Repetitive Strain Injury

Prevent Computer User Injury With Biofeedback: Assessment and Training Protocol (1,2)

Erik Peper, Ph.D.
San Francisco State University, San Francisco, CA
Vietta S. Wilson, Ph.D.
York University, Toronto, ON
Will Taylor, M.D.
Blue Hill, ME
Alex Pierce
Stens Corporation, Oakland, CA
Kathy Bender
SHARE, Oakland, CA
Vicci Tibbetts
San Francisco State University, San Francisco, CA

Introduction

Improper work habits, poor workstation ergonomics, and environment can lead to physiological dysregulation such as muscle soreness, fatigue, and injury (Grandjean, 1987). Some workers develop chronic neck and upper limb pain also known as repetitive strain injury. (RSI), cumulative trauma disorder (CTD) or overuse syndrome, from long hours of repetitive tasks at personal computer workstations. Workers with RS1 suffer loss of productivity and income with increasing medical costs. RSI accounted for forty percent of workers compensation cases in 1990. Discomfort and injury can shape the way PC users feel about their job and computers. Forty million Americans use computers, and 15-20 percent are at risk for RSI symptoms (CDC, 1984). RST threatens to inflict individuals with illness and overwhelm corporations with increasing medical costs and lost productivity.

At present, workstation ergonomic analysis, proper positioning of furniture and equipment, different mice and keyboards, and periodic rest may help reduce physiological dysregulation (the incidence of muscle fatigue or injury). This mechanical approach, however, lacks two crucial elements:

· Kinesthetic awareness of psychophysiology by computer users.

· Development of skills to inhibit inappropriate and excessive bracing during task performance.

The computer user must learn to reduce tension and relax muscles when they are not used for the task. Preventing RSI involves a combination of proper ergonomics, work pattern variation (work/rest cycle), and self-regulation through blofeedback to reduce dysponetic activity (inappropriate and misdirected as well as unconscious muscle bracing). Without kinesthetic awareness and without the skills to reduce tension, ergonomic adjustments with intermittent rest periods are NOT sufficient to reduce risk for injury.

Computer users can learn preventative skills to sense muscle tension and incorporate relaxation and regeneration of muscles during data entry and mouse use. Biofeedback instruments can be used to monitor specific muscle sites and to warn the user of excessive strain or overuse habits that can lead to chronic pain or injury. This mastery process reduces the risk of RSI.

Risk Factor Analysis

The development of RSI involves ergonomic and psychophysiological contributing factors which include:

• Inappropriate ergonomic workstation setup

• VDT (monitor) induced near-vision stress

• Asymmetrical task performance

• Restricted body movements

• Absence of brief (1-2 seconds) regenerative breaks during work activity (micro-breaks) Dysponesis during task performance (cocontraction, lack of inhibition of antagonist during movement)

• Lack of somatic awareness of tension and relaxation

• Physiological tension during self-perceived relaxation

• Excessive focus on tasks and or flawless work record

• Work dissatisfaction

• Frequent previous illnesses

• Excessive physiological reactivity

• Thoracic breathing and/or breath holding during data entry

• Presence of tender trigger points

The following RSI protocol includes ergonomic and work style evaluation, psychophysiological profile, risk factor analysis, biofeedback training and education.

Ergonomic and Work Style Evaluation

Ergonomic evaluation needs to be done at the work site under normal working conditionsThe attached assessment form, SFSU WORKSTATION AND ERGONOMIC ASSESSMENT (Peper and Tibbetts, 1994) can be used as a guideline to cover most of the ergonomic risks (see also Jones, 1991; State of California, 1993). At the same time, movement analysis of task performance needs to be included because repeated asymmetrical movements increase risks (Donaldson, 1994). A table of typical computer user complaints, corresponding ergonomic factors, and areas for surface electromyography (SEMG) are listed in Table 1 (Wilson, 1994).

After evaluation, ergonomic risks are identified and solutions proposed. Many solutions can be economical such as lowering the monitor by placing the computer sideways on the floor, lowering the keyboard by attaching a keyboard drawer, raising the feet by using telephone books, and removing boxes or waste basket from under the desk so that the legs are free to move. Sometimes, the solution requires a reorganization of the office such as moving office furniture to reduce excessive reaching, or to allow distant vision.

