Dissertation

Acute Effects of Strength versus Aerobic
Exercise on Mood
Author: Richard Hedderman (B00062490)
Supervisor(s): Eugene Eivers &Jennifer Cowman
School: School of Business and Humanities
This research project is submitted in partial fulfillment of the
Bachelor of Arts in Sports Coaching and Management at the
Institute of Technology, Blanchardstown
3rd
of May, 2016

2
I have readthe Institute’scode of practice onplagiarism.Iherebycertifythismaterial,which
I nowsubmitforassessmentonthe programme of study leading to the award of (Master of
Business) isentirelymyownworkandhasnot beentakenfromthe workof others,save and
to the extent that such work has been cited within the text of my work.
StudentIDNumber: B00062490
Nameof Candidate: RichardHedderman
Signatureof Candidate: RichardHedderman
Date: 3/5/2016

3
Acknowledgements:
I would like to acknowledge and thank my two supervisors, Eugene Eivers and Jennifer
Cowman for going the extra mile in helping ensure the quality of the work done was the
highest possible.
I’d also like to dedicate this work to my parents who made this work possible.

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Table of Contents
1. Introduction:...........................................................................................................8
1.1. Introduction:........................................................................................................................................8
1.2. Forming the Research Question................................................................................................8
1.3. Outline of the Research Project:................................................................................................8
2. Literature Review ............................................................................................... 10
2.1. Introduction:.....................................................................................................................................10
2.2. Mental Health....................................................................................................................................12
2.3. Mental Health and Mood.............................................................................................................16
2.3.1. The Placebo Effect......................................................................................................................17
2.3.2. Factors affecting Mood.............................................................................................................17
2.4. Interventionson Mood................................................................................................................18
2.5. Impact of Physical Activity on Mood....................................................................................19
2.5.1. Structured Physical Activity Interventions for Mood.................................................33
2.6. Addressing the Research Problem.......................................................................................44
2.6.1. Underlying Mechanisms of Mood and Mental Health.................................................45
2.6.2. Underlying Mechanisms of Mental Illness.......................................................................45
2.6.3. Underlying Mechanisms of Exercise and Mood.............................................................47
2.6. Conclusion...........................................................................................................................................52
3. Methodology ........................................................................................................ 54
3.1. Introduction:.....................................................................................................................................54
3.2. Research Philosophy....................................................................................................................54
3.3. ResearchApproach:......................................................................................................................56
3.3.1. Qualitative Analysis and Quantitative Approach..........................................................56
3.4. ResearchDesign..............................................................................................................................57
3.4.1. Experimental protocol..............................................................................................................58
3.4.2. Subject Sampling.........................................................................................................................60
3.5. Data Collection.................................................................................................................................61
3.5.1. Questionnaire ...............................................................................................................................61
3.5.2. Profile of Mood States...............................................................................................................64
3.6. Data Analysis.....................................................................................................................................66
3.6.1. Statistical Analysis......................................................................................................................66
3.7. Ethics......................................................................................................................................................68
3.7.1. Harm.................................................................................................................................................68
3.7.3. Confidentiality & Anonymity .................................................................................................69

5
3.7.4. Consent & Right to Withdrawal............................................................................................69
3.8. Evaluating ResearchDesign.....................................................................................................69
3.8.1. Validity.............................................................................................................................................69
3.8.2. Reliability .......................................................................................................................................69
3.9. Conclusion...........................................................................................................................................70
4. Findings................................................................................................................. 71
4.1. Introduction.......................................................................................................................................71
4.2. Training Experience and Mood State..................................................................................71
4.3. The DifferenceintheAcute EffectofStrength and AerobicExerciseonMood
.............................................................................................................................................................................72
4.4. Conclusion...........................................................................................................................................74
5. Discussion:............................................................................................................ 75
5.1. Introduction:.....................................................................................................................................75
5.2. Impact of Physical Activity on Mood....................................................................................75
5.3. Impact of Aerobic trainingon Mood....................................................................................75
5.4. Impact of Strength Training on Mood.................................................................................76
5.5. A Comparison of the Effect of Aerobic or StrengthTraining on Mood.............77
5.6. Implications and Current Models forExercise for Mental......................................78
5.7. Conclusion...........................................................................................................................................79
6. Conclusion............................................................................................................ 80
6.1. Introduction.......................................................................................................................................80
6.2. Key Points and Findings..............................................................................................................80
6.3. Study Limitations and Implications.....................................................................................81
6.4. Recommendations..........................................................................................................................82
7. References:........................................................................................................... 84
8. Appendix............................................................................................................... 95
8.1. Aerobic Exercise Session............................................................................................................95
8.2. ResistanceExerciseSession.....................................................................................................96
8.3. Profile ofMood State QuestionnaireTemplate.............................................................97
8.4. Exercise Data..................................................................................................................................101
8.5. Ethical Clearance Form.............................................................................................................102
8.6. Impact on Researcher andSubject Form..................................................................- 123-
8.7. Consent Form Template...........................................................................................................139

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Tables
Table 2.1.................................................................................................................... 10
Table 2.2.................................................................................................................... 12
Table 2.3.................................................................................................................... 19
Table 2.4.................................................................................................................... 35
Table 3.1.................................................................................................................... 53
Table 3.2.................................................................................................................... 57
Table 3.3.................................................................................................................... 58
Table 3.4.................................................................................................................... 60
Table 3.5.................................................................................................................... 63
Table 3.6.................................................................................................................... 65
Table 4.1.................................................................................................................... 69
Table 4.2.................................................................................................................... 71
Figures
Figure 2.1. ................................................................................................................ 30
Figure 2.2. ................................................................................................................ 44
Figure 2.3. ................................................................................................................ 45
Figure 2.4. ................................................................................................................ 46
Figure 2.5. ................................................................................................................ 48
Figure 2.6. ................................................................................................................ 49
Figure 3.1. . ............................................................................................................... 55
Figure 3.2. . ............................................................................................................... 59
Figure 3.3. . ............................................................................................................... 61
Figure 3.4. . ............................................................................................................... 63

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Abstract:
Purpose: Current literature comparing the effect of exercise on mood state has proven
limited. This study was carried to observe the difference, if any, in the acute effects of
aerobic or strength training on mood. The hypothesis formed by the researcher was that
strength training would provide superior benefit to aerobic training in improving mood
state.
Methods: The study design was that of a randomized controlled trial with a crossover
design.Inthisstudy,2 strength-trained and 3 untrained but physically active, healthy male
subjectswere sampledforalocal gym and trained by a qualified personal trainer according
to a set exercise criteria. A Profile of Mood State Questionnaire was applied immediately
before and after each training session. Results were analyzed by paired samples t-test.
Results: There were no significant differences (p<0.05) between either interventions on
mood state pre-exercise and post-exercise. There was also no significant exercise type
differences between subjects.
Conclusion: Though some interesting trends are present, indicating a potentially superior
effect of strength training, particularly in reducing depression (p=0.1), the results of this
studyrejectthe hypothesisthatstrengthtrainingissuperiortoaerobicexercise inimproving
mood state and show no statistically significant differences between either exercise
modality in impacting mood state.

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1. Introduction:
1.1. Introduction:
The reviewof currentliterature showsalimitedamountof studiesconductedcomparingthe
effect of aerobic and resistance, or strength, exercise on mood (North et al., 1990). This
study will compare the acute effects of strength and aerobic exercise on mood state. This
will be done through a randomized controlled trial. The purpose of this chapter is to
introduce the researchquestionthatwillframe the experimentand outline the structure of
the research project.
1.2. Forming the Research Question
Whenreviewingcurrentliterature,the authornotedthe dominance of aerobic exercise as a
methodof exercise whenexaminingthe effectof exercise onmoodandmental state (North
et al., 1990). While these interventionsdemonstratedpositive effectsonmood,exercise has
manymodalities, which can be used, with strength training being one of the more popular
(Penninxetal.,2002). Uponfurtherinvestigation, the authorfoundthatfew studies existed
in which resistance or strength training was assessed in its impact on mood (North et al.,
1990; Netz et al., 2005). Also, when resistance training was used, it seemed to cause a far
greaterpositive effectonmood thanaerobicexercise (Northetal.,1990). Consequently,the
author posed the following research question:
What is the difference, if any, on the acute effect of aerobic and strength exercise
on mood?
This question is the basis for the research project detailed in this report. From reviewing
existingliterature,the authorhypothesizesthat there will be a significant difference in the
two exercise modalities in their impact on mood and that strength training will cause a
greater beneficial effect on mood than aerobic exercise. In this project, the details of the
study and its findings are reported.
1.3. Outline of the Research Project:
Firstly, in the literature review chapter, the author reviews existing literature concerning
mental healthand global prevalence of common mental illnesses, the link between mood
and mental healthandthe impact of exercise, particularly aerobic and resistance exercise,
on moodand mental health,bothinthe shortandlongterm. Thiswas done to ascertain the
currentviews onmood,mental healthandthe impactof exercise on these variables, and to
assess effective methods used in implementing exercise and measuring Mood.

9
Secondly,inthe methodologychapter,the authoroutlines how the studywill be carriedout.
Keydecisionswill include the trainingsessions shouldbe structured,the subjectshe plansto
use and howhe plansto record and analyze the data.Thiswill be done toensure the means
withwhichthe findingsare givenare transparentandcan be replicatedinfuture research
Afterthe methodologychapter,the findingschapterwill report the results of the study and
explain the findings and potential reasons for the reports results. This will be done to
ascertainif the researchquestionwasanswered,whythiswas so,andto supportany further
research relevant to this study.
The discussionchapterwill thenexamine the findings as they relate to previous literature.
Implications will thus be considered existing mental health and exercise models.
The final chapter will present research conclusions. This chapter will summarise the key
pointsof thisproject,identifylimitations,andproviderecommendationsforfuture research.

10
2. Literature Review
2.1. Introduction:
To date, a lot of research has been conducted on the impact of structured physical activity
on mental health(Hunt;1936; Freud,1981; WHO, 2001). However,there islimited research
on the effects of strength training and aerobic exercise on mood state (North et al., 1990).
The objective of this study, consequently, is to compare the immediate effects of both
aerobic and strength training on mood. However, prior to carrying out the study, a
comprehensive reviewof literaturemustbe carriedoutto illustrate the current evidence of
the effect of structured physical activity and emphasise the need for the subsequent
experiment.
The purpose of this chapter is to review the current literature1
in order to formulate the
researchproblem,whichwill identifyandjustifythe researchquestion.Itwill also providean
overview of relevant literature and inform the discussion in chapter 5. To do this, a
systematic review of existing literature will be carried out. According to the Cochrane
Reviewers Handbook (Higgins and Green, 2006), this will require all studies collected and
1 All studies were obtained from hand searches, digital searches on internet search
engines PubMed and Google Scholar, utilizing the keywords: exercise, physical, activity,
strength, aerobic, training, mood, mental, health, as well from cross referencing from
meta-analytic studies on exercise and mood and reviewing unpublished dissertations
from the Cochrane database.

