This article contains an overview of Repetitive Strain Injury (RSI), constructed from various excerpts.








- Brief Summary
- Contents
- Summary
- Description
- Symptoms
- Causes
- Mechanisms
- Treatment








This article contains an overview of Repetitive Strain Injury (RSI), constructed from various excerpts, which are drawn from the following sources:

[1]
Repetitive Strain Injury
A Computer User's Guide
Authors: Emil Pascarelli, MD, and Deborah Quilter
Copyright © 1994 by Emil Pascarelli and Deborah Quilter.
Published by John Wiley & Sons, Inc.

[2]
Dr. Pascarelli's Complete Guide to Repetitive Strain Injury
What You Need to Know About RSI & Carpal Tunnel Syndrome
Author: Emil Pascarelli, MD
Copyright © 2004 by Emil Pascarelli.
Published by John Wiley & Sons, Inc., in Hoboken, New Jersey.

[3]
It's Not Carpal Tunnel Syndrome!
RSI Theory and Therapy for Computer Professionals
Authors: Suparna Damany, MSPT, and Jack Bellis
© 2000 Suparna Damany and Jack Bellis
www.RSIProgram.com
Published in 2000 by Simax in Philadelphia, PA.

[4]
www.nhs.uk/conditions/repetitive-strain-injury-rsi
Note: The NHS is the UK National Health Service.











Dr Emil Pascarelli, [2], page 3:

RSI is a general term used to describe a disorder in which people develop symptoms such as pain, numbness, stiffness, and weakness as a result of sustained repetitive work, often done under adverse conditions. These can range from ordinary daily stress to truly bad work setups and work conditions. Usually the pain or other symptoms affect their work and other normal activities. RSI is a widespread illness involving soft tissues of the upper body - nerves, muscles, tendons, ligaments, and blood vessels.

Dr Emil Pascarelli and Deborah Quilter, [1], page 49:

Repetitive strain injury is an umbrella term for several cumulative trauma disorders caused by overuse of the hand and arm. The tendons, tendon sheaths, muscles, ligaments, joints, and nerves of the hand, arm, neck, and shoulder can all be damaged by repetitive movements. These soft tissue injuries fall into three basic categories: tendon, ligament, and muscle disorders; nerve disorders; and neurovascular disorders, which affect both nerves and blood flow.

Dr Emil Pascarelli, [2], page 9:

In a survey of nearly five hundred of my patients, the most common early signs of RSI were aching or pain in the forearms or hands, numbness and tingling in the hands, weakness in the arms, and spasms or twitching in the forearms.

NHS, [4]:

The symptoms of RSI can range from mild to severe and usually develop gradually.

They often include:

- pain, aching or tenderness
- stiffness
- throbbing
- tingling or numbness
- weakness
- cramp

At first, you might only notice symptoms when you're carrying out a particular repetitive action.

But without treatment, the symptoms of RSI may eventually become constant and cause longer periods of pain. You may also get swelling in the affected area, which can last for several months.

Dr Emil Pascarelli, [2], page 20:

The Most Frequent Symptoms of RSI

Here are the most common symptoms found in 485 of my patients. Some of the subjects had multiple simultaneous symptoms.

- Pain, aching, "spasm" in extremities: 329 (68 percent)
- Hand and finger numbness: 55 (11 percent)
- Weakness and fatigue: 44 (9 percent)
- Tenderness/swelling/information: 43 (9 percent)
- Tingling in the fingers: 42 (9 percent)
- Tightness/stiffness/rigidity of upper body and neck: 34 (7 percent)
- Loss of motor control: 5 (1 percent)

Suparna Damany and Jack Bellis, [3], page 73:

Tendinitis occurs frequently in the shoulder, elbow, and forearm. It is identified by the telltale location of pain, and the nature of the symptoms, more so than any test. For instance, if you have aching pain at the shoulder, elbow, or forearm, and it's not clearly felt in a specific muscle, tendinitis is the top suspect. The tendons that move fingers are very common sources of aching or soreness in the forearm, so tendinitis here is a frequent diagnosis.