In cases of asymmetrical job patterns, the person is guided to do the job alternately using opposite sides of the body as well as changing the position of furniture (phones, files) to balance movement patterns. For example, during the morning, place the phone on the left side and lift the receiver with the left hand, while during the afternoon, place the phone on the right side and use the right hand.

An additional factor commonly overlooked is appropriate vision correction, especially for people who wear bifocals. Prescribed reading glasses (often used at the computer) force the user to tilt the head back or hunch forward since the focal distance is not set at the distance of their workstation monitor (Grandjean 1987). Some users may need to have special computer monitor reading glasses.

Equally important, computer users need to be aware of the work/rest cycle. This means both very short breaks and movements during task performance and larger body movements during frequent longer breaks.

Psychophysiological Profile

After ergonomic assessment and adjustments, a physiological assessment should be done. If possible, it should include an actual work site assessment, which can easily be done with a laptop computer and MyoTrac2, MyoDac2, or ProComp. The comprehensive profile consists of different phases which can also be selectively used depending upon the computer user's need.

The psychophysiological profile consists of physiological monitoring during: a) task performance, b) simulated emotional stress, c) extended data entry, and d) movement symmetry. The purpose is to assess dysponetic activity (misdirected and inappropriate bracing patterns), the length of short breaks, the effect of emotional stress upon physiological reactivity, physiological recovery, asymmetrical muscle cocontractions, and somatic awareness.

The profile assesses the individual at the computer either at the job site or at a simulation of the workplace setting. The data entry task needs to include the actual data entry pattern of the user (e.g. keyboard, mouse, and/or trackball). The initial assessment does not include feedback, although all the data is recorded for later analysis.

IMPORTANT: The protocol should be adapted to assess real task performance such as job related data entry, reaching for the phone with the right and left hand, etc.

After the protocol has been completed, the data can then be reviewed with the client to show the individual's physiological responses. This information is then used to determine self regulation strategies to improve health. This feedback is usually done directly after the assessment so that the information can be used to begin retraining.

Sensor Requirements and Placement

The minimum requirement for the assessment is two channels of surface electromyograph (sEMG). A two channel SEMG assessment will require moving sensor leads to different muscle sites during different phases of the assessment. A more comprehensive assessment would include a minimum of 4 channels of SEMG, respiration, skin temperature (Temp) and skin conductance response (SCR).

Two channel SEMG sensor placement:

A. Forearm SEMG: place active sensors midpoint on the extensor and flexor muscles to monitor forearm tension. The purpose for monitoring the forearm is that most subjects do not relax the fingers or wrist muscles as long as the fingers are on the keyboard or holding the mouse.

B. Neck and shoulders SEMG: place one active sensor over the left scalene and the other midpoint on the right trapezium (see Fig. 3). The purpose of monitoring the neck and shoulders is that most subjects raise their shoulders and tend toward thoracic breathing patterns during task performance. The left scalene to right trapezium placement will also monitor bracing by the scalene and sternocleidomastoid muscles.

Four channel SEMG sensor placement:

Sensors are placed to allow bilateral analysis during the symmetry assessment. The most common bilateral electrode placements (right and left) include the following muscles: upper trapezium, lower trapezium, sternocleidomastoid, rhomboid, and pectoralis. The purpose for monitoring upper and lower trapezium is to enhance scapular stabilization since the lower trapezium will inhibit the upper trapezium activity. (For exact electrode locations see: Soderberg, 1992: This manual is free and available from NIOSH, see recommended sources for more information; and Basmailan & Blumenstein, 1980.)

Comprehensive monitoring includes thoracic and abdominal respiratory patterns and breathing rate, peripheral temperature, skin conductance, and heart rate. Monitoring should also include the following SEMG placements, bilateral cervical paraspinals, masseters, temporalls, deltoid, upper and lower trapezium, pectoralis, infraspinatis, wrist extensors and flexors, and possibly, tibialis and gastrocnemius.

Assessment Protocol

· Describe the protocol sequence.

