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LEADING ARTICLE Sports Medicine 13 (6): 365-375, 1992 0112-1642/92/0006-0365/$05.50/0 © Adis International Limited. All rights reserved. SP01140 Return-to-Work Evaluation after Coronary Events Special Emphasis on Simulated Work Activity Joyce Landes and Joe L. Rod Santa Clara Valley Medical Center, Divisions of Cardiology and Physical Therapy, San Jose, California, USA Interest in objective methods to facilitate return to work after coronary events has grown in recent years. Evidence of this interest can be observed in conferences focusing on this topic, such as the Workshop on Occupational Cardiology (Denolin 1988) co-sponsored by the World Health Organi- zation, the 'Associazione Nazionale dei Centri per Ie Malattie Cardiovascolari', Societa Italiana di Medicina del Lavoro e Igiene Industriale, and the European Society of Cardiology, and the 20th Be- thesda Conference (DeBusk 1988) sponsored by the American College of Cardiology and co-sponsored by the Association of Life Insurance Medical Di- rectors of America. Few studies, however, pertain- ing directly to the practical methods of accomplish- ing return to work have been published to date. In this article, the usefulness, methodology, and out- comes of simulated work activity are described in the context of epidemiological data, factors influ- encing return to work and methods utilised to en- hance return-to-work rates. 1. Epidemiology of Coronary Artery Disease Despite a declining death rate due to cardio- vascular disease, heart attacks claimed 513 700 lives in the United States in 1987, the most recent year for which statistics are available. Another 1 000 000 survived heart attacks that year. Currently, 5 000 000 people in the US have a history of heart attack, angina, or both. Based on the Framingham study, 5% of heart attacks occur in people under age 40 and 45% occur in people under age 65. Thus, a significant part of the work force is affected by coronary artery disease. Several studies have shown that approximately 15 to 20% of patients who suf- fer a cardiac event do not return to work. Those patients who do return to work do so after unnec- essary delays and with decreased efficiency (Cay & Walker 1988; Dennis et al. 1988). The cost due to disability payments and lost productivity is esti- mated at a staggering $US6.8 billion dollars in the US for 1990 (American Heart Association 1989). The Social Security Administration reports annual disability payments of approximately $US5.1 bil- lion for cardiovascular disease, accounting for 30% of the total disability payments made (Guillette et al. 1988). According to a study by Picard et al. (1989), the performance of an Occupational Work Evaluation of low risk patients reduced the time to return to work from a mean 75 days to a mean 51 days. Projecting the cost benefit onto an estimated 300 000 low risk employed survivors annually, an annual cost savings of US$800 million could be realised in the United States. Maisano and Gob- bato (1988) at the Workshop on Occupational Car- diology stated that many of the patients who do not return to work could do so 'if they were re- habilitated and adequately evaluated'.

Return-to-Work Evaluation after Coronary Events

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Page 1: Return-to-Work Evaluation after Coronary Events

LEADING ARTICLE

Sports Medicine 13 (6): 365-375, 19920112-1642/92/0006-0365/$05.50/0© Adis International Limited. All rights reserved.

SP01140

Return-to-Work Evaluation after Coronary EventsSpecial Emphasis on Simulated Work Activity

Joyce Landes and Joe L. RodSanta Clara Valley Medical Center, Divisions of Cardiology and Physical Therapy,San Jose, California, USA

Interest in objective methods to facilitate returnto work after coronary events has grown in recentyears. Evidence of this interest can be observed inconferences focusing on this topic, such as theWorkshop on Occupational Cardiology (Denolin1988) co-sponsored by the World Health Organi­zation, the 'Associazione Nazionale dei Centri perIe Malattie Cardiovascolari', Societa Italiana diMedicina del Lavoro e Igiene Industriale, and theEuropean Society of Cardiology, and the 20th Be­thesda Conference (DeBusk 1988)sponsored by theAmerican College of Cardiology and co-sponsoredby the Association of Life Insurance Medical Di­rectors of America. Few studies, however, pertain­ing directly to the practical methods of accomplish­ing return to work have been published to date. Inthis article, the usefulness, methodology, and out­comes of simulated work activity are described inthe context of epidemiological data, factors influ­encing return to work and methods utilised to en­hance return-to-work rates.

