Anthropometry and Range of Motion

Anthropometry Introduction Definition The study of the dimensions and certain other physical characteristics of the human body It is derived from the Greek words ‘anthropos’ (man) and ‘metron’ (measure). Critical element in workplace design Accommodate users Large volumes of data available Different sexes, ages, and geographical regions Freivalds A., (2009) . Niebel’s Methods, Standards, and Work Design. McGraw-Hill

Anthropometry. This is the branch of ergonomics that deals with body shape, size, weight, strength, proportions, and working capacity of the human body. It is the technology of measuring human physical traits such as size, reach, mobility and strength. It is the study of human body measurement for use in anthropological classification and comparison.

ANTHROPOMETRICS Achieving good physical fit cannot accept one mean feature when one considers the range in human body sizes across the population. The science of anthropometrics provides data on dimensions of the human body in various postures. Biomechanics considers the operation of the muscles and limbs, and ensures that working postures are beneficial, and that excessive forces are avoided.

Anthropometric side of ergonomics is: Matching the physical form and dimensions of the product or work space to those of it’s user; and Matching the physical demands of the working task to the capacities of the work force.

TYPES OF ANTHROPOMETRIC DATA Structural Anthropometric Data Functional Anthropometric Data

1.STRUCTURAL ANTHROPOMETRIC DATA Structural anthropometric data are measurements of the bodily dimensions of subjects in fixed (static) positions. EXAMPLES To specify furniture dimensions. To determine ranges of clothing sizes.

2.FUNCTIONAL ANTHROPOMETRIC DATA Functional anthropometric data are taken under conditions in which the body is engaged in some physical activities. EXAMPLES Design of crane cabs Design of vehicle interiors

USES OF ANTHROPOMETRIC DATA To fit the task to the person. To avoid physical mismatches between dimensions of equipment and products and the corresponding user. To design for variability in people and not for the average. ADVANTAGES OF ANTHROPOMETRIC DATA Increase accuracy Reduce Fatigue Better comfort Reduce chance of injuries Time management

ANTHROPOMETRY THERE ARE SOME STEPS TO CONSIDER: Decide who you are designing for Ex. Designing an office chair, consider dimensions for adults of working age not those for children or the elderly. Designing a product for the home, such as a kettle, user group would include everyone except young children

Decide which body measurements are relevant Ex. designing a mobile phone, consider the width and length of the hand, the size of the fingers grip diameter. Ne need to be interested in the height or weight of the user (although the weight of the phone might be important!) 3. Decide whether you are designing for the 'average' , extremes or other? (Anthropometric design rules)

Anthropometry Introduction Factors affecting body dimensions Human Variation Age Gender Ethic Origin Long-term population Shifts Clothing and Personal Equipment Kroemer, K.H.E.., Grandjean, E. (1997) Fitting the Task to the Human. Taylor & Francis

Anthropometry Introduction Body dimensions is based on no clothes. Clothing will add to physical dimensions Footwear and gloves can affect anthropometric dimensions Allowances should be made to compensate Pheasant, S., Haslegrave, C., (2006). Bodyspace: Anthropometry, Ergonomics, and the Design of Work. Taylor and Francis Group.

1.BODY DIMENSIONS Minimum dimensions A door handle must not be lower than the highest standing knuckle height in a population so that all users can open the door without stooping.

MINIMUM DIMENSIONS CONT….. The width of a chair must be no narrower than the hip breadth of a large woman.

MINIMUM DIMENSIONS CONT….. The height of a doorway must be no lower than the stature of a tall man (plus an allowance for clothing and shoes).

MAXIMUM DIMENSIONS A door lock must be no higher than the maximum vertical reach of a small person.

MAXIMUM DIMENSIONS CONT… Seat heights and depths must not exceed the maximum height and buttock–knee lengths of small users.

Anthropometric design rules 1. Design for the individual Best design BUT very expensive Design dimensions to fit a specific individual Example: Design of a space suit 2. Design for an adjustable range From 5th percentile (small female) to 95th percentile (large male) Adjust to fit a wider range of people Best BUT expensive Example: Design of industrial chairs 3. Design for extremes For the small female (5th percentile) OR the large male (95th percentile) Examples: Design of the door post - for the large male Design of a shelf - for the small female 4. Design for the average Not recommended Design for 50th percentile Only when used for a short duration Example: Design counter at the supermarket or a public place Freivalds A., (2009) . Niebel’s Methods, Standards, and Work Design. McGraw-Hill

EXAMPLES Easy reach Vehicle dashboards, Shelving What is it that you are aiming for with your design? Design examples: Examples of measurements to consider: Users that your design should accommodate:  Easy reach Vehicle dashboards, Shelving Arm length, Shoulder height Smallest user: 5th percentile Adequate clearance to avoid unwanted contact or trapping Manholes, Cinema seats Shoulder or hip width, Thigh length Largest user: 95th percentile A good match between the user and the product Seats, Cycle helmets, Pushchairs Knee-floor height, Head circumference, Weight Maximum range: 5th to 95th percentile A comfortable and safe posture Lawnmowers, Monitor positions, Worksurface heights Elbow height, Sitting eye height, Elbow height (sitting or standing?) Easy operation Screw bottle tops, Door handles, Light switches Grip strength, Hand width, Height Smallest or weakest user: 5th percentile

