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Chair
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A chair is a type of seat, typically designed for one person and consisting of one or more legs, a flat or slightly angled seat and a back-rest. It may be made of wood, metal, or synthetic materials, and may be padded or upholstered in various colors and fabrics.
Chairs vary in design. An armchair has armrests fixed to the seat;[1] a recliner is upholstered and features a mechanism that lowers the chair's back and raises into place a footrest;[2] a rocking chair has legs fixed to two long curved slats; and a wheelchair has wheels fixed to an axis under the seat. [3]
Etymology
[edit]Chair comes from the early 13th-century English word chaere, from Old French chaiere ("chair, seat, throne"), from Latin cathedra and ultimately Greek καθέδρα kathedra ("seat, throne").[4][5][6]
History
[edit]

The chair has been used since antiquity, although for many centuries it was a symbolic article of state and dignity rather than an article for ordinary use. "The chair" is still used as the emblem of authority in the House of Commons in the United Kingdom[8] and Canada,[9] and in many other settings. In keeping with this historical connotation of the "chair" as the symbol of authority, committees, boards of directors, and academic departments all have a 'chairman' or 'chair'.[10] Endowed professorships are referred to as chairs.[11] It was not until the 16th century that chairs became common.[12] Until then, people sat on chests, benches, and stools, which were the ordinary seats of everyday life. The number of chairs which have survived from an earlier date is exceedingly limited; most examples are of ecclesiastical, seigneurial or feudal origin.[citation needed]
Chairs have existed since at least the Early Dynastic Period of Egypt (c. 3100 BC). They were covered with cloth or leather, were made of carved wood, and were much lower than today's chairs – chair seats were sometimes only 10 inches (25 cm) high.[13] In ancient Egypt, chairs appear to have been of great richness and splendor. Fashioned of ebony and ivory, or of carved and gilded wood, they were covered with costly materials, magnificent patterns and supported upon representations of the legs of beasts or the figures of captives. Generally speaking, the higher ranked an individual was, the taller and more sumptuous was the chair he sat on and the greater the honor. On state occasions, the pharaoh sat on a throne, often with a little footstool in front of it.[13]
The average Egyptian family seldom had chairs, and if they did, it was usually only the master of the household who sat on a chair. Among the better off, the chairs might be painted to look like the ornate inlaid and carved chairs of the rich, but the craftsmanship was usually poor.[13]
The earliest images of chairs in China are from 6th-century Buddhist murals and stele, but the practice of sitting in chairs at that time was rare. It was not until the 12th century that chairs became widespread in China. Scholars disagree on the reasons for the adoption of the chair. The most common theories are that the chair was an outgrowth of indigenous Chinese furniture, that it evolved from a camp stool imported from Central Asia, that it was introduced to China by Christian missionaries in the 7th century, and that the chair came to China from India as a form of Buddhist monastic furniture. In modern China, unlike Korea or Japan, it is no longer common to sit at floor level.[14]
In Europe, it was owing in great measure to the Renaissance that the chair ceased to be a privilege of state and became a standard item of furniture for anyone who could afford to buy it. Once the idea of privilege faded the chair speedily came into general use. Almost at once the chair began to change every few years to reflect the fashions of the day.[15]
Thomas Edward Bowdich visited the main Palace of the Ashanti Empire in 1819, and observed chairs engrossed with gold in the empire.[16] In the 1800s, chairs became more common in American households and usually there was a chair provided for every family member to sit down to dinner. By the 1830s, factory-manufactured “fancy chairs” like those by Sears, Roebuck, and Co. allowed families to purchase machined sets. With the Industrial Revolution, chairs became much more available.[15]
The 20th century saw an increasing use of technology in chair construction with such things as all-metal folding chairs, metal-legged chairs, the Slumber Chair,[citation needed] moulded plastic chairs and ergonomic chairs.[17] The recliner became a popular form, at least in part due to radio and television. In the 1930s, stair lifts were commercially available to help people suffering from Polio and other diseases to navigate stairs.[18]
The modern movement of the 1960s produced new forms of chairs: the butterfly chair (originally called the Hardoy chair), bean bags, and the egg-shaped pod chair that turns. It also introduced the first mass-produced plastic chairs such as the Bofinger chair in 1966.[19] Technological advances led to molded plywood and wood laminate chairs, as well as chairs made of leather or polymers. Mechanical technology incorporated into the chair enabled adjustable chairs, especially for office use. Motors embedded in the chair resulted in massage chairs.[20]
Materials
[edit]
Chairs can be made from wood, metal, or other strong materials, like stone or acrylic. In some cases, multiple materials are used to construct a chair; for example, the legs and frame may be made from metal and the seat and back may be made from plastic. Chairs may have hard surfaces of wood, metal, plastic, or other materials, or some or all of these hard surfaces may be covered with upholstery or padding. The design may be made of porous materials, or be drilled with holes for decoration; a low back or gaps can provide ventilation. The back may extend above the height of the occupant's head, which can optionally contain a headrest. Chairs can also be made from more creative materials, such as recycled materials like cutlery and wooden play bricks, pencils, plumbing tubes, rope, corrugated cardboard, and PVC pipe.[21]
In rare cases, chairs are made out of unusual materials, especially as a form of art or experimentation. Raimonds Cirulis, a Latvian interior designer, created a volcanic hanging chair that is handmade out of volcanic rock.[22][23] Peter Brenner, a Dutch-born German designer, has created a chair made from lollipop sugar – 60 pounds (27 kg) of confectioners' sugar.[24]
Design and ergonomics
[edit]Chair design considers intended usage, ergonomics (how comfortable it is for the occupant),[25] as well as non-ergonomic functional requirements such as size, stacking ability, folding ability, weight, durability, stain resistance, and artistic design.
Seat height
[edit]
Ergonomic design distributes the weight of the occupant to various parts of the body. This is done by having an easily adjustable seat height.[26] A seat that is higher results in dangling feet and increased pressure on the underside of the knees ("popliteal fold"). It may also result in no weight on the feet which means more weight elsewhere. A lower seat may shift too much weight to the "seat bones" ("ischial tuberosities"). Gas springs are attached to the body of the chair in order to give height adjustment and more comfort to the user.
Some chairs have foot rests. Around 15% of women and 2% of men need foot rests, even at the 16-inch (41 cm) chair height.[27] A stool or other simple chair may have a simple straight or curved bar near the bottom for the sitter to place their feet on.
Actual chair dimensions are determined by measurements of the human body or anthropometric measurements. The two most relevant anthropometric measurements for chair design are the popliteal height and buttock popliteal length.
For someone seated, the popliteal height is the distance from the underside of the foot to the underside of the thigh at the knees. It is sometimes called the "stool height". The term "sitting height" is reserved for the height to the top of the head when seated. For American men, the median popliteal height is 16.3 inches (41 cm) and for American women it is 15.0 inches (38 cm).[28] The popliteal height, after adjusting for heels, clothing and other issues, is used to determine the height of the chair seat. Mass-produced chairs are typically 17 inches (43 cm) high.[citation needed]
Researchers such as Mary Blade and Galen Cranz found that sitting on the edge of a high stool with feet on the floor is less harmful for the lower back than sitting up straight on a conventional chair.[29]
Reclining angle
[edit]
Different types of chairs can have a variety of seating positions, depending on the intended task. Typically, chairs intended for people completing work or dining can only recline very slightly (otherwise the occupant is too far away from the desk or table). Dental chairs are necessarily reclined. Research has shown that the best seated posture is a reclined posture of 100°–110°.[30] In order to recline, the back-rest may be independently adjustable. A reclining seat and back will reduce the load on the occupant's back muscles. In general, if the occupant is supposed to sit for a long time, weight needs to be taken off the seat area and thus "easy" chairs intended for long periods of sitting are generally at least slightly reclined.
