Acute fatigue and burnout

Tilburg University

Acute fatigue and burnout

Veldhuizen, I.J.T.

Publication date:

2003

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Citation for published version (APA):

Veldhuizen, I. J. T. (2003). Acute fatigue and burnout. [s.n.].

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•A•

UNIVERSITEIT * 0 VAN TILBURG_*

BIBLIOTHEEK TILBURG

Copromotor: Dr. J.deVries

© I.J.T. Veldhuizen, 2003

Cover_{photographs byIngrid Veldhuizen} Sculptures fromthe Sagrada_{Familia, Barcelona}

Graphicdesign&cover:Universal Press

Allrights reserved. No part of this thesis maybe reproducedor transmitted in any form or

by any means, electronic or mechanical, including photocopying, _{recording or any}

informationstorageorretrieval system, withoutpermission inwriting fromtheauthor.

Printed_byUniversal_Press, Veenendaal

ISBN9090175083

Thestudies presented in this thesis were conducted as part ofthe Netherlands concerted

research action on _{'Fatigue atWork' granted by}the_{Netherlands Organization}forScientific

Research _(NWO) (Grant no. _{580-02.105), and by WORC,} research institute _{of Tilburg}

Acute

_Fatigue

and

Burnout

PROEFSCHRIFT

ter verkrijging vande graad vandoctor aande UniversiteitvanTilburg,

op gezag van derectormagnificus, prof. dr. F. A. van derDuynSchouten,

in het openbaarteverdedigentenoverstaan van een doorhet_{college voor}

promotiesaangewezencommissie in de aula vandeUniversiteitopmaandag

24 november 2003 om 14.15 uur

door

Ingrid

Johanna Trees Veldhuizen

Doing research hassince long appealed to me. It is wonderful to have many years

of research time at one's disposal while

writing

adissertation.

Several peoplehavecontributed to the realisation ofthis thesis and showed interest

intheprocess

of

writing it.

First I would like

to thank my promotor, Anthony Gaillard, and copromotor,

Jolanda de

Vries. Tony, I am

much indebted to your genuine interest and your

encouraging way

of

advising me in the past years. Your equability proved to be a

comforting

characteristic. I have very

much enjoyed discussing the research

findings with you.

Our discussions have certainly sharpened my ideas. I want to thank you for yoursupportand interest, andthecappuccino's and appleturnovers.

I

have appreciated your help in

swiftly

reviewing my

writings in the last few

months. _{Jolanda, I would like} to _{thank you for your help in understanding and}

discussing the research findings, especially when they concerned the

realm of

personality. I value the way youare always prepared to make time, and I appreciate

the times you reminded me

of

agreed deadlines. You are easy to talk to. It is true

that you display a high speedin reading andcorrectingtexts.

Many personshaveparticipated in my experiments over the lastyears. I would like

to thank the students and employees who have taken the time to endure almost

twelve hours

of

continuous testing. In preparing the physiological

results for

analysing, the help of Ton Aalbers in

writing

software proved to be

of

essential importance.

Many colleagues have witnessed some part of my research

efforts. I would like to

thank my colleagues fromcorridor five and six for the many laid-backlunches we

shared.

Jeroen I want

to

thank for both

his humour and

lending his ear for

discussions about my physiological results. The telephone calls and emails from

Antje formed always a pleasant break. Saskia, it is a pleasure to share chocolate

and _{my morning cup}

of

coffee with youand Dianne.

I am grateful to all

my colleagues of the department Psychology and

Health. I

would also like

to thank Ton Heinen from WORC, research Institute

of Tilburg

University.

Marieke, Maike, Elles, Hanneke, Manonen Dianne, I would like to thank

for

their

her own way to my peace of mind and well-being. I deeply value our friendship

andthehumour weshare.

My parents havealways supported mewith theirwarm interest in my well-being. I

find

it

heart warming to feel

their love. I

enjoy being in their company, sharing

food, wineandstories. I would liketothank themfor their affection andhospitality for me, Henk and our son Thomas. It is wonderful to see them and Thomas have

fun. I would also like

to thank my brother Robert and his wife Sandra for the

enjoyablemeals andconversations weshared.

Finally, my words of love go to my own family, Henk and Thomas. Henk, your

love has _{always provided me with} a source

of

peace and quietness. I consider

myself rich

for

feeling your love. I

truly

value the warm home we have created.

Thomas, seeing your broad smile and hearing your laugh is a _{greatjoy. Coming}

home to your cheerfulness is a wonderful experience. I look forward to times to

come, together with ournewlyexpected child.

Nijmegen,October 2003

Chapter

1 Introduction 1

Chapter

2 General methodology 17

Chapter

3 The influence

of

_{mental fatigue}on _{facial EMG activity 29}

duringasimulated workday

Chapter4 The effects

of

_{enduringfatigue}and_personality on acute 53

fatigue

Chapter

5 The influence

of

_{enduringfatigue}and _personalityon heart 73 rate and heart rate _variability

Chapter

6 Prediction

of

_{enduringfatigue usingphysiological,} 105

performance-based,andsubjectivemeasures

Chapter

7 Fatigue effectson facialEMG activity,heart rate, and 125

heartrate_{variability in employees}

Chapter

8 The effects

of

_{enduringfatigue}and_personalityon acute 147

fatigue inemployees

Chapter

9 Prediction

of

_{enduring fatigue in employees using} 163 physiological, performance-basedand _subjective measures

Chapter

10 Comparison oftheresults

for

students andemployees 177

Chapter

11 Conclusions 197

Samenvatting (DutchSummary) 205

1

1 Introduction

In _daily usage, fatigue refers tovarious experiences due to quite different causes,

varying from physical _{exertion, lack}

of

sleep, and illness, to burnout. The term fatigue is also used to refer to the feelings we have as a result

of

long-term

performance. Subjective feelings

of

fatigue can thushavedifferentorigins. Already

in the _{early twenties,} Muscio suggested in his paper 'Is a fatigue test possible'

(Muscio, 1921, in _{Bartlett 1953),} to abandon the use of the term fatigue. In his view, it wasnot possibletodevelopan acceptable testforfatigue. Such a testcould

only be acceptable

if

there was a _{general, acceptable and agreed}

definition of

fatigue. At that time, the _{description of fatigue that} was _{widely used was the}

following (Meijman, 1995): 'The condition caused by activity in which the capacity

for repeating the activity that caused it is_{diminished' (Health of Munition Workers}

Committee, 1916).