11
reviewed tomeetpre-determinedcriteria2
. Forafull breakdownof the differencesbetween
a narrative and systematic review, see Table 2.1. This method of review was selected
because of itshighlyquantitative nature.Assuch,itwill provide a descriptive answer to the
researchquestion.Forthe purpose of thisreview,mental disorderswill include depression,
bipolar disorder, anxiety or schizophrenia.
As such,thischapteris structuredas follows:Section2.2. will review the currentresearchon
mental health and the prevalence of mental illness. Section 2.3. will examine the link
between mood and mental health. It will also examine factors that affect mood, including
the placebo effect. Section 2.4. will then investigate previous interventions carried out on
mood. Section 2.5. will then focus on structured physical activity specifically, as an
intervention onmood.Itwill also focusonthe type of physical activity, particularly strength
and aerobic training and its impact on mood. Section 2.6. will then address the research
problem. It will do this by reviewing limitations in the literature and stating the research
problem. It will then address potential underlying mechanisms of mood to justify the
researchquestionandformulate a hypothesis.The chapterwillthenconclude,by reviewing
key findings and the rationale for this study.
2 To be included, the studies must meet the following criteria: They must include a direct
assessment of mood state through a full Profile of Mood State Questionnaire or related
survey. It must use structured physical activity as an intervention for a mood state
outcome. It can also describe and explain a process or mechanism behind mood or
exercise, or research on general mental health or mood disorders. Structured physical
activity, for the purpose of this review, must also meet criteria. It must involve the
subjects being supplied with a structured exercise program. It must also contain some
supervision and documentation of the subjects adherence or completion of the program.
The terms of structured physical activity and exercise will be used interchangeably in
this study.

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Table 2.1.: The main differences between a narrative and systematic literature review.
Features Narrative Literature Review SystematicLiterature
Review
Question Broad Specific
Source Not usually specified,
potentially biased
Comprehensive sources,
explicit search approach
Selection Not usually specified,
potentially biased
Criterion-based selection,
uniformly applied
Evaluation Variable Rigorous critical evaluation
Synthesis Often Qualitative Quantitative*
Inferences Sometimes evidence-based Usually evidence-based
*A quantitative synthesis that includes a statistical method is a meta-analysis
Source: Higgins and Green, 2006
2.2. Mental Health
Mental health has been an area of research interest since the early 18th century with the
establishment of institutions and asylums for the mentally ill (Proctor et al., 2009). This
research has receivedmainstreamattentiondue tothe large numbersaffected (Wang et al.,
2007).
It isestimatedthatover400 millionindividualssufferfrommental orneurological disorders
as of 2001 (WHO, 2001). More recently, the World Health Organization (WHO) reviewed
previous studies done and concluded that mental disorders are “commonly occurring”
(Wang et al., 2007). Many national studies agree (Moffit et al., 2010; Phillips et al., 2009;
Alonso et al., 2004; Regier et al., 1993). These studies examined the mental health of male
and female adults using either data from national institutes or questionnaires to ascertain

13
the prevalence of mental disorders. This included bipolar disorder, schizophrenia,
depressionandanxietydisorders.A full breakdown of the studies and their findings can be
found in Table 2.2.
One studyinNewZealanddemonstrateda 38-65% prevalence of mental disorder or illness
over their lifetime (Moffit et al., 2010). Similarly, in China, a study showed a 17.5%
prevalence of Mental disorders among the population sampled (Phillips et al., 2009).
Alongside this, a study on European citizens showed 14% of the population studied had
sufferedfrommental disorderovertheirlifetime (Alonso et al., 2004). This matches further
studies from America, showing a 28.1% prevalence rate of mental disorders among the
studied populations (Regier et al., 1993). Therefore, it is clear that mental illness is a far
reaching phenomenon.
These disorders have an impact on quality of life (Goldney et al., 2004; Spitzer et al., 1995).
Theycan also potentially cause veryseriousphysical problemsincludingself-harm,increased
illnessand death (Klonsky et al., 2003; Bostwick and Pankratz, 2000). Therefore, beyond its
global reach, mental illness represents a serious threat to public health.

14
Table 2.2.: An overview of literature examining the lifetime prevalence of mental disorders in populations from different global regions.
Studieson Mental Disorders
Study Location Population(n) Percentage of
total
population(%)
Methods Findings Discussionand Limitations
Moffitet al.,
(2010)
NewZealand Healthymales
and females
studiedfrom
birthto late
adulthood(32
yearsold)
(1,037)
0.03 Structured
Clinical
Interviewfor
Diagnosticand
Statistical
Manual,or
DSM-IV,
Questionnaire
Average 38%-65% lifetime
prevalence rate forany
mental disorder
Prevalence rate of Mental disorders
overlifetimehigherthanexpected.
More studiesneeded.
Phillipset al.,
(2009)
China Healthyadult
malesand
females
(113,000,000)
8.49 Chinese version
of DSM-IV
Questionnaire
Average 17.5% monthly
prevalence foranymental
disordersinstudied
populations
Highprevalence of mental disorder
amongadultpopulation.More studies
withlargersample needed

15
Alonsoet al.,
(2004)
Europe
(Belgium,
France,Italy,
the
Netherlands
and Spain)
Healthyadult
(>18 years)
malesand
females
(21,425)
0.01 Composite
International
Diagnostic
Interview
(WMH-CIDI)
withDSM-IV
Questionnaire
Average lifetime
prevalence of 14%and
yearlyprevalenceof
10.2% of any mood
disorder
Mental disorderswere frequent,more
commonin female,unemployed,
disabledpersons,orpersonswhowere
nevermarriedorpreviouslymarried.
Youngerpersonswere alsomore likely
to have mental disorders,indicatingan
earlyage of onsetformood,anxiety
and alcohol disorders.
Regieret al.,
(1993)
NorthAmerica Healthyadult
malesand
females(18,
571)
0.01 Interviewsand
data collection
fromthe US
National
Institute of
Mental Health
Average 28.1% monthly
prevalence of Mental
disorders
Highmonthlyprevalence of mental
disordersacrossa varietyof
demographics
Note: percentage of total population,asofthe year of each study’spublication(PopulationReferenceBureau, 2010; 2009; 2004; 1993), calculatedto
allowassessmentof statistical powerof findings

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2.3. Mental Health and Mood
Mood state offersa methodof identifyingthe mental wellbeing of an individual (McNair et
al., 1971). A person’s mood has been defined as their balance of emotional levels in a
previous narrative review (Gross and Muñoz, 1995). A person’s transient and consistent
moodstate has beenshownasa prominentindicatorof anindividual’s overall mental state
and health(Keyes,2002).There is now an entire areaof mental healthandillness concerned
solelywithmoodexpressionand regulation, that of mood disorders (Keyes, 2005). Indeed,
mental health has often been considered and described as the collective, chronic mood
state of a person (Gross and Muñoz, 1995). This indicates the importance and validity of
assessing an individual’s mood state.
Consideringthe above, examinationof the moodstate of an individual atanyone time could
be used as a monitoring and diagnostic tool (Gross and Muñoz, 1995). This has been
demonstratedandverifiedinmanystudies, includingawide range of subjects,including the
diagnosis of healthy populations (Fontani et al., 1991). It has also been validated in the
diagnosisof depressedpopulations(Brewer,1993) and bipolaror schizophrenicpopulations
(Lorr et al., 1982). It is now even being utilized in the sport psychology field to improve
athletic performance (Beedie et al., 2008). This shows that the mood state of an individual
can be a valid means of assessing and monitoring mental health.
As such, if mood state can be quantitatively measured, then overall mental health can be
quantified (McNair et al. 1971). However, the research into mood and its influence on
overall mental healthisnotwithoutlimitation.The difficultyof assessingthe highlydynamic
state of the human mind has been noted (Gross and Muñoz, 1995; Hunt, 1936). Gross and
Muñoz note the difficulty of measuring mood due to emotions lacking a distinct definition
and category. The study describes them a “fuzzy category” due to mood states being
transientinnature andthe placebo effect being deeply rooted in psychosocial factors. The
attainmentof true objectivelymeasured outcomes is thus far more difficult in psychology-
basedstudies.Unlikemore physicallybasedmeasurementsandinterventions any objective
measurement of psychological processes, e.g. through Magnetic Resonance Imaging or
assaysof hormonesandbrainmatter,isexpensive and not always possible. This presents a
limitation for studies on mood states as it questions the studies’ validity and reliability.
Because of this,the PlaceboEffectmustbe reviewedasitpresentsasignificantconfounding

17
factor inpsychological studies(Benedettietal., 2005). This will allow the phenomenontobe
better understood and accounted for when carrying out the study.
2.3.1. The PlaceboEffect
The ‘Placebo Effect’ is described as “a psychobiological phenomenon that can be
attributable to different mechanisms, including expectation of clinical improvement and
pavlovian conditioning...which causes a definitive outcome after a sham treatment”
(Benedetti et al., 2005). This phenomenon can have a physiological effect on subjects
mental, physical and even immunological state (Price et al., 2008). This acts to confound
results, and makes it difficult to ascertain if the results are achieved directly from the
intervention, or social interactions between the subjects and one of the above factors.
Knowledgeof previousstudyoutcomeshas alsobeenshowntoelicita placebo effect (Price
et al., 2008). This limitation could be addressed by examining clear, measurable,
physiological processes that correlate with these emotions such as blood work or biopsies
(Hunt, 1936).
However,thiswouldprove expensive andimpractical forthe author.Inorderto counterthis
limitation,anynon-interventionmeasure must either be controlled as much as possible, or
documented and reported so that it may be recognised as a possible confounding factor.
Areaslike social interaction,asubject'sbeliefs,lifestyle andinteractionwiththe intervention
must be considered carefully (Lewin et al., 2009). There should also be care taken to
replicate the study design as closely as possible to previous studies so as to ascertain any
differences and their cause is not due to differing study design (Higgins and Green, 2008).
These measures can help increase the validity and reliability of a study and its results,
allowingforgreatercontributionof datato the current consensus(Isaacand Michael, 1971).
Consideringthis,below, factorsaffecting mood will be reviewed and analysed. This will be
done so that any potential confounding factors can be recognized and accounted for when
designing the methodology behind the approach to the author's study.
2.3.2. Factors affectingMood
In support of Gross and Muñoz’s, 1995 assessment of emotion, a large number of diverse
stimuli has been shown to affect mood (Kendall, 1954). These include social interaction
(Chou et al., 2011), physical activity (Raglin and Morgan., 1985), nutrition (Soh et al., 2009),
personal experiences,worklife andattitudes(Elovainio et al., 2004). Experiments have thus
manipulated factors such as enjoyment and social interaction through utilizing music