Back and head support
[edit]The back of the chair will support some of the weight of the occupant, reducing the weight on other parts of the body. Some back-rests support only the lumbar region, while shoulder height back-rests support the entire back and shoulders. Headrests support the head as well and are important in vehicles for preventing "whiplash" neck injuries in rear-end collisions where the head is jerked back suddenly. Reclining chairs typically have at least shoulder-height back-rests to shift weight to the shoulders.
Padding
[edit]There may be cases where padding is not desirable, such as chairs that are intended primarily for outdoor use. Where padding is not desirable, contouring may be used instead. A contoured seat pan attempts to distribute weight without padding. By matching the shape of the occupant's buttocks, weight is distributed and maximum pressure is reduced.
Armrests
[edit]A chair may or may not have armrests; chairs with armrests are termed "armchairs". In French, a distinction is made between fauteuil and chaise, the terms for chairs with and without armrests, respectively. In Germany, an armchair was once called a Krankensessel, or sick-chair, because it was intended for people who were too ill to stand or sit without extra support.[31]
If present, armrests will support part of the body weight through the arms if the arms are resting on the armrests. Elbow rest height is used to determine the height of the armrests. Armrests should support the forearm and not the sensitive elbow area. Hence in some chair designs, the armrest is not continuous to the chair back, but is missing in the elbow area. Armrests further have the function of making entry and exit from the chair easier (but from the side it becomes more difficult).
Seat size and legroom
[edit]For someone seated, the buttock popliteal length is the horizontal distance from the back most part of the buttocks to the back of the lower leg. This anthropometric measurement is used to determine the seat depth. Mass-produced chairs are typically 15–17 inches (38–43 cm) deep.[citation needed]
Additional anthropometric measurements may be relevant to designing a chair. Hip breadth is used for chair width and armrest width. The buttock-knee length is used to determine "leg room" between rows of chairs. "Seat pitch" is the distance between rows of seats. In some airplanes and stadiums the leg room (the seat pitch less the thickness of the seat at thigh level) is so small that it is sometimes insufficient for the average person.
Types of chairs
[edit]
A wide variety of chairs have emerged throughout the ages, some based on formal usages, and others based on domestic needs, and some based on needs within the workplace or various professions.
Office chair
[edit]An office chair is one used by employees within an office. Modern office chairs are usually adjustable and wheeled. Caster wheels are attached to the feet of chairs to give more mobility.
Dining room chair
[edit]A dining room chair is a specific type of design, used around a dining room table. It can be found in most ordinary residential homes, and also may appear in formal settings, such as any formal event or reception that includes a formal meal or banquet.
Work chair
[edit]A work chair is a specialized chair, adapted to the needs of a particular profession or setting. For example, a designing chair will be used for designers who sit at high easels; it will usually have added height.
Rocking chair
[edit]Some chairs have two curved bands of wood (also known as rockers) attached to the bottom of the legs. They are called rocking chairs.
Kneeling chair
[edit]
A kneeling chair adds an additional body part, the knees, to support the weight of the body. A sit-stand chair distributes most of the weight of the occupant to the feet. Many chairs are padded or have cushions. Padding can be on the seat of the chair only, on the seat and back, or also on any arm rests or foot rest the chair may have. Padding will not shift the weight to different parts of the body (unless the chair is so soft that the shape is altered). However, padding does distribute the weight by increasing the area of contact between the chair and the body, and thus reducing the amount of pressure at any given point. By contrast, a hard wood chair feels hard because the contact point between the occupant and the chair is small. In lieu of padding, flexible materials, such as wicker, may be used instead with similar effects of distributing the weight.
Seats
[edit]
Chair seats vary widely in construction and may or may not match construction of the chair's back (back-rest).
Some systems include:
- Center seats where a solid material forms the chair seat
- Solid wood, may or may not be shaped to human contours
- Wood slats, often seen on outdoor chairs
- Padded leather, generally a flat wood base covered in padding and contained in soft leather
- Stuffed fabric, similar to padded leather
- Metal seats of solid or open design
- Molded plastic
- Stone, often marble
- Open center seats where a soft material is attached to the tops of chair legs or between stretchers to form the seat
- Wicker, woven to provide a surface with give to it
- Leather, may be tooled with a design
- Fabric, simple covering without support
- Tape, wide fabric tape woven into seat, seen in lawn chairs and some old chairs
- Caning,
- Rush, wrapped from rush, heavy paper, strong grasses, or hand twisted while wrapped with cattails to form the seat, usually in a pattern of four trapezoids meeting in the center, and on rare occasions, in elaborate patterns
- Reed,
- Rawhide
- Splint, ash, oak or hickory strips are woven
- Metal, Metal mesh or wire woven to form seat
Standards and specifications
[edit]
Design considerations for chairs have been codified into standards. ISO 9241, "Ergonomic requirements for office work with visual display terminals (VDTs) – Part 5: Workstation layout and postural requirements", is the most common one for modern chair design.
There are multiple specific standards for different types of chairs. Dental chairs are specified by ISO 6875. Bean bag chairs are specified by ANSI standard ASTM F1912-98. ISO 7174 specifies stability of rocking and tilting chairs. ASTM F1858-98 specifies plastic lawn chairs. ASTM E1822-02b defines the combustibility of chairs when they are stacked.
The Business and Institutional Furniture Manufacturer's Association (BIFMA)[32] defines ANSI/BIFMA X5.1 (titled: General-Purpose Office Chairs – Tests) for testing of commercial-grade chairs. It requires:
- chair back strength of 150 pounds (68 kg)
- chair stability if weight is transferred completely to the front or back legs
- leg strength of 75 pounds (34 kg) applied one inch (25 mm) from the bottom of the leg
- seat strength of 225 pounds (102 kg) dropped from six inches (150 mm) above the seat
- seat cycle strength of 100,000 repetitions of 125 pounds (57 kg) dropped from 2 inches (51 mm) above the seat
The specification further defines heavier "proof" loads that chairs must withstand. Under these higher loads, the chair may be damaged, but it must not fail catastrophically.
Large institutions that make bulk purchases will reference these standards within their own even more detailed criteria for purchase.[33] Governments will often issue standards for purchases by government agencies (e.g. Canada's Canadian General Standards Board CAN/CGSB 44.15M[34] on "Straight Stacking Chair, Steel" or CAN/CGSB 44.232-2002 on "Task Chairs for Office Work with Visual Display Terminal").
Chairs may be rated by the length of time that they may be used comfortably – an 8-hour chair, a 24-hour chair, and so on. Such chairs are specified for tasks which require extended periods of sitting, such as for receptionists or supervisors of a control panel.
Accessories
[edit]
In place of a built-in footrest, some chairs come with a matching ottoman. An ottoman is a short stool that is intended to be used as a footrest but can sometimes be used as a stool. If matched to a glider chair, the ottoman may be mounted on swing arms so that the ottoman rocks back and forth with the main glider.
A chair cover is a temporary fabric cover for a side chair. They are typically rented for formal events such as wedding receptions to increase the attractiveness of the chairs and decor. The chair covers may come with decorative chair ties, a ribbon to be tied as a bow behind the chair. Covers for sofas and couches are also available for homes with small children and pets. In the second half of the 20th century, some people used custom clear plastic covers for expensive sofas and chairs to protect them.
Chair pads are cushions for chairs. They contain cotton or foam for padding. Some are decorative. In cars, they may be used to increase the height of the driver. Orthopedic back-rests provide support for the back. Car seats sometimes have built-in and adjustable lumbar supports. These can also be used on kitchen chairs.
Chair mats are mats meant to cover different types of flooring. They are usually made from plastic. This allows chairs on wheels to roll easily over the carpet and protects the carpet or floor. They come in various shapes, some specifically sized to fit partially under a desk.
Remote control bags can be draped over the arm of easy chairs or sofas and used to hold remote controls for home cinemas. They are counter-weighted so as to not slide off the arms under the weight of the remote controls.
Chair glides are attached to the feet of chairs to prevent them from scratching or snagging on the floor.
An antimacassar is a cloth covering for a headrest to protect the fabric and enable easy washing.
