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2 b. Work Recommendations - Encourage normal activity to avoid debilitation and unnecessary risks 
Work Recommendations for reasons of Comfort, not Safety - only if Patient rejects Normal Activity  
CAUTION: Professional prescriptions to limit a patient's work activity should be approached with the same trepidation and warnings as prescribing dangerous drugs. (See Off Work Risks) Moreover, there is no data to justify limiting work to reduce spinal loading to protect the back (Martimo et al.,`07). 
After Assurance of nothing dangerous and a recommendation of Normal Activity ,some individual's fear of discomfort may be too great to continue immediately with normal work activities. Some work limitations, of the shortest duration as possible, may be required to avoid triggering hostility before the severest symptoms resolve or conditioning can begin to improve activity tolerance. When ever activities at work are limited for more than 3-4 days, an alternative activity (see treatment) must be started to minimize the debilitation impact of limited activity. The only medically justifiable parameter for recommending work limits involves lifting, though sitting occasionally become an issue. The amount and time of each limitation can be negotiated based upon the second question in the initial history about specific limitations (How long can you Safely Stand, Sit, Walk, Lift) applied to the AHCPR Guidelines example as a basis for negotiating limited work recommendations (see Requested Work Limitations). When ever possible, avoid prolonging or worsening symptoms through debilitating reduced activity that makes spring training-like conditioning necessary to again be comfortable. Also see Activity Paradigm
Table Work Intolerance Recommendations (See Appendix for Work Recommendations and Understanding) 
Should the patient seek suggestions, suggest a short period of limiting as when possible bending, twisting or reaching when lifting. One might suggest getting up and moving around for a few moments (not minutes) after sitting for 20-50 minutes depend upon the patient's level of muscular reconditioning. Otherwise for comfort only, alterations can vary from a rolled up lumbar towel or side pillow to a standing desk according to patient's options.  Unassisted lifting limitations can simulate the NIOSH LIFTING GUIDELINES of 1981 and 1993 which are extremely conservative. For back problems lifting can be compassionately limited to 20 to 60-80 pounds alone or lifting limits of 20 to 35-40 pounds alone for women over 50 years (see table AHCPR Work Intolerance Recommendations).  
This system can be used for cervico-thoracic spine problems as well. For unilateral cervico-thoracic radicular problems you can reduce the unassisted lifting weight recommendations for the involved arm alone to half of what would be recommended for both arms, e.g. 10 to 30-40 pounds for a lift or 10 to 15-20 pounds for an unassisted one arm alone lift for women over 50 years of age. When requested to estimate a limited hours of work per day, point out that it should be negotiated at work and not an issue of safety. Comfort depends upon the patient's endurance, varying greatly by periods of inactivity and at different levels of conditioning. While questions about safety arise, we must remember that the 1980 NIOSH lifting Guide was based upon an interpretation of three laboratory cadaver studies.  
NIOSH was unable to associate lifting and neck problems in 1997.  In a longitudinal Swedish report (Fredriksson et al.`00) for neck/shoulder problems lifting risks, no significant association were found for exposure to “high physical loads” (i.e., lifting either 40kg for women or 60kg for men; or physical exhaustion at the end of the working day). The impact on neck/shoulder disorders from separate factors was moderate. Only combining physical and psychosocial factors, with work-related and non-work-related factors, produced relative risks above 2. This 22 year project studied the cumulative incidence rate from 1970-1992, but one-year prevalence rate sought only in 1993.  Most other association studies do not separate neck from shoulder issues. Other association studies since generally have rather low Odds Ratios of <3 for risk factors and neck/shoulder problems (Andersen et al.`02, Aasa et al.`05, Ostergren  et al.`05). USE LIMITING WORK RECOMMENDATIONS WITH CAUTION!  (See Off Work Risks
Why we fear lifting? The Lifting Equation to calculate appropriate lifting limits from the NIOSH Lifing Guide table above leans heavily toward the safety of employees as original data was complied from three cadaver studies. According to Andersson and Chaffin's 1984 Occupational Biomechanics Text, the Lifting equation is base upon the following laboratory cadaver studies: First was published in 1957 in English (Perey). Second published in 1962 in Japanese only (Sonada). Third presented in 1965 but never published (Evans & Lissner).  Thus, the articles' materials and methods sections are a bit sketchy and cadavar based conclusions assume that a percentage of women 40 years of age are at risk of fracture bending 20 degrees, lifting 10 Kg then turning 20 degrees with a bag of groceries (a little more than twice as load estimated for sitting at bedside before rising). At 50 years of age the cadaver studies indicated that almost half the women would have fractures lifting two bags of groceries from the floor. The assumptions are extremely conservative as no reliable medical studies support the thought of suspected danger or safety (See studies of Primary Prevention).  