1. Epidemiology of CoronaryArtery Disease

Despite a declining death rate due to cardio­vascular disease, heart attacks claimed 513 700 livesin the United States in 1987, the most recent yearfor which statistics are available. Another 1000 000survived heart attacks that year. Currently,5 000 000 people in the US have a history of heart

attack, angina, or both. Based on the Framinghamstudy, 5% of heart attacks occur in people underage 40 and 45%occur in people under age 65. Thus,a significant part of the work force is affected bycoronary artery disease. Several studies have shownthat approximately 15 to 20% of patients who suf­fer a cardiac event do not return to work. Thosepatients who do return to work do so after unnec­essary delays and with decreased efficiency (Cay &Walker 1988; Dennis et al. 1988). The cost due todisability payments and lost productivity is esti­mated at a staggering $US6.8 billion dollars in theUS for 1990 (American Heart Association 1989).The Social Security Administration reports annualdisability payments of approximately $US5.1 bil­lion for cardiovascular disease, accounting for 30%of the total disability payments made (Guillette etal. 1988).

According to a study by Picard et al. (1989), theperformance of an Occupational Work Evaluationof low risk patients reduced the time to return towork from a mean 75 days to a mean 51 days.Projecting the cost benefit onto an estimated300 000 low risk employed survivors annually, anannual cost savings of US$800 million could berealised in the United States. Maisano and Gob­bato (1988) at the Workshop on Occupational Car­diology stated that many of the patients who donot return to work could do so 'if they were re­habilitated and adequately evaluated'.

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2. Factors Influencing Return to Work

Return-to-work rates vary significantly incountries around the world. Rates in the UnitedStates, Canada and England have been reported ashigh as 85%. On the other hand, rates in Germany,France and Switzerland rarely exceed 50% (Dan­chin 1988; Gehring et al. 1988). The influencingfactors are both medical and nonmedical. The lit­erature presents conflicting opinions as to the in­fluence of various medical factors.

Consensus of opinion considers the followingkey factors influencing re-employment: physicianadvice, patient's perceptions of health, exercise ca­pacity, disease severity, social welfare system, fi­nancial status, age, type of occupation, length oftime absent from work, employer's attitude, emo­tional problems and family influence (Blumenthalet al. 1988; Davidson 1983; Guillette et al. 1988;Kavanagh & Matosevic 1988;Shanfield 1990).Ka­vanagh (1988) followed 1150 men with a diagnosisof myocardial infarction (MI) or coronary arterybypass graft (CABG) during 1986-87. 70.6% werewhite collar workers and 29.4% were blue collarworkers. Six months after the episode, 13.8% of bluecollar and 7.7% of white collar workers had failedto return to work. Investigation into the reasonsfor not returning to work revealed 55% admittedsocioeconomic circumstances did not encouragethem to work, 35% reported negative medical ad­vice and 10% stated their employers' reluctance torehire them. Dennis et al. (1988) described em­ployed low risk patients citing 'their perceptions oftheir health and the medical advice they receiveregarding re-employment' as the chief influenceson the timing of return to work.

CABG patients have demonstrated return-to­work rates from 50 to 90%, which is no better thanmedically managed MI patients (Hammermeisteret al. 1979; Kinch1aet al. 1985; Russell et al. 1986;Stanton et al. 1983). A good functional capacityfollowing CABG does not necessarily predict post­operative employment. The major predictors ofre­turning to work after successful CABG arenonmedical, and include the length of preoperativeunemployment and the nature of physician advice

Sports Medicine 13 (6) 1992

(Cay & Walker 1988; Davidson 1983; Stanton etal. 1983; Walter 1988). Efforts aimed at reducingpreoperative unemployment times and ensuringconsistent, specific and positive physician adviceshould, therefore, increase the rate of return to workfor CABG patients.

3. Return-to- Work Evaluation

Frequently, a patient's physician is requested tocertify the ability to resume work - either the pre­vious position, a modification of the previous po­sition or entirely new work. Physician recommen­dations are often based on subjective opinions(Dennis 1988). Inaccurate determination fre­quently results in either delays in re-employmentor persistent disability. The costs of such an errorare socioeconomic, and affect the individual's fam­ily and personal self-worth (Sheldahl 1985).

Task Force I at the 20th Bethesda Conferencerecommended consideration of 3 aspects in eval­uating return to work: (a) the capability of the in­dividual to perform the job; (b) the risk to the in­dividual of performing the job; and (c) the risk tosociety if the individual is performing the job (Pryoret al. 1988). In evaluating patient capability andjob risk, an analysis of both the characteristics ofthe job and the patient's physical capacity must bemade.