18
listening, group social activities and psychotherapy with great effect (Unwin et al., 2002;
Särkämo et al., 2008; Otto et al., 2005). It is clear there are many factors that can affect an
individual’s mood state. Therefore, the above factors must be considered when designing
the experiment in order to prevent confounding of results. This could occur through the
inadvertent manipulation of the above factors other than physical activity (Grimes and
Schulz, 2002).
Nonetheless,fromreviewingthe meta-analysesreferencedabove(North etal.,1990; Netz
et al., 2005; Särkämoet al., 2008), no factor seemstohave as large an impacton an
individual’smoodthantheirphysical fitnessandhealth(Thayer etal., 1994). Thayerand
colleague's1994 studyis a critical additiontothisreview asitisone of the few studiesthat
directlyattemptstocompare structuredexercisetounrelatedmodalitiestocompare it’s
efficacyinmoodregulation.Thoughthe systematicreview isnarrow initsscope,including
only4 studies,ituniquelyexaminesboththe mechanismsbehindmoodregulation,suchas
distractionorengagementinactivity,andsystematicallycomparesexercise withgroup
activitiesormusiclistening.Thisstudy,alongwiththe otherreviewsandmeta-analyses
listedabove are furtherillustratedinTable 2.3.Asseenabove,the manipulationof all the
above factorshas been,andisto thisday, attemptedinexperimentalinterventionsinorder
to ascertaintheirefficacyinimprovingmood(Netz etal.,2005; Soh et al., 2009; Särkämo et
al., 2008). Below,these experiments will be reviewedinanefforttofindwhichtype of
interventioncouldpotentiallybe aseffective,ormore effective,inimprovingmoodthan
exercise and,if so,thenthe reasonforthese resultswillbe examined.
2.4. Interventions on Mood
Having ascertained the wide range of factors affecting mood, previous studies have
attemptedtomanipulate certainstimuli in controlled interventions to assess its efficacy in
impacting mood state (Proctor et al., 2009). The most common purpose of these
interventions is to assess the efficacy of the intervention to improve mood and overall
mental health (Barton et al., 2012). Structured physical activity has been proposed as a
mechanism to improve mood (Dubnov and Berry, 2000) but so has music (Särkämo et al.,
2008) and social interaction (Unwin et al., 2002). Indeed, interventions of music listening
and group activities has shown positive effects on mood and mental state across a broad
range of populations(Särkämo etal.,2008). However,asstated,structuredexercise,suchas
aerobicexercise orresistance training,has proven to have the largest effect on mood state

19
inall populations(Thayeretal.,1994; WilliamsandTappen,2007). The reason for this could
be due to the large physiological effect exercise has on both the brain and body
(Wackerhage,2014. Thiswill be examined further below. But the area of physical activity is
very diverse and context specific. This diversity merits specific investigation in order to
thoroughlyunderstanditsapplication.Below,the impactof physical activityonMoodand as
an intervention in studies is examined.
2.5. Impact of Physical Activity on Mood
Specifictothisstudy,physical activityandwellbeinghasalsoshowntobe a significantfactor
affectingmood(Freud,1981).Indeed,a person’s fitness state has shown to be a significant
factor inchronic moodstate and overall mental health(Stewart et al., 2003). This has led to
a numberof trialsexaminingthe impactof structured physical activity or exercise on mood
state (North et al., 1990; Petruzzello et al., 1991; Lawlor and Hopker, 2001). As stated, the
influenceof exercise andphysical activityonmoodstate andmental healthhasbeenanarea
of interestasearlyasFreud’s observational studies (Freud, 1981). Freud observed physical
work as having a distinctly positive correlation with mental health in his 1981 study. Since
then,a numberof studieshave setoutto examine the effectsof physicalactivity,specifically
structured exercise, on mood and overall mental wellbeing (Steptoe and Cox, 1988;
McLafferty et al. 2004).
A 2005 systematic review and a 2008 narrative review examined the relationship of
structured exercise on both healthy and with mentally ill populations (Peluso et al., 2005;
Strohle,2008). Both reviews identified a “strong correlation” between structured exercise
and a short and long-term improvement in mood state. The 2005 review by Peluso and
colleagues’systematicallycollectedandanalyzedall studiesthatimplementedarandomized
controlled trial methodology. A 1999 and 2001 narrative review declared a transfer of this
positive effect to overall mental wellbeing (Fox, 1999; Arent et al., 2000). These reviews
offer an overall view of a possible correlation between mental health and structured
exercise. However, they lack the quantitative and objectively descriptive nature of meta-
analysesoncontrolledtrialsof structuredexerciseuse onmoodstate. This is due to the use
of descriptive statistical analysis, such as effect size calculation or weighting of a study's
results, which occurs in a meta-analysis. This allows meta-analyses to present a clear,
quantitative overview of the literature and present a causative link, if one exists.

20
Notingthis,anumberof meta-analysescollectedandexaminedrandomizedcontrolledtrials
on the impact of structured exercise on mood state. One examined published and
unpublished data from randomized controlled trials. It examined the effect of structured
exercise on mood in all populations as diagnosed through a Questionnaire (North et al.,
1990). Anotherexaminedthe effectof state,ortransient,circumstance specific,and trait, or
inherent,anxietyinadultmale andfemales,asdeterminedbyProfile of Mood State (POMS)
questionnaires. It also reviewd related surveys and physiological measurements like
Electroencephalography,andthe impactof exercise (Petruzello etal.,1991). Meanwhile one
2005 meta-analysisexaminedthe impactof exerciseand mood on elderly individuals (Netz
et al., 2005). All meta-analysesfoundastrongeffectof structure physical activityorexercise
on mood and mental state. Therefore, it is clear that there is a positive and causative
relationshipbetweenphysical activity and mood. For further information on these studies,
see Table 2.3.

21
Table 2.3.: An overview of the recent reviews and meta-analyses conducted on structured physical activity’s impact on mood state. Note: The effect size
is a statistical measurement of the effect an intervention had on the measured parameters (Vincent, 2012).
Meta Analyses
Study Population Methods/Study Inclusion Findings Discussion and Limitations
North et al.,
(1990)
All available populations,young
(<18), adult (>18) and elderly(>50)
malesandfemales,bothhealthy
and sufferingfromamental
disorderthrough biological or
subjective assessment.
Electronicandmanual search
of databases.80 studies
included,bothpublishedand
unpublishedworks.
Chronicand acute exercise is
effectiveinimprovingmental
health,butmore effectivein
disturbedandill populations.
Most effective for25-64 year
oldcategory.
Longerduration≥21 weeks)
programsproduce superior
resultsbutshortprograms (≤ 4
weeks) andsingle sessionsare
still effective.
25-64 yearoldscouldhave
showngreatesteffectsize due
to beingthe largest
demographicstudied.
Home,academicand medical
basedprogrammescouldhave
provenmosteffectivedue to
higheradherence inhome
basedprogrammesandhigher
supervisioninacademicand
medical basedsettings.

22
Greatereffectof exercise over
psychotherapy,relaxationand
enjoyable activities.
Home basedprogrammesand
rehabilitationandacademic
settingprove mosteffective.

23
Petruzelloet al.,
(1991)
Adultmalesandfemaleswithstate
and traitanxietydisorder(mean
age = 34.16)
Electronicand manual search
of databases.Anystudy
examininganexercise and
mental healthrelationship
was included.
Exercise hasan anxiolytic,or
anxiety-reducing,effect.
Minimumof 21 minutes
requiredtoelicitaresponse is
suggested.
Longerexercise program
durationproduce superior
effect.
Aerobicexerciseshoweda
large effectwhile anaerobic
exercise showedclose tono
effect.
Insignificantresultsfor
anaerobicinterventionscould
be due to the comparativelylow
studiesdone onthe modality
(13 studieson anaerobic
exercise against173 studieson
aerobicexercise forstate
anxiety,withonly2studieson
anaerobicexercise done
comparedto 51 on aerobic
exercise fortraitanxiety).
There wasalso a large standard
of erroracknowledgedinthe
meta-analyses.

24
Netzet al.,(2005) Elderlyhealthymalesandfemales
(≥ meanage of 54 years old)
Electronicandhand searchof
databases.36 studies
included.
Aerobicexerciseshowedthe
greatesteffect,withaneffect
size of 0.29, but wasnot
statisticallydifferentfrom
strengthtraining,withan
effectsize of 0.23.
CombinedAerobicand
strengthtraininghadthe
lowesteffect.Sessionlength
and frequencyhadapositive,
but insignificantcorrelation
witheffectof interventions.
Betterresultswere seenin
previouslysedentary
individualsthanpreviously
trainedor active individuals,
thoughall individualswere
benefitted.
Studysuggestsbothaerobicand
resistance exercise are equally
beneficial.
Interferenceeffectof
combiningaerobicand
anaerobicmodalitiesappearsto
be presentinpsychological
measurements.
A minimumintensityappearsto
be neededforbothaerobic
exercise andstrengthtraining
to elicitabeneficialeffect.
Suggesteddiminishingreturns
for trainedindividuals.

25
Programme durationhada
negative correlationwith
effectof intervention.
Lightintensitycalisthenic
exercise showednosignificant
difference fromcontrol
groups.

26
Arent et al.,
(2000)
Elderly(meanage of >60 years)
malesandfemales,bothhealthy
and mentallyill ordisturbed.
Electronicandhand searches
of databases.Studiesmust
have includedan
investigationof anexercise-
moodrelationship.
Exercise demonstrated
superioreffectover
motivational interventionsand
yoga or stretchingexercises.
Resistance training
demonstratedthe greatest
effectonmood(withaneffect
size of 0.80), followedby
combinedAerobicand
strengthtraining(withan
effectsize of 0.37) followedby
aerobicexercise (withan
effectsize of 0.26).
Physicallyactive individuals
had bettermoodStates
throughout.
Mediumintensityexercise had
greatesteffect.
It shouldbe notedthathigh
intensityexercise showedthe
secondhighesteffect,despite a
far smallernumberof studies.
There alsoseemedtobe
diminishingreturnsaftera
durationof 6 weeks,with6
weekprogramsdemonstrating
bettereffectsthanlonger
programmes.