· Have the person sit comfortably at the computer station. (Do the ergonomic assessment and modifications as needed.)

· Attach physiological sensors and verify signals.

· After each step of the assessment have the person rate their subjective stress/tension.

PHASE 1: EFFECT OF POSITION AND TASK ON PHYSIOLOGY
PURPOSE: To assess subjective muscle tension awareness, posture and task performance upon the physiology.

PROCEDURE:

1. Sit comfortably with hands resting on lap (30 seconds baseline).

2. Place fingers comfortably (their normal mode) on the keyboard at home row (30 seconds).

3. Type a standard text (a sample letter or materials that simulate a normal job task) (60 seconds).

4. Place fingers comfortably on the keyboard without pressing keys (30 seconds).

5. Place hands back on lap comfortably in a relaxed position (30 seconds baseline).

RISK PATTERNS: The following are common physiological patterns which may be identified and may increase risk. 

1. Absence of regenerative micro-breaks 1-2 seconds epochs of low SEMG activity every 1020 seconds from activated muscles. 

2. Increased scalene/trapezius SEMG activity when the person's fingers are on the keyboard. (Covert dysponesis: the person is unaware the shoulders are raised when preparing to type.) 

3. Increased forearm SEMG activity as long as the fingers were on the keyboard. (The SEMG increased even when the person thought the arms and hands were relaxed at the keyboard.) 4. Increased respiration rate and thoracic breathing when the person types (increased nervous arousal) and decreased respiratory sinus arrhythmia. 

4. Increased SEMG activity, increased respiration rate and thoracic breathing after hands were placed back on lap (lack of or slow recovery). 

5. Low correlation between subjective sense of stress/tension rating and SEMG activity. 

PHASE 2: EFFECT OF EMOTION ON PHYSIOLOGY
PURPOSE: To assess the impact of negative emotions upon physiology.

PROCEDURE:

1. Sit comfortably in front of the computer, hands on lap.

2. Think, feel, imagine, visualize an angry, resentful, and frustrating job-related or personal experience and indicate when these angry/ resentful feelings/thoughts are present. 

3. Continue to experience the negative feelings/ thoughts with hands on lap (30 seconds). 

4. Continue to experience the negative feelings/ thoughts, and type a standard text (60 seconds). 

5. Let go of the negative feelings/thoughts and rest/relax with hands on lap (60 sec. baseline).

RISK PATTERNS: The following are common risk patterns, in addition to those described in PHASE 1, which need to be retrained. 

1. Increased SEMG activity and arousal during typing as compared to phase 1 baseline and typing tasks. 

2. Slow recovery back to baseline measures following the instructions of letting go of the negative imagery while resting hands on lap. 

PHASE 3: EFFECT OF CONTINUED TASK PERFORMANCE ON PHYSIOLOGY

PURPOSE: To assess the impact of long duration work pattern upon physiology.

PROCEDURE:

1. Sit comfortably with hand resting (relaxed) on lap (1 minute baseline). 

2. Type a standard text (a sample letter or materials that simulate a normal job task) (10-50 minutes).

3. Sit comfortably with hand resting (relaxed) on lap (1-5 minute baseline).

RISK PATTERNS: The following are common risk patterns, in addition to those described in PHASE I and 2, which need to be retrained. 

1. Sustained upper trapezium SEMG activity lasting longer than 30 seconds without the presence of regenerative 1-2 seconds microbreaks of very low SEMG activity. 

2. Increased scalene/trapezius SEMG during data entry without micro-breaks. 

3. Increased forearm SEMG while the fingers are on the keyboard. 

4. Increased respiration rate and thoracic breathing during data entry. 

5. Slow recovery back to baseline measures following typing task. 

6. Absence of gross body movements.

PHASE 4: SYMMETRICAL MOVEMENT ANALYSIS FOR MUSCLE CO-CONTRACTION AND RECOVERY ANALYSIS 

PURPOSE: To assess SEMG imbalance during movement patterns (Taylor, 1993; Wilson, 1994; and Skubick, Clasby, Donaldson, & Marshall, 1993; Donaldson, 1994). 

