Office Ergonomics.

Prolonged use of poorly designed office seats and sitting in inappropriate positions can lead to back and neck pain problems.

We work, chat and laugh seated in offices, yet when the day is over we return home complaining of backache, muscle contractions around the neck, back, and shoulders, and numbness or reduced sensitivity in the legs, among other problems. “Perhaps it was the long day’s work and stress, but hope tomorrow will be better as we have beaten the deadline,” we console ourselves. While these are some of the contributing factors to the physical distress that often suffer, hardly do we associate these pains with the poorly designed chairs and desks or the overall design of the offices where we work.

Alice Wanjugu, a retiree, says that she spent most of her working life as a secretary with a clearing and forwarding company within Nairobi’s Industrial Area. Today, five years after retirement, she still complains of the same severe back problems she used to experience during her working days. This happens even when she hasn’t done much work.

“Sometimes I think it is because I am growing old, though I have felt these pains since I started working about thirty years ago,” she says. With this problem, she cannot do strenuous work and has spent a considerable amount of money on physiotherapy. Where she in an advanced country, Alice would have been compensated by her previous employers, for having her use poorly designed chairs and desks that have subsequently subjected her to a lifetime of chronic back pains.

It is today estimated that managers, secretaries, cashiers, and clerical workers spend about 70 percent of their working lives sitting positions. The amount of time that these people spend sitting has been lengthened by modern information technology whereby one no longer has to stand or walk around to look for files or to post letters. Today, all this can be done with a mouse click, albeit at the expense of the physical health of the people concerned.

According to Spine-health.com, a leading online journal on spinal issues, sitting in office chairs for prolonged periods of time can cause pain in the lower parts of the back or worsen an already existing back or neck problem. Sitting in back, neck, shoulders, arms, and legs. As Salim Abdallah, manager at the Aga Khan University Hospital in Nairobi explains, there is a tendency to slouch forward o downward when one sits in a chair for a long time. “This posture overstretches the spinal ligaments and strains the discs around the spine. If this poor sitting behavior is continued, it can result in damaged spinal structures and recurrent back pain problems”.

Various studies conducted in this area reveal that there are five major causes of back pain problems for working people:

 Sustained or prolonged sitting in the same posture. This reduces blood flow to the back and lower parts of the body, which in turn leads to depletion of nutrients in muscles and tissues within the affected areas. Thus, a buildup of metabolic wastes in tissues, which poisons the surrounding cells, hence the pain or reduced levels of sensitivity in body organs. Experts advise on the need to keep changing sitting positions depending on one’s comfort level. While most people associate fidgeting with nervousness, health specialists says that it is to some extent important for your health.

 Awkward or non-neutral postures of the spine. Twisting, bending, or flattening of the lower back can cause back pains, as they stretch or overwork the muscles and ligaments on the back. These postures can squeeze or even rapture the cartilaginous discs between the spinal column leading to excessive pain, especially when nerve fibers are affected. To avoid this, one should sit upright or in a posture that allows for even weight distribution across the various supportive muscles and tissues in the body.

 Compression forces. These can come in form of lifting or carrying heavy loads either in your arms, on your shoulders, or back. The natural tendency among most people is to bend their backs and use the spinal cord for support when lifting heavy objects. However, this adds excessive weight to the spine, which can cause snapping of the spinal column. Snapping can occur even when one is doing simple tasks such as lifting or moving desks and chairs and can lead to disability. When lifting heavy objects, care should be taken to ensure fair weight distribution across the body. A good way of doing this is by bending at the knees and lowering the hip in order to reach and lift such objects.

 Localized contact stress: Pressure on the back or legs can affect blood flow both at the site of pressure and in the legs and feet. This can once again result from prolonged sitting in the same position with the legs firmly on the ground. Besides shifting of sitting position and taking a walk in order to avoid this problem, one should consider using a chair that allows enough room for leg movement underneath it. A footrest under the desk would also come in handy as it allows for better blood flow to the lower parts of the body.

 Repetition without breaks: Repeated bending, twisting or lifting can outpace the body’s ability to repair itself after exertions. This is more so with people who are obsessed with physical exercising and weight lifting. To avoid this, physical tasks or exercises should be conducted moderately and at the recommended intervals. For a comfortable and productive working environment, “there is need to consider the general design of office,” says Christine Matundura, an interior designer at New Line Furniture Ltd. In Nairobi. One of the most crucial tools in this regard is the chair on which workers spend most of their office time.

An ergonomic office chair can help one maximize back support and maintain a good posture when seated. It is also important to adjust chair to the proportions of the individual’s body in order to improve comfort and reduce aggravation to the lower back and neck. This should also be done considering the height of the office desk or computer that one uses, as well as the type of work that one does.

“For instance”, says, Mr. Abdallah, “placing the computer at a location that requires one to keep turning, say, to the right, whenever a visitor comes into the office can have a negative cumulative effect on one’s right side of the neck”. The same applies to the habit whereby secretaries talk while holding the phone between the chin and the shoulder, and typing on the keyboard at the same time. This might seem a convenient position for some as it allows for multitasking, but experts say it should be avoided at all costs.

The computer monitor should neither be positioned too high up nor lower than the eye level, while the keyboard and mouse should be easily accessible. When working on the computer, one’s elbows should be at a right angle or more, and the wrists at a free or neutral position – neither hanging downwards nor folding upwards to reach the keyboard.

While traditional office chairs offer a considerable degree of comfort for most people, modern designs offer more in terms of comfort and flexibility. Such allow for greater freedom of turning around and other movements within the office space, posture shift, and relaxation.

CHARACTERISTICS OF WELL DESIGNED OFFICE CHAIRS

Office chairs come in countless makes and brands, but a good one should have a fair combination of the following characteristics:
 Allow for posture change. Chairs allow for posture change if they can recline, are large enough to permit occasional off-center postures: keep the individual at a height that allows his legs to assist in posture changes, allow different postures for legs and feet; have firm cushions, have easy to use adjustment mechanisms for height and tilt-lock release; and offer lower back or pelvic support, among other features.

 Reduce muscle activity required while sitting. In the absence of back support, back muscles work about the same amount as when in a standing position However, this activity drops when one uses a chair that facilitates back recline, one that has armrests, as well as allows for straightening or extending of legs.

 Reduce the weight carried by the spine. The upper body weight of a person sitting without back support accounts for about one-half of the total body weight. However, a chair’s backrest helps reduce the weight burden on the spinal discs, besides offering a comfortable sitting position.

 Restore the natural lower back shape. A well-designed chair can serve this purpose in a number of ways. It can come with a supportive curve in the lumbar area of the backrest; allow for adjustment of seat in relation to the backrest to widen the angle between the trunk and thighs; have a contoured seat pan to facilitate change of the pelvic angle, or stabilize the pelvis with the support at the base of the spine.

 Reduce pressure in the skin and other tissues. High chairs leave the occupant’s legs suspended in the air and this increases pressure on the underside of the thighs. This reduces blood flow to lower body parts and can cause numbness in legs. Fitting a cushion on hard flat seats can lengthen the period that it takes for such discomfort to be experienced. However, too much of soft cushion can put pressure on the buttocks, thus causing discomfort and muscular pain.

Has adjustment mechanisms. Adjustable chairs can make up for people’s variations in size and structure. However, perhaps the most important adjustment mechanisms that a good chair should have are seat pan depth – ability to move the backrest in or out through a sliding pan to change the front and back depth; and height adjustment – for comfortable positioning of feet on the ground.