Overview :
The VISA (Victorian Institute of Sport Assessment) score can be used to grade the severity of symptoms in patients with patellar tendinosis (jumper's knee). It can be used to monitor patient's over time and to assess the impact of various interventions.
The Victorian Institute of Sport is in South Melbourne, Victoria, Australia.
Questionnaire
(1) How many minutes can you sit pain free?
• points = INTEGER (MINIMUM (100, (minutes/10))
(2) Do you have pain walking downstairs with a normal gait cycle?
• points from 0 to 10
• severe strong pain: 0 points
• no pain: 10 points
(3) Do you have pain at the knee with full active non-weight bearing knee extension?
• points from 0 to 10
• severe strong pain: 0 points
• no pain: 10 points
(4) Do you have pain when doing a full-weight bearing lung?
• points from 0 to 10
• severe strong pain: 0 points
• no pain: 10 points
(5) Do you have problems squatting?
• points from 0 to 10
• unable: 0 points
• no problems: 10 points
(6) Do you have pain during immediately after doing 10 single leg hops?
• points from 0 to 10
• strong severe pain/unable: 0 points
• no pain: 10 points
(7) Are you currently undertaking sport or other physical activity?
• not at all: 0 points
• modified training +/- modified competition: 4 points
• full training +/- competition but not at same level as when symptoms began: 7 points
• competing at the same or higher level as when symptoms began: 10 points
(8) Complete EITHER 8a, 8b, OR 8c, selecting as follows:
• If you have no pain while undertaking sport, please complete 8A only.
(8a) If you have no while undertaking sport, for how long can you train/practice?
• If you have pain while undertaking sport but it does not stop you from completing the activity, please complete 8b only.
(8b) If you have some pain while undertaking sport, but it does not stop you from completing your training/practice, for how long can you train/practice?
• If you have pain that stops you from completing sporting activities, please complete 8c only.
(8c) If you have pain that stops you from completing your training/practice, for how long can you train/practice?
Question nil 0-5 mts 6-10 mts 11-15 mts > 15 minutes
8a 0 7 14 21 30
8b 0 4 10 14 20
8c 0 2 5 7 10
total VISA score =
= SUM(points for responses to all 8 questions)
Interpretation:
• minimum score: 0
• maximum score: 100
• The higher the score, the better the patient's condition.
• Patients may be categorized into groups based on 81-100, 61-80, and < name="ref">References:
Visentini PJ, Khan KM, et al. The VISA Score: An index of severity of symptoms in patients with jumper's knee (patellar tendinosis). J Science and Medicine in Sport. 1998; 1: 22-28.
Friday, June 22, 2007
Carpal Tunnel Syndrome
Definition
Carpal tunnel syndrome is a disorder caused by compression at the wrist of the median nerve supplying the hand, causing numbness and tingling.
Description
The carpal tunnel is an area in the wrist where the bones and ligaments create a small passageway for the median nerve. The median nerve is responsible for both sensation and movement in the hand, in particular the thumb and first three fingers. When the median nerve is compressed, an individual's hand will feel as if it has "gone to sleep."
Women between the ages of 30 and 60 have the highest rates of carpal tunnel syndrome. Research has demonstrated that carpal tunnel syndrome is a significant cause of missed work days due to pain. In 1995, about $270 million was spent on sick days taken for pain from repetitive motion injuries.
Causes & symptoms
Compression of the median nerve in the wrist can occur during a number of different conditions, particularly those conditions which lead to changes in fluid accumulation throughout the body. Because the area of the wrist through which the median nerve passes is very narrow, any swelling in the area will lead to pressure on the median nerve. This pressure will ultimately interfere with the nerve's ability to function normally. Pregnancy, obesity, arthritis, certain thyroid conditions, diabetes, and certain pituitary abnormalities all predispose to carpal tunnel syndrome. Other conditions that increase the risk for carpal tunnel syndrome include some forms of arthritis and various injuries to the arm and wrist (including fractures, sprains, and dislocations). Furthermore, activities which cause a person to repeatedly bend the wrist inward toward the forearm can predispose to carpal tunnel syndrome. Certain jobs that require repeated strong wrist motions carry a relatively high risk of carpal tunnel syndrome. Injuries of this type are referred to as "repetitive motion" injuries, and are more frequent among secretaries who do a lot of typing, people working at computer keyboards or cash registers, factory workers, and some musicians.
