Date: Thu, 18 Feb 1993 20:56:11 +1200 From: Keith Stewart Here is some information written by our ergonomist Frank Darby. Keith Stewart Occupational Safety and Health Service Department of Labour New Zealand ARTICLE ONE (This taken from a resource presented to people at a seminar) OCCUPATIONAL OVERUSE SYNDROME QUESTIONS 1. Exactly why are some people are affected so severely? This is impossible to answer with certainty. However, susceptibility is shown in many ways. Reactivity to drugs or pollens and, through genetic inheritance, susceptibility to a variety of medical conditions are examples. There is no reason why susceptibility to OOS should be any different. Another personal aspect is our reaction to our environment - our stress reactivity. Some people are more reactive to stressors than others. This is neither good nor bad in itself, it is just the way we were made. There are two aspects to this reactivity - physiological and psychological. Physiological reactivity reflects the nature of our bodies. Comments below will amplify this point. Psychological reactivity will also receive comment. People who are naturally tense or who drive them selves hard, for example are more at risk as mentioned in the answer to the next question. 2. How much of OOS is a variation of hypochondria? Surely those that are the most susceptible to OOS are those that are looking for excuses for poor performance. This is a risky assumption. The second proposition may, of course, be true for a particular case, but is an extremely dangerous generalisation. The exact percentage of people with OOS who come into this category is impossible to say. I and my colleagues believe it is very small. This mechanism, when it does operate, is usually on a sub-conscious level. The reverse of the second sentence above might hold for a particular individual - those that strive are most at risk. These are the valuable employees and to label them as poor performers looking for an excuse would be a grave error. You also need to be able to answer the question: which came first, the poor performance or the OOS problem. To answer the question of susceptibility fully we need to explore the types of individual susceptibility that could exist. These are: 1 A person with a tense personality. Some people are naturally tense. (We found one or two who could not relax during the session). 2 The person who strives. People who drive themselves to do a good job on time may well be at greater risk. These are valuable employees. There are many instances where they have, for some reason, suddenly crashed. They often work through breaks, work overtime whenever offered, are slow to detect aches and pains in their own bodies because their discount their importance and are quick to accept urgent deadlines etc. All these add up to a person at risk by placing more straws on the camel's back. 3 Altered function in the pain/nervous system On another tack, one group of researchers found altered pain system responses i n the affected (but not the non-affected) arms of a group of people with OOS i n one arm compared to a group of non-affected controls. This is consistent with the idea that nervous traffic and muscle tension sets o ff some undesirable reaction. It seems as if the pain system resets itself to start reacting at lower levels of provocation. Even just one good provocative incident is enough to so reset the pain system. i.e.: (and as we know) a person who spends a week on urgent work (perhaps even only a day or two) may set off the reaction and leave thems elves with a long term problem. Although it is easy to be misled by simple pictures of complex systems, it seem s also that no exercise does not allow the setting of the pain system to rise to its normal state, and that some exercise, not to the point of pain, is indi cated. (I have written asking for details of the exercise regime that the phys iotherapist he uses has developed, and for a report on its efficacy). See the answer to the next question as well. 3. How do you recognise when someone is potentially at risk when furniture et c. is correct? 4. How do we know when people may have potential problems? It is impossible to tell who is susceptible by a diagnostic or predictive test. We suspect that some people may be more liable to these conditions through thei r personality- the kind of person who is tense and/or drives themselves to be productive. An alert manager should be able to recognise this characteristic in an individual. Because there are other types of susceptibility this will account for only some of the people who are susceptible. Therefore, the only ways to deal with this problem are to: 1 Educate and training people 2 Detect problems early. The second point means that staff should feel (be made to feel) free to speak t o their supervisors to report aches and pains. A system should be in place to follow up such reports and provide the needed personal and workplace assessmen ts. This need not be formal - especially in smaller offices - the important t hing is that the personUs problem is dealt with promptly. Correct furniture (good ergonomics), by itself, will guarantee nothing, as is just one aspect of a solution. This is good news, by the way, as you donUt ne ed to throw money at so called ergonomic furniture - which it often is not.. Much ergonomic furniture must cater for everybody that might use it in every p ossible situation. This approach is certainly necessary where different people use the same workstation - where there is shift work, for example. Where the workstation is used by only one person a different approach is better . This is where we assess the needs of each individual at each workstation, ta king into consideration the task they do. We then tailor the workstation to th eir needs. The approach is more costly in terms of time and intelligence on the part of the manager and/or supervisor, but blanket spending on furniture i s reduced. When a person leaves, the process will need to be repeated. 