According to

this definition

there are

no observable

performance criteria for fatigue, other than those indicated and measured by the

test itself, against which the adequacy of the test is validated. To measure the

above stated _{condition, performance}criteria _{are needed,} whichare _{independent of} the diminished _{capacity. However, the} onlypossible criteria that can be used are

directly related to the _{performance decline}

itself. And it is

this decline that is

explained in terms

of

changes within that capacity. In order to escape from this

viciouscycle, Muscioproposedto banish the term fatigue. More than seventyyears

later, prevailing literature and research _historyhas shown that the term _{fatigue is}

still

_{widely used andeven gains}in interest. It is now generallyacceptedthat fatigue cannot be seen as a_{univocal concept with}a _{single test}tomeasure it.

Several research lines have contributed tothe_{development of}the concept.

The research on fatigue has its starting point somewhere in the mid-nineteenth

century. Research started in the laboratory and was mainly focused on muscular

fatigue (Browne, 1953). From research _{focussing on} the

_{contractibility of the}

striated muscles of a frog leg (Kronecker, 1871) tothe

_{falling off in}

the_{ability of a}

human muscle to contract

fully

when repeatedlystimulated (Mosso, 1894). At the

end of

the _{nineteenth century, fatigue was seen as} the decline

of

_performance

duringlong-term performance. This view has hada_largeimpactbecause

it

_implied

that fatigue was 'something' concrete and could be _{measured (for} an extensive

reviewsee _{Meijman, 1991; Meijman, 1995).}

In between world wars, anew conception on _fatiguearose from the work

of Bills (1931, as _{cited by Holding, 1983). He noted that short periods}with extra

long response times emerged frequently during a colour-naming task. These

periods were called 'mental blocks' (lapses in attention). When the number and

length ofthe mental blocks increased, subjects made more errors.

Bills'

research

gave a new impetus to the study

of

fatigue. It was realised that the main interest

4 Acutefatigueandburnout

thatresearchshouldbeaimed at thecentralinformationprocessing level(Meijman,

1991).

Around world war _two, Bartlett _{(1943) further elaborated this viewpoint.}

By that time it was

well known that simple tasks with repetitive stimulation,

showed a _{straightforward decline in performance. However, there} was

little

information about how complex tasks and skills were effected by enduring

performance. In the _{famous 'Cambridge Cockpit} Studies' airmen were observed

while _{performing long-lasting}

tasks in

a

_flight

simulator.

_{Bartlett (1943)}

summarizedthe results and emphasized the way in whichthe central organization

of

skills broke _{down under fatigue. Fatigue} showed

itself

at first as a

shift in

criteria

of

_{performance (i.e., accepting more errors} and

_{slowing down in}

performance). Then, lapses in attention occurredandattention began tobereserved

for items

of

_{central importance. The} skilled_{responses became}more variable as was

evident inthe timing

of

actions. Manycorrect actions were executed at thewrong

times. As Holding (Holding, 1983, p. 153) formulates it: "The skill seemed to loose cohesion, the overall pattern of action disintegrated into separate components, the

instruments were apparently perceived one by one, and the appropriate control

responses were no longer smoothly sequenced". On the basis of these results,

Bartlett _{proposed in 1953 three psychological} criteria

of

_{fatigue: (1) irregular}

internal timing, ₍₂₎ splitting up or disintegration ofthe field

of

display, and (3)

acute stage

of

minor discomfort. These are: "the three leading psychological criteria of deterioration in an activity set up by the exercise of that activity under its normal conditions" (Bartlett, 1953, p.5). Bartlett draws attention to timing and

organisation aspects ofperformance and accordingly to the central _{regulation of}

performance and not only to its quantative decline(Meijman, 1995).

In the last two decades the research on fatigue has been intensified. This

might well be due tochanges in work and work environment. We are

living in a

society with astrongemphasis on informationtechnology, modern communication

techniques and aboveall increased efficiency. Thishas renewed_{the psychological}

interest and research on fatigue. At the same time it has been shown in different

disciplines that fatigueplays a veryimportant role in allkinds

of

chronic diseases.

In mental disorders likeburnoutanddepression as well as in,forinstance,diseases

like multiple sclerosis, rheumatism and cancer. Recently, there has been arevival

in the literature abouta syndromewhich is characterised bya principal complaint

of chronicand _{disabling fatigue} for which no _{medical explanation has}been found

yet: the Chronic Fatigue Syndrome (CFS) also known under the name

of

Myalgic

Encephalomyelitis (ME) (Clements, Sharpe, Simkin,

Borrill

&

Hawton, 1997;

Joyce

&

Wessely, 1996).

The presentstudy concentrates on a form

of

enduring fatigue that has to be

distinguished from CFS. Thefocus

ofthe

presentstudy is on work-relatedenduring

fatigue, inparticularon Emotional Exhaustion, which is one ofthe components of

the burnout syndrome. Burnout can be distinguished from other psychological

disorders. Employees with a high risk forburnouthave_{problemsmaintaining their}

work performance. They experience many psychosomatic complaints, are often

absent at work, and have a high risk forworkincapacity.

Fatigue is a _{major complaint in} the _{general population as well as in}

primary care. It can have a _far-reaching influence on a _person's life. Prevalence

ratings offatigue inthe communityrange fromapproximately 20% among men to

30% _among women and are similar in most countries (Cox et al., 1987; Wessely,

Hotopf,

&

Sharpe, 1998). It is one of the most frequently reported complaints

among work-related problems leading to absence of work and work incapacity

(Foets

&

Sixma, 1991; Schaufeli

&

Houtman, 2000; Wessely, 2001). Thus, fatigue

can have_{high societal as well} as_personalcosts.