Symptoms of carpal tunnel syndrome include numbness, burning, tingling, and a prickly pin-like sensation over the palm surface of the hand, and into the thumb, forefinger, middle finger, and half of the ring finger. Some individuals notice a shooting pain which goes from the wrist up the arm, or down into the hand and fingers. With continued median nerve compression, an individual may begin to experience muscle weakness, making it difficult to open jars and hold objects with the affected hand. Eventually, the muscles of the hand served by the median nerve may begin to grow noticeably smaller (atrophy), especially the fleshy part of the thumb. Untreated, carpal tunnel syndrome may eventually result in permanent
weakness, loss of sensation, or even paralysis of the thumb and fingers of the affected hand.
Diagnosis
The diagnosis of carpal tunnel syndrome is made in part by checking to see whether the patient's symptoms can be brought on by holding his or her hand with the wrist bent for about a minute. Wrist x rays are often taken to rule out the possibility of a tumor causing pressure on the median nerve. A physician examining a patient suspected of having carpal tunnel syndrome will perform a variety of simple tests to measure muscle strength and sensation in the affected hand and arm. Further testing might include electromyographic or nerve conduction velocity testing to determine the exact severity of nerve damage. These tests involve stimulating the median nerve with electricity and measuring the resulting speed and strength of the muscle response, as well as recording the speed of nerve transmission across the carpal tunnel. In 2002, a report stated that three medical organizations had concluded that electrodiagnostic studies were the preferred methods of diagnosing carpal tunnel syndrome, offering the highest degrees of sensitivity and specificity.
Treatment
Carpal tunnel syndrome is initially treated with splints, which support the wrist and prevent it from flexing inward into the position that exacerbates median nerve compression. Some people get significant relief by wearing such splints to sleep at night, while others will need to wear the splints all day, especially if they are performing jobs that stress the wrist.
The activity which caused the condition should be avoided whenever possible. Also, the actions of making a fist, holding objects, and typing should be reduced. The patient's work area should be modified to reduce stress on the body. This may be achieved by correct positioning and with ergonomically designed furniture. Performing hand and wrist exercises periodically throughout the day can be beneficial.
Researchers found that the carpal ligament can be lengthened or released without surgery through osteopathic manipulation and weight loading. Combining the two gives additional benefit because manipulation lengthens the ligament at one end and weight loading increases the length at the other end. Patients can be taught a stretching exercise for self-manipulation of the ligament.
A National Institute of Health (NIH) panel concluded that traditional acupuncture may be a useful alternative or complementary treatment for carpal tunnel syndrome. Studies have shown that both laser acupuncture and microamp transcutaneous electrical nerve stimulation (TENS) can significantly reduce the pain associated with carpal tunnel syndrome. Both of these therapies are painless. Greater than 90% of the patients treated reported no pain or pain that had been reduced by more than half. Patients in this study were also using Chinese herbal medicines, deep acupuncture (including needle acupuncture), moxibustion, and omega-3 fish oil capsules. All patients were able to return to work and the pain of most patients remained stable for up to two years. Persons over the age of 60 years had a poorer response.
Some studies have shown that persons with carpal tunnel syndrome are deficient in vitamin B6 (pyridoxine) and that supplementation with this vitamin is beneficial. Carpal tunnel syndrome should improve within two to three months by taking 100 mg three times daily. The patient should consult with his or her physician when taking high doses of this vitamin.
Chinese and homeopathic remedies include:
arnica; 30c dose
astra essence
Rhus toxicodendron; 6c dose
Ruta graveolens; 6c dose
Allopathic treatment
Ibuprofen or other nonsteroidal anti-inflammatory drugs may be prescribed to decrease pain and swelling. Diuretics may be used if the syndrome is related to the menstrual cycle. When carpal tunnel syndrome is more advanced, steroids may be injected into the wrist to decrease inflammation.