27
Systematic Reviews
Study Population Methods Findings Discussion
Pelusoet al.,
(2005)
Healthyandmentallyill individuals
(>18 years).
Electronicsearchof MedLine
database.87 studiesused.
Mainlyaerobicinterventionstudiesused
but anaerobicwasshowntobe
effective.
Long termeffectivenessof exercise on
moodis inconclusive.
Exercise canbe counterproductive if
obsessive exercise orovertraining
occurs.
Highintensityexercisewasshownin
some casesto worsenmood,whereas
moderate intensityexerciseshowed
improvements.
Obsessive exercise,
overtrainingand
decreasesinmood
withhighintensity
exercise were shown
mainlyinstudieson
elite level athletes.
Long-termeffectsare
inconclusivebut
promising.

28
Thayer et al.,
(1994)
Healthyadults(>18 years).
Combinedpopulationof 436.
Reviewof 4 studiesonself-
regulationof mood.All
studieswere observational in
nature.
Subjectslistedarelativelysmall amount
of methodstheyusedhimselfregulation
of mood.
Social interaction andcognitive
techniqueswere mostcommon
methods.
Exercise wasratedas mosteffective
in ‘changinga badmood’.
More knowledgeable individuals,or
‘experts’seemedtouse exercise more
as a method.
Eatingand watchingTV were less
effective.
Small numberof
studiesreviewed.All
qualitative findings
and data.
Quantitative studies
and examination
neededtoverify
occurrencesof these
methodsandtheir
effectiveness
objectively.

29
Lawlor and
Hopker, (2001)
Depressedadults(>18years). Electronicandhand searches
of databasesandcontyearsith
expertsinthe field.14studies
included.
Exercise showntoproduce favourable
short term(≤10 weeks) improvementsin
moodbut studiesonlongterm(≥12
weeks) isinconclusive due tolackof high
qualitydata.
As effective,insome casesslightlymore
effective,thancognitive therapy.
Overall studyclaimedaninconclusive
resultdue toa lackof goodqualitydata.
Nearlyuniversally
studiedaerobic
interventions,with
onlyone
anaerobic/strength
trainingstudyused.
Studiesusedavery
highconfidence
interval andp value
(p<0.01 and p<0.001),
whichcouldcause a
Type 2 error.

30
Narrative Reviews
Study Population Methods Findings Discussion
Strohle,(2009) Populationsof all agesandmental
healthstatusfoundtobe included.
Narrative overviewof currentliterature.Noclear
search,selectionorinclusioncriteria.
Exercise seemsto
reduce mood
disordersymptoms.
More studiessince
Lawlorand Hopker's
2001 reviewseems
to strengthen
exercise asa
treatmentformood
disorders.
Participationin
exercise impacts
mooddisordersand
vice versa.
Studycouldbe
furtherstrengthened
by segmentingtype of
exercise usedand
throughthe
employmentof a
systematicprocess
and structure.

31
Fox et al., (1999) All adult(>18 years) populations
foundto be included.
Narrative overviewof currentliterature.53
studiesreferenced.
Exercise showntobe
an effective
treatmentfor
depressionand
anxietydisorders.
As effective as
therapy
interventions.
Exercise iseffective
inpreventingmany
mental illnesses.
Exercise use could
helpmental health
throughimproving
sleep.
Studynotesthe lack
of an intervention
includingbothdiet
and exercise use on
effectsonmood.
Exercise wasstatedas
improvingmental
healththroughmood
and self-perception,
addinga potential
mechanismforits
effect.

32
The positive effect of exercise in mood has been demonstrated through greater perceived
quality of life and physical capability (Rejeski, 2001). This has been shown in healthy, and
physically or psychologically impaired populations (Motl et al., 2009; Goodwin, 2003). This
acts to challenge conventional therapies in treating mental illness. In fact one study, a
randomizedcontrolledtrial,examined the effectof antidepressant medication, exercise, or
a combinationof both,ondepressedpopulations.The results showedthe greatesteffectfor
exercise alone (Babyak et al., 2007). These results are illustrated in Figure 2.1. below. This
couldimplya potential interference effectof depressionmedicationonthe beneficial effect
of exercise.Thisis animportantfinding,consideringthatmostdepressionmedicationhasan
average 30% remissionrate (KrishnanandNestler,2008),meaningpermanent recoveryonly
occurs in 30% of cases. This argues a case for prioritising exercise over conventional anti-
depressantmedicationsuchasselectiveserotoninreuptake inhibitors(KrishnanandNestler,
2008).
Figure 2.1.: The recovery rate from depression of each group in a randomized controlled
trial comparing exercise and anti-depressant medication.
Source: Babyak et al., 2007.

33
As stated, itisclearthere is a positive relationshipbetween structured physical activity and
mood and a clear causative link between the two. However, North and colleague's 1990
meta-analysis demonstrated large differences between the effects of different types of
physical activity. In the analysis, activity was segregated by exercise type, duration and
adherence, with all sections showing different effects, or magnitude of effect, on mood
state. Therefore,furtherresearchisrequired toexamine physical activitywithin the context
of the type of exercise beingcarriedout.The dosage of the exercise prescribed, in terms of
intensity and volume, and the total duration of the study are also important (Netz et al.,
2005).
2.5.1. Structured Physical ActivityInterventionsfor Mood
As can be seen the above reviews and meta-analyses, there is a wealth of research on
physical activityinterventionsforMental Health.However,asmentioned,exercise hasmany
forms of aims and executions. Exercise can take the form of aerobic exercise, flexibility
exercise,powertraining,strengthtrainingorevenamix of anyof the above methods(NSCA,
2008).
Thiscomplicatesthe researchof exercise onmoodbecause it has been shown that not only
is each adaptive process unique, but also mutually exclusive to some degree (Coffey and
Hawley,2007). Thisresearch demonstrated astronginterferenceeffect at a molecular level
to the stimuli of strength training versus aerobic training. There have also been studies
showing a complementary adaptive effect of some stimuli, such as strength training and
powertraining(Adams etal.,1992). The implicationsof aninterferenceeffecthas also been
demonstrated in a meta analysis on exercise and mental health (Netz et al., 2005). This
meta-analysisshowedcombinedaerobicandresistance training to have the smallest effect
size on psychological parameters, indicating interference of effect.
The unique, diverse and often mutually exclusive effects of different exercise modalities
shows it is important to consider physical activity interventions and their effects on mood
within the context of the training method. One difficulty here is that the methods used in
physical activityinterventionsare notverydiverse,usuallyconsisting of aerobic, strength or
flexibility training (North et al., 1990). Below, the most researched methods of exercise in
the mental healthfieldof studywill be examined:Resistance or strength based training and
aerobic or cardiovascular training.

34
2.5.1.1. Aerobic Exercise
Aerobic exercise, such as low to moderate intensity jogging or cycling, has been the
dominantformof exercise researched in relation to mood and mental health (North et al.,
1990; Petruzello et al., 1991; Lawlor and Hopker, 2001). Intensity of the aerobic exercise in
these studies is usually prescribed at 50%-70% each individual's maximum heart rate.
In terms of efficacy, aerobic training alone has been shown to acutely increase mood in
healthypopulations(SteptoeandCox,1988), as well asin populationswithmental disorders
(Dimeoetal., 2001). All of the above meta-analysesalsoprovideevidence forthe efficacy of
structured aerobic exercise on improving mood state (North et al., 1990; Pettruzello et al.,
1991; Netz et al., 2005), as assessed through POMS questionnaire or Beck’s Depression
Inventory. These studies are further illustrated in Table 2.4. Two of the meta-analyses
mentioned above showed aerobic exercise to have the greatest effect in improving mood
(Netzetal., 2005; Petruzello etal., 1991). Assuch, aerobicexercisehasbeenshowntobe an
effective means of improving mood.
However,whenreviewingthe studies included in the aforementioned meta-analyses, one
shows only 7 studies utilizing anaerobic training reviewed, compared to 222 studies using
aerobic-type training (North et al., 1990). Another lists only 13 studies with anaerobic
training compared to 173 aerobic training (Petruzello et al., 1991). This uneven amount of
studies acts to decrease the overall effect size calculated for anaerobic, or resistance
training, on mood state in these meta-analyses and could mask the true effect of strength
trainingonmood.The predominantinterestinaerobictrainingandmoodstate ismostlikely
due to the increase in Amino-Monophosphate Kinase, or molecular signals Amino-
Monophosphate Kinase, or AMPK and Brain-Derived Neurotrophic Factor Brain-Derived
NeurotrophicFactor,orBDNF, beingassociated, primarily, with aerobic adaptation (Coffey
and Hawley,2007; Wackerhage,2014). These molecularsignalsand their associated effects
will be discussed further below.
As aerobicexercisehasproventobe the predominantformof physical intervention, it leads
the author to questionif othermethods,such as strength training, would be as effective, if
not more so.Below,the researchconductedthusfaron strengthtraining as an intervention
for mood.

35
2.5.1.2. Strength Training
Strength training uses weighted or resistance exercises to increase strength and muscle
mass throughanaerobic mechanisms (NSCA, 2008). As such, strength or resistance training
is often called anaerobic training or exercise (North et al., 1990). Despite the obvious
interest in physical activity as an intervention for mental health, there has been relatively
little research on exercise method outside of aerobic training in physical interventions for
mood. As mentioned above, North and colleague's, showed only 7 articles using strength
training, compared to the 18 who underwent ‘various aerobic training’ and the 24 that
utilized walking or jogging. Nevertheless, resistance training still showed a 3-fold greater
effect than aerobic activity interventions. This shows that strength training can also be an
effective intervention to improve mood and mental health.
When looking at studies in isolation, as opposed to reviews, resistance training alone has
again been shown to improve mood in healthy populations (McLafferty et al., 2004) and in
impaired and depressed populations (Dalgas et al., 2010; Singh et al., 1996). It has also
shownbenefitforimprovingmemoryandcognition (Peig-Chiello et al., 1998). Even though
there islessstudiesdone onthe meansof strengthtraining,the work that has been done in
the area shows a clear beneficial effect on mental health.
Thoughboth interventionshave proved effective in improving mood, literature comparing
the two interventionsislimited.However, there are a few studies that must be considered
withinthisreviewas they compare both types of exercise on mood state (Bromen-Fulks et
al., 2015; Penninx et al., 2002). Below, these comparative studies will be examined. A
detailed review of the studies is also shown in Table 2.4.
2.5.1.3. Aerobic versus Strength Training
In terms of research comparing the efficacy of either aerobic or resistance exercise, two
metaanalysishave researchedthistopic(Broman-Fulksetal., 2015; Penninx et al., 2002). As
stated, North’s meta analysis shows a three times greater effect for resistance exercise.
Meanwhile Netz andcolleaugue’s2005 study showsaerobicexercise tobe non-significantly
superior,withonlya0.03 difference ineffect size between aerobic and resistance training.
This difference would be considered statistically trivial (Vincent, 2012). When examining
randomizedcontrolledtrials,there wasfoundtobe nodifference inacute effects of anxiety
reduction in either the resistance or aerobic exercise group (Broman-Fulks et al., 2015).
These studies reinforce the idea that strength training can be at least as effective, if not