Important job characteristics include the type ofphysical work (i.e. static or static-dynamic), the en­ergy requirements, environmental stressors andpsychological stressors (Haskell et al. 1988; Shel­dahl 1985). Occupational medicine physicians canbe especially helpful in providing objective job an­alysis information.

Evaluating patients for return to jobs which maypose a risk to public safety is especially difficultbut accuracyis essential.On-the-job conditions suchas those confronted by firefighters are difficult toreplicate in the laboratory setting. The goal, how­ever, is to estimate the probability of an individualexperiencing a coronary event on the job when itwould otherwise be unlikely (Haskell et al. 1988).

The initial occupational assessment should be­gin as soon as the patient is clinically stable. The

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20th Bethesda Conference recommended testing at5 weeks for an uncomplicated MI, 7 weeks afterCABG, and 1 week after coronary angioplasty(Haskell et al. 1988).

3.1 Physiological Response to OccupationalWork Demands

Occupational work is a combination of static orisometric and dynamic work. The relative contri­bution of each is dependent upon the type of taskperformed. Sheldahl et al. (1985) state that the en­ergy cost of specific jobs is influenced by the rateof work, efficiency and size of worker, orthopaedicdisability, and degree of automation available on­the-job. Work related factors such as temperaturestress, psychological stress, awkward body posi­tions .and static work can significantly increasemyocardial oxygen demand. The haemodynamicresponse to work varies according to the presenceof the different work-related factors.

Static work generally results in higher systolicand diastolic blood pressures, but lower heart rateand rate pressure product than dynamic work. Theanginal threshold, identified by maximum ratepressure product (RPP) achieved on a symptom­limited graded exercise test (SLGXT), is reprodu­cible for similar dynamic workloads in the work­place. When a large static component is added tothe dynamic work, however, the anginal threshold,represented by RPP, shifts upward. Thus an indi­vidual can sustain a higher workload doing iso­metric and/or isodynamic work than dynamic workbefore evidence of myocardial ischaemia is noted(DeBusk 1978).

For patients with severely decreased left ven­tricular function (class III or IV NYHA) who donot possess a normal cardiac reserve, a sudden in­crease in blood pressure and, hence, sudden in­crease in myocardial oxygen demand secondary tostatic exercise can result in dire consequences.Graves et al. (1988), in a study comparing themetabolic and haemodynamic responses to sub­maximal exercises in 12 hypertensive responders,found a great variation in systolic blood pressureresponse to static work involving carrying hand-

367

held weights. He recommended 'careful observa­tion of blood pressure response to exercise withhand-weights ... before prescribing hand-weightexercise where increased cardiac afterload is con­traindicated'.

Sheldahl et al. (1983) assessed the cardiovas­cular responses of 52 patients ~ 2 months after MIto carrying graded weight loads of 20 to 50lb (9 to23kg) while walking on the treadmill at a com­fortable speed. One-third of the patients reached adiastolic blood pressure of 120mm Hg, an end-pointto their test protocol. The diastolic blood pressureresponse to static exercise was significantly greaterthan that achieved during dynamic exercise. Thesafety of increasing diastolic blood pressure togreater than or equal to 120mm Hg repeatedlyeither in a work day or in doing activities of dailyliving has not been established in patients with pre­vious MI (Sheldahl et al. 1983). Saito et al. (1987)also found that continuous activity increased bloodpressure to a greater extent than intermittent ac­tivity. This further suggests the need to establishappropriate blood pressure end-points which canbe safely generalised to the job.

Borg's rating of perceived exertion (RPE) scale(1982) is frequently used as a method for patientsto subjectivelymonitor their own safeactivity level.In our study of the safety and clinical applicabilityof a specific simulated work activity protocol, RPEat a safe prescribed training threshold based onSLGXT correlated with different haemodynamicresponses to the same perceived threshold of workin simulated work activity (Rod et al. 1989).Thus,we recommend determining haemodynamic re­sponses in cardiac patients engaging in weight­carrying or weight-lifting activities for specific ex­ercise prescription, treating hypertensive responsesas necessary.