1.1 Mental versus_{physical fatigue}

In every day life, people often talk about mental and physical fatigue as _being conceived of as two totally different and unrelated phenomena. After cognitive

processing people experience a different kind

of

tiredness than after physical

activities. After a long workday atthe office, people generally say they 'feel tired'.

Theywould probably protest if theywere obliged to goon working inthe evening hours _(left aside _secondary interests like _{pleasing their boss, or being extremely}

motivated to finish their _work). But these same people are still perfectly able to

exercise sports after their

tiring

workday. They will also be capable

of

reading a

book ora_{newspaper. On}theotherhand,professional sportsmen will feeltiredafter

a long day exercising and training but they too will be able to execute related or

differentactivities at the end of the day.

Mental fatigue is considered as a

_{response of mind and body to the}

reduction in resources due to mental task execution (Gaillard, 2001). It can be a

response to both too high and too low levels

of

workload. Mental fatigue is

task-specific, whichmeans that switching from mental activitieshas beneficial effects

on the feeling

of

fatigue. It is believed to be a gradual and cumulative process,

inferred from decrements in _{performance from} task _{requiring alertness and}

memory retrieval (Gawron, French,

&

Funke, 2001; Holding, 1983). Mental

fatigue can be seen as a diffuse sensation

of

weariness, a disinclination towards

physical or mental effort(Grandjean, 1979). Physical fatigue can becharacterised

as a direct response to physical effort or exertion. Physical exhaustion is often

accompanied by muscular fatigue, resulting in reduced power and slower

movements. Muscular _{fatigue is} an _{acutely painful phenomenon,}

_{arising from}

depletion inthe overstressed muscles(Grandjean, 1979). It isrelatedtochanges in

peripheral physiological processes as a result

of

physical effort (Meijman, 1991).

Physical fatigue is considered to be task a-specific. When people feel tired after

cycling, they will not be up

to rowing exercises either. The

magnitude of

6 _{Acute fatigue and}burnout

This relationship is notclear in mental fatiguewhere itis

difficult

_{to predict}which

people

will

sustain certainmentalactivities.

1.2 Fatigue as abiobehaviouralstate

Feelingtired is not only determined bythe _{present, but alsoby}future activities. It

is also influenced by task demands that still have to be _{performed. "When people} declare that they are tired, it seems implausible that they are only indicating a

feeling of a'version or conflict. The statement seems to imply a prediction,

suggesting that continuous performance will suffer, that carelessness or skimping

on the job will follow unless an extra effort is made, and so on" (Bolding, 1983,

p. 147).

Hemingway (1953) sawthe _{state of the body as}acondition

of

_equilibrium,

the outcome of different forces having an impact on the body.

_{This dynamic}

equilibrium implies a balance

of

forces. According to Hemingway (1953, p.69):

'The signs and symptoms of fatigue may show themselves either as a failure to

maintain an equilibrium position or by an obvious exaggeration of one or more oj

the forces which are employed in giving the equilibrium position'. Wi hin the

human body all kinds

of

_{different physiological systems}

_{(governed by the}

autonomous nervous system) areconstantly active inorder to keepthe organism in

an _{optimal energetical} state. Each _system(e.g. blood_pressure)triesto maintain its

own balance, a _{dynamic equilibrium,} also called homeostasis _{(Gaillard, 2003).}

Normally, one is unaware ofthe _{physiological activity}in_{these systems. However,}

under the influence of for example mental effort or strong emotions, you might

suddenly noticethe pounding of yourheart and your rapid andshallowbreathing.

Different factors can influence this

equilibrium, i.e.

the momentary

psychophysiological state: _{(1) circadian rhythms, (2)} activities related to the task

and thetask_{situation, (3) environmental factors (internal,}

for

_{example lack}

of

_sleep

and _{physical condition,} and _{external, such} as noise and temperature), ₍₄₎ mental

effort (which is

itself

_{largely dependent upon motivation), and (5) emotions.}

The circadian rhythm stands for the occurrence of a body process that

repeats ona _cycle

of

_{approximately}24 _{hours (Kalat, 1998). It appears that}atleast

two different mechanisms underlie human circadian rhythms. One mechanism

seems to control activity levels and the other regulates body temperature. In

studying fatigue and consequently the biobehavioural state of the organism, one

should especially be aware

of

these _{circadian rhythms.} The _{naturally occurring}

changes inalertness andactivitylevels and_{in feelings}

of

tiredness and_accordingly

in physiological measures should not be _interpreted as _{consequences of task}

performance. It should be kept in mind thatthe _{constantlyfluctuating} state of the

organism is in firstinstance due to biologicallyembeddedprocesses. Lack

of

sleep

The biobehavioural state is also influenced by the type, duration and intensity ofthe activities he or she is _{executing. Tasks and task situations can be}

stimulating, in thattheyintrinsicallymotivate aperson.The sensitivityto fatigue is

also dependent upon individual characteristics. Some people,

for

example

introverts, appear to be less sensitive to monotonous work. Other people profit

from stimulation such as music, orthe presence fromother co-workers. Different

tasks require differentcognitiveandphysiological processes, andthereforechange the state

ofthe

organism. Muscle movements, forinstance, activate the body,while

passive and monotonous workcan lower its energetical statetherebyinfluencing a

person's attention.

Emotions' can have _strong effects on _{task performance. Processing of} information takes place on a cognitive as well as on an affective level. Although

one is often unaware of his orhers actual _{affective processing, its outcome can be}

striking. Strong emotions have 'control precedence,2 (Frijda, 1988). As such, they

demanddirect attention and can interferewith_{ongoing (processing)}activities. Due

totheir influence(e.g. over-reactivity),apersonsenergeticalstatemaybecome less

suitable fortask_performance(Gaillard

&

Wientjes, 1994). To summarize,different

factors can affect the current biobehavioural state ofa person. Acute fatigue, as

opposed to enduringfatigue, can be regarded asa_{normal, healthy phenomenon, a}

biobehavioural state, which is task specific and reversible. After a good rest or a

night sleep, feelings of fatigue will disappear. When however a _{"sensation of}

fatigue occurs before adequate or even any work is accomplished- or will not disappear with rest-" (Schwab, 1953, p. 143) a person finds himself to be in an

long-lasting state

of

_{fatigue. In contrast} with acute _{fatigue, enduring fatigue is}

regarded as a state that is not easy to reverse. It is task

a-specific and will not

vanish by rest orsleep.