Dr Emil Pascarelli, [2], page 4:

What Causes RSI?

There are many causes, not all of them obvious. The kind of work you do is perhaps primary, because repetitive keyboard use or repetitive manual activity of any other kind can be a major cause. Long work hours without sufficient breaks and meeting deadlines under stress are also contributors. Poor lighting, poor ventilation, crowding, and other undesirable work environmental issues are additional factors. Even the routine activities of daily life - driving, housekeeping, cooking, gardening, home repairs, can lead to RSI. If you're not sitting or moving correctly, you're damaging yourself repeatedly when you're at work. If your job forces you to work too fast, or to work on irregular schedules, you are at risk. Your physical condition also affects your susceptibility. Poor posture and physical fitness, lack of exercise, deficient diet, and irregular sleep patterns can all be contributory. Stress from family problems, work-related conflicts, or financial affairs can manifest themselves in RSI. Anxiety, depression, fear, and panic also contribute. Sometimes there is a hereditary predisposition to RSI from height, weight, sex, age, or double-jointedness or other anomalies. Medical problems such as diabetes, arthritis, thyroid disease, or hypertension can all make RSI more severe. Finally, smoking, alcohol, and drug use, along with all the other problems such habits bring with them, can also contribute to RSI.

Suparna Damany and Jack Bellis, [3], page 18:

Our Theory In A Nutshell

RSI is caused by working in an extremely repetitive fashion, in one position, for years. Your muscles lock up in that position and fatigue, causing your posture to collapse forward. The unnaturally tensed muscles get inflamed and frequently pinch your nerves and blood vessels. Your body lays down fibrous tissue to accommodate the fixed posture, tethering nerves in place and causing excessive wear and tear on them. The constant repetition, contorted positions, and small range of motion cause tendons to get sticky and inflamed, causing irritation and fluid buildup. All of these changes reduce circulation and overwhelm what would normally be the body's ongoing recuperative process.

If you treat individual sore spots instead of the whole superstructure of the arm, the symptoms will move from one spot to another. Instead, you must recondition the entire upper extremity, and the way you work, including workload, posture, ergonomics, strength, stamina, flexibility, and overall health.

To understand why this all happens, we present the number one physiological truth of RSI: muscles, tendons, and bones (collectively the musculoskeletal system) will adapt somewhat to almost any habitual posture and activity. Unfortunately, they will do this with no regard or accommodation whatsoever to the nervous system, which has no such adaptability. Your nerves may be the messengers of the deteriorating state of affairs, or the actual recipients of the damage.

NHS, [4]:

Cold temperatures and vibrating equipment are also thought to increase the risk of getting RSI and can make the symptoms worse.

Note: These are the mechanisms for the particular RSI variants / aspects that I think may have been involved in my case. Various other mechanisms are discussed in the sources but are not included here.



Dr Emil Pascarelli and Deborah Quilter, [1], page 14:

Thousands of repetitive movements cause microtrauma to muscle tissues, which leads to inflammation. The debris left by inflammation creates scar tissue, which binds down the muscle and in turn stresses tendons. Stretching can reverse the injury process and promote healing.

Dr Emil Pascarelli and Deborah Quilter, [1], pages ix-x:

I am often asked why this did not happen to people who worked on typewriters. In the early days of the typewriter, hitting the keys too rapidly would jam the typebars. The QWERTY keyboard was introduced by the Remington Arms Company in 1873 to distribute the workload throughout the keyboard and avoid jamming. Over time, productivity increased with improvements in the mechanical typewriter. The typewriter allowed built-in rest time for the correction of errors and the insertion of paper. Because the keys were stepped, people supported their arms and wrists with their upper body. With the advent of the flat keyboard, this all changed. The new keyboard looked innocent enough, except that now people could rest their hands on the desk to use the keys. It could handle all you could type at any speed, even beyond human capability, yet because there was no paper involved, errors were corrected with additional keystrokes and rest breaks were taken less frequently.