5. What is the link between OOS and psychological problems? In short - interesting but overrated. It is often said that the person got the OOS problem as a result of a psycholog ical problem. In this case the manager or doctor usually sees the person afte r they have got the OOS problem and note a psychological one as well. But whi ch came first. This is a very common trap. Unless there is extremely strong evidence that there was a psychological condition BEFORE the OOS developed, th en it is an extremely dangerous to conclude that the OOS problem was a result . Only too commonly people with severe chronic pain (constant severe pain lasting more than three months) DO develop psychological problems as a result of the pain. (Often these people area able, after more time, to cope with the pain a nd lead fulfilling lives). The phrase Rall in the mindS is often used to mean that someone has a psycholog ical problem. This phrase is meaningless because the brain cannot generate pa in signals. When it is used it blocks communication between the person and the doctor or manager. At the very least it is non-therapeutic. The Rall in the mind attitudeS is entirely irrelevant anyway - the bottom line is that a person in pain needs and deserves relief. Telling them a falsehood d oes not help them get over the pain and will almost always increase it. The pe rson needs to understand the origin and nature of their problem. What is true that the state of the mind influences the way pain is perceived. This results from the physiological control of the pain system by nervous mess ages flowing down from the brain. This is good news because it indicates that psychological therapy - even the placebo effect - is of use in the treatment o f chronic pain syndromes. A common therapy for people with pain is psychological and/or psychiatric coun selling. Some resist this treatment because they perceive a stigma associated with these words. Most are helped once they get past this barrier. 6. Can what you said today actually be put in practice within the Work Force? Does it work? 7. What are the implementing procedures for control and assist ance? Staff at the Sutherland Shire County Council, one of SydneyUs largest, became f ree of OOS when the following system was introduced. 1 Existing staff were properly informed, educated and trained in promoting c omfort to prevent OOS. The nature and causes of OOS, working technique, relax ation, micropauses, exercises were the topics. 2 New staff were properly trai ned, as in 1. 3 Workstations were assessed, see attached sheet and our checkl ist 1. 4 Managers and supervisors were educated about their responsibilities. 5 Staff were encouraged to report symptoms of pain early - see attached sh eet. 6 Staff believed they could do this without fear of reprisal. 7 Staff so reporting were dealt to by: (i) being sent to a medical specialist who gave them: a medical assessment instruction in working and relaxation techniques minimisation of time off work involving the person in the solution and (ii) having an immediate ergonomic assessment of their workstation. a rapid response to the recommendations of the assessment. and (iii) a regular review of the case As a result of this the Council experienced no cases of OOS where time off work was required, except for one person who slipped through this net, went to her own doctor and was given poor treatment and advice. This was in a large orga nisation at the height of the epidemic in Sydney (about 1984). With current ACC legislation, the costs of implementing a system such as the ab ove are likely to be less than increased premiums should people be off work wi th OOS. 8. Why hasn't the simple use of relaxation not been more widely publicised? It has, at least to some extent. It is a relatively recent concept, but is bei ng used by most Occupational Health Nurses in New Zealand and Australia now. But generally, you are right. In almost all publications on OOS, there is litt le mention of relaxation. OSHA and the HSE (opposite numbers to OSH in the United States and the UK) have little overt time for relaxation. They prefer to concentrate on getting the ergonomics right - fitting the task to the person - so that the issue Rdoes no t ariseS. There is nothing wrong with this but it does miss out on an opportu nity. My view is that however good the ergonomics are, people still have to use their bodies , so they might as well know how to do it the best way possible. There are many instances where people working at identical workstations (ergonomica lly optimal) have seen one person get OOS and the co-worker avoid it. My fear here is that employers will want to concentrate on relaxation to the exclusion of the other strategies. The concept of relaxation, used in the sense of Rworking with relaxed musclesS can unify our prevention strategy as long as we do not carry it too far: 1 Good ergonomics promotes relaxation. 2 Work organisation should not place undue time pressures on people, preventing relaxation. 3 Personal relations should promote relaxation. 4 The use of good working techniques can promote relaxation. 5 Learning relaxation techniques can promote comfort and productivity. 6 exercises and Micropauses promote relaxation. We should not carry the emphasis on relaxation too far. If there is one t hing that the OOS saga has taught us, it is that there is no one way of guaran teeing a solution. Ergonomics, relaxation, work organisation and all the othe r aspects needs to be considered together. 