1.3 Acuteversus_{enduring fatigue: recovery}and accumulation

Acute and _{enduring fatigue can} be conceived of as two different biobehavioural

states _{(Gaillard, 2001).} Different (task) situations demand different patterns of

mental and physiological processes. Body and mind need to be

_{'readf, i.e. the}

psychophysiological state of the person must be _{optimal in order to perform a}

certain task well.

Little

is known about the transition process from acute to

enduring fatigue. Duringa_{workday, all kind}

of

_{physiological mechanisms respond}

Emotions aredefined as either (1) non-instrumental behaviours and behaviour characteristics, (2)

physiological changes, or(3)subjective, evaluative experiences,causedby external or internal (mental) events and

their significance (Frijda, 1988).

Controlprecedence is seen as themostcharacteristic featureofemotions.Thismeansthatemotions

tendtoinciteachange in control and effect.Inother words, they demandachange inbehaviour. It is in the nature

8 _{Acute fatigue and}burnout

to the work or workenvironmentresulting in elevated activation levels. Normally

at the end of

the workday, de-activation processes are responsible for restoring

baseline levels. These _{physiological control systems} centre on a _dynamic

equilibrium(homeostasis) aiming at an optimal energetical state ofthe organism,

and aquick return tobaselineafterwork. Recovery at the end ofaworkdaythereby

means _reducing the amount

of

activation build _{up during the day.}

If

_{recovery is}

incomplete, de-activation

of

physiological reactivity is inadequate, which could

result in a residue

of

activation. Gaillard (2003) defined residue as the extent to

which theeffects

of

workload of one dayare

still

present the next morning. When

recovery is also insufficient during the next days, these residues can accumulate

causing an imbalance in the activation and _{de-activation processes. Thus}

insufficient recovery from work canresult into enhanced _{physiological activation}

levels and emotionalarousal _during work and into sustained_{activation after work}

for _{longer periods (Frankenhaeuser}

&

Johansson, 1986;

Ursin & 01ff, 1993;

Vrijkotte, Van

Doornen, & De Geus, 2000).

This means that _{physiological}

reactivitycan_{spill overto other workdays and tonon-workingsituations. This may}

be thecritical_{mechanism underlying}thetransitionfromacute_{to enduring fatigue.}

The question still remains why incomplete recoveryoccurs. Two possible

explanations can be found in

_{either (1)}

the _theory

of

'sustained' activation

(Frankenhaeuser

&

Johansson, 1986; Ursin & 01ff, 1993) or (2) a disorder in the

physiological control systems.

With

regard to 'sustained activation', research has

shown that enduring (repetitive) exposure to

mild

stressors as well as a one time

exposure to a very intensivestressor, can bringthe nervous andendocrine system

into a state

of

continuous activation

_{(Schnall et al.,}

1990; Schnall, Schwartz,

Landsbergis, Warren,

&

Pickering, 1998; Van Egeren, 1992;Vrijkotte et al., 2000).

Due to unsuccessful coping, a person does not sufficiently

recover from mild

stressors or mental effort _during a _workday. This state

of

continuous activation

persists because the _{physiological mechanisms responsible} for de-activation are

immobilised byhigher controlsystems.According tothesecondexplanation,these

higher control systems are under the influence ofpsychological factors such as

effort and strong emotions. This may lead to deregulation of the physiological

control systems, causing, in the long_run, enhanced baseline levels. As a result of

these changed set points, apermanent increase in for instanceblood pressure can

occur (Singer

&

_{Davidson, 1986).}

To summarise, when peoplemobiliseextra energy (through mentaleffort)

tokeeptheir performance at therequired level, this can lead to disturbances in the

physiological controlsystemswhentheircopingisunsuccessful andtheirrecovery

insufficient. These disturbances can_{accumulate gradually, carrying over from one}

day to the next. The _{outcome being} a state ofsustained activation _{or permanent}

enhanced baselines. This

_{disruption of}

the _{energetic homeostasis may lead to}

2 How tomeasurefatigue?

Researchon _{fatigue has been}done_{mainly with}the

_following

_{three approaches: (1)}

research on the relationship between work characteristics and _{enduring fatigue}

(more specifically, burnout), (2) studies on acute _{fatigue induced} by long-term

performance, investigating how acute fatigue builds up during extended work

periods, and (3) surveyresearchinvestigatingthe _{relationship between personality}

and_enduring, mostlywork-related, fatigue.

Due tothe _{multidimensionality of}the _concept

of

_{fatigue, fatigue has been}

measured_usingseveral dependentvariables:

1. neuroendocrine responses such as excretion of catecholamines and cortisol _{(e.g., Frankenhaeuser, 1980;} Frankenhaeuser

&

Johansson,

1986; Rissler, 1977,1993; Sluiter, Frings-Dresen,Meijman, & Van der

Beek, 2000; Sluiter, Frings-Dresen, Van der Beek,

Meijman, &

Heisterkamp, 2000; Sluiter, Van der Beek,

&

Frings-Dresen, 1998)

2. _{psychophysiological} measures such as heart rate and heart rate

variability

(e.g.,Brookhuis &De Waard, 2001; Hancock

&

Desmond,

2001;Hancock, Meshkati,

&

Robertson, 1985;Meijman, 1997;Mulder

& Mulder, 1981;Veltman

&

Gaillard, 1993;

Vrijkotte,

2001;

Vrijkotte

et al., 2000)

3. performance-basedmeasures such as reaction times and number of

errors or correct_{responses (e.g.,} Akerstedt, Patkal,

&

Dahlgren, 1977;

Baas, Charlton,

&

Bastin, 2000;

Bills,

1935; Brown, 1994; Patkai,

Akerstedt,

&

Pettersson, 1977; Siddall

&

Anderson, 1955; Soetens,

Deboeck,

&

Hueting, 1984)

4. _{subjective ratings (Baranski,Pigeau,}

&

_{Angus, 1994; Van Veldhoven}

& Meijman, 1994; Vercoulen, Alberts,

&

Bleijenberg, 1999; Zijlstra,

1994).