Table: NIOSH Lifting Guide Data Conservative Basis (modified Fig. 6.25 Andersson-Chaffin '84) 
Such assumptions may be the reason we have been unable to wipe out back pain as an industrial injury through "presently known ergonomic principles" in the 10 years after this goal was set at the 1985 NIOSH Ten Year Planning Atlanta conference (May of 1985). Efforts by Waters et al, in '99 and Dempsey et al.`00 to validate the NIOSH Lifting Equation have failed. While Waters et al.`99 abstract is somewhat confusing one must evaluate the lack of statistical significance of highest lift load category where Confidence Intervals (CI) are not both on the same side of 1.0 as the Odds Ratio (0R) reported, e.g., no statistically significant difference.  Then comes more reliable information about primary prevention. (also see Primary prevention below and  Off Work Risks
Primary Prevention 
After the first prospective randomized primary prevention trial of Daltroy et al,'97, questioned the use of ergonomic education there have been now 4 trials that eliminated or reduced lifting loads. In a search concluded in late 2005 Cochrane collaborators Martimo et al.,`07 evaluated the six controlled trials and five cohort studies relative material handling advice and assistive devices for preventing and treating back pain in workers. They reported: Manual material handling advice and training with or without assistive devices do not prevent back pain, back pain-related disability or reduce sick leave when compared to no intervention or alternative interventions and no evidence is available for the effectiveness of MMH advice and training or MMH assistive devices for treating back pain.  Yassi et al,'01 verified reduction in normal lifts & device availability, Smedley et al,'03 had increase in the most trained group,  Hartvigsen et al,`05 verified absence of lift devices in control group, Jensen LD, et al.`06, verified differences in exertion by questionnaire, are supported by training prevention program trials by Izelenberg et al.`07 and Lavender et al.`07 in making very strong points that teaching proper lifting and eliminating or reducing lifting does NOT effectively reduce the report of back problems or time lost from work. Harkness et al, '03 prospective risk factor study further the question lifting as the cause of back problems and the longitudinal study of Maul et al, '03 did not find 8 years of high risk lifting to cause any expected worsening of the human back condition as might be expected reviewing the original Lifting Equation data above.  A large part of the problem may well lie in the area of trying to physically prevent non-physical influences on complaints and disability. 
Carragee et al.,`06 prospective cohort study about minor trauma found non-physical issues (abnormal psychometrics, smoking, and compensation issues), accurately identified 80% of serious LBP events and 93% of LBP disability events. This prospective longitudinal study followed 200 subjects without low back pain for 5 years. Back problem frequency, severity and disability were not predicted by frequency nor severity of traumatic events.  Adverse outcomes were not predicted by structural findings or incident of minor trauma (fall <3 feet, MVA <30 MPH, lift <60 lbs.). The presence or absence of advanced structural findings did not make subjects more likely to become symptomatic whether or not they experienced a minor trauma events. Of further interest, the minor trauma had no impact on MRIs. MRIs rarely changed and had no association with the frequency of low back episodes or disability. Minor trauma had no impact on the frequency or severity of back symptoms or disability.  Prospective studies from Bigos et al.`92 to Carragee et al.`06 have questioned the physical impact of an event in one's experience with back problems which is now confirmed for lifiting events by Martimo et al.,`07
The history of attempts to prevent episodes of back problems is an excellent example of the clinical epidemiology's ability to stratify the reliability of data when searching for reliability. Retrospective studies for back problem prevention tend to heavily point in the direction of the interests of their authors. Then prospective cohort studies of potential risk factors, being less capable of hiding potential bias, seem like they are bucking popular opinions based upon retrospetive associations. A few trials allowing greater scrutiny for methodological faux pas, tended to move closer to one side with only occasional contrary results. Finally Controlled Trials, RCTs or OCTs with documented similar study groups and the greatest methodological transparency, lean heavily in the same direction. Now employers, clinicians and legislators can now make informed evidence based decisions after the consistent failure of ergonomic attempts to prevent episodes of back problems by teaching proper lifting (Donchin et al.`90, Daltroy et al,'97, van Poppel et al.`98, Izelenberg et al.`07) or programs that actually reduce lifting (Yassi et al,'01, Smedley et al,'03,  Hartvigsen et al,`05, Jensen LD, et al.`06). This is further supported by prospective longitudinal studies from Boeing Study of aircraft builders to Thelin et al., 2008 study of farmers
Only exercise for primary prevention of back problems has been found effective in seven of eight Controlled Trials (Donchin et al.`90, Gundewall et al.`93, Lonn et al.`99, Soukup et al,`99, Soukup et al,`01, Larsen et al.`02b, Maul et al.`05, Suni et al.`06) and ineffective in one RTC by Alexandre et al.`01. Prospective Controlled Trials studying primary prevention of back problems, neither support the use of shoe inserts (Larsen et al.`02b and Milgrom et al.`05), nor back belts or braces (Controlled trials by Walsh et al.`90, van Poppel et al.`98, Kraus et al.`02 and large prospective cohort (Wassel et al.`99). The initial impressions by Walsh et al.`90 and Kraus et al.`02 could not be validated due to dissimilarity in the comparison groups. As noted above ergonomic education and even 4 clinical trials studying programs that reduce lifting have been proven to be INEFFECTIVE in primary prevention of back problems. 