The most severe cases of carpal tunnel syndrome may require surgery to decrease the compression of the median nerve and restore its normal function. Such a repair involves cutting that ligament that crosses the wrist, thus allowing the median nerve more room and decreasing compression. This surgery is done almost exclusively on an outpatient basis and is often performed without the patient having to be made unconscious. Careful injection of numbing medicines (local anesthesia) or nerve blocks (the injection of anesthetics directly into the nerve) create sufficient numbness to allow the surgery to be performed painlessly, without the risks associated with general anesthesia. Recovery from this type of surgery is usually quick and without complications.
In 2002, researchers in the Netherlands reported that after studying about 80 patients over two years, surgery proved more successful than nighttime splints in freeing up compressed nerves of patients with carpal tunnel syndrome. Many patients in the splint group ended up choosing the surgery option after several months of wearing splints.
Expected results
Without treatment, continued pressure on the median nerve puts the patient at risk for permanent disability in the affected hand. Alternative medicines have been shown to reduce pain. Most people are able to control the symptoms of carpal tunnel syndrome with splinting and anti-inflammatory agents. For those who go on to require surgery, about 95% will have complete cessation of symptoms.
Prevention
Avoiding or reducing the repetitive motions that put the wrist into a bent position may help to prevent carpal tunnel syndrome. People who must work long hours at a computer keyboard, for example, may need to take advantage of recent advances in ergonomics and position the keyboard and computer components in a way that increases efficiency and decreases stress. Early use of a splint may also be helpful for persons whose jobs put them at risk of carpal tunnel syndrome.
Carpal tunnel syndrome is a disorder caused by compression at the wrist of the median nerve supplying the hand, causing numbness and tingling.
Description
The carpal tunnel is an area in the wrist where the bones and ligaments create a small passageway for the median nerve. The median nerve is responsible for both sensation and movement in the hand, in particular the thumb and first three fingers. When the median nerve is compressed, an individual's hand will feel as if it has "gone to sleep."
Women between the ages of 30 and 60 have the highest rates of carpal tunnel syndrome. Research has demonstrated that carpal tunnel syndrome is a significant cause of missed work days due to pain. In 1995, about $270 million was spent on sick days taken for pain from repetitive motion injuries.
Causes & symptoms
Compression of the median nerve in the wrist can occur during a number of different conditions, particularly those conditions which lead to changes in fluid accumulation throughout the body. Because the area of the wrist through which the median nerve passes is very narrow, any swelling in the area will lead to pressure on the median nerve. This pressure will ultimately interfere with the nerve's ability to function normally. Pregnancy, obesity, arthritis, certain thyroid conditions, diabetes, and certain pituitary abnormalities all predispose to carpal tunnel syndrome. Other conditions that increase the risk for carpal tunnel syndrome include some forms of arthritis and various injuries to the arm and wrist (including fractures, sprains, and dislocations). Furthermore, activities which cause a person to repeatedly bend the wrist inward toward the forearm can predispose to carpal tunnel syndrome. Certain jobs that require repeated strong wrist motions carry a relatively high risk of carpal tunnel syndrome. Injuries of this type are referred to as "repetitive motion" injuries, and are more frequent among secretaries who do a lot of typing, people working at computer keyboards or cash registers, factory workers, and some musicians.
Symptoms of carpal tunnel syndrome include numbness, burning, tingling, and a prickly pin-like sensation over the palm surface of the hand, and into the thumb, forefinger, middle finger, and half of the ring finger. Some individuals notice a shooting pain which goes from the wrist up the arm, or down into the hand and fingers. With continued median nerve compression, an individual may begin to experience muscle weakness, making it difficult to open jars and hold objects with the affected hand. Eventually, the muscles of the hand served by the median nerve may begin to grow noticeably smaller (atrophy), especially the fleshy part of the thumb. Untreated, carpal tunnel syndrome may eventually result in permanent
weakness, loss of sensation, or even paralysis of the thumb and fingers of the affected hand.