3.2 Graded Exercise Test

A multitude of articles and texts have docu­mented the many benefits of the graded exercisetest (Cohn 1988; DeBusk et al. 1986; Schlant et al.1986; Ellestadt 1986; Rabbani & Antman 1989;Weiner et al. 1984). In 1980, DeBusk and David-

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son reported the use of treadmill exercise testing 3weeks following an uncomplicated MI to deter­mine the occupational work potential of 196 menaged 70 or less. They found it to be very useful instratifying low from high risk patients, enabling lowrisk patients an early return to employment andguiding future medical direction of the high riskpatient. Rod et al. (1982) reported similar findingsin patients following cardiovascular revascularisa­tion procedures.

The primary purposes of the GXT are to de­termine the functional capacity and to identify anyabnormal responses to exercise. The results shouldbe evaluated in the framework of the job require­ments. According to Task Force II of the 20th Be­thesda Conference (Haskell et al. 1988), an indi­vidual should be able to exercise 'free of significantcardiac dysfunction that is at least twice the av­erage energy requirement and 20% more than theexpected peak energy requirement on the job'.

Poor performance in the initial GXT does notpreclude eventual employment. Further medical orsurgical intervention may be indicated. Referral toa cardiac rehabilitation programme may facilitateimproved functional capacity and modification oflifestyle as appropriate. After a determinate reha­bilitation programme, the patient should be re­evaluated for return to work.

3.3 Simulated Work Activity

The graded exercise test does not take into ac­count the effect of the work, weight-carrying,weight-lifting, working in body positions other thanupright, and working in the presence of environ­mental or psychological stressors. In occupationsaffected by the aforementioned factors, return-to­work recommendations should not be made basedexclusively on GXT outcomes. Haskell et al. (1988)at the 20th Bethesda Conference recommended labwork simulation or on-site monitoring 'may benecessary for occupations posing unusually taxingphysical, psychological or environmental stress, es­pecially those posing a risk to the public'.

Many patients can benefit from a simulatedwork activity (SWA) test. Patients who perform well

Sports Medicine 13 (6) 1992

on SLGXT and are stratified into the low risk group(> 7 METs) but who are returning to work with alarge static component should have an SWA testto evaluate their blood pressure response to staticand isodynamic work. Patients hypertensive at restor in response to dynamic exercise should also beassessed performing static activities. For mediumto high risk patients returning to selected job tasksor leisure activities, SWA provides more accurateassessment than the SLGXT of a patient's abilityto safely resume such workloads. Patients whoseSLGXT is borderline for recommending return toemployment at a given workload can frequentlybenefit from SWA (Haskell et al. 1988; Kavanagh& Matosevic 1988; Rod et al. 1989; Sheldahl 1985).These patients may actually respond adequately tostatic workloads, which are more relevant to thework place, then to dynamic work. For patients un­able to do a dynamic exercise test or whose GXTend-point is limited by a noncardiac reason but whoare returning to heavy manual labor, SWA can as­sess their cardiovascular response to static and iso­dynamic work.

The results of SWA may reassure anxious em­ployers, patients, and families of the safety of re­turning to work. Specific guidelines regarding theamount of weight a patient can lift or carry on-the­job can also be given. Two of the most significantfactors influencing return to work - physician ad­vice and patient's perception of health - are bothpositively influenced by the completion of SWAtests. Patients and families are tested in an atmos­phere conducive to receiving instruction about en­ergy conservation, proper body mechanics, and ap­plication ofobjective test results to activities outsideof the clinical lab. An added advantage of SWA isthe ability to standardise procedures, the provisionof quantifiable results, and the ready availabilityof trained emergency personnel and equipment(Haskell et al. 1988; Kavanagh & Matosevic 1988;Rod et al. 1989; Sheldahl et al. 1985).

3.4 On-Site Testing

Some occupations m!1y not be capable of beingadequately reproduced in a clinical lab to evaluatefunctional capacity via SWA. In occupations with

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Return-to-Work Evaluation after Coronary Events

environmental stress factors, such as temperatureextremes, humidity, altitude or the wearing ofheavy, confining clothing, on-site testing may benecessary. In occupations with significant psycho­logicalstress eliciting emotional factors such as fear,anxiety, and/or excitement, on-the-job analysis isalso necessary. Examples of such jobs are police­men, firefighters, and air traffic controllers; theseoccupations are also public risk jobs where the needfor accurate assessment is essential to protect thepublic's safety.

On-site testing requires taking portable tele­metry to the workplace to monitor ECG in com­bination with the haemodynamic response to aworker's daily routine. Kavanagh (1988), in de­scribing on-site testing as done at the Toronto Re­habilitation Centre, recommends a physician andtherapist or technician perform the evaluation to­gether.

