Anthropometrics

Standing Working Heights Sitting Working Heights Reaches Gender Strength Differences Postural Strength Differences

Design so the large can fit, the small can reach and the weak can lift, lower, push, pull and carry. Anthropometrics

Anthropometric Measurements Anthropometrics looks at the variability between people and utilizes principles of statistics to do this.

Percentiles Body dimensions can be plotted on a graph with the measurements on the horizontal x axis increasing toward the right from the zero point. The frequency of occurrences is plotted on the vertical y axis, increasing toward the top from the zero point.

Anthropometrics and Design It is not customary to design for everyone. The military has chosen to exclude 5% at the small end of the curve and 5% at the large end of the curve, thereby accommodating 90 of the measured population in the Military Standards

Anthropometric Measurements

Dimension5 th 50 th 95 th MaleFemaleMaleFemaleMaleFemale Standing Vertical Grip Reach Standing Forward Grip Reach Height Eye Height Shoulder Height Elbow Height Sitting Vertical Grip Reach Sitting Height Sitting Eye Height Sitting Elbow Height Adapted from: Pheasant, Stephen, (1996). “Bodyspace: Anthropometry, Ergonomics and the Design of Work”, Bristol, PA: Taylor & Francis.

Anthropometrics 50th Percentile Male Reach = 30.9” 50th Percentile Female Reach = 28.0” 95 th Percentile Male Reach = 33.3” 5 th Percentile Female Reach = 25.8”

Things To Consider Determine what body dimensions are relevant. Determine what population group is relevant. Use the anthropometric data as a guide and a place to start. It does not replace employee input. Just because something does not fall within anthropometric guidelines does not mean it is necessarily a significant ergonomic risk. When designing workstations or equipment, you will never be able to accommodate everyone. Try to accommodate as much of the population as you can, given the space and cost parameters you have to work within.

Standing Workstation Height NIOSH 1997 Publication, Elements of Ergonomics Programs

Horizontal Reach Envelopes NIOSH 1997 Publication, Elements of Ergonomics Programs

Choosing Working Postures Standing – For heavy, bulky loads – When frequent movement is required –When there is no knee room under the equipment –Where there is limited front-rear space

Choosing Working Postures Sitting –For accurate control, fine manipulation. –For continuous light manipulation work. –For close visual work with prolonged attention. –For limited headroom, low work heights.

Sagittal Reach Envelopes As the arm moves though its normal range of motion it creates an arc and creates the primary reach arc and the secondary reach arc. The primary reach arc places minimal stress on the shoulder and low back. The secondary reach envelope can place stress on the shoulder and increases stress on the low back. Reaching beyond the secondary reach arc will require forward bending and significantly increases stress on the low back.

Strength Variability: Females vs. Males Body PartPercent Strength of Females vs. Males Arms60 % Trunk64% Legs72%

Male Grip Strength & Age Male (lbs) Percentiles Mean Adapted from: Australian Fitness Norms, 1992, The Health Development Foundation, Adelaide, p.32.

Female Grip Strength & Age Female (lbs) Percentiles Mean Adapted from: Australian Fitness Norms, 1992, The Health Development Foundation, Adelaide, p.32.

Posture Dependent Strength Variability

Ear-Eye-Line The EE line is determined by using the ear-hole and the junction of the eyelids. The EE line describes the posture of the head and serves as reference for the angle of the line of sight.

Line of Sight The line of sight connects the pupil with the visual target. Eye movement within about 15 degrees above and below the average line-of-sight angle is still comfortable.

Practical Application of Anthropometrics This video clip from NASA shows how Anthropometri c data was applied to the design of equipment.