PROCEDURE For SCM SEMG assessment:

SENSOR PLACEMENTS: Use two or four EMG channels, place SEMG active sensors on the right and left sternocleldomastoid (SCM) (optional: right and left upper trapezius). 

1. Sit comfortably in front of the computer with the hands on lap, while looking straight ahead (5 seconds).

2. Rotate head to the right, as if looking over the right shoulder, while keeping the torso facing forward (5 seconds).

3. Rotate head to face forward (5 seconds).

4. Rotate head to the left, as if looking over the left shoulder, while keeping the torso facing forward (5 seconds).

5. Rotate head to face forward (5 seconds).

6. Repeat rotation sequence 5 times. 

ALTERNATIVE MOVEMENT PATTERN: Have person perform real job tasks such as reaching for the phone, manuals, or turning pages with one hand and then the other hand. Repeat movement 5 times. 

PROCEDURE For upper trapezium assessment: 

SENSOR PLACEMENTS: Use two or four EMG channels, place SEMG sensors on right and left upper trapezium (optional: right and left SCM). 

1. Sit comfortably in front of the computer with the arms and hands hanging along the sides of the body with the palms facing toward each other (5 seconds). 

2. While keeping the elbow straight, lift both arms up until they are horizontal (90 degrees to the body) and hold for 6 seconds. Then return the arm to hang along side the body. (In this movement, the palms initially point towards the floor.) 

3. Repeat movement sequence 5 times.

ALTERNATIVE MOVEMENT PATTERN: Have person perform movements which mimic common job movements. 

OPTIONAL: Repeat one cycle of the above movement patterns while changing the time duration 30-60 seconds at the full extension. (Do not continue if pain occurs.) Allow at least 120 seconds for recovery between right and left movements. 

RISK PATTERNS: The following are common risk patterns, in addition to those described in PHASE 1, 2, and 3, which need to be retrained. 

1. Asymmetry in SEMG activity during movement. For example, right SCM SEMG significantly higher when head turns left than left SCM when head turns right or vise versa; similarly, asymmetry in SEMG trapezius activity when arms are moved upward.

2. Significant co-contraction of antagonist during rotational movement. For example, left SCM SEMG is activated while head turns to the left.

3. Breath holding or very shallow breathing during movements.

4. Lack of awareness of breath holding.

5. Lack of awareness of co-contraction and asymmetrical muscle use patterns.

6. Slow SEMG recovery to baseline after five repetitions or after longer holding.

Data Review

Review the recorded data from the assessment protocol. Identify physiological response patterns and work habits which may increase the risk of RS1. The most commonly observed risk patterns are the absence of muscle tension awareness (awareness of muscle tension does not correlate with SEMG activity), inability to relax muscles, dysponesis (bracing of the trapezius during data entry), increased arousal during data entry, absence of regenerative micro-breaks during typing tasks (see Figs. 4 and 5), asymmetry and co-contractions during movement, and absence of gross body movement patterns.

Training and Education

The training protocol consists of reducing the observed risk patterns and generalizing these new skills into the person's work behavior. If significant dysponesis is observed, a more detailed SEMG analysis of specific muscles is required. The more specific the feedback, the more successful will be the skill acquisition.

The general training themes consist of increasing awareness of dysponetic activity, inhibiting co-contraction by tightening the correct agonist and inhibiting the antagonist, encouraging regenerative micro-epochs of very low SEMG activity of an activated muscle, reducing arousal (startle) during data entry through methods

such as continued breathing, developing movement patterns using both sides of the body equally, and teaching that health consists of the alternation between activity and regeneration (movement and relaxation). The training goals are enhanced when monitored with portable EMG trainers (MyoTrac and MyoTrac2) or computer based systems (ProComp, FlexComp or MyoDac2). The general psychophysiological concepts to achieve training goals are:

1. Encourage lowering of arousal during task performance and breaks. Teach diaphragmatic breathing to reduce hyperventilation (Peper, 1990). 

2. Teach momentary regenerative breaks during continued task performance. Sustained muscle activity of greater than 30 seconds needs to have regenerative epochs (1-2 seconds) of low EMG activity. The micro-breaks are much more important than the muscle tension during the task (Taylor, 1993). 