Diagnosis
The diagnosis of carpal tunnel syndrome is made in part by checking to see whether the patient's symptoms can be brought on by holding his or her hand with the wrist bent for about a minute. Wrist x rays are often taken to rule out the possibility of a tumor causing pressure on the median nerve. A physician examining a patient suspected of having carpal tunnel syndrome will perform a variety of simple tests to measure muscle strength and sensation in the affected hand and arm. Further testing might include electromyographic or nerve conduction velocity testing to determine the exact severity of nerve damage. These tests involve stimulating the median nerve with electricity and measuring the resulting speed and strength of the muscle response, as well as recording the speed of nerve transmission across the carpal tunnel. In 2002, a report stated that three medical organizations had concluded that electrodiagnostic studies were the preferred methods of diagnosing carpal tunnel syndrome, offering the highest degrees of sensitivity and specificity.
Treatment
Carpal tunnel syndrome is initially treated with splints, which support the wrist and prevent it from flexing inward into the position that exacerbates median nerve compression. Some people get significant relief by wearing such splints to sleep at night, while others will need to wear the splints all day, especially if they are performing jobs that stress the wrist.
The activity which caused the condition should be avoided whenever possible. Also, the actions of making a fist, holding objects, and typing should be reduced. The patient's work area should be modified to reduce stress on the body. This may be achieved by correct positioning and with ergonomically designed furniture. Performing hand and wrist exercises periodically throughout the day can be beneficial.
Researchers found that the carpal ligament can be lengthened or released without surgery through osteopathic manipulation and weight loading. Combining the two gives additional benefit because manipulation lengthens the ligament at one end and weight loading increases the length at the other end. Patients can be taught a stretching exercise for self-manipulation of the ligament.
A National Institute of Health (NIH) panel concluded that traditional acupuncture may be a useful alternative or complementary treatment for carpal tunnel syndrome. Studies have shown that both laser acupuncture and microamp transcutaneous electrical nerve stimulation (TENS) can significantly reduce the pain associated with carpal tunnel syndrome. Both of these therapies are painless. Greater than 90% of the patients treated reported no pain or pain that had been reduced by more than half. Patients in this study were also using Chinese herbal medicines, deep acupuncture (including needle acupuncture), moxibustion, and omega-3 fish oil capsules. All patients were able to return to work and the pain of most patients remained stable for up to two years. Persons over the age of 60 years had a poorer response.
Some studies have shown that persons with carpal tunnel syndrome are deficient in vitamin B6 (pyridoxine) and that supplementation with this vitamin is beneficial. Carpal tunnel syndrome should improve within two to three months by taking 100 mg three times daily. The patient should consult with his or her physician when taking high doses of this vitamin.
Chinese and homeopathic remedies include:
arnica; 30c dose
astra essence
Rhus toxicodendron; 6c dose
Ruta graveolens; 6c dose
Allopathic treatment
Ibuprofen or other nonsteroidal anti-inflammatory drugs may be prescribed to decrease pain and swelling. Diuretics may be used if the syndrome is related to the menstrual cycle. When carpal tunnel syndrome is more advanced, steroids may be injected into the wrist to decrease inflammation.
The most severe cases of carpal tunnel syndrome may require surgery to decrease the compression of the median nerve and restore its normal function. Such a repair involves cutting that ligament that crosses the wrist, thus allowing the median nerve more room and decreasing compression. This surgery is done almost exclusively on an outpatient basis and is often performed without the patient having to be made unconscious. Careful injection of numbing medicines (local anesthesia) or nerve blocks (the injection of anesthetics directly into the nerve) create sufficient numbness to allow the surgery to be performed painlessly, without the risks associated with general anesthesia. Recovery from this type of surgery is usually quick and without complications.
In 2002, researchers in the Netherlands reported that after studying about 80 patients over two years, surgery proved more successful than nighttime splints in freeing up compressed nerves of patients with carpal tunnel syndrome. Many patients in the splint group ended up choosing the surgery option after several months of wearing splints.
Expected results
Without treatment, continued pressure on the median nerve puts the patient at risk for permanent disability in the affected hand. Alternative medicines have been shown to reduce pain. Most people are able to control the symptoms of carpal tunnel syndrome with splinting and anti-inflammatory agents. For those who go on to require surgery, about 95% will have complete cessation of symptoms.
