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Designing and selecting long-duration seating for the aging.

New design considerations for an important factor in residents' everyday lives

Seating design and selection is a critical component of the success of any nursing home environment. The design of a comfortable chair for the elderly has fascinated designers and human factors research specialists for many years. Barbara Laging|1~ published one of the earliest articles discussing chair comfort related to aging. Correspondingly, industry has produced many examples of seating for the elderly for the markets both of the United States and Europe. Meanwhile, significant "human factors" work on the study of appropriate seating dynamics has gone on for some time on both continents.|2-4~

This article will focus specifically on the most current directions for appropriate lounge seating and issues related to older occupants' sitting for long periods of time. Technology relating to appropriate long-duration seating has developed considerably in the past ten years. These developments greatly enhance comfort when aging adults occupy seating for long periods of time and, additionally, offer greater chair variability to accommodate a wider range of adult body dimensions.

First and foremost, it is important to understand that there is a distinction between the seating behaviors of older people and of younger adults. The decision to occupy a chair is partly determined by the ease with which an individual can sit down and get up from it. Younger adults with ample strength in the upper legs, full flexibility in the knee and hip joints, and no degeneration of muscle and bone bone through pathological loss (arthritis, arteriosclerosis) are able to move into and out of chairs easily. Aged adults, especially many older than 70, cannot enter and egress chairs as easily. Many aged adults in advanced years over an age of 80 have two or more pathological afflictions -- usually including arthritis -- and experience significant difficulty moving into and from seating, as well as increased discomfort while they are seated.

Gerontological researchers have shown that a comfortable chair becomes a "control center"|5~ for older people: a place from which they can monitor their environment and involve themselves in activity for long periods of time. Additionally, a chair is part of personal possession and helps define a sense of personal place within an environment.|6,7~ In essence, when older people decide to be seated in a comfortable chair, they are choosing a place with meaning and strategic position within the environment -- and they are likely to sit for a long period of time.

Unfortunately, many older people while sitting feel discomfort faster than younger people do because they do not have the cushion of tissue over the base of the hips that they had in youth. Sixty percent of the weight of the torso is placed upon the two ischial tuberosities -- two boney protuberances on the base of the hips. These two projections of bone bear down and scrub the tissue on the buttocks, causing discomfort. If the seated durations are long enough, the pressure on this portion of the buttocks can lead to the formation of decubitus ulcers or pressure sores. In addition, if the chair cushion is not properly designed, the load on the spinal column presses the top of the pelvis, forcing this bone to rotate forward. As the pelvis rotates, the tissue on the buttocks is placed in a shear load -- or a scrubbing frictional motion -- that is one of the primary causes of pressure sores while seated among institutional older patients.

When seat cushions seem hard to an older person, they will build up the surface with soft materials such as pillows, blankets, towels -- literally anything that falls to hand to make the seat comfortable. This is usually ineffective because the problem lies in the lack of seat suspension. Seat suspension is the use of both a spring and damping medium working in combination to prevent bottoming or the stopping of deflection or extension downward into the seat cushion. New elasticized webbing materials used as spring media and medium density polyurethane foams used as damping or cushioning materials will alleviate this problem. Meanwhile, ramming, i.e. adding height to the profile contour of the leading edge of the seat cushion, will help to prevent rotation of the pelvis and the shear load problem.

Another consideration that has caused difficulty in chair design and manufacturing is the wide variation of body sizes and seated angle preferences among male and female elderly. Men generally prefer more recline in the back angle of a chair than do women. The difference can be as great as 114 degrees from the horizontal for men and 103 degrees for women.|8~ The feel difference in variation in back angle is significant -- and differing preferences are strongly held among men and women.

The standard dimension for seat depth from the leading edge of the seat cushion to the seat back is 17 inches. The height of the cushion off the floor is recommended at 17 inches. However, these dimensions are based upon modal data: characteristics of the largest number of adults in one category of dimensional relationships. Many more adults deviate from these characteristics and are not accommodated by these standards.

