TPB and mental toughness 1 Running head: TPB and mental ......TPB and mental toughness 5 75 multiple and accumulating stressors over a 6-week period to succeed in their goal to pass

TPB and mental toughness 1

Running head: TPB and mental toughness

Mental Toughness as a Moderator of the Intention-Behaviour Gap in the Rehabilitation

of Knee Pain

1Daniel F. Gucciardi*

1School of Physiotherapy and Exercise Science, Curtin University

Author Notes

*Address correspondence to Daniel Gucciardi, School of Physiotherapy and Exercise

Science, Curtin University, GPO Box U1987, Perth, Australia, 6845. Email:

[email protected]

To appear in: Journal of Science and Medicine in Sport

Accepted for publication: 29th June 2015

mailto:[email protected]


Abstract 1

Objectives: The purpose of this study was to investigate the role of mental toughness in 2

maximising the effect of intentions to perform rehabilitative exercises on behaviour among a 3

sample of people with knee pain. 4

Design: Cross-sectional survey, with a 2-week time-lagged assessment of exercise behaviour. 5

Methods: In total, 193 individuals (nfemale = 107, nmale = 84) aged between 18 and 69 years 6

(M = 30.79, SD = 9.39) participated, with 136 (70.5%) retained at both assessment points. At 7

time 1, participants completed an online, multisection survey that encompassed measures of 8

demographic details, severity of problems associated with the knee (e.g., pain, symptoms), 9

past behaviour, mental toughness, and the theory of planned behaviour constructs (TPB; 10

attitudes, subjective norms, perceived behavioural, intentions). Two weeks later, participants 11

retrospectively reported their exercise behaviour for the past 14 days using an online survey. 12

Results: Moderated regression analyses indicated that mental toughness and its interaction 13

with intention accounted for an additional 3% and 4% of the variance in exercise behaviour, 14

respectively. Past behaviour, attitudes, and mental toughness all had direct effects on 15

behaviour, alongside a meaningful interaction between intentions and mental toughness. 16

Specifically, intentions had a stronger effect on exercise behaviour among those individuals 17

high in mental toughness compared to those low in this personal resource. 18

Conclusions: The results of this study shed new light on the intention-behaviour gap by 19

indicating that mental toughness increases the likelihood that intention is translated into 20

action. 21

22

Keywords: intention-behaviour gap; mentally tough; personal resource; physical activity; 23

resource caravan; self-regulation 24


Introduction 25

Exercise – which includes general (e.g., walking) or disease-specific 26

recommendations (e.g., muscle strengthening) regarding planned and structured bodily 27

movements – is often prescribed for the prevention and rehabilitation of health conditions 28

such as knee osteoarthritis1, cancer2, and stroke3. Meta-epidemiological evidence indicates 29

that exercise is just as effective as drug therapy in the secondary prevention of coronary heart 30

disease, treatment of heart failure and prevention of Type 2 diabetes4. Despite these well 31

documented benefits of exercise for health and well-being, adherence to exercise 32

recommendations is often poor and therefore compromises the effectiveness of treatment5. 33

Thus, there is a need to better understand those factors that maximise peoples’ engagement in 34

exercise for rehabilitative and proactive purposes. 35

A diverse range of psychological, behavioural, environmental and social factors are 36

important for the initiation and maintenance of health behaviours6. As theory-based 37

interventions are more effective than atheoretical approaches7, considerable work has been 38

devoted to developing and testing theoretical explanations for health behaviours. Social-39

cognitive theories have received widespread attention as a backdrop upon which to better 40

understand individual-level determinants of behaviour. With regard to exercise, the theory of 41

planned behaviour (TPB8) is one of the most widely adopted frameworks. Within the context 42

of the TPB, one’s intention to engage in the target behaviour is the primary determinant of 43

whether or not one enacts the behaviour. Intention reflects the degree to which one is willing 44

or ready to engage in the behaviour, and the amount of effort they plan to exert towards it. In 45

turn, there are three distal cognitive and affective processes by which individuals form 46

intentions to enact behaviour: attitudes refer to one’s overall evaluation of the experiential 47

(affective) aspects and outcomes (instrumental) of the behaviour; subjective norms reflect 48

one’s perceptions of social pressure from significant others to perform or not carry out the 49


behaviour; and perceived behavioural control captures one’s beliefs regarding the ease or 50

difficulty with which the behaviour can be executed. The usefulness of the TPB for 51

explaining a range of health behaviours including exercise is supported by meta-analytic 52

evidence9. 53

Intentions are clearly important for exercise behaviour10, yet there is a noticeable 54