As sculptural and art forms
[edit]Christo created Wrapped Chair in 1961[35] with found objects (chairs), lacquer, canvas, rope, and paint. It is an early work showing his and his wife Jeanne Claude’s iconic style of partially or wholly hiding objects within wrapped cloth and ropes. Their work developed into large-scale public site-specific artworks and environmental art, which the pair are most well known for. For Wrapped Chair, Christo plays with the identity of the object by concealing parts and revealing others. There are multiple variations of this work and similar ones involving chairs displayed at museums around the world, including a similar work titled Two Wrapped Chairs from 1961.[36]
In the same year that Christo created Wrapped Chair, Pablo Picasso also created La Chaise.[37] Made of painted sheet metal, Picasso’s sculptural chair exemplifies what many artists love about the chair as a subject: the contrast of form and function.
One and Three Chairs, 1965, is a conceptual artwork created by Joseph Kosuth.[38] The work is an assemblage of a manufactured chair, the photo of said chair, and the dictionary definition of the word chair. This work changes each time it is installed, since the location selects and photographs the chair for installation. A dominating part of Kosuth’s work is the impersonal aspect of all the parts since his artistic hand is not easily seen in the pre-made objects presented.[39]

The Broken Chair is a monumental sculpture in wood, constructed of 5.5 tons of wood, 12 metres (39 ft) high standing across the street from the Palace of Nations in Geneva. It has broken leg symbolizing opposition to land mines and cluster bombs. In 2001, Steve Mann exhibited a chair sculpture at San Francisco Art Institute. The chair had spikes that retracted when a credit card was inserted to download a seating license. Later other museums and galleries were equipped with the "Pay to Sit" chair, with a global central seating license server located in Toronto. The first sitting session was free, with a database of persons who had already used their free session.
In a performance piece at the 2012 Republican National Convention, Clint Eastwood addressed an empty chair, as if it represented President Barack Obama (meant to be construed as MIA or ineffectual). The address was controversial, with critics describing it as bizarre and supporters describing it as poignant.[40] Japanese designer Tokujin Yoshioka has created several chairs as art forms such as "Honey-pop": honey-comb paper chair (2001), "Pane chair": natural fiber chair (2006), and "Venus": natural crystal chair (2007).
New York industrial designer Ian Stell creates steel and wood kinetic sculptures that transform into chairs, including Roll Bottom Chair (2016) that turns into a secretariat desk and Loop that transforms into two interlocking chairs when expanded (2015).[41][42][43]
In language
[edit]- If someone "nearly fell off their chair" after being informed about something, it was because they were very shocked or surprised.[44]
- An orchestra awards the best player in a particular section a "chair" or "principal seat" based on ability. The first chair of the section plays the solos, and in string sections, determines the bowings. In professional orchestras, the first chair player receives higher pay. It is also common for this position to be known as "first stand" or "first desk", a reference to the portable lectern on which the musicians put their sheet music. However, the person who is first chair in the first violin section is usually referred to as the concertmaster in the US or leader in the UK.
- In academia, an endowed chair is a prestigious appointment for a professor, paid for by a dedicated funding source.
- A chair is the highest officer of an organized group, such as the chair of the board, the head of the Board of Directors in a company or non-profit organization.
- "Musical chairs" is a common party game, and a colloquial expression to describe people shuffling from seat to seat, around different locations, or from one job title to another.
- In American slang, to say someone will "get the chair" is to say that they will be executed by an electric chair.[45] Alternatively, it can be a metaphor for other harsh punishment.[45]
- An armchair can be used as shorthand for undue comfort or domesticity, as with an armchair theorist or armchair general.
See also
[edit]- List of chairs for an extended list of types, such as the lift chair, papasan chair, swivel chair.
- Chair pose
- Chair squat
- Riding-like sitting
- Seating assignment
- Splat (furniture), the central vertical element of a wooden chair back
References
[edit]- ^ "Armchair". The Free Dictionary By Farlex. Retrieved 13 May 2012.
- ^ "Recliner". Dictionary.com. Retrieved 13 May 2012.
- ^ "Wheelchair". Dictionary.com. Retrieved 13 May 2012.
- ^ Harper, Douglas. "chair". Online Etymology Dictionary.
- ^ cathedra. Charlton T. Lewis and Charles Short. A Latin Dictionary on Perseus Project.
- ^ καθέδρα. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project.
- ^ "Is This the World's Most Famous Chair?". TreeHugger. Retrieved 11 June 2017.
- ^ "Architecture of the Palace". www.parliament.uk. Retrieved 13 May 2012.
- ^ "Speaker's Chairs". The House of Commons. Retrieved 13 May 2012.
- ^ "Professor". The Free Dictionary By Farlex. Retrieved 13 May 2012.
- ^ "What is an "Endowed Chair?"". The University of Utah. Archived from the original on 31 May 2012. Retrieved 13 May 2012.
- ^ Cregan-Reid, Vybarr (26 October 2018). "Anthropocene: why the chair should be the symbol for our sedentary age". The Conversation. Retrieved 9 November 2018.
- ^ a b c "Furniture". Ancient Egyptian Furniture. Archived from the original on 21 October 2008. Retrieved 13 May 2012.
- ^ Kieschnick, John. The Impact of Buddhism on Chinese Material Culture, Princeton University Press, 2003, pp. 222–248.
- ^ a b "From Benches to Barstools: A History of Chairs, Posture, and Society". Random History. Archived from the original on 10 July 2012. Retrieved 13 May 2012.
- ^ The Monthly Review, Or, Literary Journal. 1819. p. 291.
- ^ "What is an ergonomic chair?". Canadian Centre for Occupational Health and Safety. Retrieved 13 May 2012.
- ^ "Inclinator Company Of America". disabilitymuseum.org. April 1933. Archived from the original on 15 June 2021. Retrieved 13 April 2022.
- ^ Glenday, Craig (September 2015). Guinness World Records 2016. Guinness World Records Limited. p. 149. ISBN 978-1-910561-01-0.
- ^ "Definitions for Massage Actions for Massage Chairs". About.com Furniture. Archived from the original on 23 June 2012. Retrieved 13 May 2012.
- ^ "26 Chairs Made from Recycled Materials". Home-Designing. March 2009. Retrieved 13 May 2012.
- ^ "Hanging chair made out of Volcanic Rock". BornRich: Home of Luxur. Archived from the original on 25 April 2012. Retrieved 13 May 2012.
- ^ "Hanging chair made out of Volcanic Rock – Bornrich". 21 March 2012. Archived from the original on 9 July 2015. Retrieved 21 July 2017.
- ^ LaBarre, Suzanne (19 April 2011). "A Chair Made From Lollipop Sugar, Customized With Your Licks". Co.DESIGN. Retrieved 21 July 2017.
- ^ "What is an ergonomic chair?". Canadian Centre for Occupational Health and Safety. Retrieved 13 May 2012.
- ^ Inkeles, Gordon; Schenke, Iris (2010). Ergonomic Living: How to Create a User-Friendly Home & Office. Touchstone. p. 115. ISBN 9781439146323. Retrieved 5 June 2021.
- ^ Alan Hedge, ed. (2017). "15.5.1.4". Ergonomic Workplace Design for Health, Wellness and Productivity. CRC Press. ISBN 978-1-4665-9843-0.
- ^ "Basic Body Measurements". cdc.gov. Archived from the original on 30 March 2009.
- ^ Cranz, Galen (2000). The Chair: Rethinking Culture, Body, and Design. W. W. Norton. p. 176. ISBN 9780393319552. Retrieved 6 June 2021.
- ^ Hedge, chapter 1.3.3
- ^ "International Vanities". The Living Age. Fifth series. Vol. V. Boston: Little and Gay. 1874. p. 105.
- ^ "BIFMA". bifma.org.
- ^ "06-12a.html". state.tx.us. Archived from the original on 8 September 2006. Retrieved 21 July 2017.
- ^ "CGSB 44.15M". TechStreet.com.
- ^ "Wrapped Chair". Cleveland Museum of Art. Retrieved 9 January 2024.