Prevention
Avoiding or reducing the repetitive motions that put the wrist into a bent position may help to prevent carpal tunnel syndrome. People who must work long hours at a computer keyboard, for example, may need to take advantage of recent advances in ergonomics and position the keyboard and computer components in a way that increases efficiency and decreases stress. Early use of a splint may also be helpful for persons whose jobs put them at risk of carpal tunnel syndrome.
Thursday, June 21, 2007
How to Lift and Carry Safely
Lifting and carrying are power jobs—when you lift and carry the wrong way, you can damage your back. Back injuries are the most common type of injury in the workplace, causing approximately 900,000 disabling injuries in 1995. Over half of these injuries are from lifting.
Back injuries may be difficult to treat and may have lengthy and expensive rehabilitation times.
Whether you are lifting at home or at work, make an effort to take care of your back. The National Safety Council recommends a number of tips to prevent unintentional injuries and keep your back strong and healthy.
Power warm-ups
You will work better if you start each day with slow stretches. These warm-ups let you ease comfortably into your workday and help you avoid injuries.
Leg and back warm-up
Prop one foot on a chair or a stool for support
Take a deep breath
Ease forward slowly—keep your back slightly curved
Blow slowly outward as you ease forward to a seven count
Repeat seven times
Switch and do the same with the other foot
Backbend
Stand with your feet about 12 inches apart
Support the small of your back with your hands
Hold your stomach in firmly and take a deep breath
Arch backward—bend your head and neck as you go, blowing air slowly out for seven counts
Repeat seven times
Power lifting tips
Protect your hands and feet by wearing safety gear
Size up the load—tip it on its side to see if you can carry it comfortably. Get help if the load is too big or bulky for one person. Check for nails, splinters, rough strapping and sharp edges
Lift it right—make sure your footing is solid. Keep your back straight, with no curving or slouching. Center your body over your feet, get a good grip on the object and pull it close to you. Pull your stomach in firmly. Lift with your legs, not your back; if you need to turn, move your feet and don't twist your back
Tough lifting jobs
Oversized loads: do not try to carry a big load alone; ask for help. Work as a team by lifting, walking and lowering the load together. Let one person call the shots and direct the lift. Use proper mechanical devices for heavy loads.
High loads: use a step stool or a sturdy ladder to reach loads that are above your shoulders. Get as close to the load as you can and slide the load toward you. Do all the work with your arms and legs, not your back.
Low loads: loads that are under racks and cabinets need extra care. Pull the load toward you, then try to support it on one knee before you lift. Use your legs to power the lift.
Always use your stomach as a low back support by pulling it in during lifting.
Remember, a strong, healthy, powerful back is vital to your job. It also helps you enjoy life. Take pains to avoid injuries by making it a full-time job to take care of your back!
Back injuries may be difficult to treat and may have lengthy and expensive rehabilitation times.
Whether you are lifting at home or at work, make an effort to take care of your back. The National Safety Council recommends a number of tips to prevent unintentional injuries and keep your back strong and healthy.
Power warm-ups
You will work better if you start each day with slow stretches. These warm-ups let you ease comfortably into your workday and help you avoid injuries.
Leg and back warm-up
Prop one foot on a chair or a stool for support
Take a deep breath
Ease forward slowly—keep your back slightly curved
Blow slowly outward as you ease forward to a seven count
Repeat seven times
Switch and do the same with the other foot
Backbend
Stand with your feet about 12 inches apart
Support the small of your back with your hands
Hold your stomach in firmly and take a deep breath
Arch backward—bend your head and neck as you go, blowing air slowly out for seven counts
Repeat seven times
Power lifting tips
Protect your hands and feet by wearing safety gear
Size up the load—tip it on its side to see if you can carry it comfortably. Get help if the load is too big or bulky for one person. Check for nails, splinters, rough strapping and sharp edges
Lift it right—make sure your footing is solid. Keep your back straight, with no curving or slouching. Center your body over your feet, get a good grip on the object and pull it close to you. Pull your stomach in firmly. Lift with your legs, not your back; if you need to turn, move your feet and don't twist your back
Tough lifting jobs
Oversized loads: do not try to carry a big load alone; ask for help. Work as a team by lifting, walking and lowering the load together. Let one person call the shots and direct the lift. Use proper mechanical devices for heavy loads.