These

studies have led to

a

growing body

of

knowledge on the

multifaceted concept

of

fatigue. However,there arefewstudies thathavecombined

the abovementioned methods.

Physiological and neuroendocrine measures can _{provide important}

additional information about the biobehavioural state ofa _{person. It is even less}

common to include personality as (mediating) factor. Personality characteristics

determine to a large extent a persons view on (work) situations and the way they

are_managed. Consequently, differentpeople

will

react

with

different physiological

reactivitypatterns andbehaviour- and coping styles on the same combination of work parameters (such as high task load and low decision

latitude). What is

stressful for one person might be a _{challenge for} the other. In the _{present study}

physiological, subjective and performance-based measures are used to map out

10 _{Acute fatigue andburnout}

3 Design ofthestudyand research questions

This dissertationsearches to_{explorethe concept}

of

_{fatigue using}acombination of

approaches and measurementmethods. Fatigueisconceived of asabiobehavioural

stateevoked_{bymental task performance. As outlinedabove, enduring fatigue may} be caused_{by accumulation}

of

_{continuing spillover}effects

of

acute_{fatigue, brought}

about bythe mobilisation

of

energy through mental effort or emotions induced by

work demands. One of the aims ofthis thesis istoinvestigate therelationbetween

acute and _{enduring fatigue. Enduring fatigue} is _{measured by} a _{person's score on}

the Emotional Exhaustion scale ofthe Utrecht Burnout Scale _{(Schaufeli & Van}

Dierendonck, 2000). The

_{building up of}

acute _fatigue is _{manipulated by}

participation

of

persons in a _{simulated workday (long-term performance, LTP).}

Several times during the workday, participants had to execute astandard memory

test (Sternberg _task, Sternberg, 1966; 1969) in order to assess their current

biobehaviouralstatebyusingtheir_{performance (reaction times, number}

_of

correct

responses) and physiological measures: facial_{EMG activity, heart rate,} andheart

rate variability. At

four different times during the day, subjective

feelings of

fatigue were assessed

_{using a set of}

state _{fatigue questionnaires.} Before the

experiment_started,allparticipantsfilled outanextensivepersonality andaburnout

questionnaire, in orderto_investigatetheeffects

of

_personalityand_{enduring fatigue}

Enduring characteristics: Dependentvariables: Performance Simulated Enduringfatigue , workday

*

(LTP) Subjective I fatigue 7 - 4day tests - evening test Personality Physiological activation

Figure1._{General design}ofthe_study.

Fatigue was manipulated in three ways: (1) The building up

of

fatigue

during the simulated workday,

tested by the

four tests

during the day; (2)

Evaluation ofthe effects

of

fatigue

still

present in the evening afterthe simulated

workday. This was done bythe _{execution of a long} taskversion ofthe _Sternberg

test inthe _{evening; (3) Comparing two groups}

of

subjects with a high orlowscore

on theEmotionalExhaustionscale ofthe UBOS.

The presentdissertation aims to answerthe

following

questions:

- Are

the _{physiological} measures _{(facial EMG, heart rate} and heart rate variability), the _{performance-based measures and} the _subjective

_{ratings of}

fatigue, sensitive tothe building up

of

fatigueduringlong-term performance?

- Is

the biobehavioural

state of

a person in the evening influenced by the building up o

f

fatigue at the end oftheworkday?

- Are

the reactivity patterns (physiological, performance-based, and subjective

ratings) during the workday and _{evening influenced} by personality and

enduringfatigue (seeFigure 1)?Inotherwords: Can acutefatiguebe _predicted

12 _{Acute fatigue and}burnout

- Is it possibletodiscriminate between people withandwithout_{enduring fatigue}

complaints onthebasis ofthe reactivitypatterns (physiological,

performance-based, andsubjective) during the workday?

Theseresearchquestions willbe examined in two population samples:students and employees. Within each _sample, two _groups

of

_subjects are _{distinguished:} subjects scoring high and low on enduring

fatigue. It is of

further interest to

investigate whethertheresults found inbothsamples arecomparable toeach other.

4 Outline of

the thesis

Chapter 2 _gives a

_{description of}

the research _{design and the general}

methodology. Chapter 3 describes research ontonic _{EMG activity as} an index of

mental effort and fatigue. It is investigated in the studentpopulation whether the

activity of

two facial muscles is sensitive to the effects

of

fatigue

during a

simulated workday. This chapter further examines whether

_{activity at the end of}

theday influencesactivity in theevening.

In Chapter 4 the effects

of

_{enduring fatigue} and _personality on acute

fatigueduring the dayare _{investigated among students. Aim of thischapter was to}

explore whether both were able to predicttheincrease inacute fatigue. InChapter

5 it is statedthat heart rate and heart rate _variabilityare known indices

of

mental

effort. It is _{explored in} the student _sample whether both measures are _{affected by}

differentlevels

of

_{enduringfatigue. Based on}the results

of

_{Chapter 3,}this chapter

also _{explores whether}

_{scoring high or low on}

the _{personality dimension}

Extraversion (extravertsversus_introverts)results intodifferentheart rateandheart

rate_{variabilitypatterns.}

Chapter 6 addresses the

_{question if we can}

do better than chance in

predictingwhether students

will

_{score high or low}on_{enduring fatigue on}the basis

of a set

of

_{physiological}

_{(facial EMG, HR,}

_{HRV), performance (reaction times,}

number

of

correct_{responses), andsubjective ratings. In Chapter 7}the _{sensitivity of}

the facial EMG measures, HR and HRV, to differences in enduring fatigue is

investigated amongemployees. Possible differences with the results found among

studentsare noted.