Dr Emil Pascarelli and Deborah Quilter, [1], page 50:

Tendinitis

Tendons connect muscles to the bone. Tendons consist of tissue that has little stretch or rebound, so if you tax your tendons beyond their strength by overuse or hold your hands rigidly for hours on end, tiny tears occur in them, leading to tendinitis. Friction from overuse can cause inflammation and contribute to tendinitis. Because of the tendons' anatomic function, they are highly susceptible to repetitive strain injuries.

In general, larger muscles do the big work and smaller tendons perform fine actions. The extensor muscles of the forearm, for instance, are only about the size of a pencil in circumference. When people rest their wrists on the edge of the desk while they work, they overload the tiny muscles and tendons of the hand and forearm. Computer work requires the assistance of powerful muscles of the shoulders and back, but these muscles cannot be engaged if people rest their wrists while they type.

Suparna Damany and Jack Bellis, [3], page 73:

Tendinitis

Tendinitis is inflammation of the tendons, due to the irritating, repetitive hammering motion of the fingers as you type. Tendons don't have much if any flexibility or "give" so the incessant action of hitting the keys can cause minute tears. And typing's many forced positions, such as holding the pinkie finger in a raised position can place excessive stress on the tendons.

Dr Emil Pascarelli and Deborah Quilter, [1], page 51:

Tenosynovitis

In areas where tendons must curve around bones or change directions, they often pass through tendon sheaths. These protective coverings perform the same function as the housing of a speedometer cable or a pulley. The inner wall of the tendon sheath secretes a slippery substance, called synovial fluid, to lubricate movement. If the tendon and the sheath rub together, the resultant irritation is called tenosynovitis. If this friction continues, the sheath can eventually respond with an overproduction of fluid. If the tendon sheath swells and won't fit comfortably into areas where the anatomy is already snug, such as the carpal tunnel, nerve compression can result.

Dr Emil Pascarelli and Deborah Quilter, [1], page 57:

Cubital Tunnel Syndrome

Also known as flexor carpi ulnaris muscle syndrome, cubital tunnel syndrome strikes people who work with their elbows bent at right angles for long periods of time, as in the case of computer workers. It involves a possible nerve entrapment that occurs in the underarm over the pathway of the ulnar nerve. Symptoms include loss of sensation, numbness, tingling, and muscle atrophy.

Suparna Damany and Jack Bellis, [3], page 74:

The Cubital Tunnel is the groove in the elbow (the ulna bone) around which the ulnar nerve glides, or attempts to. If the nerve becomes hampered in its usual slip-sliding through this tunnel, it can create excessive wear and tear and compromise nerve function. In this syndrome it's the pinkie and half of the ring finger that experience numbness, tingling, pain, or other unusual sensations.

Dr Emil Pascarelli and Deborah Quilter, [1], page 57:

Guyon's Canal Syndrome

Guyon's canal syndrome, also called ulnar tunnel syndrome, is compression of the ulnar nerve in the wrist in another tunnel, near the carpal tunnel. Ulnar tunnel syndrome may be associated with trauma to the ulnar nerve caused by repeated radial deviation or dorsiflexion. Symptoms include numbness in the ring and middle fingers and difficulty grasping. Pain may be aggravated by both dorsiflexion and flexion (bending the wrist up and down).

Dr Emil Pascarelli and Deborah Quilter, [1], pages 57-58:

Thoracic Outlet Syndrome

In order to remain healthy, muscles must receive a plentiful supply of oxygen-rich blood. When both arteries and nerves are compressed, the result is thoracic outlet syndrome, which includes a number of ailments. Signs of this problem include pain in the entire arm and numbness, coldness, and weakness in the fingers, hand, and forearm. Symptoms can be provoked by carrying heavy loads, or working with the arms elevated, such as when styling hair or writing on a blackboard.