- ^ "Christo: Early Works, 1958–1963, rue de Ponthieu, Paris, June 10–October 8, 2022". Gagosian. 2022-06-01. Retrieved 2024-01-10.
- ^ "Collection Page". Musée Picasso Paris. Retrieved 9 January 2024.
- ^ "Joseph Kosuth. One and Three Chairs. 1965". MoMA. Retrieved 9 January 2024.
- ^ Goldie, Peter; Schellekens, Elisabeth, eds. (2009). Philosophy and conceptual art. Oxford: Clarendon Press [u.a.] ISBN 978-0-19-956825-3.
- ^ Tina Daunt (5 September 2012). "Invisible Obama: The Backlash for Mitt Romney and Clint Eastwood". The Hollywood Reporter. Retrieved 7 January 2016.
- ^ Ford (aldenta.com), Designed by Tina Roth Eisenberg (swiss-miss com) and built by John (29 September 2020). "Roll Bottom". swissmiss. Retrieved 10 October 2020.
- ^ "Ian Stell Online Shop | Shop Design at Pamono". pamono.com. Retrieved 10 October 2020.
- ^ "Collection #2 "Progressland" Curated by Andrew Zuckerman | Chamber | Artsy". www.artsy.netnull. Retrieved 10 October 2020.[permanent dead link]
- ^ "Nearly/Almost Fall off your Chair". Cambridge Dictionary. Retrieved 22 August 2016.
- ^ a b "Chair". Dictionary.com. Retrieved 22 August 2016.
Further reading
[edit]
The dictionary definition of chair at Wiktionary- . Encyclopædia Britannica. Vol. 5 (11th ed.). 1911.
- de Dampierre, F. (2006). Chairs: A History. Harry N. Abrams. ISBN 0-8109-5484-2
- Fiell, C. (2005). 1000 Chairs. (25th ed.). Taschen. ISBN 3-8228-4103-X
- Miller, J. (2009). Chairs. Conran. ISBN 1-84091-523-4
Chair
View on GrokipediaA chair is a seat typically having four legs and a back for one person.[1] It consists of a raised seat surface, a backrest, and often armrests, distinguishing it from stools or benches designed for multiple occupants.[2] Chairs represent one of the earliest developed forms of furniture, with archaeological evidence indicating their use as far back as ancient Egyptian tombs from around 2600 BCE, where wooden chairs covered in leather or cloth served elites.[3] Over millennia, chair designs evolved from rigid, status-symbol thrones in antiquity—such as the Greek klismos with its curved legs—to more accessible folding varieties and, later, mass-produced ergonomic models reflecting advances in materials like steel and molded plastic.[4] This progression mirrors shifts in societal needs, craftsmanship, and industrial capabilities, transitioning from symbols of authority to ubiquitous tools for daily comfort and productivity.[5] In contemporary contexts, chairs encompass diverse types tailored to functions like dining, office work, or relaxation, with ergonomic features such as adjustable heights, lumbar support, and waterfall seat edges prioritized to mitigate musculoskeletal strain during prolonged sitting.[6] Iconic designs, including the Eames lounge chair, exemplify mid-20th-century innovations blending aesthetics, durability, and human-centered engineering.[7] Research underscores the importance of these adaptations, as improper seating correlates with health issues like back pain, prompting standards in adjustable backrests and seat tilts for optimal spinal alignment.[8]
Etymology and Terminology
Etymology
The English noun "chair," denoting a seat typically for one person with a backrest, entered the language in the early 13th century via the Middle English form chaere or chayere.[9] This borrowing traces directly to Old French chaiere (also spelled chaire), documented from the 12th century onward, which encompassed meanings such as a movable seat, throne, or professorial bench.[9] The Old French term evolved from Latin cathedra, a word for a raised seat or chair, especially one associated with authority figures like teachers, bishops, or presiding officials in assemblies.[9] Latin cathedra itself derives from Ancient Greek kathédra (καθέδρα), literally "a sitting down," formed by compounding katá ("down" or "upon") with hédra ("seat" or "base").[10] In classical usage, kathédra referred to a teacher's bench or stool in lecture settings, emphasizing its connotation of elevated position rather than mere furniture; this semantic layer persisted into ecclesiastical Latin, where cathedra denoted a bishop's throne, influencing related English terms like "cathedral" (the church containing the bishop's seat).[11] The shift toward denoting portable, back-supported seats in medieval Europe reflected broader cultural adaptations, distinguishing chair from simpler stools (stool from Old English stōl, unrelated etymologically) or benches.[9] Over time, the word's semantic range expanded in English to include metaphorical senses, such as a position of leadership ("to chair a meeting," first recorded in 1651), directly evoking the authoritative seat.[9] Cognates appear in other Romance languages, like Italian sedia (from Latin sedes, "seat") diverging earlier, while cathedra-derived forms persisted in contexts of formal seating.[9] This Indo-European root for seating structures underscores a conceptual link between physical support and hierarchical status across ancient Mediterranean societies.[10]Basic Definitions and Distinctions
A chair is a piece of furniture designed for seating one person, consisting of a raised seat surface supported by legs or a pedestal, and distinguished by the presence of a backrest to provide lumbar and upper-body support.[1][12] The seat is typically flat or slightly contoured and positioned at a height of approximately 17 to 19 inches (43 to 48 cm) from the floor to accommodate average human ergonomics for sitting with feet flat on the ground.[13] While most chairs feature four legs for stability, variations exist with three legs, a central pedestal, or other supports, but the core elements remain the elevated seat and backrest.[2] Chairs differ from stools primarily in the inclusion of a backrest; stools are backless seats elevated on legs or a base, intended for shorter-duration sitting or as footrests, lacking the supportive structure for prolonged upright posture. Benches, by contrast, are elongated seats designed to accommodate multiple individuals side-by-side without individual backrests or arm separations, often fixed or used in communal settings like parks or dining areas. Sofas or couches extend the chair concept to multi-person seating with continuous upholstery and deeper cushions, emphasizing reclined comfort over individual isolation. The term "seat" serves as a broader category encompassing all these forms, referring generically to any surface or structure intended for human sitting, whether freestanding furniture or integrated components like those in vehicles or theaters. These distinctions arise from functional needs: chairs prioritize solitary, supported sitting for tasks requiring focus, whereas alternatives adapt to group use, brevity, or informality.[13]Historical Development
Ancient and Prehistoric Origins
In prehistoric eras, prior to the development of complex sedentary societies, humans primarily sat on the ground, natural rocks, or felled logs, with no archaeological evidence indicating the construction of raised seats with backs akin to later chairs. The advent of Neolithic farming communities around 7000–5000 BC introduced more structured living spaces, but seating remained rudimentary; for instance, at the site of Skara Brae in Orkney, Scotland (c. 3100–2500 BC), inhabitants built stone furniture including recessed beds, storage boxes, and low ledges or benches integrated into house walls, which could function as seats but lacked portable frames, backs, or armrests characteristic of true chairs.[14][5] The chair proper, defined as an elevated seat with a backrest for individual use, originated in the ancient Near East and Egypt during the late 3rd millennium BC, coinciding with urban civilizations where such items denoted social hierarchy and comfort for elites. In Mesopotamia, early attestations include clay miniature models of chairs recovered from royal tombs at Ur (c. 2600–2500 BC) by excavator Leonard Woolley, depicting four-legged seats with backs, and seal impressions showing folding variants as far back as c. 2500 BC, suggesting portability for rulers or officials.[15] Physical wooden examples are scarce due to environmental degradation, but cuneiform texts and bas-reliefs from Sumerian and later Assyrian periods describe chairs padded with rushes or felt, often elevated to require footstools, underscoring their role in ceremonial and domestic settings.[16][17] In Egypt, chairs first appear in Old Kingdom tomb contexts from the 3rd Dynasty onward (c. 2686–2613 BC), with depictions and rare surviving fragments from the 5th Dynasty (c. 2494–2345 BC) showing low-slung wooden seats (typically 25–40 cm high) crafted from imported cedar or ebony, adorned with ivory inlays, leather upholstery, and symbolic motifs like lion legs signifying power.[18] These artifacts, preserved in arid tomb environments, reveal advanced mortise-and-tenon joinery and were reserved for pharaohs, nobles, and deities, as evidenced by their inclusion in funerary inventories like that of Queen Hetepheres I (c. 2580 BC), where disassembled chair components were found alongside carrying poles for transport.[17] Such designs prioritized stability and status over ergonomics, reflecting causal links between material scarcity, craftsmanship, and hierarchical social structures.Classical Antiquity to Middle Ages