High loads: use a step stool or a sturdy ladder to reach loads that are above your shoulders. Get as close to the load as you can and slide the load toward you. Do all the work with your arms and legs, not your back.
Low loads: loads that are under racks and cabinets need extra care. Pull the load toward you, then try to support it on one knee before you lift. Use your legs to power the lift.
Always use your stomach as a low back support by pulling it in during lifting.
Remember, a strong, healthy, powerful back is vital to your job. It also helps you enjoy life. Take pains to avoid injuries by making it a full-time job to take care of your back!
BACK CARE FOR SITTING WORK
Professor Alan Hedge, PhD Director Human Factors and Ergonomics Laboratory Cornell UniversityDepartment of Design and Environmental Analysis Ithaca, NY http://ergo.human.cornell.edu
Sitting has become a way of life for many Americans. We sit in cars, buses, trains or planes when we travel, we sit to eat meals, we sit and watch TV, we sit in classrooms, and for many of us, we sit most of the day at work, often in front of a computer all day. Studies of sedentary workers show that low back problems are associated with poor chair design and inappropriate sitting posture.
Although for many activities we could stand just as easily as sit, for example, we could stand to watch TV, stand to eat, and stand in front of a computer all day. There are at least three good reasons why we prefer sitting.
Sitting uses about 20% less energy compared with standing to do the same work, so comfortable sitting helps to relieve fatigue.
Sitting helps to reduce the strain on our back muscles and on the intervertebral discs of the lumbar spine, providing that we sit back in a supported, reclined posture.
Sitting gives us greater postural stability for performing fine manipulative tasks, such as eating with a knife and fork, sewing, writing, etc.
(Image reproduced courtesy of Humanscale)
Anatomical Changes During Sitting
When we change from a standing posture to a sitting posture anatomical changes occur. The lumbar spine changes shape depending on what we sit on and how we sit. If we sit on a flat surface, such as a bench, bleachers or stool, without any back support we tend to hunch the body forwards for support, often resting our arms on our legs to reduce fatigue. As we hunch forwards, the lower back curves outwards into a kyphotic shape. This is generally regarded as an unhealthy posture if sustained for a prolonged period. With nothing to lean back on, the upper body becomes fatigued and we typically regard this as an uncomfortable way to sit. However, this is the way that many people end up sitting over the course of each workday, so it isn't surprising that studies of sedentary workers, such as office workers, have frequently reported high levels of postural discomfort. [2] What we want is to be able to sit and maintain the lumbar spine in a posture called lordosis.
Ergonomic Chair Design
If we sit on a good ergonomic chair, the seat pan is curved from back to front to encourage the pelvis to rotate forwards, and this helps the lumbar spine to maintain lordosis. As we sit back the lower back should be well supported by a contoured lumbar support. The average preferred height for a good lumbar support is abut 7.5 -inches above the compressed seat surface (19 cm), and the mean preferred seat depth (horizontal distance from front of seat to lumbar support point) is about 15.25-inches (38.7 cm). Ideally, the chair should have a backrest that is sufficient high to provide support to the thoracic region as well. [3] Also, make sure that the seat is height adjustable (15" - 22"), the backrest angle is adjustable (100° - 120°), the armrests have a minimum 16.1” width and have adjustable height (7.1”-10.6” above compressed seat height). [4] Studies of office chairs show that users often cannot correctly identify or operate chair controls [5], so make sure that the chair has user-friendly controls.
(Image reproduced courtesy of Humanscale)
Safe Sitting
Keeping the spine healthy requires periodic changes in posture, and dynamic movement helps to promote circulation and reduce muscle fatigue. Sitting in any static posture for a prolonged period eventually will become uncomfortable. This means that there isn't a fixed posture that's best for everyone, all of the time, whatever the task at hand. Rather, there is a desirable range of movement that works well for most people doing most of the kinds of tasks performed when sitting.