Dr Emil Pascarelli and Deborah Quilter, [1], page 68:

Muscle damage can cause problems other than biomechanical inefficiency. Muscles deteriorate and rebuild as a natural process of life, but when they are overused, the body can't catch up with the destruction of delicate tissues and may replace them with scar tissue, which is inelastic.

Overuse of the muscles causes cells to break down, releasing waste products, which produces pain and inflammation.

[...]

Muscle shortening in the forearms also strains the tendons of the fingers because they have to work harder than they should. Tendons stretch very little, so the shortened muscle and tight tendon cause increased friction from shearing and you get further inflammation and tendinitis. Inflammation can cause swelling, which can make the tissue press on the nerve, and this can lead to neurological problems.

Suparna Damany and Jack Bellis, [3], page 63:

In many patients, the [ulnar] nerve gets caught in fibrous tissue that builds up in the triceps area of the upper arm, particularly one spot a little above the inside of the elbow area.

Suparna Damany and Jack Bellis, [3], page 67:

As a rule, wherever a nerve gives a branch to a muscle, RSI problems are associated with the spot. These spots often become trigger points where the nerve is trapped by fibrous tissue. This causes tenderness in the specific spot, but more importantly prevents the nerve from smoothly slipping and sliding as you change positions.

Dr Emil Pascarelli and Deborah Quilter, [1], page 14:

The first step toward recovery is getting out of pain. Pain management begins with physical therapy. Muscles and other soft tissues need to move to remain healthy. Deep tissue massage remodels scar tissue and allows muscle more range of motion. Stretching and strengthening exercises help keep muscle supple, toned, and pain free.

Suparna Damany and Jack Bellis, [3], page 109:

In the most serious RSI cases, a reasonable goal is to achieve a state where you can manage your symptoms. We want to get your body to a point where it is healing more quickly than your work habits are tearing it apart.

Suparna Damany and Jack Bellis, [3], page 54:

If you get enough sleep, your shoulder muscles have the stamina to keep your upper torso from collapsing into the nerve network that innervates the arms.

Suparna Damany and Jack Bellis, [3], page 69:

It's easy to surmise that repetitive, excessive contortions of the wrist - away from the neutral position - would induce abrasion, and therefore result in swelling. That is almost certainly a factor, but if that were the whole explanation, carpal tunnel surgery would have a wild success rate and folks would run around saying: "Get carpal tunnel surgery and you'll be able to work like a maniac for another ten years." Instead, they say, "I had the surgery, and I'm still in pain." Our explanation is that inflammation of the muscles in the lower arm causes fluid buildup which is most noticeable in the confines of the carpal tunnel. Neither the size of your carpal tunnel, nor abrasion through it is the ultimate cause.

Dr Emil Pascarelli and Deborah Quilter, [1], pages 77-78:

The first thing to be aware of regarding surgery and RSI is that in most cases, the damage to muscle and tendon cannot be surgically repaired. If this tissue heals at all, it will happen slowly, through rest and physical therapy. Surgical procedures do exist for carpal tunnel syndrome, Dupuytren's contracture, deQuervain's disease, ulnar nerve entrapment, and several other afflictions mentioned in this book.

[...]

Surgery is sometimes necessary to preserve nerve function, without which you could lose protective sensation in the hands, or to prevent the pressure caused by the bone overgrowth of osteoarthritis from crowding the median nerve. However, surgery has been implicated in the onset of reflex sympathetic dysfunction, especially with carpal tunnel syndrome and Dupuytren's contracture, so it is not something to be taken lightly.

Suparna Damany and Jack Bellis, [3], page 84:

Diagnosing Specific RSI Syndromes

Your doctor's determination of the cause of your symptoms is called the diagnosis. But "repetitive strain injury", the way we've described it as a broad causative complex is not yet accepted as a diagnosis. The traditional approach is to identify one or more of the many localized conditions that present symptoms, such as tendinitis or carpal tunnel syndrome as the diagnosis. Our view is that for computer-related RSI, where the patient has been typing for several years, these are often inadequate diagnoses because addressing the problem at the local site doesn't solve the problem. The problem typically moves as you focus on one spot, or spreads out in all directions, becoming oppressive.