36
more effective,inimprovingmoodasaerobicexercise. However, a finding from Penninx et
al., 2002, refutesthis.The studyfound thatresistance training showed no significant effect
on mood over 15 months and did not fare any better than the control group, who
completed no training. This is noteworthy because strength training alone has, as shown,
alreadyproveneffective at improving mood state (Broman-Fulks et al., 2015; McLafferty et
al., 2004). A meta-analysis has also shown strength training to be more than three times
more effective than aerobic training (North et al., 1990).
A possible explanationcouldlayinthe design of the study and some observations made by
saidstudy.There are a numberof studydesignflawsthe author found when examining the
paper. Firstly, as in previous studies, intensity of the Aerobic training was carefully
prescribedandmonitored,as 50%-70% each individual's maximum heart rate reserve. This
implies a minimum intensity threshold for the efficacy of aerobic exercise in improving
mood.Indeed,all previous studiesshowedsuchanimprovementutilizing aminimumof 50%
of an individuals’ maximum heart rate. However, no such measure was in place for the
resistance training protocol, with subjects merely prescribed dumbbells according to
preference, even though research has shown a minimum of 60% intensity relative to an
individual’s strength is required to elicit an optimal strength or anaerobic adaptation
(Campos et al., 2002).
Despite thislackof intensity,when reviewing the highest adhering group of the resistance
exercise group,those who adhered to 79% or more of the program, there was shown to be
not onlya significanteffectonmood,but a greater effect than the highest group of aerobic
exercise adherers.Thiscouldimplyaminimumthreshold of training frequency for strength
trainingtobe effective inimpactingmoodstate,asthe highestfertileof adhererscompleted
three resistance training sessions per week. Though the majority of the above studies are
longitudinal measures, all studies show a significant acute effect when measured. This
suggests that the acute effect of an intervention may illustrate the long-term efficacy in
affecting mood (North et al., 1990). However, considering the data above, it is clear that
there is no clear consensus yet on whether strength or aerobic exercise is superior in
improvingmoodandmental health.Thispresentsthe researchproblem, whichus discussed
below.

37
Table 2.4.: An overview of Randomized Controlled Trials on both aerobic and strength exercise on mood state and comparative studies of the two
exercise modalities.
Aerobicexerciseeffectonmood
Study Population
(n)
Methods Findings DiscussionandLimitations
Steptoe
and Cox,
(1988)
Young,
healthy
female adults
(32)
Modified Profile
of Mood State
Questionnaire
applied
immediately
before and after
the trial.
Low intensity exercise in vigour and exhilaration.
High Intensity exercise showed a worsening of
mood state.
Subjects were exclusively female, who have
been shown to respond less wellto higher
intensities (Hakkinen, 1991) and hold higher
slow twitchfibers (Martel et al., 2006).

38
Dimeo et
al., (2001)
Depressed
male and
female adults
(12)
DSM-IV
Questionnaire
applied before
and after 10 days
of exercise.
Exercise
consisted of 30
minutes of
walking on a
treadmill at a
blood lactate
level of 3
Millimoles per
Liter, or at the
lactate threshold.
Significant reduction in depression scores by the
end of the trial.
It should be noted there was no control
group, howeverall patients were resistant to
selective serotonin reuptake inhibitor
prescription.

39
Resistancetrainingeffectonmood
Study Population
(n)
Methods Findings DiscussionandLimitations
McLafferty
et al.,
(2004)
Healthy
elderly
(mean age -
66.9) males
and females
(28)
Profileof Mood
State
Questionnaire
applied before
and after 24
weeks of
resistance
training.
Significant improvements in confusion,tension,
anger and total mood disturbance scores, but not
for vigor,depression or fatigue.
No statistically significant sex dependent
differences between the effectof exercise and
mood.
Clear favorableeffectof resistance exercise
on mood.
Intensity of exercise was 80% 1 Repetition
Maximum, whichcould verify that higher
intensity exercise is required or optimal for
mood improvement.
No sex differences observed could be due to
the female subjects being postmenopausal
and, therefore unaffectedby menstrual cycle
mood changes (Sander et al., 1983).
Dalgaset
al., (2010)
Young
individuals
suffering
from
Multiple
Sclerosis
(31)
Major
Depression
Inventory and
Fatigue Severity
Scale applied
before and after
12 weeks of
resistance
training and
again 12 weeks
after training
ceased.
Significant improvements seen in mood and
Fatigue.
These improvements persisted even 12 weeks
after training ceased.
Suggested long-term benefit to exercise on
mood and mental health, even if training is
ceased or disrupted.

40
Singhet
al., (1996)
Elderly
(mean age:
71.3)
depressed
individuals
(32)
Beck's
Depression
Inventory and
Rating Scale of
Depression
applied before
and after 10
weeks of
resistance
training
Significant improvement in all depression scores.
Increased morale and social interaction also
present.
Exercise may help improve mental health
through secondary factorssuch as increased
social interaction and physical capability.

41
Peig-
Chiello et
al., (1998)
Healthy
elderly
(mean age:
73.2) males
and females
(46)
Psychological
well-being
Questionnaire
and cognitive
tests applied
before and after
8 weeks of
resistance
training and 1
year after
training had
ceased.
Significant improvement in cognitivetests but not
in psychological well-being questionnaire when
compared to the controlgroup nothing the short
and long term.
There may be large and persistent cognitive
benefit to resistance exercise.
Psychologicalwell-being questionnaire was
not externally validated and highly
customized. This may not be a reliable
observation on the effectof resistance
training on mental well-being.

42
Comparativestudies
Study Population
(n)
Methods Findings Discussion
Penninxet
al., (2002)
Elderly
individuals
(>60 years
old) with
osteoarthritis
(439)
Centre for
Epidemiological
Studies
Depression Scale
administered
before and after
3, 6 and 9
months of
exercise
prescription.
Aerobic group significantly lowered depressive
symptoms overtime.
Resistance training showed no significant
difference in depression fromthe controlgroup.
When subjects were segmented by
adherence rates, the highest segment of
adherers to the resistance exercise showed a
greater benefit on mood than aerobic
exercise.
While aerobic exercise had a set intensity
relative to an individual’s maximum heart
rate reserve, no such prescribed intensity
existed for resistance training and these
subjects were allocated weight accordingto
comfortand choice.

43
Broman-
Fulkset
al., (2015)
Healthy
males and
females (77)
Anxiety
Sensitivity Index,
Acute Panic
Inventory,
Distress
Tolerance Test
and Acute
DiscomfortTest
applied
immediately
before and after
a single bout of
aerobic or
resistance
exercise.
Both aerobic exercise and resistance exercise
improved anxiety sensitivity.
Neither formof exercise effecteddiscomfortor
distress tolerance.
Once again aerobic exercise was carried out
to a set intensity of 65-75% maximum heart
rate whereas resistance exercise had no set
intensity and only had the criteria of a
weight the subject couldcomplete at least 10
repetitions with. Though in this case sets of a
resistance exercise was carried out to
exhaustion, e.g. until another repetition was
impossible.

44
2.6. Addressing the Research Problem
The above review shows that there is merit in applying resistance training when
improvement in mood state and mental health are the objectives (McLaffert et al., 2004).
However, there is still some uncertainty as to whether a difference in effect between
aerobic training and resistance training exists. If there is a difference, the question then
becomes which shows superior results (Netz et al., 2005). This presents a need for more
comparative research to be done. This presents the research question:
What is the difference, if any, between the acute effects of aerobic or strength
exercise on mood?
A comparative study analysing the acute differences of strength and aerobic exercise on
moodcan act as a startingpointto more longitudinallyfocusedstudies.These studies could
then review the effects of strength or aerobic training over months or years and it’s effect
on mental health. It will also provide some evidence for the prediction of the efficacy of
either intervention. This evidence would stem from previous research showing beneficial
acute effectscausing beneficialchroniceffects(Northetal., 1990). Indeed, North concludes
inthe 1990 studythat the subjectswhoshowedpositiveacute effects showed proportional
benefit chronically.
However,whilethe body of research is compelling in illustrating the research problem, an
importantnote tomake wasthat the mechanismsbehindthe positive relationship between
activity and depression was cited as “unknown” (Peluso et al., 2005). This ambiguity of a
causative linkincurrentresearchpresentsdifficultywhendataisextrapolatedby healthcare
professionals (Krishnan and Nestler, 2008). This leads to a lack of overall understanding in
the impact exercise has on mood. This lack of understanding then makes it difficult to
hypothesise what the difference, if any, between aerobic or strength exercise on mood
could be. This raises an important question as to what the underlying mechanisms behind
mood improvement with exercise are. This area is vital to consider as it helps clarify the
relationship found between exercise in mood (Taylor et al., 1985). It can present a clear
theoretical framework as to how exercise impacts mood and how strength training may
affectmooddifferentlytoaerobictraining. These relationships will allow the author to form
a hypothesisastowhichinterventionmay presentsuperiorimprovement in mood. As such,
below,the potential underlyingmechanismsbehindmood,exercise and its relationship are
reviewed.

