April 2022

Clinical Perspective On Sitting: How to Improve Sitting Posture of Individuals with Disabilities and Others

Figure 1. Normal sitting posture with proper pelvis alignment: (from left to right) frontal, side, and top views.

By Dalia Zwick, PT, PhD

It is well understood that the feet are the foundation of the body when standing. But even in a seated position, the feet play a foundational role in the body’s support, balance, and posture.

Think about what a chair does: Galen Cranz, PhD, an architect and Alexander Technique (a system of body-mind postural education) practitioner, published a book called The Chair: Rethinking Culture, Body, and Design, where she explores challenges in chair design. Should the angle of a chair be flat, tilted backward to stop forward slide, or tipped forward to prevent sacral seating? How high should the chair be to serve both tall and short people? Should chairs have a back for trunk and lumbar support? She concludes that decisions made about any one of these factors affect all of the others.1 Her main message is that people who can move freely need to be encouraged to frequently change position and posture to improve their well-being while seated.

But what about people who have difficulty moving and changing positions, and those with disabilities who have difficulty maintaining a sitting posture? And what about people who may not be aware that they sit in awkward positions that may, in the long run, hurt their bodies?

The focus of this article is on how physical therapists and other healthcare professionals can help improve comfort and body posture in sitting, with a focus on the position of the feet.

Pauline Pope, FCSP, BA, MSc, SRP, a UK physiotherapist who has years of experience working with individuals with complex disabilities and body shape challenges, distinguishes between good and bad posture. She explains that a bad posture is one that causes damage to the body; however, she also adds that any posture has the potential to cause damage if not relieved or changed when the sensory signal from stressed tissue is ignored. Pope further states that an ideal “good” posture allows for effective functional performance, is energy efficient, and does not damage the body.2

It is also important to distinguish between posture as a structure; posture ability, which is the ability to get in and out of posture; and posture control, which is about balance. When we describe posture, we give information on how the body as a structure is aligned or arranged at a given moment. The focus of this article is not on posture control or balance, but on the body structure in terms of range of motion, alignment, and symmetry. For able-bodied people and those with disabilities, the ability to control, change, and adjust posture depends on the supporting surface and internal and external force disturbances in balancing the body. When the body moves voluntarily, it needs to have an anchor or fixed point, such as the feet or the pelvis, that the muscles can rely on like a closed chain.

How We Sit

Figure 2. Abnormal sitting posture (from left to right) front and side; top view of abnormal sitting posture with knees turned out, abduction, and external rotation of the hips

Sitting with feet planted on the floor is key in balance control and posture alignment (Figure 1). One should observe the feet when checking the sitting posture of the patient as foot posture in a semi weight bearing position such as sitting may help to observe foot distortion when present. Observing patients while sitting, one may find that their pelvis may be tilted backward and their knees turned out, abducted, and externally rotated (Figure 2). It is important to understand that this habitual sitting will affect the posture of the foot and ankle. This can even be translated into standing. It is suggested that, when sitting, patients are educated so they know to align their pelvis so they are sitting directly on their ischial tuberosities, their legs (at knee level) forward in line with the sagittal plane, and to align their feet with their big toe pointing forward and longitudinal arch raised. Observing the habitual posture can help in assessment, and asking the patient to improve and realign their posture can offer an opening for patient education. Podiatrists and therapists who treat feet impairments can help their patients by sharing with them some pointers on how to pay attention to and improve their posture while sitting.

The way we sit depends on our postural habits as well as anatomical and physiological constraints. Sitting posture is often influenced by ability, cultural habits, and sensory awareness combined with knowledge, or lack thereof, of proper posture. It is also influenced by what type of surface one sits on. For example, a lifetime of sitting unsupported on the floor develops muscle and joint flexibility required for floor- and chair-sitting, however, a lifetime of habitual chair sitting lacks the muscle and joint flexibility for floor-sitting. This, and the fact that cross-legged positions are also beneficial to chair-sitting, contributes to why people in India regularly sit on train seats and waiting-room benches in the cross-legged position—they find this way of sitting more comfortable than sitting on chairs,3 and why, in the West, people unaccustomed to sitting cross-legged rapidly become uncomfortable in such a position.