Localized diagnosis ignores the notion that your entire upper extremity is fighting a war to hold your hands up in front of you for 10 or 20 years. An over-simplified diagnosis does the most harm when it results in a mechanical fix - surgery - that does nothing to address the root cause. If your problem has its root cause at, and only at the site where you have surgery, then perhaps you will be fortunate, and surgery will be your solution... good for you. If your problem is from your spine and neck all the way to your fingertips, then surgery where you happen to have your first or most prominent symptoms is ill-fated.

Suparna Damany and Jack Bellis, [3], pages 109-111:

Your treatment regimen should include almost all of the following techniques. [...] The one notable exception concerns the first two items, relieving muscle spasms and resolving nerve trigger points. You might have to emphasize only one of these two techniques.

Deep Massage for Muscle Spasms
If you have sore, inflexible muscles, you need to break the hidden muscle spasms with intensive, deep massage, preferably by a trained therapist. The muscle spasms will initially pop under the therapist's touch. As they resolve they will crunch a little, and eventually role smoothly when pressed. This can take as long as eight weeks to resolve, and more weeks to rebuild healthy tissue. You may find that ice packs relieve the discomfort from the process itself.

Localized Massage to Eliminate Trigger Points
Eliminate trigger points that are entrapping nerves with vigorous, localized massage. In normal activity, you won't even notice these spots, but when pressed, they will feel just like a splinter does - a small but intense irritation. Although a therapist will probably be most effective treating these, you may be able to treat them yourself by pinching the spot, and while holding it, and while holding it, performing the movement that the nearby muscle would ordinarily cause.

"It took Suparna 21 sessions (two a week, 45 min each) to zero-in on and break through the fibrous tissue on my ulnar nerve at the elbow. The surgeon who operated on my arm never once probed to look for this spot. When the fibrous buildups were completely broken through, it took another four months to reach a point where my work tolerance consistently improved. The most likely explanation for this is that the nerve took that long to heal. I probably caused this lengthy recovery time by working for several months without treating my symptoms."
- Patient E.

Reduce Your Short-Term Workload
For the short-term, reduce your workload as much as necessary to facilitate the healing process. Take whatever measures you have to. If you damage your nerves, the healing process will take a lot longer.

Improve Your Seated Posture
For the long-term, adjust your workstation, your energy level, and your concentration, to maintain a posture in which your shoulders and head are not collapsing into your chest. The goal is relaxed balance. When your head is balanced over your shoulders, the muscles are less tense. Emphasize diaphragmatic (abdominal) breathing to further reduce the pressure on your chest.

Stretching and Mobilization
Have a therapist perform active stretching and mobilization to increase mobility where the nerves are most likely to be pinched or compressed, such as the brachial plexus and the area under the collarbone. Restore flexibility, resilience, and range of motion with self-stretching exercises. Continue stretching exercises for the rest of your keyboarding career.

Strengthening and Endurance Exercises
Increase muscle vitality and stamina with strengthening exercises. Especially emphasize muscles that hold your shoulders back, hold your arms up, and extend (open) your fingers. These are all likely to be in a state of constant fatigue.

Perform Exercises Called "Glides"
To counteract nerve entrapment, perform motion exercises called glides. In a glide, you move your hand or arm from one position to another, without any force or resistance, to put a nerve or tendon through its maximum range of motion.

Improve Ergonomics
Establish workstation ergonomics that enable you to work in the most neutral (least stressful) positions.

Use Large Muscle Movements When Working
Adopt keyboarding techniques that emphasize the use of large muscles, such as the shoulders and upper arms instead of small muscles such as those that drive the fingers. In extreme cases, you may have to resort to typing with three fingers, or even one finger on each hand. Use the same principles with the mouse, avoiding finger and wrist movements and pinching actions.