45
2.6.1. UnderlyingMechanismsofMood and Mental Health
As stated, a lot of research has been conducted in psychology and mental health over the
last century (Hunt, 1936; Freud, 1981; Proctor et al., 2009). However, many of the studies
have beenfocusedonindirectandsubjective measurements such as POMS questionnaires
and relatedsurveysonperceivedemotions. These states prove very difficult to objectively
measure due to a demand for complex technology and procedures (Krishnan and Nestler,
2008). This stands in contrast to more physical sciences, such as medicine. In these fields,
direct,objective measurementslikebiopsies or X-Ray scans were carried out as early as the
19th century (Hopper, 1995). As stated above, Gross and Muñoz, in their 1995 review,
describe emotions as a “fuzzy category” but also as clear biological processes. However,
researchintothe physiological mechanismsbehindmoodstates,mental healthandillnesses
such as depression has been described as difficult due to ethical as well as technological
restraints (Krishnan and Nestler, 2008).
Despite this,progress has been made recently in regard to neurobiology and biochemistry
that couldhelpidentifyunderlyingprocessesbehindmood andmental health(Phillips et al.,
2008). This research offers objective means to assess psychological interventions and
validate their results. This is shown in one of the meta-analyses, that utlized objective
measures such measurements of brainwaves, skin temperature readings and heart rate
readings.Thiswasused intandemwith questionnaireresultstoassessanxietylevelsandthe
subsequentimpactof exercise on these measures (Petruzello et al., 1991). This shows that
the inclusion of objective measuresare possible in studies on mood and mental health and
that mood and mental health have physiological links. Below, these links are explored
further.
2.6.2. UnderlyingMechanismsofMental Illness
As shown above, the prevalence of mood state, mental health and illness demonstrates
physical characteristicsandrelationships(Phillips etal., 2008). In one study the contribution
of the limbic system in the brain, specifically the amygdala, in emotional control and
personality is detailed (Krishnan and Nestler, 2008). Another showed the influence of the
nearby prefrontal cortex (Phillips et al., 2008). Both of these areas have been shown to be
affectedby mental illness (Phillips et al., 2008; Krishnan et al., 2008). Indeed, Krishnan and
Nestler’sworkdemonstratedthatdepressedindividualshave been shown to have less grey
matterand overall smallerAmygdalaeandHippocampi.Thiscouldexplainthe poor memory
recall andemotional control of these populations.Meanwhile, Phillips and colleague's 2008

46
study acknowledged studies that show reduced Gray matter in the Prefrontal Cortex and
Anterior Cingulate Gyrus, with an enlarged Amygdala, when compared to healthy
populations. For an illustration of the effects of mental disorders on the brain, see Figure
2.2., 3 and 4 respectively. All of these areas of the brain, and their functions, have been
shown to be affected by exercise and their molecular responses (Wackerhage, 2014).
Below, the impact of exercise on these responses are examined.
Figure 2.2.: The neurobiological impactofdepressiononthe Hippocampusand the Nucleus
Accumbens region of the Amygdala (NAc) and associated levels of BDNF.
Source: Krisnan and Nestler, 2008.

47
Figure 2.3.: The neurobiological impact of BiPolar Disorder on the brain.
Source: Phillips et al., 2008.
2.6.3. UnderlyingMechanismsofExercise and Mood
Exercise hasbeenreportedtohave beneficialeffectson mood (Taylor et al., 1985), memory
(VanderBorght et al., 2007), and has correlatedwithbrain matter growth (Colcombe et al.,
2006). One of the underlyingmechanismstothese beneficial effectscould be the molecular
cascade thatoccurs as a resultof adaptationtoexercise.A full illustrationof these processes
can be seen in Figure 2.4.
Whenan individualundergoesstructuredphysical activityorexercisethere hasbeen shown
to be an increase in both Vascular Endothelial Growth Factor, commonly abbreviated to
VEGF, and Brain Derived Neurotrophic Factor, or BDNF (Wackerhage, 2014). This is a
response tobyproducts caused by exercise, like an increase in Nitric Oxide and Adenosine
Monophosphate Kinase,orAMPK(Huntand Navalta,2012). These are molecularsignalsthat
cause physiological processestotake place.VEGFhas beenshowntoincrease capillarisation
in gray matter in the brain, increasing blood flow to the brain (Radak et al., 2013).

48
Meanwhile,BDNFhasbeenhypothesizedtobe one of the primarymolecularsignalstobrain
matter growth (Jones et al., 1994).
These underlyingmechanisms are conducive to brain matter growth and health. This could
explain the benefits of exercise on mental health, which could explain the subsequent
improvement on mood (Taylor et al., 1985). Exercise induced endorphins have also been
proposed as a role in mood due to exercise (Harte et al., 1995). There has been some
verification in
Figure 2.4.: The molecularresponse to exercise and its associatedeffectson the brain and
nervous system.
Source: Singhal et al. 2014.

49
However, as mentioned above, the molecular signaling processes and subsequent
adaptationsare specifictothe trainingstimulus imposed (Coffey and Hawley, 2007). Coffey
and Hawley's 2007 review showed that adaptation to aerobic exercise leads to a greater
amount of AMPK-mediated signaling, whereas strength training causes greater Protein
Kinase B-mediated signals, which then increases Mammallian Target of Rapamycin, or
mTOR, levels, which increases protein synthesis, with AMPK down-regulating mTOR and
increasingPeroxisome proliferator-activated receptor gamma co-activator 1-alpha, or PGC-
1-alpha, which causes mitochondrial biogenesis, or an increase in muscular mitochondrial
growth. This could lead to the belief that aerobic training would be superior to strength
training due to the subsequent proportional BDNF increase with AMPK production
(Wackerhage,2014). However,strengthtrainingmayproduce greater levels of Nitric Oxide
(Collieretal., 2008), whichwouldcause subsequently greater VEGF signaling (Wackerhage,
2014). Figure 2.5. illustrates Nitric Oxides effect on muscle growth and blood vessel
proliferation. There is also a larger neural involvement in strength training (NSCA, 2008),
which would cause greater neural adaptation and brain matter growth in both the motor
cortex and relatedareas,accordingtoWackerhage’s2014. The difference anduniquenature
of the physiological responsestostrengthoraerobicresponsesisfurtherillustratedinFigure
2.6.
These mechanisms, along with the promising effect demonstrated for strength training in
North’s 1990 meta-analysis, leads the author to hypothesize that strength training may be
more beneficial for both acute and chronic mood state and mental health.

50
Figure 2.5.: The impact of eNOS, or endothelial Nitric Oxide, Synthesis on subsequent
molecular signals, particularly VEGF and it's associated adaptations of muscle growth,
mitochondria formation and Angiogenesis. Note: Angiogenesis refers to the creation of
new blood vessels.
Source: Wackerhage, 2014

51
Figure 2.6.: The unique molecular response and subsequent adaptations to different
exercise stimulus. Note how AMPK increases cause an associated downregulation, or
“blocking” ofMammalianTargetofRapamycin,or mTOR signalling,decreasingassociated
protein synthesis and consequent muscle hypertrophy.
Source: Coffey and Hawley, 2007.

52
As can be seenfromthe examinedmechanismsandphysiologicalprocessesabove,thereisa
cleartheoretical frameworkthat argues for the efficacy of exercise in improving mood and
mental healththatisbeginningtobe verified in vivo. However, as shown above, exercise is
diverse and heterogeneous in nature, with different means of exercise, each having their
ownunique physiological effects.There isalsoaphysiological basisforarguingthat strength
training may, in fact, be superior to aerobic training for improving mood state.
2.6. Conclusion
Currently, there is limited research comparing the effects of strength training and aerobic
exercise on mood (North et al., 1990; Pettruzzello et al., 1991). The purpose of this chapter
was to review the current literature on mental health, mood and physical activity and its
underlying mechanisms. This was done to illustrate the research problem and form the
researchquestion. Fromreviewing the literature above, it is clear there is a lot of research
on the impact of physical activity on mental health (Fox, 1999). However, a lack of
comparative research on the effects of strength training and aerobic exercise, or strength
training alone on mood state exists. This formed the research problem.
The lack of comparative data has thus demonstrated difficulties when applying these
findingsinexercise prescription (Petruzzello et al., 1991; Lawlor and Hopker, 2001). Though
aerobicexercise proveseffective,strengthexercise has also shown to be as effective (Netz
et al., 2005) or more effective (North et al., 1990) in improving mood. This led to the
formation of the research question:
What is the difference, if any, between the acute effects of aerobic or strength
exercise on mood?
StrengthtrainingproducesgreaterVEGFstimulationandassociatedprocessesandpotential
subsequentneuraladaptations(Wackerhage,2014; Collier et al., 2008). This, along with the
promisingresultsof strengthtrainingonmoodthus far (North et al., 1990) led the author to
hypothesisethatstrengthtrainingwill leadtoa greater improvement in mood than aerobic
exercise.
Though most of the studies listed focus on longitudinal effects of exercise and mood, the
acute effects mirror that of longitudinal effects (North et al., 1990; McLafferty et al., 2004).
These findings strengthen the purpose of the comparative study to be conducted by the

53
author onthe immediateeffects of both aerobic and strength training on mood state. As it
allows the findings to offer predictive data on what longitudinal outcomes may present.
This study will add to the sparse comparative research. This can then provide a basis for
furtherresearch of structuredphysical activityprogramson the effects of mood and mental
state.Thisresearchcan be appliedinpractical programdesignforbothhealthyandmentally
ill populations.

54
3. Methodology
3.1. Introduction:
North et al. 1990 highlights the need for greater utilization of anaerobic methods in
improving mood. In doing so, these authors call for comparative studies to be carried out.
Therefore,asnotedinChapter2, this study seekstoassess the difference between aerobic
and strengthtrainingonan individual'smoodstate.Tothisend, the purpose of this chapter
is to detail the methodology and methods that will be used.
Section 3.2. will consider the research philosophy of this study, before the research
approach is discussed in Section 3.3. Subsequently, section 3.4. will discuss the research
design, which will lead into Section 3.5. with the study’s review of the data collection
procedures.Section 3.6. will then explain how the collected data will be analysed. Finally,
Section 3.7. and Section 3.8. will review the ethical considerations of the research project
and evaluate the researchdesign,respectively.The chapterwillthenconclude by reviewing
the key decisions made in how the study will be carried out.
3.2. Research Philosophy
The examinationof the different philosophies that can be held by a researcher is important
as it can influence interpretation of data, both quantitative and qualitative, and can
influencethe type of experimental approachused (Gratton and Jones, 2007). There are two
distinctbranchesof philosophyinscientificresearch:positivismandinterpretivism (Crossan,
2003). These perspectives are presented in Table 3.1.