On-site testing has the benefit of being the mostaccurate assessment method attainable when donewith the proper equipment and by the appropriatepersonnel. Disadvantages include the cost, the test­ing and travel time, the need for specialised equip­ment and the need for specially trained personnel.The disadvantages of on-site testing may often ap­pear prohibitive, but the benefit to the individualand community in returning patients to work whomay otherwise resort to long term disability makeson-site testing worthwhile.

4. Simulated Work Activity Guidelinesand Protocols

Recent studies have evaluated the usefulnessandhaemodynamic responses of varying combinationsof static and dynamic work. Different methodol­ogies have been described by different investiga­tors to date. Standardised protocols to be used bymultiple clinicians have not yet been established.

4.1 Studies

Sheldahl et al. (1985) have developed tests thatsimulate different types of work requirements andmay be administered following an initial SLGXT

369

4 to 8 weeks after MI or CABG. Specific SWA testsare selected based on an analysis of a patient's realjob requirements.

Patients whose jobs entail sustained static­dynamic work receive a weight-carrying test (WCT).Patients carry weight loads of 20, 30, 40 and 50lb(9, 14, 18 and 23kg), while ambulating on a tread­mill at approximately 2mph (3.2 km/h). Eachweight is carried for 2 minutes followed by a 2- to3-minute rest period. The 50lb limit was deter­mined because the authors state 'this represents thepeak weight-carrying load expected of most indi­viduals in occupational settings'. ECG is continu­ously monitored. Blood pressure and heart rate aremeasured at the end of each minute. The end-pointsof the protocol included fatigue, SBP ~ 250mm Hg,DBP ~ 120mm Hg, exercise-induced hypotension,limiting angina, ST depression ~ 3mm and ven­tricular tachycardia ~ 3 consecutive PYCs. A studyof 52 post-MI patients, based on this protocol,showed 38% completed the entire protocol. Theend-points for incomplete tests were DBP ~ 120mmHg in 16, arm fatigue in 12, and arrhythmia andangina in I each. Patients showed a higher meanrise in SBP and DBP, but lesser mean rise in heartrate and RPP, in the weight-carrying test than inthe SLGXT.

A second test described by the authors was re­petitive weight-lifting (WLT) used to evaluate workdone in occupations such as farming, warehousing,truck driving, and masonry. The test was dividedinto four 6-minute work stages with 2-minute restintervals between stages. Each patient was in­structed to set a pace of lifting which he or she feltcould be sustained for 30 minutes. In stage I, thepatient moved a 30lb (14kg) weight repeatedly be­tween the floor and a 33-inch (84cm) high table.In stages 2, 3 and 4, 40lb (18kg), 50lb (23kg) and40lb weights, respectively, were moved accordingto the stage I protocol. ECG was continuouslymonitored. Blood pressure was measured while thepatient held the weights momentarily at the end ofthe second and sixth minutes of each stage. End­points were identical to the weight-carrying test.Blood pressure responses fluctuated widely duringlifting and releasing weights. The mean haemo-

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dynamic response was intermediate to the WCTand the SLGXT.

Sheldahl et al. (1985) report that either of theabove protocols can be modified to match the jobspecifications. Other SWA tests may utilise weight­lifting equipment, arm ergometry, heat or coldstressors, and the use of questionnaires to screenfor psychological stress.

Rod et al.(1989) had a dual purpose to theirstudy of a clinical protocol for SWA. First was theassessment of its applicability in a clinical settingfor patients after cardiac events in order to facili­tate safe return to heavy physical work. The secondobjective was to evaluate the validity of RPE as aparameter for exercise prescription in SWA.

15 patients from 2 to 21 months after MI, PTCA,and/or CABG underwent SWA after performing at~7 METs on an SLGXT. All patients performed aWCT and a WLT adapted from the protocol ofSheldahl et al. (1985). Table I presents the criticalelements of the test procedure.

The test results demonstrated the safety andusefulness of the test. Ten of the 15 patients per­ceived the test as being very helpful and havingrestored their confidence in returning to manuallabour. We established 95mm Hg as the upper ac­ceptable diastolic blood pressure limit for return to

Sports Medicine 13 (6) 1992

the work force. Five patients exceeded this limit.Three patients stopped the WCT before complet­ing the test protocol, because of their hypertensiveresponse. Recommendations regarding changes inmedication were influenced by both the simulatedwork activity stage at which the hypertensive resultoccurred compared with the estimated workloadneeded on the job, and the magnitude of the hy­pertensive response.