9. Where do you seek understanding treatment and advice for sufferers.? This can be difficult. Most doctors do not, in our experience, have a particul arly good grip on OOS. The following are possible strategies: 1 Contact one of the Occupational Health Nurses at your local OSH Branch Off ice, or one of our Medical Officers at the Penrose, Dunedin and Head Offices. S/he may be able to tell you of a doctor with particular competence in OOS. 2 Use the grapevine to find out if there is an OOS support group in your are a. The group organiser may be able to tell you if there is a doctor who is go od at dealing with OOS. Take care, however, with support groups. They can te nd to support the suffering rather than the person (this is a well recognised phenomenon, not just my prejudice speaking). They can do well if run on objec tive lines. The next comment applies only to people with long term intractable pain. 3 Refer your staff to books. A list is attached2. A great deal can be gaine d by reading. This does two things: it gives people relief that they are not the only ones with the problem RIUm not a freakS. And it gives people direct h elp. PeopleUs ability to get information from books varies, of course, (some a dults canUt read). This could be assessed discreetly in a particular case. In this case get the family and friends involved if possible, and refer to a Citi zenUs Advice Bureau. Remember that whatever YOU, a manager, do will be therapeutic in some way. Your response to the person will either be therapeutic or non-therapeutic - this i s inevitable because people respond to each other. Hinting to the person (IUm thinking of the sub- conscious reaction here rather than the conscious) that they are to blame will be counterproductive. The person with pain (not RinS, R withS) needs and deserves relief. 10. Where does one get practical advice for the acquisition of furniture and design of the layout? 11. How do we go about providing appropriate ergonomic fu rniture? There are several options here. 1 Consultants can provide advice. Contact the New Zealand Ergonomics Society for a list of people in your area that can act in this way3. 2 A number of texts have advice. (see1 and 4). 3 OSH field staff can give limited advice. (See under Department of Labour in the white pages of the phone book). 4 OSH is conducting an ergonomic assessment of office chairs shortly. Results of this will be available for purchase. As important here is the question: How can I get bad advice? Neglecting the input of staff and relying on some designers who think in macro terms of how things look rather than the micro terms of how things function, w ill both lead to bad advice. To get good input from your staff, see the appen dix, which can be adapted to suit your purposes and budget.. 12. When is it most likely to become a problem in my workplace and how do we h ave everything in place to avoid it? All other things being equal, OOS seems to happen or resurge after some sort o f change in the workplace. Some examples of changes are obvious, others are le ss so: 1 The arrival of a new supervisor 2 A sudden change in workload 3 A person off (sick or leave), leaving others to cope with an increased workload. 4 Some uncertainty developing in the workplace - job changes, 5 Deadlines at the end of the month Any one of these might be the straw on the camels back for an individual. To anticipate and prevent these problems is a management function. 13. How do we get the message relating to OOS across to staff? 14. How do we educate staff on how to reduce OOS? OOS offers a great opportunity to develop good staff relations. The fact that you are taking an interest in your staff by organising OOS training should go far. You need trainers who are credible and trusted. When you hire trainers, get the m to submit a resume of their thinking on OOS and a seminar programme in advan ce. See that this fits in with your knowledge of OOS and the overall scene at your work - ask for an independent opinion if you can. Ask to see their evalu ation questionnaire. Make sure that trainers deliver their message in a way that makes it possible f or your staff to make up their own minds and come to their own decisions. Avo id Rdo this - do thatS trainers. Get your own feedback from your staff about trainers. Contact the addresses below for the names of experienced trainers in this field in your area5 15. How do we encourage staff in the ways they can accept to reduce OOS in the mselves? 16. How do get staff to do the job who haven't got a problem? How do we get staff to be disciplined in actions required to avoid the problem? 17. H ow do we deal with periodic lack of staff committed to avoiding OOS? 18. How do we deal with the ability of staff to learn more about the remedies of OOS? 19 . How do we persuade staff to take it seriously? 20. How can we promote accepta nce that there is a problem? I have answered some aspects of these questions. In what follows I will assume that staff have been given training and education about OOS, and that because management has done an ergonomic assessment of workstations and made the requ ired workplace modifications, staff are able to avoid the problem, all other th ings being equal. This is a frequently asked question and there are two aspects to its answer: Can people do what is necessary to avoid OOS? Do they do what is necessary to avoid OOS? Lets list what we want people to do to avoid OOS: 1 Appreciate the nature and causes of OOS 2 Know how to adjust their workstations to minimise muscle tension. 3 Learn relaxation. 4 Use relaxed working techniques. 5 Take breaks. 