Chapter 8 explores the predictive power

of

personality and enduring

fatigueon acute _{fatigue among employees. Chapter} 9addresses the_{discriminating}

power

of

physiological, performance-based and _subjective measures _{on scoring}

high and lowon_{enduring fatigue.}

In Chapter 10 the results found in the student sample are compared to the outcomes in the employee sample. Finally, Chapter 11 summarises the main

findings on each research _question and discusses the possible differences found,

between students and _employees. It further addresses _{methodological}

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2

1 General methodology

In the current chapter, methods are described in _general terms. A more detailed

description will

be

_{given in}

the

_following

_{chapters. Two experiments were}

executed, onewithstudents and one with white-collarworkers.

1.1 Participants

1.1.1 Students

Forty-sixundergraduate studentsparticipated in theexperiment (24 women and 22

men, mean age = 21.7 years). Onthe basis

oftheir

score on the subscale Emotional

Exhaustion (EE) of

the Utrecht _{Burnout Scale (UBOS,} see _{questionnaires),}

subjectswere distributed intwo groups: _{high-score (HS) group (10}women and 13

men, mean age = 20.2 years) versus low-score(LS) group (14 women and 9 men,

mean age = 23.1 years). The high-score group consisted

of

participants scoring

above the 75-th percentile (mean EE score = 2.63, SD = 0.51). Participants with a

score equal orbelow the 75-th percentile, the low-score group, weredesignated as

control subjects (mean EE score = 1.33, SD = 0.50). Table 1 summarises for the

HS and LS groupthescores on the UBOS.

1.1.2 Employees

Thirty

white-collarworkers participated inthe experiment (19 women and 11 men,

mean age = 45.1 years). Subjects participated voluntarily and received a small

participation fee (55 euro) and a refund

of

their travelling expenses. Half of the participating

_{workers (N =}

15) indicated to suffer from enduring fatigue.

According to their company physician, they did not suffer from other health

problems that might cause their feeling

of

fatigue. Both workers and physician

ascribed the fatigue as being related to work activities. The other workers

experienced no fatigue problems. All workers were asked to fill out the questions

onthe subscaleEmotional Exhaustion

ofthe

Dutchversion

ofthe

MaslachBurnout Inventory(seequestionnaires). Thegroup workers feelingtiredshowed a mean EE

of 4.57 (SD = 0.72), and will be _{called High-score group (HS group,} 10 women

and 5 men, mean age = 46.07years). The healthyworkergroup showed a mean EE

of 2.15 (SD = 1.06) andis _designatedasLow-score group (LS group, 9women and

6 men, mean age = 44.13 years). See Table 1 for scores on the UBOS for each

20 Acutefatigueandburnout

Table 1. Mean age and mean scores (standard deviations between parentheses) on the Utrecht

BurnoutScaleforstudents_{and employees.}

UBOS Participants N Age EE D C Students LS group 23 23.1 1.33 (0.50) 1.74_{(0.55) 3.99 (0.68)} HS group 23 20.2 2.63 _(0.51) 2.15 (0.80) 3.85 (0.70) Employees LS group 15 44.13 2.15(1.06) 1.85(1.29) 4.68 (0.86) HS group 15 46.07 4.57(0.72) 2.73 (1.28) 4.25 (0.98)

Note EE=Emotional Exhaustion; D = Distance; C=Competence

1.2 Simulated Office

The experiment was

carried out in

a simulated office with office equipment,

including a_computer. The _experiment lasted_{approximately}ten _{hours (from 09:00} am untill 19:35 pm). Several office tasks that collectively made up a fictitious

organization of a conference _{were presented to} the _{subjects in} a _{morning and}

afternoonworksession. Theworksessions lasted threehours. The mainofficetasks

were _(a) formulating a suitable lecture arrangement for the supposed conference

speakers, (b) writing down a

_{publication list of}

the conference _{contributions, (c)}

drawing up ahotel _{planning for} the listed participants, (d) making_{travellingplans}

for participants, (e) making all sorts

of

preparations forthe succeeding congress,

and (f) correcting multiplefakecontributions forthe conference book. Toincrease

the realistic

character of

the simulated workday, subjects were frequently

interrupted withsmall tasks, suchas lookingup phonenumbersandtakingnotes.

1.3 ProbeTest: Sternberg task

During and after the simulated _{workday subjects were} tested with the _Sternberg

task (1966, 1969). The current task was a self-paced Short Term Memory

searching task (DOS version). This standard task was used to estimate the

biobehavioural state ofthe subjects indifferent _{phases of}the _{workday. Due to the}

self-paced character of the task lapses in attention result directly in performance

changes. Subjects were instructedto react both as fast and asaccurate as _possible. The stimuli were presented on the computerscreen in

front of

the subjects. Each

trial

started with the presentation of the so-called memory set on the computer

screen. The _memory set contained four _randomlyselected letters ofthe _alphabet

selection fromthe entire alphabet. The memoryset remained on screen for 1500

ms followed bya fixation cross _{lasting for 500} ms. _{Immediately after}the fixation

cross extinguished, a single probe letter was presented. Subjects had to decide

whether or not

the probe

letter was part of

the memory set by pressing a corresponding key on the keyboard. The probe letter remained on screen for maximally 10 s. After _{responding, subjects received} averbatim feedback_message

on the screen ("good",

"wrong", or "too

_late"). After the feedback stimulus

disappeared, thenexttrial started. Thenumbers

of

correctresponses as wellastheir

corresponding reaction timeswere recorded.Two versions of the task were used: a

shorttest_{session and a long}testsession. The shorttest sessionconsisted of a 5-min

task period (T), preceded andfollowed by a 5-min rest

_{period (R) [R (5 min) - T}

(5 min) - R (5 min)]. The long

test session consisted of two 25-min task periods

surrounded by 5-minrest_{periods [R (5 min) - T (25 min) - R (5 min) - T (25 min)}

- R (5 min)].