3. Develop muscle strength, flexibility and bilateral symmetry appropriate for task performance through movement exercise and workstation rearrangement (Wilson, 1994).

CAUTION.- Any numbness, tingling, prickling sensation or loss of sensation or dropping of objects should be evaluated by a physician. These symptoms are most prevalent in the early morning, evening or wakes the person from sleep. 

TRAINING GOALS:

A. OPTIMIZE ERGONOMIC CORRECT POSITION

Implement the ergonomic improvements derived from the ERGONOMIC WORK STYLE EVALUATION.

Optimize body position at the workstation with SEMG monitoring. For example, place sensors on deltoid or trapezium to identify the neutral arm position while hands are on keyboard (Fig. 6) (Peper and Shumay, 1994).

B. EMG GOALS

1. Inhibit scalene/trapezius SEMG activity while fingers are on the keyboard during rest and data entry. This means the person learns to sense bracing in the shoulders and lets the shoulders stay relaxed during data entry.

2. Inhibit finger/wrist flexor/extensor SEMG activity when fingers are resting on keyboard.

3. Inhibit shoulder girdle and arm bracing (excessive SEMG activity) while using a mouse.

4. Inhibit SEMG co-contraction of muscles such as SCM.

5. Teach scapular stabilization utilizing lower trapezium and serratus anterior SEMG feedback to inhibit upper trapezium activity (Bender, 1993).

6. Monitor SEMG and inhibit dysponetic activity from relevant muscle groups while performing job related keyboard entry tasks.

C. RELAXATION / STRENGTHENING PRACTICES

1. Head rotations: SLOWLY look over right shoulder. Hold 20 seconds back to center. Repeat on the other side. (Minimize shoulder movement as much as possible.)

2. Side head bends: Put right ear to right shoulder. Hold 20 seconds back to center. Repeat on other side (minimize shoulder movement as much as possible).

3. Turkey pull: GENTLY pull your neck backwards as if someone had a string attached to the back of your neck and was pulling it backward. Keep the jaw parallel to the ground and shoulders relaxed. Do 2-30 times daily.

4. Shrug shoulders backward and forward in a circular motion, go slowly. Several circles should be executed-- each of a different diameter.

5. Place arms at sides as if you were standing at attention. Keeping arms as straight as possible raise them up over your head until the backs of your hands meet above your head. Ensure that palms face down as arms extend. The action should look like a slow motion jumping jack (or a very lethargic duck trying to fly). Do not arch lower back.

6. Do Dynamic Relaxation of the neck, shoulders, arms, wrists, hands, and fingers (Peper and Holt, 1993). Teach internal mastery of high and low muscle tension and the ability to relax the muscle at will.

7. Take brief I to 2 seconds regenerative breaks every 30 seconds during keyboard data entry and mouse use. For example, drop hands to the desk top or lap, the SEMG of the neck and shoulders should instantly return to low baseline levels. 

D. EMOTIONAL CONTROL 

1. Enhance awareness of how negative emotions contribute to dysfunctional patterns.

2. Develop communication and problem solving skills to resolve work and/or family conflicts.

3. Teach thought stopping and/or task focusing exercises. 

E. IMPLEMENTATION

1. Generalize the above learned skills while performing relevant keyboard entry tasks at the actual job site.

2. Breathe diaphragmatically and decrease breathing rate during relevant task performance.

Suggestions and Implications

Every person who uses or begins to use a computer should be instructed in somatic awareness, proper ergonomics, and rest/ activity cycles. For many people, a signal from a small portable SEMG feedback device can help facilitate awareness of dysponesis during data entry and mouse use. Both the MyoTrac and MyoTrac2 offer the option for delayed tone feedback. This delayed feedback ignores the normal stretching, yawning, and other brief movements, whereas sustained SEMG activity triggers a warning feedback tone. In addition, external reminders to trigger brief regenerative breaks as well as encourage episodic body movements may reduce the risk of RSI (e.g., timed alarms or automatic data entry interrupts). Finally, this protocol can be used to teach computer users preventative skills to avoid RSI and mobilize health.

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