6 Report aches and pains early. This list makes it obvious that unless staff have a minimal level of instructio n and hardware and that a system is in place to receive and act on reports of pain, they will not be able to do the right things. We have discussed instruc tion and ergonomics, so I will take up from the point where there is resistanc e by staff to the measures you have suggested. Try to find out why there is resistance. If it is neglect or indifference then you will be able to point out that the job description, which the person has previously agreed to, requires these measures you are insisting on. Point ou t that when one person neglects to work safe, it impacts on others. You may ne ed varying degrees of firmness here, which will be supported, of course, by yo ur earlier efforts in education, ergonomic assessment etc. Where there is some deeper seated reason - it may be disbelief or even distrust of what you are suggesting, then you need to find this out so that it can be discussed. May be a dominant personality is undermining your good efforts. If all this fails, you can consider getting a person with OOS to come and talk to staff. This can be difficult to manage - people can end up scared rather than informed. 21. Eye strain is the most common complaint I have from keyboard operators. How do we adjust operating time on VDUs to overcome OOS? 22. Ho w do we deal with eye strain? This is a big topic. Eyestrain is a commonly reported, genuine complaint of VD U operators. In the long term, however, VDU operation does not appear to affe ct eye health. It is best to think of eyestrain as Ocular Fatigue. This is not playing with w ords, but reflects the fact that the visual system includes the eyeballs, the muscles which control the position and focus of the eyeball, the nervous syste m, the visual information processing centres in the brain, and the muscles of the head, neck and shoulders which support the visual apparatus. Just as we said that OOS results from muscle tension, it may be useful to think of ocular fatigue as stemming from stillness of the eyes, head and therefore the upper body. This is another form of muscle tension. In addition to this ( simplistic) viewpoint, we need to recognise the nature of the visual task of l ooking at a VDU screen. VDU work can be very different from reading paper. Many who use the game Tetr is can attest that when you score up about 5000, your eyes get tired! This is d ue to the extreme concentration on the visual task. Much VDU work requires th is close visual concentration, though it is probably not as extreme as Tetris. There is no doubt or question that VDU work causes ocular fatigue. Conversely, VDU work appears NOT to cause long term visual deterioration at a faster rate than it normally deteriorates. Several studies followed groups of VDU and non-VDU operators for several years and found that the rate of change of visual status is identical in both groups. What confuses many people is that they begin work at a VDU and find they get p roblems. The explanation for this is as follows: In the population at large 20 to 30% of people have some visual defect whi ch would benefit by correction with glasses or contact lenses. Of this group, some have a minor defect only, but are so picky that they must have glasses. Others donUt mind coping with a greater defect - they donUt want to wear glass es. When people in the latter group begin VDU work, their defect begins to bo ther them. In other words, VDU work often shows up people with a visual problem. To cope with this, the following six strategies can be used: 1 Eye examinations for employees. Identify the people with problems before they begin work. If they need correct ion, special glasses ground for a reading distance of about 700mm are best. B ifocals, trifocals and varilux lenses seem to cause problems because of the ne ed to tip the head back to see thought the lower portion of the lens. A compe tent optometrist will be on the ball here. Note that an examination by an opt ometrist gives a better result than the use of a visual screening device. If you have large numbers of people, you should be able o negotiate a special dea l with a local optometrist. 2 Optimise the visual ergonomics of work. Provide a VDU screen which is adjustable for height, distance from the viewer a nd tilt. There are two visual problem with VDU: reflections in the screen an d glare from bright sources of light in the field of view. Correct the former by placing the screen in a position which will avoid reflections, move lights and tilt the screen downward or fit a screen filter (last resort). The latte r can be corrected only by repositioning the screen or masking the glare with heavy drapes. Many blinds do not attenuate the light enough to provide a solu tion. 3 Spread the workload evenly over the day and the week. Try to avoid peaks of urgent or concentrated work. 4 Train people in Rrelaxed lookingS. The message about working relaxed should be transferable here. People who squi nt or stare to look at their screen can be identified by observation, and sent for an eye examination. A view of a distant scene will promote a far gaze - which is relaxing in relati on to the close up constant focusing needed for the VDU screen. A view out of a window helps here. Paradoxically, an effect similar to a far focus can be o btained by looking at a small intricate sculpture, placed close by, with plent y of fine detail. 5 Give people breaks. Ten minute breaks every hour are good for visual relaxation from demanding task s. 6 Education and training. Education and training on the above. You should contact an optometrist experie nced in VDU work for details. 23. How do we deal with irregular work flows? I find this difficult to answer as I do not have direct knowledge of the partic ular situation(s). In general terms, however, there are two situations to deal with: 1 When work flows can be modified to remove irregularities. A detailed task analysis of the work should reveal where time can be saved or reallocated. 