The preferred way of sitting involves the following:
Make sure that the seat height is correctly adjusted so that your feet are on the ground or on a solid surface like a good footrest.
Recline back in the chair, with the chair backrest angled between 100-110-degrees, so that the chair back can help support the weight of the torso.
Make sure that the chair has good lumbar support in the right area for your shape and size of back. If there is an adjustable support, use this to get the best position. If not, use a rolled towel or a cushion to improve your lower back support.
Make sure that the seat pan is the right size for you and doesn't press behind your knees.
Look for a chair that doesn't tip up the seat pan when you recline because this can put pressure under the thighs and behind the knees.
If the chair has arms, make sure that these are correctly adjusted for height so that your shoulders are relaxed, not hunched or raised when you rest on the armrests.
If the chair has a high neck/headrest make sure that this can be used in different sitting positions.
Now that your body is in a good, supported posture you should be ready to work without any discomfort, but remember to take periodic breaks, and to change posture, get up and move around.
(Image reproduced courtesy of Humanscale)
Tips for Choosing the Best Ergonomic Chair
When choosing a chair ask yourself the following questions:
1. Is the chair comfortable to sit in for the way that you work?
a) Does the shape of the seat fit you and let your legs move freely?
b) Is the cushioning comfortable and made of a breathable material?
c) Do you have at least one-inch free space on either side of your hips and thighs?
d) Do you have at least one-inch free space between the edge of the seat and the back of your knees?
e) Can you sit comfortably with your feet on the floor or a footrest?
2. Can you easily adjust the important features of the chair?
a) Can you adjust seat height while you are sitting in the chair?
b) Is the range of height adjustment of the chair adequate?
c) Can you adjust the position of the lumbar support and is this comfortable?
d) Can you recline the chair back to a comfortable position?
e) Are the controls easy to understand and use?
3. Is the chair stable when you sit on it?
a) Does it have a 5+ pedestal base so it won't easily tip over?
b) Does the chair move easily when you need to?
c) Can you swivel easily so that you don't have to twist your back to turn?
4. Does the chair have comfortable armrests?
a) Are the armrests broad, contoured, and adequately cushioned?
b) While sitting can you adjust the height of the armrests?
c) Can you easily move the arms out of the way if you need to do this?
If you answered "No" to any of the questions then the chair you are considering might not be right for you. If you answered "Yes" to all of the questions, then this chair will work for you. Remember, you will probably sit for a large part of your life, so make sure that your chair is a source of comfort and pleasure, not discomfort and pain.
Professor Alan Hedge, PhD Director Human Factors and Ergonomics Laboratory Cornell UniversityDepartment of Design and Environmental Analysis Ithaca, NY http://ergo.human.cornell.edu
Sitting has become a way of life for many Americans. We sit in cars, buses, trains or planes when we travel, we sit to eat meals, we sit and watch TV, we sit in classrooms, and for many of us, we sit most of the day at work, often in front of a computer all day. Studies of sedentary workers show that low back problems are associated with poor chair design and inappropriate sitting posture.
Although for many activities we could stand just as easily as sit, for example, we could stand to watch TV, stand to eat, and stand in front of a computer all day. There are at least three good reasons why we prefer sitting.
Sitting uses about 20% less energy compared with standing to do the same work, so comfortable sitting helps to relieve fatigue.
Sitting helps to reduce the strain on our back muscles and on the intervertebral discs of the lumbar spine, providing that we sit back in a supported, reclined posture.
Sitting gives us greater postural stability for performing fine manipulative tasks, such as eating with a knife and fork, sewing, writing, etc.
(Image reproduced courtesy of Humanscale)
Anatomical Changes During Sitting
When we change from a standing posture to a sitting posture anatomical changes occur. The lumbar spine changes shape depending on what we sit on and how we sit. If we sit on a flat surface, such as a bench, bleachers or stool, without any back support we tend to hunch the body forwards for support, often resting our arms on our legs to reduce fatigue. As we hunch forwards, the lower back curves outwards into a kyphotic shape. This is generally regarded as an unhealthy posture if sustained for a prolonged period. With nothing to lean back on, the upper body becomes fatigued and we typically regard this as an uncomfortable way to sit. However, this is the way that many people end up sitting over the course of each workday, so it isn't surprising that studies of sedentary workers, such as office workers, have frequently reported high levels of postural discomfort. [2] What we want is to be able to sit and maintain the lumbar spine in a posture called lordosis.