The consistently of controlled trials attests to their reliability. They supports the benefits of exercise in preventing of back problems. We know neither the exact reason nor specifically the best technique. But exercise benefits seem to heavily outweigh risks for an intervention that can be provided at minimal cost to society, patients or employers. The varied successful exercise approaches strongly suggest possible benefits of exercise interventions to be well beyond the intended physiological goals. 
Since great resources have been poured into ergonomic interventions, one cannot overlook the lack of proven efficacy of related educational efforts or attempts to reduce lifting loads to prevent back problems. Indoctrination alone or conventional wisdom until recently made an examination of the failures of lifting prevention a "polemic" event. Considering the overwhelming trend in reliable scientific evidence, it can no longer be politically incorrect to consider possible explanations for the lack of impact reducing lifting load that might include:  
1. Objective outcomes may not be sensitive enough to realize the benefits of such programs as suggested by Yassi et al,'01. Yet, they are sensitive enough to realize the prevention benefits of exercise.  
2. Perhaps the rates of back problems are inherent and that lifting or other minor trauma may not be a trigger to more or worse back problems as noted from before the Boeing study to Carragee et al.`06 minor trauma paper and now be supported by 4 failed trials (Yassi et al,'01, Smedley et al,'03,  Hartvigsen et al,`05, Jensen LD, et al.`06,) studying reduced lifting programs aimed at preventing events of back problems. Moreover, award winning identical twin studies that control for many individual variance issues, find lumbar MRI spinal aging impact very modest even with wide variations in work and other exposures.Battie, Videman 274e-g Only smoking seems to speed aging of the spine as the overwhelming influences on what is seen on MRI are genetic factors. 
3. Lifting might be a trigger but only to episodes inherently expected as supported by Carragee et al.`06 minor trauma.  
4. Lifting near one's capacity may trigger back problems. If so it exercise may be effective by improving one's capacity thus providing the protection against back problems as found in 7 Controlled Trials. If the capacity is important, reducing that capacity by avoiding activity may have the opposite effect, thus explaining the failure of prevention attempts using of devices and techniques to reduce back lifting loads in 4 trials. Avoidance's resultant lowering of lifting capacity hypothetically may then allowing lower lifting stress to trigger back problems. Thus, eliminating the potential triggers at work may debilitate people making them more susceptible to back symptoms at lower level tasks during less stressful activities of daily living.  
5. Lifting may be an issue independent of rate of subjective back complaints or back problems.  
6. Non-physical issues overwhelming the minor physical issues in impacting the objective outcomes of back injury claims and disability as suggested by multiple studies from Boeing to Carragee and Simon et al., `07. (See Disability Risks)  
7. If Controlled Trials, despite being the highest level of reliable science, are somehow wrong about reducing lifting in nurses or hospital personnel and reducing lifting truly is so effective in prevention of back problems then why the need for legislation.  If effective such preventive techniques would be immediately adopted due to either the good intentions or the greed of employers? At present legislating mandatory use of additional resources to reduced or eliminated lifting could not be considered an evidence based decision making.  
Thus, resources for primary prevention of back problems should either be spent on proven effective methods or to support Controlled Trials studying promising prevention methods. Contrary to 1994 when the AHCPR US Dept. Health and Human Services low back guideline was published, we now have high level studies (Controlled Trials) to guide our primary prevention efforts. Controlled Trials are proven capable of discerning primary prevention controversies. 
No longer must we fear offending "conventional wisdom" enthusiasts by besmirching sound judgments. We are armed with the ability to make evidence based decisions. It is immoral to knowingly squandering resources that only benefit the providers in the face of reliable evidence. To do otherwise is contrary to a sworn oath for professionals. Irrespective of belief and good intention, is it not corrupt to misdirect resources with no primary benefit to patients or society in the penumbra of reliable scientific evidence to the contrary.  
Ergonomics is important for designing work efficiency. But reliable information from Controlled Trials does not support continued resources for primary prevention of back problems based upon intermediate mechanical outcomes, related conventional wisdom or other untested hypotheses generated by lower level studies.  
It is a matter of applying resources through with better knowledge that improves goal making and potential achievement. A good outcome has many fathers and failure is an orphan. A positive impact has an explanation. But using an argument based upon conventional knowledge since proven wrong is unacceptable. We bled people for infection based on testimonials long after it was proved ineffective. No one wanted to recognize a mistake and be unable to take credit for those who survived. More recently science has illuminated similar issues about spinal fusion for disk pain, diets, estrogen replacement and many others. All are the errors were based on retrospective information. "Post hoc ergo propter hoc" ("it came after that, therefore it was the result of that") is too often faulty a logic in medicine and law. In each situation the intentions are good but cannot be based only upon only the loudest testimonials. Fortunately, we now have the tools to gather reliable information from sound transparent prospective trials to improve our aim at real issues and avoid the time and resource wasting mistakes of the past. 
See Job Activity Limitation Risks 
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