‘gap’ in that good intentions do not always translate into action11. Accordingly, considerable 55

effort has been directed towards clarifying our understanding of variables that may moderate 56

this association. There is a large body of work that has focused on post-intentional, self-57

regulatory strategies such as action and coping planning as a means by which to translate 58

exercise intentions into behaviour12. Meta-analytic evidence indicates that these self-59

regulatory techniques are effective processes by which to translate physical activity intentions 60

into behaviour13. Despite the benefits of these self-regulatory techniques for bridging the 61

intention-behaviour gap, adherence to these strategies are modest14. An alternative yet 62

complementary approach is to examine personal resources that capture individual differences 63

in peoples’ existing self-regulatory capacity. 64

Learning about individual differences that may foster or forestall purposeful processes 65

designed to regulate thoughts, emotions and behaviours is likely to generate new insights into 66

the intention-behaviour relation. Representing one such personal resource, mental toughness 67

refers to a psychological capacity to attain and sustain one’s self-referenced standards or 68

objectives (e.g., goals, performance) despite varying degrees of situational demands15. Since 69

perseverance is a key behavioural signature of mentally tough individuals16,17, there is reason 70

to believe that this personal resource may foster the translation of intentions into behaviour. 71

For example, research has shown that individuals who self-report high levels of mental 72

toughness are more likely to produce higher levels of work performance, achieve more 73

progress towards academic and social goals over a university semester, and withstand 74


multiple and accumulating stressors over a 6-week period to succeed in their goal to pass a 75

selection test15. Qualitative work indicates that mentally tough individuals identify, evaluate 76

and re-assess goals18, and use long-term goals as a source of motivation19. Mental toughness 77

is therefore one potentially important source of individuality that may underpin the effective 78

regulation of thoughts, emotions and behaviours or the application of self-regulatory 79

strategies in the pursuit of volitional behaviours like exercise rehabilitation. 80

The purpose of this study was to test whether or not mental toughness can bridge the 81

intention-behaviour gap. As mental toughness is a personal resource that fosters behavioural 82

perseverance on a task17 and therefore facilitates positive outcomes for volitional behaviour15, 83

it is expected to moderate the intention-behaviour association such that the strength of the 84

relation will be greatest for people with high levels of mental toughness when compared with 85

low levels of this personal resource. As the TPB is most pertinent when behaviour is 86

volitional (i.e., driven by the will or intent of an individual to perform some action8), the 87

focus in this study is on people with knee pain who have been prescribed rehabilitative 88

exercises by a physiotherapist. Although the home-based rehabilitation exercises have been 89

prescribed by a physiotherapist, it is up to individuals as to whether or not they execute these 90

behaviours according to the professional advice. The TPB has been used extensively to study 91

a wide variety of health behaviours, yet there have been few applications of this theoretical 92

framework in people with knee pain. Thus, this study also provided an opportunity to test the 93

robustness of key theoretical expectations of the TPB. 94

Methods 95

A total of 193 individuals (nfemale = 107, nmale = 84) aged between 18 and 69 years (M 96

= 30.79, SD = 9.39) participated in this study. Of the 193 participants who started the study, 97

136 (70.5%) completed both assessment points. People who met the following criteria were 98

eligible to participate: in the past month, experienced (i) knee pain accompanied by morning 99


stiffness lasting less than 30 minutes, (ii) crepitus on active movements, (iii) tenderness of the 100

bony margins of the knee joint, and (iv) had consulted a physiotherapist about their knee pain 101

and therefore had been provided with information regarding specific rehabilitative exercises. 102

Participants were excluded if they had ever experienced a cardiac event (e.g., heart attack), 103

had major bone or joint surgery (e.g., ACL), or a BMI greater than 3520. 104

Demographic data were collected by self-report and included age, gender, height, and 105

weight. The subscales of pain, symptoms and function in activities in daily living from the 106

Knee Injury and Osteoarthritis Outcome Score21 provided an assessment of the severity of 107

problems associated with the knee. Mental toughness was assessed using an established 8-108

item inventory15. Items designed to capture the theory of planned behaviour variables were 109

developed in accordance with Azjen’s22 guidelines (see Appendix A of the Supplementary 110