2 When irregular work flows cannot be remedied. In this case staff should not be left hanging. They should be informed of why the irregular work flow is necessary and unavoidable. They should know exactl y what is expected of them - both the goals and the performance specifications . Goodwill from staff can make up for a good deal of pressure at work. But it has to be earned, of course. If people perceive that unfair demands are being pl aced on them, then they will react unfavourably. If they are left uninformed t hey may assume that the demand is unfair. In principle, when people work hard to deal with urgent work they will need a compensating period when work is not so fully demanding. The need to meet urg ent unexpected deadlines should therefore be anticipated and catered for in ad vance. If the normal workload is just on the borderline of being too much, there may b e no slack left over to deal with crises. This situation should be anticipate d, and you may need to have quick access to temporary staff to cope. Where te mporary staff need training to do the task, their use will not be an option fo r sudden demands. In this case the tasks which do not need special training s hould be identified and given to temporary staff. In summary, we need to remove uncertainty and provide clear goals and performan ce specifications. And always reward people for good performance. 24. What is the effect of outside stressors on OOS? Much of the comment above relates directly. To summarise, stressors are of thre e kinds: 1 Physiological. The amount of physical work required. 2 Environmental. Noise, vibration, fumes and fumes (etc.), lighting, air - quality, heat. Work organisation, personal relations. etc. 3 Thoughts The relevant thing is not the stressors, but the stress reaction exhibited by t he person. Stress has general effect of adding straws onto the camelUs back. Stress overloads the nervous system with nervous traffic, with the effects li sted above becoming more likely. 25. How do we encourage certain staff not to aggravate OOS symptoms by similar home occupations ie knitting (to excess) and similar hand and craft occupatio ns? Tell them the issues. Discuss the situation openly. Staff (and management) need to accept that work is a partnership. Just as home activities can impact on work, so work activities can impact at ho me. Owing to our industrial relations RheritageS, these things are sometimes difficult to talk about. If a manager should ask a person to make changes to activities at home, because these activities appear to influence the work situ ation unduly, s/he should be quite sure that work life does not unduly influen ce the home situation. The word RundulyS is, of course, the catch. It is her e that personal skills and goodwill are needed on both sides to find a solutio n/compromise. Too often the question of blame arises in these situations. We need to remembe r that even when the blame question is answered (if it can be), the undesirabl e situation remains unchanged. The pragmatic questions, leaving aside the bla me one, should get the attention. Some USA companies supply their workers with personal protection (for example, earmuffs against noisy activities such as shooting). The rationale is that th e cost of a person off with a problem at work far outweighs the cost of the pr otective equipment. Appendix How to harness the power of the team. One of the main principles of ergonomics is to involve the users of a system in its design. Users have an intimate knowledge of the system they use, but there are two problems in obtaining this information. 1 Getting it. 2 Controlling and collating it. Often, when we ask a user what they think of a system, they will say RitUs OK S, or RI donUt like itS. But they will be able to offer little detail that th e designer can use to improve the system. The reverse problem can arise whe n people do start providing detail - it becomes uncoordinated and different u sers begin working at cross purposes or get captured by a strong personality and so on. What we need is a method which will both draw information out of pe ople and then collate it, discarding the unusable and unimportant on the way. The following outline is from D. D. OUBrien, a creative planner6. The part icular application was to design a new type of supermarket checkout for a maj or grocery retailer in the UK. This approach is used to elicit from groups of staff their ideas and feelings about changes in workplace design. Generally, groups of six or eight operato rs, with one or two facilitators, meet three times over a fairly short period for about 2 - 4 hours each time. Session One Introduction: This provides a general overview of design objectives. Word Map: Participants are asked to make an inventory of the equipment requir ed at their workplace. Round Robin Questionnaire: Participants are presented with a series of very s imple open ended statements such as "A good work counter is..... " This is pa ssed around to everybody, with each attempting to complete the sentence with a different ending to that chosen by the others. Individual Silent Drawing Exercise: Each participant is required to produce s ketches of both plan and perspective views of their ideal workplace incorpora ting the new equipment. At this stage, only very general ideas need to be pro duced. It is beneficial to discourage communication at this point, in the hop e that a variety of different ideas and designs will be forthcoming. The conf idence necessary to produce such drawings may be promoted, and further useful information gained as a by product, by the participants drawing their own w orkplaces first, highlighting good and bad points. Individual Presentation and Discussion: Each participant is required to prese nt a final sketch to the rest of the group, to explain the reasoning behind t he design and to discuss this. After all the sketches have been discussed, th e facilitator should then lead a general discussion, bringing up any points t hat may not have been previously considered. Session Two Drawing in pairs: In this session the group is divided into pairs who are req uired to produce a larger sketch, with more emphasis on detail such as the po sitioning of equipment and seating arrangements. Presentation and Discussion: Each drawing is presented to the rest of the gro up by its authors. Discussion at this point is directed towards choosing the best proposal, but no firm decisions need to be reached as each group will ge t a further chance to demonstrate their ideas using cardboard models of the s ystem. Simple layout modelling using cardboard models: This should be conducted in a laboratory type setting, with a clearly defined space similar to that of eac h participant's own workstation Participants are given strong cardboard model s of their workplace equipment. In addition they should be provided with a n umber of mock up work counter modules, chairs and stools, so that they can be st represent the ideas developed in the drawing exercise. Discussion: This should be geared towards eliminating inferior designs and fo rming a consensus of opinion as to the optimal layout. Session Three Building a complete mock up of the system: This should continue the work of t he last session, incorporating further details such as workplace height and d epth, and placement of ancillary equipment. Discussion This should consider the implications of the inclusion of addition al aspects in the mock up and the best options should be decided upon. Modifi cations The above modifications are incorporated. Trial and Assessment: This involves a detailed assessment of the workstation design, incorporating as many as possible of the operations to be carried out at the workstation, with participants taking turns to act as operators and c ustomers. REFERENCES 1 Department of Labour Occupational Overuse Syndrome: Checklists for the Evaluation of work. Wellington 1991 2 TEXTS ON PAIN Chronic Muscle Pain Syndrome Paul Davidson Villard Books (1990) Defeating Pain: The War Against a Silent Epidemic Patrick Wall, M Jones Plenum Press (1991) The Challenge of Pain Ronald Melzack & Patrick Wall Penguin 2nd ed. (1988) The Fabric of Mind Richard Bergland Penguin (1985) Controlling Chronic Pain Connie Peck Fontana/Collins (1985) Mastering Pain Richard Sternbach Ballantine Press (1987) 3 Carol Slappendel President, New Zealand Ergonomics Society P O Box 802, Palmerston North 4 GENERAL ERGONOMICS Department of Health Seating for office workers. Wellington 1989. Pheasant S T Bodyspace: Anthropometry, Ergonomics and Design Taylor and Francis. 1986 Grandjean E. 4th Edition Fitting the task to the man Taylor and Francis, 1991 5 Useful contacts: The President New Zealand Ergonomics Society P O Box 802 Palmerston North Address of the New Zealand Society of Physiotherapists.: The Executive Director New Zealand Society of Physiotherapists P O Box 27 386 Wellington Address of the New Zealand Association of Occupational Therapists: The President New Zealand Association of Occupational Therapists P O Box 68 291 Auckland 6 OUBrien D D. User oriented stuctured thinking procedures for the concept stages of sys tems desgn.. London. Home Office. ARTICLE TWO (This taken from an information paper: KS) MUSCLE TENSION The human neuromuscular system is not ideally suited for static work, requiring prolonged, isometric muscle contraction. Consequently, a large number of ind ividuals are unable to tolerate intense static work as a regular occupation fo r the entire working shift, day after day, for years on end, without ill-effec ts. These effects may include muscule stiffness, pain, tension, or even sympt oms or signs of neuromuscular disorders. The remarkable fact, however, is tha t some individuals do not develop any such ill-effects, in spite of constant e xposure to static work. It has been repeatedly observed that two people may work side by side in the sa me task, and that one may develop problems while the other does not. It is no t merely a matter of faulty ergonomics or working procedure. Ergonomic improv ements may make no improvements to the situation. Sex and age are important factors, as are the work rate and work intensity. In dividual differences in the way tasks are performed, including visual and neur omuscular concentration, arm support and the application of micropauses, may p lay a role. Similarly, it is conceivable that individual differences in mental stress affec ting peripheral neuromuscular tension may play a role. This in turn may be ca used by unsolved personal problems or conflicts. Or it may be caused by the i nability to relax while involved in a monotonous manual static task, allowing the mind to be free, and the thoughts to drift on their own way. Individual d ifferences in the ability to sense the state of tension of one's own muscles ( muscle sense), may also be a fact. Adapted from chapter 14 (Muscle Tension) of: "The Physiology of Work" Kaare Rod ahl Taylor and Francis, London 1989 ARTICLE THREE (This adapted from an information handout : KS) Keeping Comfortable at a Computer Computers are finding their way into every nook and cranny. Unfortunately, this jocular reference is more than just a joke because it is often a nook or cranny that the computer is squeezed into. Awkward postures held for a long time are the consequence and muscle aches and pains the frequent result. Many office workstations are poorly set up for computers, with the most common fault being a computer placed on a desk 750mm deep. It really requires a 900mm distance to accommodate the screen, copyholder and keyboard. Why do we get uncomfortable when using computers? Unlike a book, a computer can't be moved about. The result is that to look at the screen we need to keep our heads still. Other body parts are therefore characterised by stillness. The result may be muscle discomfort , even pain. In the extreme Occupational Overuse Syndrome (OOS) may develop. Here, the constant movement of fingers is misleading. Movement is not the cause of OOS, which is rather thought to happen as follows: Muscles and tendons get blood through very fine vessels (capillaries) passing between the muscle fibres. A tense muscle squeezes on these vessels and they collapse, slowing the flow of blood. When blood flow stops, the muscle has enough stored energy to cope with brief periods of tension. When this is used up it switches to a form of working (anaerobic) which is very inefficient. This uses up the energy store in the muscle very quickly and leads to a build up of acid wastes in the muscle (lactic acid). It is these acid wastes that causes the discomfort and pain by stimulating pain receptors. This muscle pain makes the neighbouring muscles come out tense in sympathy by a reflex action (the splinting reaction). This is a normal reaction to injury and is good where bracing is needed for acute injuries like a broken bone. In the extreme, however, a vicious cycle may result because the cause of the splinting reaction was muscles being held tight for too long All this indicates the need for movement and relaxation to prevent muscle fatigue and OOS. How to get comfortable at a computer workstation? Understanding good posture helps appreciate what is required in the design of a computer workstation. The elements of good posture, which are few, are listed here and are followed by tips for workstation design. Most of these suggestions do not require expensive equipment. Keep your shoulders low and relaxed: Try shrugging your shoulders to find out when they are at their lowest and what they feel like when they are relaxed. To keep your shoulders low and relaxed, the keyboard must be at the correct height. This may need to be as low as 650mm for a short adult and you will need an adjustable height chair. If your keyboard height can't be altered you will need a footrest. Let your elbows swing free: Elbows should hang more or less vertically under the shoulder. If chair backrests are too wide elbows will poke out and the wrists will be held sideways. Armrests should not get in the way of elbows and shoulders or they will need to be held out or raised respectively Both these actions result in prolonged muscle tension/. Keep your wrists straight: Keeping wrists straight is one of the best ways to promote comfort. Wrists are often bent up when people rest their hands between bouts of keying, so a wrist rest is an excellent idea. It also helps remove tension from shoulders. All you need is a block of dense foam at least 100 mm wide running along the front of the keyboard at the right height for you. A consequence of this is that the desk may need to be 900mm deep to allow up to 500mm for the screen, 200mm for the keyboard and 200mm for the copyholder and wrist rest. Computers placed on existing 750mm deep desks is one of the commonest computer workplace design faults. Look level, not down: Looking down may place a strain on your neck muscles. Being able to touch type means you don't have to look at the keys, so it is well worth while to learn. The middle of the screen should be at shoulder height - use a telephone book to raise it. Another valuable thing is a copyholder. Place it between the keyboard and the screen if you cannot touch type, or beside the screen if you can. Pull your chin in to look down: If you must look down, rotate your head by pulling your chin in. Imagine a rod through your head just below your ears and rotate your head using this line as an axle. Keep the hollow in the base of your spine: You will need a chair that provides proper support in this region. The best height for the backrest needs to be established by experiment and so it must be adjustable for height. Try leaning back in the chair: Realise that there is a difference between leaning back and slouching. There is nothing wrong with leaning back slightly to type. In fact, it is better for your spine. You can't write leaning back but you can use a keyboard this way. One thing to avoid is leaning forward. Alter your posture from time to time: There is no such thing as a single good posture. Our bodies were made to move. Therefore: Use micropauses and breaks: A micropause is a three second relaxation every three minutes. Three seconds is all that is needed to relax muscles that have been tense and to restore blood flow. The better you are able to relax your arm and shoulder muscles during the micropause, the more relief you will experience. Therefore, learn relaxation techniques. A two minute break for a stretch every 20 minutes is a good idea too. Ten minute breaks every hour do not provide good relief from muscle tension although they do provide rest from stressful jobs or from demanding visual tasks. Have good lighting. If your lights are placed so that they reflect off the VDU screen into a your eyes, you will need to alter your posture. Think about the placement of lights (technically, luminaires) when you set up the workstation. Department of Labour Code of Practice for visual display units: Sometimes, it is impossible to obtain a good posture because the workstation cannot be adjusted or arranged to allow it. The Department of Labour Code of Practice for Visual Display Units provides a minimum standard here, and makes mandatory requirements about the workplace when an operator spends more than three hours a day at a computer. In conclusion: All the above advice may summarised by the advice: get to know how your body feels. When you are using your computer tune in to your body at frequent intervals and take remedial action when discomfort appears. DYNAMIC AND STATIC WORK Dynamic and static work differ in the following ways: Dynamic work (a) Muscles contracts and relax rhythmically (b) Blood supply to muscles is not hindered (c) Muscle action helps heart pump the