The workload for a given RPE on the SLGXTwas not applicable to the SWA workload. SimilarRPEs on the SWA tests resulted in significantlydifferent haemodynamic responses than were elic­ited on the SLGXT. Especially noteworthy, theDBP of 92 ± 8mm Hg in the WCT was signifi­cantly higher than the 81 ± 11mm Hg observedin the SLGXT. The SWA protocol employed inthis study appears safe and feasible to implementin the clinical setting.

Dafoe et al. (1990) presented a case report dem­onstrating the presence of arrhythmias during SWAtests of weight-lifting and weight-carrying whichwere not seen on the preceding standard SLGXT.In addition, these arrhythmias occurred at a lowerRPP with WCT and WLT than SLGXT. A prelim­inary job analysis revealed the patient needed tolift and carry 100lb (45kg) weights at a peak work-

Table I. Clinical simulated work activity protocol by Rod and colleagues. (a) A baseline GXT is first performed utilising the clinician'spreferred test' protocol. (b) Two SWA tests are conducted

Stages

Weight-carrying test (WeT)

4 stages; 3-minute duration each;

3-minute rest intervals

Weight-lifting test (WLT)

3 stages; 4-minute duration each; 3­minute rest intervals

Activity

Treadmill at 0% grade. 1.5­2.0 mph (2.4-3.2 krn/h):

carrying graduated weights

I 20lb (9kg)II 30lb (14kg)III 40lb (18kg)

IV 50lb (23kg)

Lift weights between floorand gurney or table 3-6times per minute

130lb

1140lb

III 50lb

Monitoring

Continuous 12-lead ECG HR.RPE each minute

BP at end of each stage.

Signs and symptoms

Continuous 12-lead ECG HR.RPE each minute.

BP at 2 and 4 minutes in

each stage

Signs and symptoms

Test end-points

According to American

College of Sports Medicine

(ACSM) except DBP >95mm Hg and/or testworkload equals that inworkplace

According to ACSM exceptDBP > 95mm Hg and/or testworkload equals that in

workplace

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Return-to-Work Evaluation afterCoronary Events

load of 9 METs. Speed, accuracy, and productionpressure were characteristics of the job. A weight­lifting and carrying protocol was devised to sim­ulate the patient's job requirements. A dynamic ex­ercise test indicated the patient's maximum work­load achieved was 12 METs with a maximum RPPof 331 x 102 and the presence of no ST changesor arrhythmias. The SWA, however, resulted inruns of ventricular bigeminy at RPP of 204 x 102

after 80 seconds of lifting a 100lb weight. TheSLGXT would have cleared the patient to returnto work, but the SWA indicated the patient wasnot safe to return to his previous position. Afterrepeated testing, in fact, the patient was advised tolimit his lifting to 20lb.

Kavanagh and Matosevic (1988)described at theWorkshop on Occupational Cardiology (1988) themultifaceted approach to work assessment of thecardiac patient utilised at the Toronto Rehabili­tation Centre. An individualised assessment is pro­vided which includes all or part of the followingsteps: obtain a job description, determine any ap­plicable trade or legal restrictions, investigate psy­chological status, perform a graded exercise test, atelemetered job simulation in the RehabilitationCentre, and an on-site assessment.

Job simulation in the facility consists of the per­formance of tasks similar to those patients en­counter in their occupations under the auspices oftherapists in either the Occupational Therapy orPre-Vocational Departments. Patients performtasks such as carpentry or house painting whilebeing continuously monitored for ECG, bloodpressure and signs and symptoms abnormalities.Patients may also be assigned to work in Centredepartments, for example, cafeteria, boiler room,external grounds, which are similar to their ownemployment setting. Monitoring proceeds the sameas if the patients simulated the activity in thetherapy areas. At times, the assessment may extendbeyond 1 day. In that case, monitoring may be acombination of Holter and work station monitor­ing. For moderate to high risk patients, work as­sessments by this facility's system are possible inan environment conducive to maximising patient

371

safety by the ready availability of trained personneland emergency equipment.