In ancient Greece, chairs were primarily reserved for elite contexts, with the klismos exemplifying refined design from the 5th to 4th centuries BCE. This form featured a curved backrest, broad top rail, and four tapering, outcurved legs splayed for stability, often crafted from wood with seats of cane, woven leather, or fabric to support relaxed reclining postures.[19] [20] Archaeological evidence from vase paintings and sculptures depicts klismos chairs in domestic and divine scenes, underscoring their aesthetic emphasis on graceful lines derived from saber-shaped supports, though everyday seating favored simpler stools like the diphros.[21] Roman adaptations prioritized functionality and symbolism, notably the sella curulis, a lightweight, foldable chair with curved legs and ivory veneers, lacking arms or backrest for portability during processions. Employed from the early Republic onward by high magistrates such as consuls, praetors, and censors, it signified imperium and descended from Etruscan or archaic Italic prototypes akin to campaign stools.[22] This design influenced public and military seating, where permanence yielded to mobility, reflecting Rome's expansionist causality in furniture evolution. The fall of the Western Roman Empire around 476 CE disrupted widespread chair production, shifting Europe toward rudimentary benches and stools amid resource scarcity and migrations, while Byzantine continuity preserved turned-wood techniques for ecclesiastical and imperial use.[23] In Christian basilicas, the cathedra—a raised, often wooden throne derived from Greco-Roman chairs—served as the bishop's fixed seat, symbolizing doctrinal authority and etymologically linking "cathedral" to this episcopal fixture by the 6th century.[24] Medieval secular chairs remained scarce outside nobility and clergy, typically featuring X-frames or turned spindles for durability, with oak or walnut construction emphasizing status over comfort for the masses who relied on floor mats or trestles. Surviving artifacts, often gilded or carved with heraldic motifs, highlight causal ties to feudal hierarchies where chairs denoted sovereignty, as in high-backed thrones for kings. The Coronation Chair at Westminster Abbey, commissioned by Edward I between 1296 and 1301 from oak sourced locally, integrated the Stone of Scone—a sandstone relic of Scottish inauguration rites—to legitimize English monarchy, featuring a gabled frame, lion supports, and enameled accents.[25] [26] First employed for Edward II's crowning in 1308, it endured defacement and repairs, embodying medieval fusion of relic veneration and architectural permanence.[25] ![Coronation Chair in Westminster Abbey]centerEarly Modern Period to Industrial Era
During the Renaissance, which began in Italy around 1400 and spread across Europe by the early 16th century, chair design shifted toward greater comfort and classical influences, with frames often constructed from walnut or oak and featuring turned legs and stretchers for stability. Upholstered armchairs, known as fauteuils, emerged among the elite, padded with horsehair or wool and covered in velvet or leather, reflecting a revival of ancient Roman forms but adapted for everyday use in wealthier households. By the mid-16th century, X-framed chairs—saddle-like seats on crossed legs—gained popularity in Spain and Portugal, facilitating portability and used in both secular and ecclesiastical settings. The Baroque period (c. 1600–1750) introduced ornate carving and heavy proportions, with chairs featuring cabriole legs, shell motifs, and richly upholstered backs to symbolize status in royal courts, as seen in French chaises à la reine with padded arms and seats for women. In England, during the Restoration (1660–1685), walnut chairs with vase-shaped splats and cane seats became common, prioritizing durability over minimalism. Transitioning to Rococo (c. 1730–1760), designs lightened with S- and C-curves, asymmetrical elements, and pastel fabrics, emphasizing intimacy; Louis XV chairs often incorporated cabochon feet and exposed wood frames gilded for Versailles interiors.[27][28] In the 18th-century Georgian era, English designers like Thomas Chippendale (active 1749–1779) innovated with eclectic styles, blending Chinese fretwork, Gothic arches, and ribbon backs in mahogany chairs, as detailed in his 1754 Gentleman and Cabinet-Maker's Director, which influenced colonial American production. George Hepplewhite (d. 1786) favored neoclassical simplicity, introducing shield- and heart-shaped backs with tapered legs and painted motifs, promoting lighter construction for middle-class homes. Thomas Sheraton (1751–1806) refined these with rectangular splats and sabre legs, emphasizing proportion and utility in his 1791–1794 Cabinet-Maker and Upholsterer's Drawing-Book. Windsor chairs, originating in England around 1700 and peaking in the 1720s–1740s, used steam-bent ash or yew for spindles inserted into oak seats, offering affordable, stackable rural seating exported widely.[29][30] The Industrial Revolution, commencing around 1760 in Britain, mechanized chair production through water- and steam-powered sawmills and lathes, reducing costs and enabling standardization; by the early 19th century, factories like those in Connecticut produced Hitchcock chairs with stenciled designs and rush seats in volumes exceeding handmade output. Michael Thonet's 1841 patent for glued bentwood revolutionized manufacturing: steaming beech wood for bending into continuous frames, his No. 14 chair (designed 1859) disassembled for shipping, yielding 10,000 units annually by 1857 and scaling to 1.8 million by 1913 via industrialized processes that minimized waste and labor. These innovations democratized chairs, shifting from bespoke craftsmanship to reproducible forms suited for urban expansion.[31][32]20th Century and Contemporary Evolution
The 20th century introduced modernist innovations in chair design, prioritizing functionality, minimalism, and industrial materials amid post-World War I reconstruction. Marcel Breuer's Wassily chair, developed in 1925–1926 at the Bauhaus, was the first to employ tubular steel framing, reducing weight while maintaining structural integrity through cantilever principles.[7][33] Ludwig Mies van der Rohe's Barcelona chair, created in 1929 for the German Pavilion at the Barcelona International Exposition, utilized chrome-plated steel and leather straps to embody the "less is more" aesthetic, influencing subsequent sleek, unadorned forms.[5][34] Mid-century developments from the 1940s to 1960s emphasized organic shapes, mass production, and synthetic materials, spurred by wartime material shortages and technological advances. Charles and Ray Eames pioneered molded plywood chairs in the 1940s, with their 1956 lounge chair—featuring rosewood, leather, and aluminum—later hailed by Time magazine in 2001 as the best design of the century for its ergonomic comfort and durability.[35] Verner Panton's 1967 Panton chair, the first fully molded plastic seat produced via injection molding, represented a shift to seamless, sculptural forms accessible through industrial manufacturing.[36] Designers like Arne Jacobsen contributed with the 1958 Egg chair, blending curved fiberglass shells with upholstery for acoustic and visual appeal in public spaces.[37] Contemporary evolution since the late 20th century integrates ergonomics, sustainability, and digital fabrication, responding to prolonged sedentary lifestyles and environmental concerns. The 1994 Aeron chair by Herman Miller, with its breathable mesh and adjustable posture support, set standards for office ergonomics based on anthropometric data, reducing strain through dynamic sitting.[38] In the 21st century, materials like carbon fiber and recycled plastics enable lightweight, customizable designs, while trends toward minimalism and smart features—such as sensors for posture correction—prioritize health outcomes over ornamentation.[39][40] Additive manufacturing, including 3D printing, allows rapid prototyping of complex geometries, democratizing bespoke production but raising questions about long-term durability compared to traditional methods.[41]Design and Construction
Materials and Their Properties
Chairs utilize a range of materials chosen for properties like compressive and tensile strength, density, durability, and environmental resistance, which determine their suitability for structural integrity under load and long-term use. Wood, especially hardwoods, dominates traditional construction due to its anisotropic strength, where grain direction provides high compressive resistance along fibers, enabling robust legs and frames capable of supporting repeated human weight without fracturing. Hickory, one of the hardest domestic woods with exceptional shock resistance, is preferred for demanding applications like rocking chairs, while oak offers toughness and visible grain for aesthetic durability in dining chairs.[42][43] Beech provides hardness and good shock resistance suitable for bentwood designs.[44]| Material Category | Examples | Key Properties | Typical Applications |
|---|---|---|---|
| Wood (Hardwoods) | Hickory, Oak, Maple, Beech | High hardness (e.g., shock resistance, toughness), natural stability when properly seasoned, moderate weight | Structural frames, legs, backs for indoor furniture requiring compressive strength |