Sitting posture depends upon more than just the chair type. In sitting, the pelvis either slouches backward (Figure 3A), plants itself firmly in the middle (Figure 3B), or rocks slightly forward (Figure 3C), thus influencing the spine above and the joints of legs below. Sitting posture is also affected by the chair design, specifically the seat-back angle, seat-bottom angle, foam density, height above floor, and presence, or lack thereof, of armrests. An example of a good seat height at work or in a study environment is when computers or monitors are at eye level. Forward-tilting, seat-bottom inclines can increase pelvis forward rotation, which increases lordosis. However, people who already possess optimal physical ability reports this posture as the most comfortable and practical. The best ratings overall are given to adjustable chairs that allow changes in position—most notably, with feet planted firmly on the floor or on a foot stool of some type.4

Disability and Sitting

Figure 3. The pelvis in sitting posture (from left to right) slouching backward, properly aligned, tilting slightly forward.

Stability of posture is a perquisite to movement. As a physical therapist, I observe how people with different levels of physical ability sit and how they adjust their body posture while they reach, move, or relieve themselves from sensory overload. Purposeful movement, such as reaching, can be initiated only when stability of body posture is achieved.5

To be engaged in movement, the posture of the body needs to be well aligned, balanced, and stable on the surface. To expand on what Pope states regarding good sitting posture, we will use the term explained by Zollars as “neutral posture,” which describes when the person’s pelvis is upright and level, the trunk is symmetrical and elongated, and the hips, knees, and ankles are in a good alignment.6 However, a neutral posture in sitting varies from one person to another depending on a variety of constraints.

I work with adults with disabilities who have difficulty maintaining their sitting posture due to weakness, reflex influence, and limitations in the range of motion and flexibility in their joints and muscles. This is a contributing factor to many of the individuals having body distortions such as scoliosis, pelvic malalignment, and rotation deviation of the knees to one side (windswept distortion). Many of these individuals often require adaptive seating to maintain their posture. Creating an adapted seating system is an important support to the body when body shape distortions are present. Some people with disabilities who use wheelchairs often sit as many as 14 hours a day in one position.

Therefore, a look at the bigger picture, is needed to help improve comfort, flexibility, and ability of the individual to stay in a sitting posture. Caregivers and therapists need to recognize, understand, and help suit the needs of individuals with disabilities to change their position in sitting. Even just taking the individuals out of the chair and into a supine position with support, and slightly altering the position of the legs can make a huge difference! There is also a need to focus on improving flexibility in joints, muscles, and other connective tissues during therapy sessions. Improving flexibility will improve muscle efficiency of posture so that the necessary long duration sitting can be endured. This can be done in therapy sessions, during which, in addition to working on improving flexibility, the individual’s body should be placed and supported in a supine position as to simulate sitting positions. In other words, instead of attempting to work against gravity, as one does in sitting, gravity is being used to our advantage.

Yoga and Sitting

As a long-time Iyengar yoga practitioner, I practice what is called yoga-asanas, or poses (positions). Iyengar yoga is known for its focus on alignment and its use of props, or external objects, to support the body. By using these props, individuals can engage in poses that would otherwise be more difficult.7 In Iyengar yoga, individuals are supported in poses for varying amounts of time, as opposed to other yoga styles, where practitioners move rapidly in and out of poses.

The aim of yoga-asanas is to help improve the ability to sit with ease for extended periods of time. This is particularly important while practicing the poses of breathing, pranayama, and meditation, as this was traditionally the aim of practicing yoga. Posture is defined in the old Yoga Sutras as “steadiness and ease.”8 The root of the word asana is “as,” meaning to sit.9 I integrate tenets and principles of yoga and therapy when working with individuals with disabilities.

I use yoga positioning based on Iyengar yoga principles to improve the range and flexibility of muscles and joints. Practicing this approach during therapy requires the use of props to support various body positions. Placing an individual into supine lying for example, a pose that in yoga is similar to a supported version of Dandasana, involves assisting the patient in supine by positioning their legs so they are supported by a bolster or a chair, simulating sitting (Figure 4). By doing this, we are trying to achieve an angle of 90 degrees at the hips and knees. Here, similar to our previously mentioned “neutral position” in sitting, the pelvis needs special attention, as it needs to be posteriorly tilted and leveled, and the trunk should be symmetrical and elongated, with the hips, knees, and ankles in good alignment. Support is also provided with a belt, which is especially important when influence of tone or reflex is present.

Therapy and Sitting

Figure 4. Supine lying yoga pose with prop support side and top views.

The position of the feet in sitting greatly contributes to the stability of the pose. The base of support in the sagittal plane is significantly greater when one sits with the feet planted on the floor as opposed to when one sits without the feet touching the floor.10 When sitting with the feet in contact with the floor, the base of support extends from the toes (the front of the base) to the rearmost end of the buttocks (the end of the base) where it contacts the seat.11 In the presence of disability, we often observe foot deformities in those who use wheelchairs, partly because the individual does not bear weight on them. This should be attended to in therapy.