Wermuth et al. (1990) conducted a study to de­termine if dynamic arm exercise tests or leg exer­cise tests were more accurate predictors of thehaemodynamic response to simulated work activ­ity for 9 patients who had sustained MI. The sim­ulated tests consisted of weight-carrying, repetitiveweight-liftingand overhead isodynamic work. Armexercise testing proved to be a more accurate pre­dictor of a patient's cardiovascular response tosimulated work tasks. As a result of the outcomeof this pilot study, the authors recommend com­pletion of both leg and arm ergometry tests.

4.2 Ergonomic Equipment

Sophisticated, computerised equipment has be­come the keystone for systems of functional ca­pacity testing advocated by various companies.Several physical tasks can often be simulated on asingle piece of equipment. The tests can be stan­dardised and provide objective information as tothe work capacity of a patient. Functional capacitytesting has been widely employed in the assess­ment of injured workers, especially those with or­thopaedic diagnoses. These same methods can alsobe applied to the cardiac patient given the inclu­sion of appropriate monitoring techniques into theassessment process. Continuous ECG monitoringand signs and symptoms monitoring as well as pe­riodic heart rate and blood pressure measurementsprovide the tester with the necessary cardiac in­formation on which to base return to work rec­ommendations.

5. Cardiac Rehabilitation

Patients who do not achieve an exercise test orsimulated work activity workload capacity com­parable to their real occupational requirements mayoften benefit from participation in an outpatientcardiac rehabilitation programme. Aerobic condi­tioning and strength training in a supervised set­ting frequently improves a patient's physical ca­pacity to return to manual labour. In addition, the

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patient receives information on proper body me­chanics, proper breathing techniques and self-pac­ing to improve the efficiency ofcardiovascular per­formance (Fletcher et al. 1990; Greenland & Chu1988; Nakai et al. 1987; Parmley 1986).

5.1 Circuit Weight-Training

Stewart et al. (1988) define circuit weight-train­ing as 'the performance of a series of weight-liftingexercises designed to improve muscular strengthand cardiovascular endurance. Strength improve­ment results from progressive resistance training.Cardiovascular endurance improves through thecontinuous activity of performing the resistive ex­ercise and moving quickly from one exercise to an­other.' Some programmes have a dynamic com­ponent consisting of leg ergometry utilisingtreadmill and cycle work in conjunction with astatic component of resistance exercises (Kelemenet al. 1986). An effective exercise prescription canbe based upon the outcome of the simulated workactivity test with the goal of achieving the neces­sary workload to safely return to work or to desiredleisure-time activities.

Until recently, weight-lifting was considered un­safe for cardiac patients due to the risk of imposinga sudden increase in myocardial workload whichbeing uncompensated would result in myocardialischaemia (McCool & Nelson 1985). In selectedgroups of cardiac patients, circuit training has beenproven safe. Haslam et al. (1988) assessed theelectrocardiographic and blood pressure responsesto upper and lower extremity static exercise. Bloodpressure was measured by invasive monitoring ofthe brachial artery to insure accuracy. They con­cluded in the group of patients studied that weight­lifting exercises resulted in clinically acceptableblood pressure and electrocardiographic responses.Another recent study compared and contrasted thecardiovascular response to aerobic versus circuittraining programmes in 13 men with known cor­onary artery disease. In addition to the traditionalmonitoring procedures of ECG, HR, BP and signsand symptoms, 2-dimensional echocardiographywas used to detect exercise-induced ischaemic left

Sports Medicine 13 (6) 1992

ventricular wall motion abnormalities. Thehaemodynamic response to resistance exercise wasappropriate including consistently adequate leftventricular perfusion.

Other studies attest to not only the safety of cir­cuit training but also the benefit of increasing aero­bic endurance, musculoskeletal strength, bodycomposition and self-efficacy in performing armtasks (Kelemen et al. 1986; Gettman & Pollock1981; Stewart et al. 1988). In a study of 25 patientswith coronary artery disease participating in a 3­year programme of circuit training, those patientsenrolled in the weight-training group had a 16%gain in self-efficacy. This is in contrast to the con­trol group enrolled in dynamic exercise only whichexperienced an II % decline in self-efficacy (Stew­art et al. 1988). Given that patients' perception oftheir health status is very influential in returningthem to work, a gain in self-confidence regardingarm tasks should have a positive influence on re­turn-to-work rates.