55
Table 3.1.: The differences between the two main philosophical outlooks in research:
Position and Interpretivism,
Source: Leitch et al., 2009
As seen above, interpretivist’s focus on understanding, and what is unique (Leitch et al.,
2009). In contrast,positivistsfavorobjectivityand tangibility. This means that quantitative,
tangible elements hold higher evidential authority than observed relationships (Crossan,
2003; Gratton and Jone, 2007; Ponterro, 2005; Yu, 1994). The purpose of this study is to
measure the impact of aerobic and strength exercise on mood. Therefore, a positivist
philosophyismostconsistentwiththe objectivesof the study.Asstated,thischoice informs
the research approach and research design. These will be further discussed below.
Assumptions Positivism Interpretivism:
Focus: Generaliseableand
representative data
Unique andcontext-specific
data
Resultsproduced: Quantitative,absolute
data
Relative context-specific
meaningsorinferences
Subjectand Researcher
relationship:
Rigid separation and
categrisation
Interactive andco-operative
Criteriafor evidence: Objective, tangible,
quantitative
Varied.Sociallyderived.
Research objective: Predictive, Explanatory
and generalizeable
data
Understanding of
motivations, unique findings
DesiredInformation: Universal patterns of
behavior, motivations
and occurences
Unique motivations,
behaviours or issues

56
3.3. Research Approach:
The researchapproach definesthe nature of the studybeingcarriedout and what the study
hopes to achieve (Choy, 2014). There are two main types of approaches: Quantitative and
Qualitative.Below,bothwill be reviewed to determine the most appropriate and effective
method for this study.
3.3.1. Qualitative Analysis and Quantitative Approach
As stated above, in order to determine the most effective method in research approach,
both a quantitative and qualitative approach must be reviewed (Gratton and Jones, 2007).
Quantitative analysisconcernsthe objective,descriptive,andusually numerical assessment
of causal relationshipsamongstanobservedphenomenon(Choy,2014). Qualitative analysis
concerns non-numerical observations of relationships between phenomena. These are
usuallybroadinscope and open-endedinresult(Grattonand Jones, 2007). The strengths of
a quantitative method are in the ability of its findings to be generaliseable across broad
populations (Choy, 2014). However, limitations in this approach include the possibility of
insignificant results causing the data to limited use as a source of descriptive information
(Choy, 2014).
This relates strongly with studies in psychology as many subjective elements such as
emotion,isverydifficultto quantitatively measured and defined (Gross and Muñoz, 1995).
Thisis perhapswhythere hasbeencall for the Profile of Moods States Questionnaire to be
simplified (Curran et al., 1995). This is in contrast to qualitative methods, which attempt to
explain the occurrences or relationships surrounding a certain phenomenon (Gratton and
Jones, 2007). This is a particular strength of the qualitative method.
As stated, the purpose of this research study is to provide descriptive data on whether
aerobic training or strength training is superior for the improvement of mood and mental
health. Thispurpose,alongwiththe researcher’sphilosophy, are the two primary reasons a
quantitative method was selected for this study. This choice, along with the nature of the
researchquestionandpurpose of the study,helpsindeterminingthe researchdesign,which
is discussed below.

57
3.4. Research Design
As mentioned, the purpose of this study is to assess the difference between aerobic and
strength training on an individual's mood state. The research being attempted is that of
empirical research. As such, this research project will use an experimental design. An
experimentisdefinedasa structuredactivityusedto collectevidence and draw a conclusion
to a hypothesis (Broota, 1989). Broota’s 1989 work details how it is used to add knowledge
to a givenfield.Assuch,thisdesignwill be usedto helpvalidate the hypothesisthatstrength
training may produce a superior acute effect on mood (Wackerhage, 2014). This approach
will utilise boththe collectionof secondarydata,seeninthe literature review,andadding to
this data through the collection of primary data through a research project (Gratton and
Jones,2007). This approachwill be utilisedinordertoprovide an objective and measurable
answer to the research question (Gratton and Jones, 2007). As such, this approach will
utilize deduction;seeFigure 3.1.,todraw conclusions from evidence from the primary data
collected.
The specific design will be that of a crossover randomized controlled trial, where subjects
will be assignedtobothconditionsatdifferenttime-points.The effectsof each intervention
condition are then compared against each other (Gratton and Jones, 2007). The primary
advantage to this type of experiment is that it allows testing of the hypothesis in a
controlled environment where external factors that may influence the result can be
accountedfor.This allows an answer to the research question to be given with a relatively
high degree of certainty (Gratton and Jones, 2007). A disadvantage of this experimental
approach liesinthe difficultyof attainingasufficientnumberof subjectsandcontrol of their
environment. This is further discussed below.

58
Figure 3.1.: The processes of Induction and Deduction in scientific research.
Source: Kristensen et al., 2008
3.4.1. Experimental protocol
As stated,thisexperimentwillbe a randomized controlled trial and use a crossover design.
This means that every subject will complete an aerobic and a strength session in random
order (Broota, 1989). Therefore, to ensure a structurally sound study, the experimental
protocol must be reviewed.
When examining the literature review chapter, a number of trends appear in the study
methods (North et al., 1990; Petruzello et al., 1991; Arent et al., 2000; Netz et al., 2005).
Firstly,a minimum intensity appears to be required in both strength and aerobic to elicit a
beneficial effect on mood (Thayer et al., 1994). Secondly, there appears to be a minimum
frequencyof three weekly strength sessions needed to demonstrate positive longitudinal
effectsonmood(Penninxetal.,2002). Thiscouldpossiblybe due toaerobicadaptation that
can occur insedentaryindividualswithsuchlightactivity as walking (ACSM, 2013). Strength
training seems to demand a higher intensity threshold for adaptation (Rhea et al., 2003).
Thisillustratesthe importance of aminimumlevelof intensityof the interventionprescribed
by the trainer. Thisleadsintothe thirdfinding.A minimaldurationof 21 minutesis required
for optimal effect in one session when acute measurements are taken (North et al., 1990;
Petruzello et al., 1991). As such, the below training parameters must be met by the trainer
and subjectinorderfor the sessiontobe judgedasviable forrecordingcanbe seen in Table
3.2.

59
Table 3.2.: The outline for the required parameters for each exercise session if
measurements are to be taken. A detailed overview of the strength and aerobic exercise
sessions can be seen Appendix 1 and 2 respectively.
Exercise Variable: Requirement:
Session structure: Exercise sessionstructure cannotbe different
among subjects selected.
Session duration: Aerobic and strength session must last a
minimum of 21 minutes in length.
Aerobic exercise intensity: The aerobic session must reach a
minimum average intensity of 60% the
subject’s maximum heart rate, as
estimated per the Karvonen formula
(ACSM, 2012), seen in Figure 3.2.
Strength exercise intensity: Strength sessions must reach a minimum
average intensity of 60% the subjects’
maximum strength, as assessed by the 1
Repetition Maximum test (NSCA, 2012).
Session timing: At least 48 hours between sessions.

60
3.4.2. Subject Sampling
The sampling procedures of subjects for a research project can be vital to the study's
reliabilityandvalidity(Grattonand Jones,2007; Campbell and Stanley, 1966). Campbell and
Stanley's1966 workoutlinesthatsubjectsshouldbe functionallyequivalent andrandomised
wherever possible. However, it is difficult to objectively set a standard for a healthy and
active individual becausedifferentorganizationsutilize different levels of activity as guides
(ACSM, 2013; NSCA, 2008). Because of this, a clear criterion was developed to stratify
subjects and aid subject sampling. This criterion is illustrated below in Table 3.3.
Table 3.3.: The subject sampling criteria.
Subject Variable: Requirement:
Subject gender: Subjects must be homogenous in gender.
Subject minimum activity level: Subjectsmustbe moderately physicallyactive,
as defined by the American College of Sports
Medicine (ACSM, 2013) through either
recreational activity or occupational activity.
Subject age: All subjectswill ideallybe male adultsoverthe
age of 18 but under the age of 60.
Trained individuals: Any subjects that have completed more than
one monthof structuredresistance training or
can meet the criteria of an intermediate or
elite level lifter (NSCA, 2008) will be denoted.

61
The above criteriawill helppreventanyvalidityorreliabilityissues,discussedfurtherbelow,
such as age related muscle loss, culminating at 60 years old (Wackerhage, 2014). Another
confounding factor is female specific issues such as menstrual cycle induced variations in
mood (Sander et al., 1983). Alongside this, fatigue has been shown to negatively impact
mood (Thayer et al., 1994). The above structure allows the researcher to control for these
variables. This will help the author produce a structurally sound research study, free from
bias and confounding factors.
Figure 3.2.: The Karvonen Formula, used to estimate the maximum heart rate of an
individual. Adapted by the author.
Source: ACSM, 2008.
3.5. Data Collection
3.5.1. Questionnaire
In this experiment, primary data will be collected in the form of the subjects’ mood state.
Thiswill be done throughadministering a questionnaire to the subjects. A questionnaire is
definedasastructuredand standardizedsetof questionsusedtoobtainspecificinformation
from a subject (Gratton and Jones, 2007). It is appropriate for this study because it is
noninvasive,low-cost,safe and easy for the subject to understand and carry out (McNair et
al., 1971). The questionnaire will take place according to a set format at a predetermined
time and location in a controlled setting (Gratton and Jones, 2007). This is to ensure
repeatability and reliability of findings. Below, in Table 3.4., the predetermined times,
locations and parameters are defined. An illustration of the timeline of the questionnaire
can be seen in Figure 3.3.
Karvonen Formula:
220 – (Subject’s Age) = Maximum Heart Rate
220 – (Age of Subject) = Maximum Heart Rate

62
Table 3.4.: Set parameters of the questionnaire.
Questionnaire Parameter: Condition:
Conditions of the Questionnaire The interview will be prescribed to the subject
face-to-face and supervised on a one-on-one
basisby a certifiedpersonal trainer. If necessary
a confidante of the interviewee can be present.
Thisis to ensure the subject is comfortable and
at ease.
Location of Questionnaire The locationof the interview will be that of the
training facility in which the session is
completed.
Timing of Questionnaire The first, or pre-session questionnaire will be
applied before the warm up, as this has shown
reliable resultsinpreviousstudies (North et al.,
1990; Penninx et al., 1991). The second
questionnaire will be appliedimmediately after
the completion of the cool down, as this has
beenalsoshowntoyieldeffectiveresult in past
studies (Steptoe and Cox, 1988).
Other Relevant Data Demographic information such as gender, age
and trainingexperience will be recorded so the
context of the findings can be better
understood (Gratton and Jones, 2007). The
details of the exercise session will also be
recorded to ensure consistency of conditions
among subjects (Broota, 1989).

63
Whendesigningaquestionnaire toassessthe moodof anindividual, itshouldbe noted that
a validatedtemplateforthistype of questionnairealreadyexistsinthe Profile of MoodState
Questionnaire (McNair et al., 1971). Below, the details of the Profile of Mood State
Questionnaire will be discussed.
Pre-Exercise
Questionnaire
Strength
Session
Post-Exercise
Questionnaire
Pre-Exercise
Questionnaire
Aerobic
Session
Post-Exercise
Questionnaire
48 Hours Rest
Figure 3.3.: Timeline of exercise sessions and questionnaire.