Reduce the Repetitiveness
Exploit every possible opportunity to reduce or displace the incessant, repetitive tasks of keyboarding. This includes everything from breaks to voice recognition software.

Reduce Stress and Combat Aging
Address lifestyle and work habits to reduce your level of work-obsessed tension, and create a more favourable balance between the destructive and restorative forces acting on your body. Work on improving your sleep patterns. Drink lots of water.

Warm Up
Do a serious warm-up routine before each work session. One way is to use a hand cream and rub your hands vigorously until your hands get very warm. Try to warm up several times a day.

Suparna Damany and Jack Bellis, [3], page 175:

Breaks

Taking breaks from your work might be the most significant and most challenging change to make in your work habits. And, despite its low-tech nature, it is the most universally agreed upon recommendation from authorities on RSI. Advice varies greatly on the right amount of break time and frequency, and there is no right answer, considering that there is no substantiation behind the advice. There is only good sense combined with experienced judgment. Here's ours:

How Long Should Breaks Be?

Our quick guideline on breaks: Take a 2-5 minute break every 15-30 minutes of work.

Take mini-breaks every 3-5 minutes, where your hands leave the keyboard and touch something else that causes you to move your entire arms.

Suparna Damany and Jack Bellis, [3], page 197:

The farther you reach out [to the keyboard], the greater the cantilever forces on your arm muscles, and the more tension you will inevitably work under. If you've been typing for years, you may be completely insensitive to this added tension when your arms are outstretched - you can't judge that your muscles are exerting force because they are steely, fibrous, and in a state of spasm. Move closer to the keyboard so you don't have to hold your arms up as much, and so your upper arms are almost straight down.

Dr Emil Pascarelli and Deborah Quilter, [1], page 14:

Posture is a dynamic, not static, concept: It means keeping bones aligned through movement and stillness, with muscles at their optimum length instead of too tight or overstretched. This balanced use of muscles affords ease of movement and freedom from pain, not the tension that comes from holding yourself stiff like the stick figures in a handout on ergonomics (which many people actually try to do!).

Dr Emil Pascarelli and Deborah Quilter, [1], pages 28-29:

Pointers - self-taught typists who hunt and peck instead of touch-type - usually rely instinctively on the strongest fingers (the forefinger and middle finger), so they are the least likely to be hurt from their style. Pointers, because they have their forearms poised in midair to hunt all over the keyboard, are less likely to rest their wrists or ulnar deviate.

[...]

Pointing can be dangerous if you hold your other fingers in a contorted position. [...] So if you hunt and peck, keep your fingers curved.

Dr Emil Pascarelli and Deborah Quilter, [1], page 46:

People are usually out of acute pain and will have regained some strength and flexibility after three to six months of therapy, but many still have flare-ups even years later. Much of your recovery will depend on you and your circumstances. If you can afford to stop working, and then work at your own pace when you return to your job, you'll probably fare better than someone who can't or doesn't want to take time off. In addition, people who respect their bodies' pain signals will do better than those who don't.

If you've been seriously injured with RSI, you need to be careful with your hands for the rest of your life, as you would with similar injuries.

Dr Emil Pascarelli and Deborah Quilter, [1], page 46:

Don't work through pain. Don't try to strengthen your hand or forearm muscles by lifting weights. Don't do chin-ups or push-ups.

Dr Emil Pascarelli and Deborah Quilter, [1], page 73:

The Role of Rest

Muscles heal better when they are allowed to move, because that way the newly grown tissue remains pliable. So the term rest (in the sense of taking to your bed) is misleading in this context. When people lie in bed and do nothing, their muscles contract. With RSI, the contraction process has already begun because damaged muscles hurt and shrink, which creates a vicious cycle of pain and contraction. Rest means that you should not do anything to stress the injured muscles, so you should refrain from doing (or overdoing) activities that led to RSI (such as using the computer) or that exacerbate your symptoms (such as knitting, playing musical instruments, gardening, or carpentry).