1.4 Procedure

The experiment lasted approximately ten hours (see Table 1).

Before the

experiment started the task procedureand programme of the daywere explained to

the subjects. Then,subjects practisedthe Sternberg task for5 _{minutes, after}which

EMG andECG electrodes were_{applied. During the day, subjects} worked in two 3

hrworksessions (one in the_{morning and one in} the_afternoon) each_{consisting of}

different office tasks in order to simulate a workday. Before and after each work

session, subjects executed the short experimental test version (test 1 -4, see Table

2). In the _{evening, subjects executed the long experimental} test _{version (test 5-6,}

22 Acute fatigue andburnout

Table2.Schedule of the simulatedworkday

Time ofday Event

0900 - 0945 _{Training,State questionnaires}

0945 - 1000 Test' 1

1000 -1300 Work_{session, Statequestionnaires}

1300 -1315 Test' 2

1315 -1400 Rest

1400 -1415 Test* 3

1415 -1715 Work_session, State_{questionnaires}

1715 -1730 Tese 4

1730 - 1830 Rest

1830 -1935 Test 5 and 6(long_testsb), Statequestionnaires

Short test_{session [R (5 min) - T (5 min) - R (5 min)].}bLongtest_{session [R (5 min) T (25 min)} -R (5min) - T (25 min) - -R (5 min)].

1.5

Trait

questionnaires

Subjects were asked to complete the following set

of

questionnaires at home, the

day prior to the start ofthe experiment: (a) the Utrecht _{Burnout Scale (UBOS,}

Schaufeli &_{Van Dierendonck, 2000), (b)}the sub-scale Need_{for Recovery (NR) of}

the _{"Questionnaire} assessing work experience and _{work appreciation" (VBBA,}

Van Veldhoven

_{& Meijman, 1994), (c)}

the _{Five-Factor Personality Inventory}

(FFPI, Hendriks, 1997; Hendriks, Hofstee, & De Raad, 1999), and (d) questions

addressing howwell rested _{subjects felt,} in_{general, in} the_{morning, and about the}

averagenumber

of

hours sleep each night.

The UBOS is a _{questionnaire measuring} burnout and can be _{applied to}

assessburnout inall _{professions. The questionnaire contains} 16items, each with a

7-point ratingscale_{ranging from}0 _{(never) to} 6 _{(always). The items makeup}three

subscales _{measuring (a) Emotional Exhaustion (EE;} 5 _{items), (b) Distance (D; 5}

items), and (c) Competence (C; 6 _{items). The} EE scale indicates the amount of

enduring fatigue. The EE

score is the mean of

five items addressing work

experience and feeling. The scale scores

range from 0 to 6 with a

high score

signallinga_{higher amount}

of

_{enduring fatigue. The}D scale assesses towhatextent

people displaya distantand _{cynical attitude toward work. The D score is the mean}

of

five items and_{ranges from 0 to 6 with a high}score_signallinga _higheramount of

distance, or put differently, a lower amount of work engagement. The C scale is

designed tomeasurefeelings

_of

competence, confidence and thefeeling

of

making

a positivecontribution to work. The scalescore is the mean of6 items and ranges

from 0 to 6. ALowscore isindicative

of

burnout. The psychometricproperties of

students as _{participants, the UBOS was adapted by substituting in each item the} word "work" by "study".

The Need forRecoveryscale contains 11 dichotomous items (yes/no). The

scale scores

range from 0 to 10 with a

high score signalling a higher need for

recovery. The scale has good

reliability

and

validity

(VanVeldhoven

&

Broersen,

1999; VanVeldhoven

&

Meijman, 1994).

The FFPI was used

to

_{assess the Big}

Five factors

of

_personality:

Extraversion, Agreeableness, Conscientiousness, Emotional

Stability, and

Autonomy (Opennessto experience). These factors represent ataxonomy

of

basic personality traits that concisely describe characteristic differences between

individuals. Extraversion reflectsthedisposition towards cheerfulness, enthusiasm,

sociability, and high activity. Agreeableness represents the inclination towards

interpersonal trust, emotional _support, and consideration

of

others.

Conscientiousness reflectsatendency towards efficiency,competenceandsense of

duty, planning, organizing, achievementandself-discipline.Neuroticismstands for

the inclination to experience emotions like nervousness, depression, frustration,

and _{guilt. Finally, Openness to Experience} describes a _receptive inclination

towards curiosity, imagination, varied experiences and ideas. The questionnaire

consists of100

brief

andconcrete behaviourallydescriptive statements.Eachscale

contains 20 statements _{(10 positively and} 10 _{negativelyphrased} items). Answers

are scored on a _5-point Likert _{scale ranging from 1, not at all applicable, to 5,} totally applicable. The psychometric

characteristics of the FFPI are good

(Hendriks, 1997; Hendriks et al., 1999).

The question"Ingeneral, howwellrested do you feel inthemorning?" was

assessed by a _{dichotomous rating} scale

_("well

_{rested", "not well rested"). The}

average number

of

hours sleep each night was a _{direct question} filled in by the subjects.

1.6 State_{questionnaires}

On the daytheexperimenttookplace, subjects completedthe following set

of

state

questionnaires at four different times (see Table 1): the Shortened Fatigue

Questionnaire (SFQ),the ScaleforPerceived Load (SPL),the_RatingScale Mental

Effort (RSME), andtheChecklistIndividualStrength (CIS-20).

The _{SFQ (Alberts, Smets, Vercoulen, Garssen,}

&

_{Bleijenberg, 1997)}

assesses the intensity

of

physical fatigue.

It

contains four

items with a 7-point

Likertscale(ranging from 1 (yes, that is true) to 7 (no, that is not true)). The scale

scores range from 4 to 28. The

reliability of the SFQ is

good (Cronbach's alpha

0.92).

