions.

The height of the handle is at 36 inches (915 mm). The armrest is 30
inches (760 mm) high. Eye level is between 43 and 51 inches (1090-1295
mm). The lap is at 27 inches (685 mm). The seat is at 19 inches (485
mm). The toe is at 8 inches (205 mm). The width of a wheelchair measured
from the outer edges of the back wheels is 26 inches (660 mm); the
length is 42 inches (1065 mm); the width measured from the outer edges
of the footrests is 18 inches (455 mm). The toes extend 6 inches (150
mm) beyond the edge of the footrests.

Note: Footrests may extend further for very large people.

![](media/image36.png){width="2.1458333333333335in" height="3.40625in"}

[]{#__RefHeading___Toc31426353 .anchor}Glossary

**Abduction -** Movement away from the midline of the body.

**Adduction** - Movement toward the midline.

**Anthropometry** - The scientific measurement and collection of data
about human physical characteristics and the application (engineering
anthropometry) of these data in the design and evaluation of systems,
equipment, manufactured products, human- made environments, and
facilities. Biomechanics describes the mechanical characteristics of
biological systems, in this case the human body, in terms of physical
measures and mechanical models. This field is interdisciplinary (mainly
anthropometry, mechanics, physiology, and engineering). Its applications
address mechanical structure, strength, and mobility of humans for
engineering purposes.

**Biomechanics -** Describes the mechanical characteristics of
biological systems, in this case the human body, in terms of physical
measures and mechanical models.

**Circumduction -** A continuous circular movement of a limb.

**Correlation coefficient or \"r\" value -** Describes the degree to
which two variables vary together (positive correlation) or vary
inversely (negative correlation). The correlation coefficient, \"r\",
has a range of values from +1.0 (perfect positive correlation) through
-1.0 (perfect negative correlation). Multiple correlation involves the
predictable relationship of two or more variables with another criterion
variable (such as a composite measurement value).

**Depression -** The lowering of a body member from its normal position.

**Design limits approach -** A method of applying population or sample
statistics and data about human physical characteristics to a design so
that a desired portion of the user population is accommodated by the
design. The range of users accommodated is a function of limits used in
setting the population portion.

**Dynamic strength** - A force exerted by limbs moving in a smooth
manner over time, such as while lifting an object.

**Elevation -** The raising of a body member from a normal position.

**Explosive strength -** The application of peak amounts of strength for
short periods of time, usually periodically, such as in running or
sprinting.

**Extension -** The straightening of a limb or an increase in the angle
between parts of the body.

**Flexion -** The process of bending a limb or decreasing the angle
between parts of the body.

**Human physical and associated measurement characteristics -** Refers
to specific physical, mobility, or strength features of human users and
to the explicit way that a human feature or capability is measured for
use as general anthropometric or biomechanics data or as data for a
specific design.

**Lateral rotation -** Turning away from the midline of the body.

**Medial rotation -** Turning toward the midline of the body.

**Percentile statistic -** Determined by ranking all data values (using
the applicable measurement values related to the selected human physical
characteristic) in the sample and determining the percentage of data
that fall at or below a specific datum value.

**Percentile value** **(or point) of the selected datum -** The
percentage of data that fall at or below a specific datum value.

**Pronation -** The downward turning of the palm.

**\"R\", The multiple correlation coefficient --** Is a statistical
number that indicates the strength of the relationship between sets of
data. The correlation coefficient can be between --1 and +1 with a
correlation of \|1\| indicates a perfect correlation. The closer the
number is to \|1\|, the stronger the relationship between the two sets
of data. It is recommended that only correlations with strong predictive
values be used (that is where r or R is at least or greater than
\|.7\|).

**Seat reference point -** A point in the mid-sagittal plane where the
seat back and seat pan intersect.

**Static strength -** Also known as isometric strength, which is steady
force exerted while the limbs are in a stationary or static position.

**Supination** - Is the upward turning of the palm, or lying face up.

**Tremor -** The oscillation of a body extremity which may occurring
along with an effort to maintain a fixed position or direction. The
degree of tremor is measured by the distance or number of departures
from the fixed path or position per unit of time. Tremor increases when
(1) effort is made not to tremble, and (2) fatigue is present. It is
greatest in vertical motion, less in front-to-back motion, and least in
side-to-side motion.