Entry criteria for circuit weight-training pro­grammes have not been uniformly established.Conservative recommendations by the AmericanAssociation of Cardiovascular and Pulmonary Re­habilitation, an organisation representing cardio­pulmonary rehabilitation professionals, call for theinclusion oflow-risk cardiac patients and high-riskadults (AACVPR 1991). The American College ofSports Medicine (ACSM 1991) states in selectpatients low level resistance exercise may be startedas early as 7 to 8 weeks so long as an SLGXT hasalready been performed. In addition, the ratio ofwork to rest period and the appropriate determ­ination of exercise weights is also based on empir­ical knowledge. One study recommends usingstandard levels of exercise resistance (40 to 60% ofthe l-repetition maximum) with 60-second restcycles between stations to allow for more completerecovery of HR and BP (Butler et al. 1987). An­other study utilised 30-second rest periods betweenstations (Kelemen et al. 1986). Definitive recom­mendations regarding programme parameters arenot yet available. Suggestions for implementing re­sistance training are outlined in manuals publishedby the ACSM (1991) and the AACVPR (1991).

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Return-to-Work Evaluation after Coronary Events

6. Recommendations

It is well established that all cardiac patients ableto achieve 2.0 METs during cardiac rehabilitationshould undergo graded exercise testing. Importantinformation regarding prognosis, functional capac­ity, arrhythmia detection and efficacy of therapyare obtained. Information gleaned during the gradedexercise test also guides recommendations for re­turn to work or leisure-time activities. In low riskpatients returning to a sedentary job or lifestyle,the graded exercise test may be all that is necessaryto make appropriate recommendations. In manyother circumstances, for example, for low riskpatients returning to heavy work or for moderateto high risk patients, the graded exercise test maybe only the first of many tests necessary to makeaccurate recommendations when the ability to per­form static or isodynamic work is in question.

Simulated work activity testing provides a safe,efficient, and practical approach to making objec­tive recommendations for a patient's return to spe­cific vocational or avocational pursuits. We havereported a clinical model for safe application byexercise test facilities incorporating a weight-car­rying and a weight-lifting protocol with conserva­tive end-points (Rod et al. 1989). The controlledstudy of simulated work activity testing is in itsincipience. Further investigation is needed in sev­eral areas related to simulated work activity: pro­spective monitoring of SWA testing's impact onreturn-to-work rates, impact on psychosocial char­acteristics, validity testing by comparing a patient'sperformance in the workplace to that noted duringSWA, inclusion of other parameters such as en­vironmental stressors or body position into the testmodel, refinement of indications and criteria forparticipation in SWA testing, determination of ap­propriate systolic and diastolic blood pressure end­points generalisable to an 8-hour work schedule,the reliability of RPE as a self-assessment tool dur­ing heavy physical work, and the necessary fre­quency of repeat SWA testing.

In cases which are difficult to simulate in thelab or for which a high degree of accuracy is es­sential, other test options may need to be incor-

373

porated. The use of computerised, ergonomicequipment and on-site testing have been describedabove.

When test results suggest a patient is not safeor capable of resuming her or his premorbid workstatus, a trial of cardiac rehabilitation may oftenrestore cardiovascular function as necessary. Theinclusion of circuit weight-training into a cardiacrehabilitation programme is also relatively new. TheSWA test may be utilised to set exercise trainingintensity when static work is to be performed. Pre­liminary studies have demonstrated the safety andeffectiveness of circuit-weight training for cardiacpatients.

7. Conclusions

Until recently, the outcome of medical man­agement of patients sustaining cardiac events wasmeasured primarily in terms of mortality statistics.In the past decade, increased attention has beenfocused on the quality of life and socioeconomicfactors for the postcoronary event patient. Progresshas been made in reducing the unnecessary num­ber of cardiac patients electing to be supported bylong term disability and in reducing delays in re­turn-to-work. A meaningful strategy for return-to­work evaluations has evolved. The following seriesof steps has demonstrated success in achieving im­provement in return-to-work statistics: job analy­sis, graded exercise test, psychological screen withappropriate referral when indicated, simulated workactivity test, physician advice, referral to cardiacrehabilitation if necessary, reinforcement by fol­low-up clinic visits, repeat testing for changes insymptoms and/or work status, and monitoring viaannual graded exercise test and simulated work ac­tivity. It is incumbent upon physicians specialisingin the care of the cardiac patients to apply this newbody of knowledge in their clinical practice. Greatbenefit will be realised by cardiac patients, theirfamilies and society.

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The Process of Training and Competitionin View of the Performances at the

1992 Barcelona Games

Date: 4-6Venue:

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For further information. please contact:

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