Dr Emil Pascarelli and Deborah Quilter, [1], pages 74-75:

Splinting

To understand splinting, you must first understand how tissue heals. When soft tissue tears, scarring occurs. This scar tissue grows randomly at the side of injury and must be encouraged to grow in the right direction and prevented from adhering to the wrong place, such as bones) by gentle movement. So immobility can prolong, or make chronic, an injury that would have healed if the normal movement were allowed. People usually view pain as a signal that they are harming themselves, but this isn't necessarily so in soft tissue injury. Though this theory is perfectly logical and sometimes correct, in soft tissue injury certain gentle movements are necessary for proper healing.

[...]

If a mobile scar is needed, as in the case of a soft tissue injury, you need to keep moving. If a firm scar is necessary, as in the case of a broken bone, you need to immobilize the area with a splint or cast.

[...]

It is particularly dangerous to type with a splint on, because over time it can cause atrophy in one group of muscles and overuse in another, and atrophy happens fast. You can lose a significant amount of muscle power within two weeks.

[..]

If splints are used for carpal tunnel syndrome, they should be worn only at night, unless your physician tells you otherwise. Splints are worn at night to prevent people from flexing their wrists in their sleep.

Suparna Damany and Jack Bellis, [3], pages 171-172:

Get Moving
One key to good posture is to maintain the proper alignment during movement. Good posture does not mean holding a single position for a prolonged period of time. The human body needs movement. Only in movement do the muscles contract and the joints move, facilitating blood flow and the subsequent nourishment to your body parts. Movement becomes essential to maintaining balanced posture, because if there is no movement, the muscles fatigue easily.

Use a Good Chair
Make sure your chair provides good support and encourages the proper curvature of the spine. Because of poorly sized chairs, many women are forced to sit too for forward. Even sitting properly puts a lot of stress on the spine, and sitting without support is worse. Make sure the seat pan is not so long that sitting all the way back is uncomfortable. Conversely, taller individuals need chairs with a longer seat pan and higher back. It's very common to need more lower back (lumbar) support than most chairs offer. Try putting a rolled up towel in the back of your chair to see if you are more comfortable. If it seems to help, specially designed lumbar supports [...] are available that attach to your chair.

Avoid Armrests
We recommend resting your hands in your lap when you're not typing. If you must rest your arms on the chair armrests, make sure they're low enough that they don't cause a shrugging action at your shoulders. Use of armrests is not recommended while you are typing.

Dr Emil Pascarelli and Deborah Quilter, [1], page 93:

After suffering the relentless abuse of millions of malaligned keystrokes, Nature is slow to forgive the body and allow it to heal. But learning to slow down proves difficult for many patients, who had no idea how long it would take to recover and often feel resentful about this. The path of healing, however, is as subtle as the slow decline into injury, marked by slight improvements, plateaus with no discernible gain, slight relapses, and then more improvements.

I was able to copy the text from source [4] directly.

I have paper copies of sources [1]-[3] in my possession. I transcribed the excerpts from them using my dictation system [paywalled].

Changes from the original text in the quoted excerpts:
- I have removed word-breaking hyphens.
- I have not preserved the original line breaks. I treat each paragraph as a single line.
- I have not preserved page divisions or page numbers.
- I have replaced any use of indentation at the start of a new paragraph with an empty line between paragraphs.
- I have substituted a hyphen with a space either side of it ( - ) for the em dash used in the original text. I have also made this substitution for every double em dash.
- In the original text, the double quotation marks were curled to indicate whether they were positioned at the start or end of a phrase / sentence / sentence_group. I have replaced them with straight quotation marks.
- I have replaced curled apostrophes with straight single quotation marks.
- I have moved punctuation out from between quotation marks if it is not relevant to the text within those quotation marks.
- I have not preserved every aspect of the formatting used in the original text (e.g. bold and italic effects).