| Metals | Steel, Aluminum | Steel: superior tensile strength and load-bearing capacity; Aluminum: low density (lightweight), inherent corrosion resistance | Heavy-duty bases, outdoor frames; steel for commercial durability, aluminum for portability |
| Plastics | Polypropylene | Low density (~0.9 g/cm³), weather and UV resistance, chemical inertness, ease of injection molding | Molded outdoor or stackable chairs emphasizing low maintenance and impact resistance |
| Upholstery | Leather, Fabrics | Leather: high abrasion resistance, longevity (outlasts fabrics), breathability; Fabrics: varied flexibility but lower durability | Cushions and seats for comfort; leather for high-wear premium seating |
Key Structural Elements
The primary structural elements of a chair form a frame that distributes the weight of a seated person, typically ranging from 50 to 150 kilograms depending on the occupant, while maintaining stability against tipping or collapse. These elements include the seat, which serves as the horizontal load-bearing surface; the backrest, providing vertical support; the legs or base, which elevate and anchor the assembly; and interconnecting members such as stretchers, rails, and spindles that enhance rigidity through tension and compression resistance.[52][53] The seat, often constructed as a flat or slightly contoured panel fixed to the frame, bears the primary downward force and must resist sagging under repeated use, with dimensions typically 40-50 cm wide and 40-45 cm deep for ergonomic fit. In wooden chairs, it may be supported by a subframe of aprons or slats connected via mortise-and-tenon joints, which interlock to prevent shear failure, as these joints can withstand forces up to several hundred kilograms before yielding. Upholstered seats incorporate springs or webbing beneath the cushion for additional flex, distributing pressure evenly across the ischial tuberosities.[54][55] Backrests, extending upward from the seat rear, counteract forward torque from the seated posture and often feature stiles (vertical uprights) and rails (horizontal crosspieces) forming a ladder-like frame, with splats or panels filling the space for lumbar reinforcement. Structural integrity relies on angled rear legs or braces merging into the backrest, angled at 5-15 degrees from vertical to balance recline forces, preventing backward toppling under dynamic loads like leaning. In metal or molded designs, the backrest integrates seamlessly with the seat via welded or bolted seams for monolithic strength.[52][56] Legs or bases, usually four in number for quadrupedal stability or a central pedestal in swivel chairs, elevate the seat 40-50 cm above the floor and must resist buckling under compressive loads exceeding 500 kg in tested prototypes. Front legs bear more shear from forward shifts, while rear legs integrate with the backrest; stretchers—horizontal bars linking legs—add lateral bracing, reducing flex by up to 50% in framed constructions joined by dowels or tenons. Modern variants use five-star bases with casters for omni-directional support, engineered to ANSI/BIFMA standards preventing failure under 113 kg dynamic cycling.[53][55][57] Armrests, when present, extend horizontally from the front legs or seat sides, providing secondary load paths for upper body weight but requiring robust attachment to avoid detachment under 45-90 kg per arm, often via brackets or integrated framing. These elements collectively ensure the chair's factor of safety against failure exceeds 4:1 in residential applications, with joint types like dovetails or pegged mortises prioritizing long-term durability over adhesives alone.[54][58]Manufacturing Techniques
Chair manufacturing encompasses a range of techniques tailored to materials such as wood, metal, and plastic, with methods evolving from handcrafting to automated industrial processes. Wooden chairs traditionally rely on joinery techniques for structural integrity, including the mortise-and-tenon joint, where a tenon protrusion from one wood piece fits into a corresponding mortise cavity in another, often secured with glue or pegs for load-bearing applications like chair legs and seats.[59] Dovetail joints, featuring interlocking wedge-shaped pins and tails, provide enhanced resistance to pulling forces and are used in chair components requiring both strength and visible craftsmanship, such as armrests or backrest supports.[59] Steam bending is employed for curved elements, heating wood to 100°C in a steam chamber before clamping into forms, allowing permanent shaping without material waste.[60] In modern woodworking production, computer numerical control (CNC) machining automates cutting, routing, and shaping with precision tolerances under 0.1 mm, enabling scalable replication of designs from digital models while minimizing human error.[61] Assembly follows, incorporating dowels or screws for reinforcement, followed by sanding and finishes like varnish applied via spray booths for durability against wear. Metal chair frames, often using steel or aluminum tubing, involve cutting via laser or plasma processes, followed by bending with hydraulic machines to radii as small as 10 mm and welding—typically MIG or TIG methods—for seamless joints capable of supporting over 300 kg static loads.[62] Powder coating or electroplating then provides corrosion resistance, baked at 180-200°C for adhesion.[62] Plastic chairs dominate mass production through injection molding, where thermoplastic resins like polypropylene are melted at 220-260°C, injected at pressures up to 100 MPa into steel molds, and cooled for 20-60 seconds to form monolithic seats and backs resistant to impacts over 50 J.[63] Mold design incorporates multi-cavity systems for efficiency, yielding up to 1,000 units per mold cycle in high-volume facilities.[64] Upholstery for padded variants entails foam molding or cutting, followed by sewing fabric covers with industrial machines using nylon threads, then stapling or adhesive bonding to frames, ensuring compliance with fire-retardant standards like California TB 117-2013.[62] Quality control integrates automated vision systems to detect defects at rates exceeding 99% accuracy across all techniques.[62]Ergonomics and Physiology
Core Ergonomic Principles
Ergonomic principles for chairs emphasize supporting the body's natural spinal curvature and joint alignments to minimize static loading, shear forces, and muscle fatigue during prolonged sitting. These principles derive from biomechanical assessments showing that neutral postures—where the spine maintains its S-shaped lordosis, hips and knees at roughly 90-110 degrees, and weight distributed evenly—reduce intradiscal pressure in the lumbar region by up to 40% compared to slouched positions.[65][66] Key features include adjustability to accommodate anthropometric variations, such as user height and leg length, ensuring the chair fits 90-95% of a target population without inducing compensatory postures that elevate risks of low back strain.[67] Seat height adjustment is foundational, positioning the pan so feet rest flat on the floor or a footrest, with thighs parallel to the ground and a slight clearance under the knees to avoid vascular compression. OSHA guidelines specify pneumatic height mechanisms allowing this for users from the 5th to 95th percentile stature, preventing popliteal pressure that can impede circulation and contribute to leg discomfort over time.[68] Seat depth, typically 16-18 inches for average adults, must permit full back contact with the backrest while leaving 2-4 inches of clearance behind the knees; a waterfall-edge design slopes downward at the front to distribute thigh pressure and reduce soft tissue deformation.[68][69] Lumbar support targets the inward curve of the lower spine, with adjustable contours at 7-8 inches above the seat pan promoting anterior pelvic tilt and reducing forward lean that flattens the lordosis. Studies indicate such supports decrease lumbar flexion moments and erector spinae activity, correlating with lower perceived discomfort in controlled trials, though fixed supports may not suit all body types without height/depth customization.[70][71] Backrests should extend to mid-scapula level, with recline options from 90 to 120 degrees to offload the spine via increased backrest pressure sharing, as reclined postures shift center of gravity rearward and lessen disc loading by 50-80% in some models.[72][65] Armrests, when present, adjust vertically from 7-10.5 inches above the seat to align elbows at 90-100 degrees, supporting shoulder relaxation without elevating traps or forcing inward shoulder roll. Padded, contoured designs prevent localized pressure points, with evidence from posture studies showing reduced upper body muscle activation when arms are unloaded.[73] Overall adjustability—encompassing tilt tension, synchro-mechanisms linking backrest and seat motion, and dynamic elements like flexible back frames—enables micro-movements, countering the static loading inherent to sitting that elevates metabolic costs and fatigue.[8] Empirical field interventions confirm that chairs meeting these criteria yield measurable posture improvements, though individual variability necessitates user education for optimal setup.[74]Health Effects and Empirical Evidence