Material). TPB instruments that have been developed in accordance with these guidelines 111

have demonstrated excellent reliability and validity in previous research23,24. Consistent with 112

the approach used in previous research25, exercise behaviour was assessed using a self-report 113

measure in which participants indicated the frequency of rehabilitative exercises performed 114

on average for 30 minutes over the past two weeks. In this study, rehabilitative exercises 115

were defined as those activities that are intended to reduce the amount of pain experienced 116

and/or strengthen those muscles that support the knee and surrounding areas with the view of 117

preventing future knee pain. 118

All study procedures were approved by [name blinded for peer-review] human 119

research ethics committee. Participants were recruited and completed the study anonymously 120

online via SocialSci (www.socialsci.com). Potential participants were recruited to this 121

platform via online advertising, print media, and live recruitment where they signed up to 122

take part in academic research in return for small points-based Amazon credits. The first 123

section of the survey contained measures to ascertain an individual’s eligibility for the study. 124

http://www.socialsci.com/


Eligible and consenting participants subsequently provided demographic details and 125

completed measures of the TPB, severity of problems associated with knee pain, mental 126

toughness, and their intended exercise behaviour over the preceding 14 days. Two weeks 127

later participants provided a self-report of their exercise behaviour over the preceding 14 128

days. 129

Data was initially screened for violations of assumptions of normality and outliers. 130

First, to examine the possibility of an attrition bias, an analysis of variance (ANOVA) was 131

performed to test for differences in the study variables at time 1 between those participants 132

who completed the time 2 survey and those who did not respond, whereas a chi-square (χ2) 133

analysis was performed for gender (see Table 1). Second, a hierarchical multiple regression 134

was performed to assess the effects of the distal predictors of intentions. Covariates were 135

entered at Step 1 (demographic factors, severity of knee problems, and past behaviour), with 136

attitudes, subjective norms and perceived behavioural control added at Step 2. Third, a 137

moderated hierarchical multiple regression was performed to assess the importance of social-138

cognitive factors and mental toughness as determinants of exercise behaviour, while 139

controlling for covariates. All independent variables were standardised prior to the regression 140

analyses; gender was dummy coded (0 = female, 1 = male). Covariates were entered at Step 141

1; the TPB variables were entered at Step 2; mental toughness was entered at Step 3; and the 142

interaction between mental toughness and intentions was entered at Step 4. This approach 143

permitted an examination of the incremental validity of mental toughness, and its interaction. 144

Simple slopes analyses of the interaction effect were plotted and tested at one standard 145

deviation above and below the mean, and at the mean of mental toughness26. 146

Results 147

Data screening revealed no violations against assumptions of multivariate outliers 148

(i.e., using a p <.001 criterion for Mahalanobis D2), skewness (all variables < + 1.3), and 149


kurtosis (all variables < + 3.6) for subscales of all study variables. However, seven univariate 150

outliers were identified with regard to the psycho-social variables (i.e., z score > + 3.29). As 151

the exclusion of these outliers did not alter the results of the main analyses, they were 152

retained for all analyses and the reported findings. Bivariate correlations among study 153

variables and internal reliability estimates of self-reported severity of knee problems, mental 154

toughness and the TPB are provided in Appendix B of the Supplementary Material. All 155

measures demonstrated adequate levels of internal reliability. An overview of the ANOVA 156

summary statistics is detailed in Table 1. Participants who responded at both time points did 157

not differ from those individuals who dropped out of the study. With regard to gender, 158

females (n = 39; 36.4%) were more likely than males (n = 18; 21.4%) to drop out of the 159

study, χ = 5.95, p = .051. 160

The control variables accounted for 12% of the variance in intention, F (7, 128) = 161

2.56, p = .017, η2 = .129, 90% CI = .012, .171 (see Steiger27 for an explanation of the use of 162

90% confidence intervals for eta squared). Only past behaviour was a meaningful 163

determinant of intention (B = .31, 95% CI = .13, .49, p = .001). The inclusion of the TPB 164

distal predictors of intentions accounted for an additional 27% of the variance, F (3, 125) = 165

18.56, p < .001, η2 = .308, 90% CI = .188, .393. Past behaviour (B = .24, 95% CI = .09, .39, p 166

= .002), attitudes (B = .30, 95% CI = .15, .46, p < .001) and perceived behavioural control (B 167