The SPL (Van Veldhoven

&

_Meijman, 1994) measures feelings

of

fatigue

during work. The SPL contains 16 items that are rated on a 5-point scale. Each

24 _{Acute fatigue and}burnout

scale,

which of the

two statements corresponds more with their momentary

physicalstate. The scale scores range from 0 to 48. The SPL has good

reliability

coefficients.

The RSME _(Zijlstra, 1994) measures subjective ratings

of

perceived

mental effort. The RSME is a _{one-dimensional visual-analogue} scale _containing

nine different verbal _{categories forminganchor points expressing} different levels

of

mental effort. The scale ranges from 0 to 150. The RSME shows systematic

relations with task

_difficulty

and_performancemeasures.

The CIS-20

_{(Vercoulen et al.,}

₁₉₉₄₎ measures _subjective

_{feelings of}

fatigue and related behavioural aspects. The CIS contains 20 _{items that make up}

four subscales: _{Subjective Experience}

of

_{Fatigue (SEF;} 8 _{items), reduced}

Concentration (CON; 5 _{items), reduced}

_{Motivation (MOT;}

4 _items) and rdeuced

Physical

Activity

level (PA;3 _items).

All

items arescored ona_7-pointLikertscale

(ranging from 1 (yes, that is true) to 7 (no, that is not true)). Thescale scores

ofthe

subscales

_{range from 8 to 56, from 5 to 35, from 4 to 28, and from 3 to 21}

respectively. Although the CIS-20 was

_initially

_developed for _{assessingfatigue in}

CE.1onic _{Fatigue Syndrome patients,} the _{questionnaire} is claimed to be _applicable

in healthypopulations as well (Bultmann et al., _{2000). Psychometric}properties of

the CIS-20 aregood_{(Bultmann et al., 2000; Vercoulen et al., 1994).}

1.7 EMG recording and analysis

All physiological signals were recorded with the VitaPort 2 System developed by

TEMEC Instruments. TheVitaPort2 System was_{expanded with two modules, the}

8-channel Universal amplifier module with Multi-connector and the 18 channel

Polysomnographymodulewith Multi-connector.

EMG activity

was _{bipolarly recorded by} means

of

_{Ag/AgC1 surface}

electrodes with contact area and _{housing of 2 and 11 mm diameter respectively.}

Electrodes were attached to the skin with electrode centres 15 mm _{apart. The}

reference electrode was an ECG snap lead electrode, placed on themiddle of the

forehead. EMG activity was recorded on the

left-hand side from

the facial

corrugator supercilii andthe frontalis_{muscles. Electrode positions were chosen in}

accordance with theguidelines presented by Fridlundand Cacioppo (1986). EMG

activitywas recorded during each entire test session, thus including rest and task

periods.

EMG signals were pre-amplified with a factor 1000 and _analogue

band-pass filtered with a

-3dB

high-pass

cut-off

frequency at 10,61 Hz and a -3 dB

low-pass

cut-off

frequency at 400 Hz. EMG signals were thendigitised bymeans of a

12-bitAD-Convertor with a _{sample frequency of 1024 Hz. Subsequently, the data}

were _{digitallyhigh-pass} filtered with a -3 dB _{cut-off frequency of 32 Hz (in}order

to lose_{unwanted movements artefacts). Ensuing, the data were stored on}a340MB

specially developed software program ACEMG (Aalbers, 2002a). First, the data

werefiltered _usinganotch

filter with -3

dB

cut-off

_{frequency points}at 0.0438 and

0.0558 Hz, respectively. Ensuing, the data were _{full-wave linearly rectified.}

Finally,the measurement_{points were integrated using 1} s_periods.

In the short test sessions, the first and last 30s _integrateddata_{points from}

each rest and task _period were omitted

_{resulting in 4 min}

_{(240 integrated data}

points) recorded EMG dataperperiod (4 min rest, 4 min task, 4 min rest). For the

analysis of EMG activity, the mean EMG amplitude per 60 s was _calculated,

leading to four mean amplitude scores for each task period. In addition to the

amplitude scores, difference scores with respect to the rest _{periods were}

determined. Before determining the difference scores, the presence of group

differences in therest_periodswaschecked. Since no _{group differences were found,}

the four

mean amplitude scores were converted into difference scores by

subtractingthe _{surrounding mean}restvalues fromeach average,thus_{resulting into}

fourdifferencescores.

For the long test session, the same datareductions and procedures were

used. This resulted in 4 min _{recorded EMG data per} rest

_{period and 24 min}

recorded EMG per task _{period. For} the _{analysis of EMG}

activity, the mean

amplitude per 240 swascalculated, leading to sixmeanamplitude scores for each

task period. In addition to the amplitude scores, rest-task difference scores with

respect to the rest periods were determined. Before determining the difference

scores, the presence

of

group differences in therestperiodswas checked. Since no

group differences were _{found, the six} meanamplitude scores were converted into

rest-task difference scores by subtracting the surrounding mean rest values from

each average, thusresulting intosix differencescores.

1.8 Heart rate recording and analysis

All

physiological signals wererecorded with the VitaPort 2 System developed by

TEMECInstruments. TheVitaPort 2 System was expanded with two modules, the

8-channel Universal _amplifier module with Multi-connector and the 18 channel

polysomnographymodulewith Multi-connector.

A

well-known _{problem that occurs when}

_{measuring HRV is its}

susceptibility to respiration. Cardiac vagal tone is traditionally measured by

spectral analysis and more specifically in he high frequency band (0.15-0.40 Hz,

Task Force ofthe_{European Society}

of

_{Cardiology and}theNorth AmericanSociety

of Pacing

and _{Electrophysiology,} 1996; Veltman

& Gaillard, 1996). The

applicability and usefulness of the HF power as a dynamic measure

of

cardiac

vagaloutflowis strongly dependent ontheassumption thatasubjectbreaths with a

constant rate

of

approximately15breaths min-1 (Pentilla et al., 2001).Toovercome

this dependency, it isrecommended to usea relativelyconstant, or fixedbreathing