Accommodation of a greater range of users can be accomplished by varying the height of the cushion and the position and angle of the seat back. Today, the most truly advanced lounge seating available for the elderly permits variability in seated angle and seat height and depth of cushion. Seated height should vary from 16 inches to 19 inches from the floor to the top of the seat cushion. Seat depth should vary from 17 inches to 19 inches at the very least. Variability should also include back rest angle that should vary from a closure of 103 degrees to 114 degrees.

Finally, any seating designed for the aging population must have armrests -- and appropriately designed armrests, at that. Adults over the age of 70 have lost an average of 40% of the upper leg strength necessary to lift upward and away from a chair.|9~ In order to expedite chair egress, it is necessary to extend the leading edge of the armrest beyond the leading edge of the cushion.|10,11~ This change permits the aging chair occupant to use arm strength effectively to supplement leg strength and pull the center of gravity of the torso over the heels of the feet to stand, rise and walk away.

In conclusion, lounge seating design has been an area of development that has benefited from advancement in technology and in human factors research over the past ten years. More information is at hand today that greatly improves seating for those elderly who are moderately disabled, as well as for those who require support and care. For the nursing home resident, the lounge chair is an important part of daily life, and its role in supporting comfort, positive behavior and independence should not be underestimated or overlooked.


1. Laging B. Furniture design for the elderly, in Rehabilitation Literature. Washington, DC, U.S. Department of Public Health, 1966; 180(27):130-40.

2. Akerblom B. Chairs and sitting, in Floyd WF, Welford AT (eds): Symposium on Human Factors in Equipment Design. London, Lewis Publishers, 1954; 29-35.

3. Grandjean E, Boni A, Kretzchmar H. The development of a rest chair profile for healthy and nostalgic people, in Grandjean E (ed): Proceedings of the Symposium on Sitting Posture. London, Taylor and Francis Publishers, 1969; 193-201.

4. Schmidke H. Ergonomic data for the design of body support, in Schmidke H ed): Ergonomic Data for Equipment Design. New York, Plenum Press, 1981; 159-78.

5. Lawton M. Vulnerability and socioenvironmental factors, in Harrel Z, Ehrlich P, Hubbard R (eds): The Vulnerable Aged: People Services and Policies. New York, Springer Publishing Company, 1990; 104-15.

6. Howell ST. Aging and social learning of a new environment, in Shimada HOK (ed): Recent Advances in Gerontology: Proceedings of the XI International Congress of Gerontology. Tokyo, International Congress of Gerontology Series Number 469, 1978; 371-6.

7. Howell ST. Designing for Aging: Patterns of Use. Massachusetts, Massachusetts Institute of Technology Press, 1980.

8. Zacharkow D. Posture, Sitting, Standing, Chair Design and Exercise. Springfield, Illinois, Charles C. Thomas Publishers, Inc., 1988.

9. Teague MA. Leisure product development: Outlining the need, in Independent Living Environments for Seniors and Persons with Disabilities: Proceedings and Directions '91. Winnipeg, Manitoba, Canada, Canadian Aging and Rehabilitation Product Development Corporation, 1991.

10. Koncelik JA. Recommendations for seating, furnishings and beds, in Designing the Open Nursing Home. Stroudsburg, PA, Hutchinson and Ross Publishers, 1986; 119-41.

11. Koncelik JA. Residential furniture and the elderly, in Aging and the Product Environment. Stroudsburg, PA, Hutchinson and Ross Publishers, 1983; 113-20.

Joseph A. Koncelik, Bach.I.D., M.A. is Professor, Department of Industrial Design, the Ohio State University, and Vice President for Research and Development, Zoetech, Inc. He is the author of over 50 publications on education and on design for the aging. Mr. Koncelik has received awards of excellence for his research from the National Endowment for the Arts and for his design work from the Institute of Business Designers and the Industrial Designers Society of America. He is listed in Who's Who in America.
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Title Annotation:seat designs for the aged
Author:Koncelik, Joseph A.
Publication:Nursing Homes
Date:Oct 1, 1993
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