64
3.5.2. Profile of MoodStates
The Profile of Mood State,or POMS Questionnaireisa Likert style questionnaire, utilizing a
1,2,3,4 and 5 numerical assignmentstodescribeemotional state (McNair et al., 1971). A full
illustrationof the Likertscale assignmentof intensityandthe listof emotionscan be seen in
Figure 3.4. and the full POMS surveycan be seeninAppendix 3. A Likert scale is a numerical
scale, usually with a minimum of five bipolar points, with which data is assigned to each
number on the scale (Allen and Seaman, 2007). In this case, 1 indicating ‘Not at all’, and 5
indicating‘Extremely’for the perceived intensity of one of the 65 emotions surveyed. This
data will be recorded on the researcher’s electronic tablet. For the POMS questionnaire,
ordinal data, defined as data that is ordered, but the distance between the data cannot be
measured(Allen and Seaman, 2007). This data within the 65 emotional adjectives are then
calculatedintosubscalesthrough the method shown in Table 3.5. (McNair et al., 1971). It is
this subscale that is used to assess overall Mood and mental state (North et al., 1990). This
questionnaire will be used due to its reliability and validity in assessing mood state,
discussed in Section 3.8.

65
Table 3.5.: Formula’sforcalculatingthe subscaleofa Profile of Mood State Questionnaire.
Source: McNair et al., 1971
Figure 3.4.: An exampleof the Likert scaleused in the Profileof Mood State Questionnaire.
Not At All A Little Moderately Quite A Bit Extremely
1 2 3 4 5
Source: Allen and Seaman, 2007
Scale Formula
Tension Tense + Shaky+ On edge + Panicky+ Uneasy+ Restless+Nervous+Anxious
Anger Angry+ Peeved+Grouchy+ Spiteful +Annoyed+Resentful+Bitter+ Readyto
fight+ Rebellious+Deceived+Furious+ Bad tempered
Depression Unhappy+ Sorry forthingsdone + Sad + Blue + Hopeless +Unworthy+
Discouraged+ Lonely+ Miserable +Gloomy+ Desperate + Helpless+Worthless
+ Terrified+Guilty
Fatigue Worn out + Listless+ Fatigued+Exhausted+ Sluggish+Weary + Bushed
Confusion Confused+Unable to concentrate + Muddled+ Bewildered+Efficient+
Forgetful +Uncertainabout things
Vigour Lively+Active + Energetic+ Cheerful +Alert+ Full of pep+ Carefree +Vigorous
Total Mood
Disturbance
(Tension+Depression+Anger+ Fatigue + Confusion) - Vigour

66
3.6. Data Analysis
Data analysis is used in quantitative research to obtain an overall objective answer to the
research question (Gratton and Jones, 2007). This is important to ensure the results of the
researchprojectare collectivelyanalysed. Thiswill provide anoverall descriptive answer to
the researchquestion(Choy,2014).As such, once the data is collected, it must be analyzed
in order to identify overall trends and to ascertain if the collective results (Gratton and
Jones, 2007). Below, the tools used to carry out this analysis will be outlined.
3.6.1. Statistical Analysis
Statistical analysis is defined as the mathematical organization and calculation of data and
overall trends(Vincent,2012).Two mainareasof statistical analysisare inferentialstatistics,
examining relationships between data sets, and descriptive statistics, concerned with the
organization of data (Vincent, 2012).
The analysisof results is vital as it allows the identification and calculation of trends in the
body of data collected (Gratton and Jones, 2007). Inferential statistics will be used to
compare the effect of exercise on mood state, and descriptive statistical analysis will be
usedto stratifythese findingsbasedonthe subjects exercise type and training experience.
Thiswill be done through a paired t-test of the Profile of Mood State’s subscales and Total
Mood Disturbance score,see Table 3.5.The pairedversion of the t-test is used because the
same subjects are used in each separate intervention. This t test will be applied to the
difference of the pre and post subscale sores in order to find the average result, and
deviationsfrom this average, for the subjects (Vincent, 2012). In using these techniques, a
number of parameters must first be determined. These are outlined below in Table 3.6.

67
Table 3.6.: The parameters, which must be assigned when applying statistical analysis,
adapted by the researcher.
Source: Vincent, 2012
The assignmentof a confidence interval,shownabove,isimportantbecause if the Interval is
too low,andthe p-value toohigh, this could cause a type 1 error, where a significant result
is declared where it should not be. A p-value that is too low could cause a type 2 error,
where the null hypothesis is incorrectly accepted (Gratton and Jones, 2007). This is an
essential area in deciding whether the findings were caused by chance, deemed
insignificant, or by the intervention, deemed significant.
Statistical parameter: Definition: Chosenparameter or
value:
Confidence Interval The degree towhichthe
researcherisconfidentthatthe
findingsare accurate.
95%
Alpha value The precursor to the probability
value,determinedfromthe
confidence interval.
0.05
Probabilityvalue The value the findingsmust
surpasswhencalculatedbya z-
testto rejectthe ‘null’
hypothesis.
> 0.05

68
As can be seenabove, the statistical analysis of a study's findings has a large impact on the
reliability and comprehensibility of a study's results and subsequent discussion. For this
reason, great care must be taken into what statistical tools are applied and how they are
applied (Gratton and Jones, 2007; Vincent, 2012).
3.7. Ethics
Ethics is referred to as an area of philosophy that focuses on people’s actions, judgments
and justifications for those (Kitchener, 2000). With the use of Profile of Moods State
Questionnaire the authorwill be collecting information concerning the mood state of each
subject. Such information is highly personal (McNair et al., 1971). As such, the ethics of
carrying out this project must be reviewed to ensure an ethically sound piece of work is
produced(AquinasandHenle,2004). Below,the author will attempt to identify three main
areas of ethical issues:Harm,Confidentialityand Consent (Rogelberg, 2004). For the Ethical
Clearance form,see Appendix 4. For the Impact of research on human subjects/researcher
form and consent form template, see Appendix 4 and 5, respectively.
3.7.1. Harm
3.7.1.1. Psychological & Social Harm
Social harm isdefinedasharmthat isthe resultof a consequence of studyparticipation that
are not primarily physical in nature (Rogelberg, 2004). This harm can include association
withcertain‘stigmas’. MoodandPsychological effectsof exercise beingthe central themeof
the research,subjectsmaybe disturbedoruncomfortable bythe assessment of their mood
state (Moller-Leimkuhler,2002).This will be addressedbythe provisionof anonymity,which
is discussed below.
3.7.1.2. Physical Harm
Physical harmisdefinedasphysical or medical injury to the body (Rogelberg, 2004). Due to
lack of invasive measures in the intervention, i.e. the survey, risk of physical harm from
administeringthe questionnaire is minimal. However, the author can ensure the facility in
which the questionnaire is conducted is in accordance with current health and safety
regulations (Health, Safety and Welfare at Work Act, 2005) to minimise any risk.

69
3.7.3. Confidentiality& Anonymity
Confidentiality is described as being charged with confidential information or secrecy and
anonymity is described simply as “without name” or identification (Wiles et al., 2012). As
stated above, this provision will help protect clients from social or psychological harm
causedby the experiment. Complete anonymitywill be impossible,asthe researcherwill be
conducting the interview. However, after completing the interview, subjects will then be
anonymised, with only relevant demographic information kept.
3.7.4. Consent& Right to Withdrawal
Consent is defined by the Psychological Society of Ireland as “the outcome of a process of
agreeingtoworkcollaboratively”(PSI,2011).It isimportantinthisstudyin ensuringsubjects
are not coerced into giving certain answers, confounding results. To ensure this does not
occur, informed consent will be obtained, with subjects Informed of the parameters, the
purpose and their involvement in the study. They will also be informed of their right to
withdraw consent within a set timeframe: Before the questionnaire is completed.
3.8. Evaluating Research Design
3.8.1. Validity
The validity of a measurement is vital in research, as it will determine how applicable the
findings of the study are to general populations (Campbell and Stanley, 1966). Internal
validity concerns that certainty that the observed findings are a result of the intervention
alone. External validity concerns the extent that the studies results can be generalized to
external populations or individuals from the study (Isaac and Michael, 1971). These factors
are important to this study as it will help determine how applicable the findings are to
general populations and circumstances (Vincent, 2012). To ensure internal validity
confounding factors such as gender, age and training type have all been controlled for.
Ensuring external validity has been done through selection of the Profile of Mood State,
shown to have very high external validity (Reddon et al., 1985), and the use of healthy
subjects, of which the research findings will be aimed.
3.8.2. Reliability
The reliabilityof astudy’smethodsrefers tothe consistencyof a measure’s results (Gratton
and Jones,2007). One of the branchesof reliability,internal reliability, concerns the extent
that the measure is consistent within itself. The other, external reliability refers to the
measuresreliabilitybetweentests(Beck et al., 1996). Reliability is important for this study,

70
as it will minimize the occurrence of measurement errors. These can be quite frequent in
questionnaires (Isaac and Michael, 1971). For this reason, it is vital that test-retest
interviews happen alone whenever possible and with sufficient time between each
interview.
Both validityandreliabilityare vital areasof the study design to consider to ensure that the
findingscanbe generaliseable toindividuals outside of the subjects of the research project
(Gratton and Jones, 2007).
3.9. Conclusion
The primary purpose of this chapter was to assess the different methods available to the
researcherincarryingout the studyand to compare and ascertainwhich was most suitable.
As such, Section 3.1. introduced the chapter. Section 3.2. reviewed existing research
philosophies, stating the relevance of a positivist philosophy in this project due its
preference of objectivedata(Leitch etal., 2009). Thiswas mostconsistentwiththe objective
nature of the research question and thus was selected. Section 3.3. then discussed the
author's research approach. Inthissection,itwas decided that a quantitative approach was
most suitable to answer the research question due to the need to objectively measure a
causal relationship between two variables, namely exercise and mood state (Choy, 2014).
Subsequently, Section 3.4. examined the experimental design, where the decision to
structure the project as a randomized controlled trial experiment was made. This was
because thistype of experimentallowedfor acontrolledenvironment in which the variable
of exercise couldbe isolatedandexaminedinitsimpactonmood (Gratton and jones, 2007).
Experimental protocol and sampling procedures were also outlined. Section 3.5. and 3.6.
reviewedthe datacollection andanalysisrespectively. Here it was decided that the Profile
of Mood State questionnaire shouldbe usedtocollectdata and a paired t-test to analyse it.
Thiswas due to the establishedvaliditylf bothmethodsinmeasuringandanalyzingthistype
of data. Finally, Section 3.7 reviewed the ethical considerations of the experiment and
outlined consent procedures, and Section 3.8 evaluated the research design’s validity and
reliability.

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