Prolonged sitting in chairs, a common feature of modern sedentary lifestyles, has been linked to elevated risks of cardiovascular disease, type 2 diabetes, and certain cancers, independent of leisure-time physical activity levels, according to a 2015 systematic review analyzing multiple cohort studies.[75] Meta-analyses confirm that accumulating sitting time in extended bouts detrimentally affects cardiometabolic health markers, such as insulin sensitivity and blood pressure, with interruptions shown to acutely improve postprandial glucose and lipid responses.[76] Furthermore, occupational sitting exceeding eight hours daily correlates with self-reported poor general health and heightened prevalence of back and neck pain, as evidenced by cross-sectional data from large worker cohorts.[77] In terms of spinal and musculoskeletal outcomes, sustained chair sitting induces biomechanical stress on the lumbar intervertebral discs, increasing intradiscal pressure and contributing to disc dehydration and height loss over time, per finite element modeling and in vivo studies.[78] Slumped postures during prolonged sessions reduce trunk muscle activation, impairing spinal stability and correlating with immediate increases in low back pain intensity, as quantified in systematic reviews of objective posture measurements.[79][80] Long-term sedentary patterns, often involving chair use, are associated with a 3% higher all-cause mortality risk per additional hour daily, based on prospective cohort data adjusted for confounders like age and exercise.[81] Sedentary behavior also accelerates biological aging via mechanisms such as chronic inflammation and telomere shortening, independent of obesity.[82] Empirical support for ergonomic chair designs mitigating these effects remains limited and mixed. Randomized trials of adjustable office chairs have shown modest reductions in musculoskeletal discomfort during short-term use, attributed to better lumbar support and adjustability, but long-term prevention of disorders like chronic low back pain lacks robust confirmation from high-quality RCTs.[74] Systematic reviews of workplace seating interventions highlight potential benefits in posture correction and reduced static loading, yet emphasize that no chair fully offsets the hazards of uninterrupted sitting, with dynamic movement and breaks proving more efficacious for health preservation.[8] Critics note that industry-funded studies often overstate ergonomic advantages, while independent analyses prioritize behavioral changes over equipment alone.[83]Debates and Criticisms of Ergonomic Claims
A 2021 systematic review of randomized controlled trials concluded that office chair interventions, including ergonomic designs, show no reliable reduction in low back pain, discomfort, or altered trunk muscle activation compared to standard seating, advising against their routine recommendation for prevention until higher-quality evidence emerges.[84] This assessment highlights methodological limitations in prior studies, such as small sample sizes and short intervention durations, which undermine claims of causal benefits from features like adjustable lumbar supports or dynamic cushions.[8] Critics contend that ergonomic chair designs overemphasize static postural adjustments while ignoring the inherent risks of prolonged sitting, which promotes hip flexor shortening, gluteal inhibition, and reduced metabolic activity regardless of support mechanisms.[85] Empirical data indicate no strong causal link between sitting duration and low back pain incidence in occupational settings, with meta-analyses finding occupational sitting as a weak or negligible risk factor after controlling for confounders like physical activity levels.[86] Instead, sedentariness contributes to broader health detriments, such as cardiovascular strain, suggesting that chair modifications address symptoms superficially without mitigating the core issue of immobility.[85] Debates also surround the purported "neutral" spine posture promoted in ergonomic guidelines, with research revealing limited empirical support for its superiority in reducing spinal loading or musculoskeletal strain over habitual or varied positions.[87] Physiotherapists exhibit substantial disagreement on optimal sitting postures, and studies emphasize dynamic movement over rigid alignment for comfort and load distribution.[88] High-end ergonomic chairs often command premium prices based on adjustability claims, yet end-users typically engage fewer than half of available functions, diminishing purported benefits and fueling skepticism about marketing-driven hype versus physiological realities.[89][90]Classification by Function and Form
Everyday and Domestic Chairs
Everyday and domestic chairs constitute the primary seating in residential interiors, serving functions such as dining, relaxation, and casual gathering. These chairs prioritize affordability, ease of maintenance, and basic comfort over specialized ergonomics, with designs emphasizing stability and portability for household mobility. Common variants include side chairs without arms for table seating and armchairs for individual lounging, often arranged in sets to accommodate family meals or social interactions.[91][92] Dining chairs, a staple in kitchens and formal eating areas, typically feature wooden or metal frames with straight or slatted backs to support upright postures during meals. Ladder-back chairs, characterized by horizontal slats across the backrest, exemplify durable, no-frills construction suited to frequent use and wiping clean. Upholstered options incorporate fabrics like wool or linen for added cushioning, selected for their resistance to abrasion in high-traffic domestic settings. Plastic or molded polymer seats appear in budget models, offering lightweight stackability and moisture resistance ideal for informal spaces.[91][93][94] Living room armchairs and lounge chairs extend domestic seating toward comfort, with padded seats and backs to facilitate prolonged sitting for reading or conversation. These often employ solid wood or metal bases for load-bearing capacity, paired with textile upholstery to mitigate pressure on the body during extended occupancy. In production, metal components enhance longevity in chairs bearing average adult weights up to 250 pounds repeatedly. Rocking chairs, a traditional domestic form, integrate curved rockers beneath fixed seats to enable gentle motion, promoting relaxation without mechanical aids.[45][92] Material choices reflect economic realities, with wood dominating frames for its natural strength and workability, while synthetics reduce costs in mass manufacturing. Global furniture output incorporates these elements, yielding chairs adaptable to varied home layouts, from compact urban apartments requiring foldable designs to spacious homes favoring robust sets. Durability testing focuses on joint integrity and fabric wear, ensuring viability for daily cycles of sitting and storage.[95][94]Professional and Specialized Seating
Professional seating refers to chairs engineered for occupational environments, emphasizing adjustability, durability, and support to sustain productivity and reduce musculoskeletal strain during prolonged use, distinct from domestic variants by incorporating task-specific features like enhanced stability and compliance with workplace regulations.[96] [97] Office task and executive chairs dominate professional applications, typically featuring pneumatic cylinders for seat height adjustment between 16 and 21 inches to align knees at 90 degrees with feet flat, synchronous tilt mechanisms for dynamic recline, and contoured lumbar supports to maintain spinal curvature.[98] [69] These designs adhere to ANSI/BIFMA X5.1 standards, which mandate tests for seat fatigue (over 100,000 cycles), backrest durability, and caster performance on varied flooring to prevent tip-overs.[99] [100] Executive models often add polished aluminum frames and higher-density foam for prestige settings, supporting up to 300-400 pounds while prioritizing breathable mesh backs for thermal regulation in climate-controlled offices.[97] OSHA guidelines further require five-point bases and adjustable armrests to avoid shoulder elevation, with empirical studies linking such features to 20-30% reductions in lower back pain incidence among desk workers.[68] [101] In healthcare, dental chairs represent a pinnacle of specialized positioning, originating with Josiah Flagg's 1790 adaptation of a Windsor armchair featuring a headrest for patient restraint, evolving by 1867 to James Beall's patented wooden model with vertical adjustment and footrest.[102] [103] Modern iterations, introduced in the 1950s by William H. Stambaugh's fully ergonomic design, incorporate electric actuators for 120-180 degree recline, integrated spittoons, and LED lighting, enabling precise intraoral access while supporting patient weights up to 500 pounds with seamless, sterilizable upholstery.[104] [105] These chairs prioritize infection control via seamless surfaces and quick-release components, with hydraulic systems calibrated for smooth transitions to supine positions, reducing procedure times by facilitating dentist ergonomics.