According to a study of sitting and standing performance, 52% of children with cerebral palsy (CP) use standard chairs and 42% use adaptive seating.11 The fact that these children with disabilities use standard chairs does not necessarily mean that the chair is suited for them or that they find the chairs comfortable. It is observed that individuals with developmental disabilities often develop contractures of muscles, which causes stiffness, around the hips. This hip stiffness can limit one or both hips’ mobility and flexibility, making sitting a challenge. Frequently, a condition described as asymmetrical limited hip flexion (ALHF) is present. This condition makes it even more difficult to sit comfortably, as most standard chairs require 90 degrees of hip flexion, or mobility. This hip asymmetry shows an association between an asymmetrical trunk, an uneven weight distribution, scoliosis, and a windswept hip distortion.12 This can be explained by the fact that the pelvis is the anatomical structure that is directly linked to the hip joint, and can therefore be expected to be most affected when hip flexion is less than 90 degrees in the sitting position.6 These distortions and limited ranges at the hip, pelvis, and trunk always necessitate the adapted seating surface and specialized wheelchair, preferably with a tilt mechanism.

The concern I have with special seating is that individuals with severe distortions and individuals who are older are frequently treated while they are still in their wheelchair. Reasons for this can include time limitations, a lack of transfer equipment, and the often-incorrect assumption that patients cannot be provided with any better sitting environment than their adapted seat in the wheelchair. An approach and focus in therapy should be on improving posture and ranges of motion as previously described. Studies show that bone/joint complications (eg, hip displacement, range of motion, windswept posture, scoliosis) had the strongest direct pathway with pain in the lower extremities, followed by reduced mobility in children and adolescents with CP.13 This pain can be reduced through thoughtful therapy, a combination of attending to the patient’s specific needs and the patient’s specific limitations.

The main point we can take from these studies is that when sitting, the pelvis should be supported to stay in an upright position where the 2 ischial tuberosities are supporting the body weight equally. The feet should be in a good position, planted on the ground or some other supporting surface such as a foot plate if a wheelchair is used. If this position cannot be achieved, the body needs to be supported.

Dalia Zwick, PT, PhD, is a senior rehabilitation supervisor working part-time managing foot and ankle services at clinics for people with disabilities in New York City.

REFERENCES
  1. Cranz G. The Chair: Rethinking Culture, Body and Design. W.W. Norton; 2000.
  2. Pope PM. Severe and Complex Neurological Disability: Management of the Physical Condition. 1st ed. Butterworth-Heinemann/Elsevier Health; 2007.
  3. Friedman U. The Atlantic. August 30, 2016. Available at https://www.theatlantic.com/international/archive/2016/08/chairs-history-witold-rybczynski/497657/. Accessed April 1, 2022.
  4. Zollars JA. Special seating: an illustrated guide. Otto Bock Orthopedic Industry; 1996.
  5. Harrison DD, Harrison SO, Croft AC, Harrison DE, Troyanovich SJ. Sitting biomechanics part I: review of the literature. J Manipulative Physiol Ther. 1999;22(9):594-609.
  6. Pope P. Severe and Complex Neurological Disability: Management of the Physical Condition. Butterworth-Heinemann/Elsevier: 2007.
  7. Evans S, Sternlieb B, Zeltzer L, Tsao J. Iyengar yoga and the use of props for pediatric chronic pain: a case study. Altern Ther Health Med. 2013;19(5):66-70.
  8. Bahn AJ. Yoga Sutras of Patanjali. Asian Humanities Press; 1992.
  9. Hewes GW. World distribution of certain postural habits. Amer Anthropol. 1955;57(2):231–44.
  10. Endo S, Asai H, Inaoka-Pleiades T. Perception of trunk inclination during sitting with feet in contact with the floor. J Phys Ther Sci. 2019;31(2):185-189.
  11. Rodby-Bousquet E, Hägglund G. Sitting and standing performance in a total population of children with cerebral palsy: a cross-sectional study. BMC Musculoskelet Disord. 2010;11:131.
  12. Ágústsson A, Sveinsson Þ, Rodby-Bousquet E. The effect of asymmetrical limited hip flexion on seating posture, scoliosis and windswept hip distortion. Res Dev Disabil. 2017;71:18-23.
  13. Schmidt SM, Hagglund G, Alriksson-Schmidt AI. Bone and joint complications and reduced mobility are associated with pain in children with cerebral palsy. Acta Paediatr. 2020;109(30):541-549.

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.