[]{#__RefHeading___Toc31426354 .anchor}References

Department of Defense. (1989). *Human engineering design criteria for
military systems, equipment and facilities* (MIL-STD-1472D).
Philadelphia, PA: Navy Publishing and Printing Office.

Department of Defense. (1990). *Human engineering performance
requirements for systems* (MIL-STD-1800A). Philadelphia, PA: Navy
Publishing and Printing Office.

Department of Defense. (1991). *Anthropometry of U.S. military
personnel* (DOD-HDBK-743A). Philadelphia, PA: Navy Publishing and
Printing Office.

Department of Defense. (1992). *Human factors engineering design for
army materiel* (MIL-HDBK-759B). Philadelphia, PA: Navy Publishing and
Printing Office.

Department of the Air Force. (1980). *Human factors engineering* (AFSC
DH 1-3). Wright-Patterson AFB, OH: ASD/ENESS.

Israelski, E. W. (1977). *Human factors handbook for telecommunications
product design*. Whippany, NJ: AT&T Bell Laboratories.

Johnson, R. F. (1984). *Anthropometry of clothing of U.S. Army ground
troops and combat vehicle crewmen* (NRDEC 54-84/034). Natick, MA: United
States Army Natick Research, Development, & Engineering.

Kroemer, K. H. E., Kroemer, H. J., & Kroemer-Elbert, K. E. (1990).
*Engineering physiology: Bases of human factors/ergonomics*. New York:
Van Nostrand Reinhold.

National Aeronautics and Space Administration. (1989). *Man-systems
integration standards* (NASA-STD-3000A). Houston, TX: National
Aeronautics and Space Administration.

Roebuck, J. A., Kroemer, K. H. E., & Thomson, W. G. (1975). *Engineering
anthropometry methods*. New York: Wiley.

Uniform Federal Accessibility Standard (UFAS). (1988). 41 CFR Ch 101
subpart 101-19.6 Appendix A. Available online from
[www.access-board.gov]{.underline}.

[]{#__RefHeading___Toc31426355 .anchor}Index

A

Abduction 14-29

Adduction 14-29

Adjustable dimensions 14-5

Anthropometric and biomechanics data 14-13

Anthropometrics

bivariate distribution data 14-12

correlation data 14-11, 14-12

distribution 14-11

representative sample 14-4

rule information 14-4

variability factors 14-13

Anthropometry 14-1

B

Biomechanics 14-1

Bivariate distribution data 14-12

Body slump 14-13

C

Carrying 14-52

Circumduction 14-29

Clearance dimension 14-5

Control force limits 14-43

Correlation coefficient or \"r\" value 14-12

Correlation data, use of 14-12

Critical life support equipment 14-5

D

Data usage 14-13

Depression 14-29

Design errors 14-6

Design limits 14-4

Direction of force

horizontal 14-47

vertical 14-48

Dynamic (mobile) body characteristics 14-28

Dynamic dimensions 14-13

E

Effects of clothing 14-9

Elevation 14-29

Exerted forces 14-43

Extension 14-29

F

Flexion 14-29

Foreign populations 14-13

G

Gaussian distribution 14-11

H

Human strength and handling capacity 14-42

muscle strength factors 14-42

push and pull forces 14-47

J

Joint motion 14-29

L

Lateral rotation 14-29

Lifting 14-52

Lifting and carrying limits 14-52

Limiting dimension 14-5

M

Medial rotation 14-29

Mobile body characteristics *See* Dynamic body characteristics

Multiple correlation data, use of 14-12

P

Population extremes

use of 14-3

Pronation 14-29

R

Range of motion 14-33

Reach 14-35

wheelchair 14-52, 14-53, 14-55

Reach envelope 14-37

Reach envelope data 14-8, 14-36

S

Seat reference point 14-36

Sizing determinations 14-5

Static dimensions 14-13

Strength

comparative 14-46

dynamic 14-42

explosive 14-42

female 14-42

static 14-42

values 14-45

Supination 14-29

T

Task considerations 14-14, 14-35

Thumb and forefinger grasp 14-39

Tremor 14-46

Trunk movement 14-28

U

User population 14-2

V

Variability factors 14-13

W

Wheelchair anthropometrics 14-52

Whole body motion 14-28