[106] Barber and salon chairs, tailored for grooming services, emphasize client accessibility with hydraulic pumps for height ranges of 18-30 inches, full recline up to 170 degrees, and 360-degree swivel for multi-angle servicing, often including porcelain or vinyl footrests that deploy automatically.[107] [108] Constructed from chrome-plated steel bases to withstand daily use exceeding 10 hours, they feature adjustable headrests with 8-10 positions and integrated tool holders, supporting weights up to 400 pounds while enabling efficient workflows in high-volume settings.[109] Industrial chairs address manufacturing and assembly demands with reinforced frames, ESD-conductive fabrics for electronics handling, and anti-fatigue designs like footrest rings on stools elevated 24-30 inches, ensuring compliance with OSHA stability requirements on concrete floors.[68] [110] BIFMA and 24/7 usage standards test for over 400,000 cycles of operation, incorporating tilt-lock mechanisms and wide bases to prevent accidents in dynamic environments, where chairs must resist impacts from tools or machinery.[111] [112] Aviation pilot seats prioritize crashworthiness, certified to 9G or 16G forward impact standards with energy-absorbing side-guards and five-point harnesses, using lightweight composites and foam padding to mitigate G-forces while allowing fore-aft and height adjustments for cockpit integration.[113] These designs, often with quick-release pins for maintenance, support pilots during missions exceeding 12 hours, incorporating ventilation systems and restraint systems tested to FAA regulations for occupant protection in ejections or turbulence.[114]Innovative and Adaptive Designs
Innovative chair designs have incorporated novel materials and manufacturing techniques to achieve unprecedented forms and functionalities. The Panton Chair, designed by Verner Panton in 1967, represented a breakthrough as the first single-form molded plastic chair with a cantilevered structure, produced via injection molding without assembly joints, allowing for efficient mass production and fluid, sculptural aesthetics.[115] Similarly, the Eames Lounge Chair, introduced by Charles and Ray Eames in 1956, utilized molded plywood and leather upholstery to create a comfortable, ergonomic recliner that balanced organic form with industrial precision, influencing subsequent furniture production.[7] Adaptive designs prioritize user-specific needs, particularly for ergonomics and accessibility, often integrating adjustable mechanisms to support varying body types and conditions. Self-adjusting ergonomic chairs employ weight-sensitive pneumatic systems that dynamically conform to the sitter's posture and movements, reducing manual adjustments and promoting spinal alignment without reliance on user input.[116] Kneeling chairs, developed in the late 20th century, shift the user's weight forward onto the shins via an inclined seat and knee pads, aiming to maintain a neutral spine position and alleviate lower back strain during prolonged sitting, though empirical studies on long-term efficacy remain mixed.[117] For individuals with disabilities, adaptive seating has evolved from rudimentary modifications to sophisticated, customizable solutions. Postural positioning chairs feature adjustable components like lateral supports and contoured seats to encourage proper alignment and prevent contractures in users with neuromuscular impairments, with designs tested for stability under loads up to 250 pounds.[118] Recent innovations include modular smart chairs equipped with sensors for real-time posture monitoring and automated adjustments, developed to mitigate sedentary-related health risks such as musculoskeletal disorders in office environments.[119] In rehabilitation contexts, chairs modified for resistance training among the elderly incorporate reinforced frames and integrated exercise systems, enabling safe strength-building while seated, as demonstrated in prototypes supporting dynamic movements without tipping.[120] Customization via additive manufacturing, such as 3D printing, allows for bespoke adaptive components tailored to individual anthropometrics, reducing fabrication time and costs compared to traditional methods, with applications in wheelchair-integrated seating for enhanced pressure distribution.[121] These designs underscore a shift toward inclusive functionality, grounded in biomechanical principles rather than aesthetic novelty alone, though claims of universal health benefits require scrutiny against controlled trials showing variable outcomes in pain reduction and productivity gains.[122]Standards, Safety, and Economics
Regulatory Standards and Testing
Regulatory standards for chairs primarily focus on ensuring structural integrity, stability, and resistance to failure under expected loads to minimize injury risks such as tip-overs, collapses, or component breakage. In the United States, the Business and Institutional Furniture Manufacturers Association (BIFMA) develops voluntary performance standards like ANSI/BIFMA X5.1-2017(R2022), which applies to general-purpose office chairs including executive, side/guest, and stacking models; it evaluates aspects like seat and back durability through cyclic loading tests simulating years of use, with a design weight limit of 253 pounds, extended to 400 pounds under ANSI/BIFMA X5.11 for heavier users.[99] [123] The American Society for Testing and Materials (ASTM) provides complementary standards, such as ASTM F1561-03(2014) for plastic chairs in outdoor commercial use, requiring seats to withstand a 150-pound static load for 30 minutes without failure, alongside impact and rear-leg stability tests.[124] [125] For children's chairs, mandatory federal regulations under the Consumer Product Safety Improvement Act (CPSIA) incorporate ASTM standards via the U.S. Consumer Product Safety Commission (CPSC); for instance, 16 CFR 1231 adopts ASTM F404-21 for high chairs, mandating tests for stability (e.g., resisting a 10-pound horizontal force at the seat edge without tipping), structural integrity under a 50-pound seated load, and warnings against leaving children unattended to prevent falls.[126] [127] Similarly, CPSC's 16 CFR 1236 incorporates ASTM F1866-11(2019) for folding chairs and stools aimed at children up to 5 years, testing for pinch points, sharp edges, and collapse resistance under dynamic loads.[128] Adult household chairs lack specific mandatory CPSC rules beyond general prohibitions on substantial product hazards under the Consumer Product Safety Act, relying instead on voluntary compliance to mitigate risks evidenced by incident data, such as rare but documented collapses leading to injuries.[129] Internationally, the International Organization for Standardization (ISO) sets benchmarks like ISO 7173:2023, which outlines test methods for chairs and stools regardless of material, assessing strength via vertical static loads on seats (e.g., 1.4 times the manufacturer's rated load), durability through repeated seating cycles (up to 100,000 for heavy use), and stability by applying forces to simulate tipping scenarios.[130] [131] These ISO protocols harmonize with regional adoptions, such as in Europe under EN standards derived from ISO, emphasizing empirical validation through laboratory simulations of real-world stresses rather than theoretical models. Fire safety regulations add another layer, particularly for upholstered chairs; in California, Technical Bulletin 117-2013 requires materials to resist smoldering ignition without open-flame testing, while federal 16 CFR 1632/1633 mandates cigarette ignition resistance for upholstered furniture to curb smoke inhalation risks from small fires.[132] [133] Testing protocols across these standards employ standardized equipment and procedures for reproducibility, including backrest fatigue tests (e.g., 20,000 cycles of 25-pound rearward force in BIFMA X5.1), armrest static loads (up to 200 pounds vertically), and impact drops from heights mimicking user falls. Compliance is verified by accredited labs, with BIFMA's program maintaining a public registry of certified products to facilitate procurement decisions based on verified performance rather than unsubstantiated claims. While voluntary standards dominate for non-children's chairs, empirical evidence from CPSC injury reports—such as over 1,000 annual furniture-related incidents involving seating—underscores their causal role in reducing hazards through load-rated designs that prevent brittle failures observed in substandard imports.[134] [135]| Test Type | Description | Example Standard Requirement |
|---|---|---|
| Static Load | Applies sustained weight to seat/back/arms to check deformation or breakage | BIFMA X5.1: 300-pound seat load for 1 minute; no permanent deformation >0.5 inch[99] |
| Durability (Cyclic) | Simulates repeated use via mechanical cycling | ISO 7173: 100,000 seat impacts at rated load; minimal wear allowed[130] |
| Stability | Tests resistance to tipping under applied forces or inclines | ASTM F404: No tip with 10-pound force on high chair tray[126] |
| Impact | Drops weights or simulates falls to assess fracture risk | ASTM F1838: 20-pound drop on outdoor chair seat; no cracks[136] |