blood (d) Waste products of en ergy production removed Static work (a) Muscles contract without relaxing (b) Blood supply to muscles is hindered ( c) Heart pumps against muscle contraction (d) Waste products accumulate in the muscle We thus expect the body to be able to perform better under conditions of dynami c work. A given level of energy is much more strenuous if it is achieved usin g only a few muscles than if many are employed. Similarly, the same energy co nsumption by static muscular effort is distinctly more tiring than if it is ap plied to dynamic work. A limit for continuous (8 hours) dynamic work is about 30 - 40 percent of the a erobic capacity. For continuous static work the limit suggested has diminished in past years and now stands at 5% of the maximum voluntary contraction (MVC). Some studies ha ve suggested that continuous static work requiring an effort as low as 2% of M VC has been the cause of musculo-skeletal problems! ARTICLE FOUR (This is contentuous Not all experts agree on this) Recent Thoughts on Chronic Pain - As applied to overuse syndromes. Dr Mike Butler, Rheumatologist and pain specialist at Auckland Hospital, has ca refully studied many patients with chronic non-malignant pain, mainly musculos keletal problems. People with pain resulting from overuse syndrome are a small part of part of a wide spectrum of people with chronic pain. This pain is two to three times mor e prevalent in women than men. Dr Butler observes that it is common to look for a RlesionS to explain the pain and, when this is not found, to seek for a psychological explanation. If thes e are the only explanations considered a fundamental assumption is made: that the pain/nervous system is in perfect working order. This assumption is seldo m stated to the patient, though comments might be made concerning a lack of ev idence of any disease of the nervous system. >From a physiological perspective, there is no reason why the pain/nervous syst em should always operate perfectly in every person. Comprehensive clinical que stioning often reveals symptoms suggestive of nervous system dysfunction. Thes e include menstrual problems, tinnitus, Reynauds disease, irritable bowel synd rome, hot flushing and night sweating. That women with chronic pain conditions outnumber men by two to three times may be due to the lability of the nervous system control associated with hormonal cycling. While the brain uses electrical signals to effect its intentions th e operation of the nervous system, including the brain, is mediated by chemica l messengers/hormones. As Bergland says RThe brain is a glandS1. Using the analogy of a computer, the kind of problems that arise in the nervous system may be likened to a hard disc crash. In other words, these problems ma y be due to hardware problems, not just software problems which we might liken to psychological effects. The provocative agent here in the case of the pers on with OOS may be called nervous traffic. Just as pollen is to hay fever, so the increased nervous function of the keyboard operator (possibly compounded b y the stress reaction) may set off the nervous system dysfunction referred to. The study required to confirm the association between people with the health ef fects listed above and the development of chronic pain is a major undertaking - and beyond the resources of a country such as New Zealand. The sample size w ould obviously need to be large, and age and sex matched controls would be req uired. Even greater problems lie in the development of diagnostic criteria to confirm the presence of the conditions listed. Dr. ButlerUs impressions, which are based on the many cases he has seen, have been discussed with leading overseas pain researchers such as Patrick Wall and Ronald Melzack 2, 3. Improved communication is needed between clinicians and basic neuroscience pain researchers. The I.A.S.P. (International Association for the Study of Pain) is the major focus for this. The VII World Congress on Pain (Organised by the I.A.S.P. takes place in Paris in 1993. A practical consequence, if the link referred to above is confirmed, is the pos sibility of predicting people that are susceptible to OOS. In the correct set ting, where trust exists between (new) employees and their employers, a self a dministered questionnaire could be given to (new) employees. If their respons es indicate a possibility of increased susceptibility, a variety of actions mi ght follow: It is interesting that the Hettinger test, shown in one study to d etect which people in a sample had OOS, reflects the state of the central nerv ous system4. 1 The person attending a relaxation class or Rstress proofingS course independently of their workplace. 2 Advice from the company occupational health nurse. 3 A full follow up at work of the workstation ergonomics and working techn iques. Some words of warning require mention: It is useless to look for simple magic bullet solutions in preventing and treating OOS. Thus the above information m ay be taken in two ways: If regard it as Rthe answerS we are bound to fail. We should see it as confirmation that a holistic approach must be taken: Practitioners dealing with overuse syndromes need to consider the whole of thei r clientUs lives5, as well as the biological functioning and neuroendocrine co ntrol. References 1 Bergland R The Fabric of Mind Viking Penguin 1989. 2 Melzack R and Wall P D The Challenge of Pain Penguin. 2nd edition 1988 3 Defeating Pain: The war against a silent epidemic Patrick Wall and Mervyn Jones Plenum Press 1991. 4 Brown D A, Coyle I R and Beaumont P E The automated Hettinger test in the diagnosis and prevention of repetition strain injuries. Applied Ergonomics. 1985, 16.2, pp113 - 118 5 Department of Labour Occupational Overuse Syndrome: Treatment and Rehabilitation, A practitioner Us guide. Wellington 1992. O