Sit Much?

Ultimately, sitting in traditional chairs can lead to “sitting-oriented disorders,” or SOD. This includes discomfort while sitting, poor posture, neck and shoulder problems, lower-back pain, strained joints in the lower extremities, weakened circulation, poor breathing, and general fatigue. The American Physical Therapy Association (www.apta.org) estimates that 80 percent of American workers experience back pain at some point in their careers. For many, it is directly attributable to poor sitting posture beginning with school days as youth and continuing into working careers as adults. According to the National Institute of Neurological Disorders and Stroke, back pain is the most common cause of work-related disability in the United States, and it is costing Americans nearly $50 billion annually.
Many Americans---young and old---spend most of their time sitting. School children spend 80 percent of their days sitting down; adults, on average, are seated for 70 percent of the day. Sitting in traditional chairs concentrates pressure on the buttocks, causing them to flatten. In addition, the position of the lower-thigh muscles while sitting impedes circulation to the lower legs and feet, which can cause swelling, varicose veins, the build-up of cellulite, and ‘cold feet.’ Muscle metabolism and functionality also are negatively impacted. Typical furniture puts the human spine in an unnatural position, and the style of seating commonly used in schools and the workplace are even worse.

On a flat seat, the pelvis rocks backward, bending the hips to 90 degrees. This changes the natural S-shape of the spine into a C-shape. The hip joints are able to accommodate the first 60 degrees of the bend and the remaining 30 degrees comes from the pelvis tipping backwards as it is pulled by the large muscles at the back of the thigh (hamstrings). This causes the natural curve of the lumbar spine to straighten. The fourth and fifth lumbar discs are the classic ‘trouble spot’ for most people because the front edges of the vertebrae are pressed together with considerable force due to the unnatural curve in the lumbar region while sitting. This puts pressure on discs that, over time, can become distorted and damaged.

In addition, sitting in a traditional chair causes the shoulder girdle to roll forward, the arms to feel heavy and the shoulder and neck muscles to become tense. The shoulder girdle is a complex network of muscles connected to the spine, so that every pelvic movement and change in spinal posture affects its function and stability. Ordinarily, when the pelvis and spine are in their natural, neutral position, the head and limbs can act in a balanced and efficient way. However, once the pelvis changes from its upright, neutral position, all other joints are affected, most significantly in the upper body.

The healthiest seated position for the back is a comfortable 135-degree angle in which the body retains its natural spinal curvature. “Sitting at 90 degrees is not good, nor is slouching forward,” said Waseem Bashir, clinical research fellow in musculoskeletal radiology at the University of Alberta in Canada. He and other researchers at the University of Alberta examined 22 healthy people with no history of back pain or surgery. Using magnetic resonance imaging (MRI) they examined the subjects lying down, sitting in a 90-degree position, in a forward-slouched-seated position and at a 135-degree seated position. The tests revealed that sitting upright or slouched for more than 10 minutes strained the erector muscles that run along each side of the spinal column. It also caused compression of the intervertebral discs in the lower back resulting in a 20-percent water loss from the soft, jelly-like central part of the disc that acts as a ball bearing. At the 135- degree angle, there was almost no water loss, muscle strain or compression.

Fortunately, there are a few nontraditional seating options that allow for a more natural curve of the spine. These options include saddle seats, ergonomic chairs, and exercise balls. Utilizing “health-oriented” types of chairs allows the body to be supported and the natural “S” curve in the spine maintained while providing the best mechanical advantage for forearms and hands while working. Balancing the body’s center of gravity and maintaining a close-to-neutral posture, these chairs also reduce muscle fatigue. While sitting in these chairs, the center of gravity falls over the supporting base---the ischial tuberosities or sit bones---thereby supporting the body as nature intended.

A saddle seat is affixed to a stool base and resembles the shape of saddle used on a horse or an enlarged seat of a bicycle. The saddle seat encourages postural correctness---the bend forward takes place at the hip rather than the lower back with no added strain. Some people prefer more active, ergonomic chairs, such as an exercise ball. With these chairs, there is no need for lumbar support because the correct lumbar curve happens naturally. A saddle seat or an exercise ball (or Swiss ball) promotes good posture, and allows a person to develop abdominal and back (core) muscles while sitting. When sitting in the upright position supported by the back, the diaphragm is not pushed up into the vital organs. Maintaining alignment of internal organs aids in overall function and wellbeing. In addition, according to Dr. G. Schumoe, a professor at Orthopedic University Hospital in Germany, the straddle position allowed with these types of chairs has “preventive value against future hip disease.” The spread of the legs, called hip abduction, ensures that hip joints have ideal alignment in their sockets such as on a saddle seat.

Front seat tilt and higher work surfaces also are viable ergonomic alte
atives to eliminate lower back strain. A half-standing position lowers the pressure on the discs of the spine. Furniture that accommodates a natural resting position (in which opposing muscles are well balanced) enhances the performance, efficiency and well-being of sitters. The recommended chair height is one-third of the person's height with the desk height one-half. Most people with back pain initially find this position very comfortable but are only able to maintain it for about five to 10 minutes because the back muscles need to be trained. Moving to the front of the seat of a traditional chair or using a forward-sloping cushion can also help reduce the tension of painful tendons and muscles in the back. Most desks are far too low, which may be improved by placing wooden blocks under the desk legs to elevate it to proper height to fit the person.

No one should sit still for too long at one time regardless of the type of chair being used. It is best to get up every half hour or so to move around. Proper posture can profoundly improve one’s health, and many professionals can offer assistance. Alexander-technique practitioners, chiropractors, Heller workers, Feldenkrais-method practitioners, physical therapists and many other bodywork professionals offer guidance on body alignment. Many exercise programs also encourage better posture and help to strengthen the back as well. These include yoga, Pilates, gyrotonics, martial arts and more. Almost everyone needs to move more and sit less, and at a minimum, it is essential to seek out ways to sit that benefit the body rather than cause it harm.