Ergonomic Chair Design
If we sit on a good ergonomic chair, the seat pan is curved from back to front to encourage the pelvis to rotate forwards, and this helps the lumbar spine to maintain lordosis. As we sit back the lower back should be well supported by a contoured lumbar support. The average preferred height for a good lumbar support is abut 7.5 -inches above the compressed seat surface (19 cm), and the mean preferred seat depth (horizontal distance from front of seat to lumbar support point) is about 15.25-inches (38.7 cm). Ideally, the chair should have a backrest that is sufficient high to provide support to the thoracic region as well. [3] Also, make sure that the seat is height adjustable (15" - 22"), the backrest angle is adjustable (100° - 120°), the armrests have a minimum 16.1” width and have adjustable height (7.1”-10.6” above compressed seat height). [4] Studies of office chairs show that users often cannot correctly identify or operate chair controls [5], so make sure that the chair has user-friendly controls.
(Image reproduced courtesy of Humanscale)
Safe Sitting
Keeping the spine healthy requires periodic changes in posture, and dynamic movement helps to promote circulation and reduce muscle fatigue. Sitting in any static posture for a prolonged period eventually will become uncomfortable. This means that there isn't a fixed posture that's best for everyone, all of the time, whatever the task at hand. Rather, there is a desirable range of movement that works well for most people doing most of the kinds of tasks performed when sitting.
The preferred way of sitting involves the following:
Make sure that the seat height is correctly adjusted so that your feet are on the ground or on a solid surface like a good footrest.
Recline back in the chair, with the chair backrest angled between 100-110-degrees, so that the chair back can help support the weight of the torso.
Make sure that the chair has good lumbar support in the right area for your shape and size of back. If there is an adjustable support, use this to get the best position. If not, use a rolled towel or a cushion to improve your lower back support.
Make sure that the seat pan is the right size for you and doesn't press behind your knees.
Look for a chair that doesn't tip up the seat pan when you recline because this can put pressure under the thighs and behind the knees.
If the chair has arms, make sure that these are correctly adjusted for height so that your shoulders are relaxed, not hunched or raised when you rest on the armrests.
If the chair has a high neck/headrest make sure that this can be used in different sitting positions.
Now that your body is in a good, supported posture you should be ready to work without any discomfort, but remember to take periodic breaks, and to change posture, get up and move around.
(Image reproduced courtesy of Humanscale)
Tips for Choosing the Best Ergonomic Chair
When choosing a chair ask yourself the following questions:
1. Is the chair comfortable to sit in for the way that you work?
a) Does the shape of the seat fit you and let your legs move freely?
b) Is the cushioning comfortable and made of a breathable material?
c) Do you have at least one-inch free space on either side of your hips and thighs?
d) Do you have at least one-inch free space between the edge of the seat and the back of your knees?
e) Can you sit comfortably with your feet on the floor or a footrest?
2. Can you easily adjust the important features of the chair?
a) Can you adjust seat height while you are sitting in the chair?
b) Is the range of height adjustment of the chair adequate?
c) Can you adjust the position of the lumbar support and is this comfortable?
d) Can you recline the chair back to a comfortable position?
e) Are the controls easy to understand and use?
3. Is the chair stable when you sit on it?
a) Does it have a 5+ pedestal base so it won't easily tip over?
b) Does the chair move easily when you need to?
c) Can you swivel easily so that you don't have to twist your back to turn?
4. Does the chair have comfortable armrests?
a) Are the armrests broad, contoured, and adequately cushioned?
b) While sitting can you adjust the height of the armrests?
c) Can you easily move the arms out of the way if you need to do this?
If you answered "No" to any of the questions then the chair you are considering might not be right for you. If you answered "Yes" to all of the questions, then this chair will work for you. Remember, you will probably sit for a large part of your life, so make sure that your chair is a source of comfort and pleasure, not discomfort and pain.
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