Range of Variability of Voluntary and Passive Movements of Body Members (in degrees)   Voluntary Passive Body Member and Movement Lower Limit Upper Limit Mean SD Lower Limit Upper Limit Mean SD Head Rotation (right) 51 95 77 16.1 72 114 97 14.1 Arm at Shoulder                 Flexion (forward) 164 191 179 7.2 171 185 185 6.4 Extension 40 71 55 10.1 51 68 68 11.9 Abduction(side) 113 154 129 11.7 116 137 137 12.4 Forearm at elbow Flexion (bend) 126 150 138 8.5 129 22 22 7.6 Pronation (turn in) 59 139 91 25.8 76 105 105 22.1 Supination (turn out) 82 114 99 11 93 114 114 15.2 Hand at wrist Flexion 73 110 95 10.6 80 106 106 13 Extension 32 80 54 15.2 67 92 92 13 Abduction 15 49 27 7 26 40 40 6.1 Adduction 52 79 66 8.1 64 74 74 7.4

Range of Variability of Voluntary and Passive Movements of Body Members (in degrees)   Voluntary Passive Body Member and Movement Lower Limit Upper Limit Mean SD Lower Limit Upper Limit Mean SD Thigh at hip joint Flexion (forward) 63 119 98 17 99 112 112 9.2 Extension 26 70 48 12.9 41 56 56 10.4 Abduction (side) 39 98 70 17 65 79 79 10.4 Internal Rotation 39 80 61 15.2 45 73 73 16.6 External Rotation 24 48 37 6.6 39 46 46 6.7 Leg at knee joint Flexion (bending) 118 136 127 6.7 129 140 140 Foot at ankle Planter Flexion (bend up) 18 43 28 7.4 22 36 36 9.9 Dorsal Flexion 25 46 37 6.6 35 44 44 4.7

Guidelines for Conversion of Standard Measuring Postures to Functional Stances and Motions To consider Do this Slumped standing or sitting Deduct 5 – 10% from appropriate height measurements Relaxed trunk Add 5 – 10 % to trunk circumference Wearing shoes Add approximately 25 mm to standing and sitting heights; more for high heels Wearing light clothing Add about 5% to appropriate dimensions Wearing heavy clothing Add 15% or more to appropriate dimensions (Note: Mobility may be strongly reduced be heavy clothing) Extended reaches Add 10% or more for strong motions of the trunk Use of hand tools Center of handle is at about 40% of hand length, measured Comfortable seat height Add or subtract up to 10% to or from standard seat height Kroemer, K.H.E.., (2008) Fitting the Task to the Human, 6th Ed. Taylor & Francis.

Anthropometry Statistical Basis for Anthropometry Statistical procedure for anthropometric data Yield a wealth of information Assist in calculating percentiles and ranges of homogenous or composite groups Anthropometric dimensions are normally distributed May be described by the mean and standard deviation Accommodate users Large volumes of data available Different sexes, ages, and geographical regions Freivalds A., (2009) . Niebel’s Methods, Standards, and Work Design. McGraw-Hill

Anthropometry Statistical Basis for Anthropometry Kth percentile Definition A value such that k percent of the data values are at or below this value and 100 – k percent of the data values are at or above this value Percentiles provide a basis for estimating the proportion of a population accommodated by a design Normal transformation z = standard normal value corresponding to population cumulative density X = value of measured dimension μ = average, or mean of dimension for population SD = standard deviation of population Freivalds A., (2009) . Niebel’s Methods, Standards, and Work Design. McGraw-Hill

Anthropometry Standard standing posture – subject stands erect looking straight ahead, arms to their side Standard standing posture – erect on a horizontal flat surface and looking straight ahead Kroemer, K.H.E.., Grandjean, E. (1997) Fitting the Task to the Human. Taylor & Francis

Anthropometry Selected Anthropometric Measurements for US Adults (All dimensions in mm, except body weight given in kg) Source: Bodyspace by Stephan Pheasant. Copyright @1998 by Taylor and Francis

If we plotted a graph of the heights (or most other dimensions) of our group of people, it would look similar to this: NUMBER OF PEOPLE HEIGHT

The graph is symmetrical – so that 50% of people are of average height or taller, and 50% are of average height or smaller. NUMBER OF PEOPLE HEIGHT

The graph tails off to either end, because fewer people are extremely tall or very short.

To the left of the average, there is a point known as the 5th percentile, because 5% of the people (or 1 person in 20) is shorter than this particular height.

The same distance to the right is a point known as the 95th percentile, where only 1 person in 20 is taller than this height.

REFERENCE Bridger R.S(2008).Introduction To Ergonomics, 3rd Edition. http://en.wikipedia.org/wiki/Anthropometry http://personal.cityu.edu.hk/~meachan/Online%20Anthr opometry/Chapter1/Ch1-7.htm IME3420 Lecture Notes by Tycho Fredericks, PhD and Anil Kumar, PhD.