= .30, 95% CI = .14, .45, p < .001), but not subjective norms (B = .10, 95% CI = -.06, .27, p = 168

.223), were important determinants of intention. 169

With regard to the prediction of exercise behaviour, at Step 1 of the moderated 170

regression, the control variables accounted for 15% of the variance in exercise behaviour, F 171

(7, 128) = 3.16, p = .004, η2 = .147, 90% CI = .029, .201. There was a significant effect for 172

past behaviour (B = 1.30, 95% CI = .67, 1.93, p < .001). The inclusion of the TPB variables 173

to the model at Step 2 accounted for an additional 11% of the variance in exercise behaviour, 174


F (4, 124) = 4.48, p = .002, η2 = .126, 90% CI = .030, .197. There were significant effects for 175

past behaviour (B = .90, 95% CI = .27, 1.54, p = .006) and intentions (B = .86, 95% CI = .17, 176

1.60, p = .015). The inclusion of mental toughness at Step 3 indicated that the main effect (B 177

= .72, 95% CI = .11, 1.33, p = .022) accounted for an additional 3% of the variance in 178

exercise behaviour, F (1, 123) = 5.41, p = .022, η2 = .042, 90% CI = .003, .113. At Step 4, the 179

inclusion of the interaction between mental toughness and intentions accounted for an 180

additional 4% of the variance in exercise behaviour, F (1, 122) = 6.30, p = .013, η2 = .049, 181

90% CI = .006, .123. There were significant effects for past behaviour, attitudes, mental 182

toughness and the interaction between intentions and mental toughness (see Table 2). Simple 183

slopes analyses indicated that the association between intentions and exercise behaviour was 184

its greatest when mental toughness was high (B = 1.172, t = 3.67, p < .001), with a less 185

amplified positive relation at moderate mental toughness (B = .50, t = 1.379, p = .17) and a 186

slightly inverse association at low levels of mental toughness (B = -.17, t = -.40, p = .69). A 187

visual display of the simple slopes is depicted in Figure 1. 188

Discussion 189

The purpose of this study was to investigate the role of mental toughness in 190

maximising the effect of intentions to perform rehabilitative exercises on behaviour among a 191

sample of people with knee pain. Overall, the findings of this study provided additional 192

support for key theoretical expectations of the TPB in a sample of people with knee pain. In 193

terms of unique contributions, the results of this study shed new light on the intention-194

behaviour gap by indicating that mental toughness increases the likelihood that intention is 195

translated into action. 196

Meta-analytic reviews of prospective correlational tests of the TPB have shown that 197

the TPB explains small and moderate amounts of variance in behaviours and intentions, 198

respectively9,10. As one of the first tests of the TPB in people with knee pain, the results of the 199


current study provided additional support for several of these theoretical expectations. First, 200

the TPB constructs explained over twice as much of the variance in intentions when 201

compared with behaviour. Second, attitude and perceived behavioural control evidenced the 202

greatest association with intentions. Third, although not amenable to change, past behaviour 203

is a primary determinant of future behaviour. Despite these positive results, several of the 204

current findings were incongruent with existing meta-analytic data9,10 and theoretical 205

expectations8. For example, the effect of intention on behaviour was attenuated by the 206

inclusion of mental toughness and its interaction with intention. Moreover, perceived 207

behavioural control was not directly related to exercise behaviour, even when mental 208

toughness was excluded from the analysis. Collectively, these results strengthen claims that 209

the efficacy of the TPB depends on the target behaviour9, and reinforce the importance of 210

formative research as a precursor to effective TPB-based interventions. 211

This study makes an important contribution to the literature by demonstrating the 212

importance of mental toughness as a determinant of exercise behaviour. Both direct and 213

moderating effects of mental toughness on exercise behaviour were examined and found to 214

be meaningful. In terms of the moderation hypothesis, intentions had a stronger effect on 215

exercise behaviour among those individuals high in mental toughness compared to those low 216

in this personal resource. This study is the first to report such an interaction effect. As these 217

effects were evidenced while accounting for control variables and the TPB constructs, these 218

findings provide further evidence for the incremental validity of mental toughness over and 219

above well-established predictors of volitional behaviours. From a practical standpoint, it is 220

encouraging that individuals with high levels of mental toughness and intentions reported 221

engaging in over three sessions of 30 mins per week, which is consistent with exercise 222

recommendations for people with knee osteoarthritis28. 223


At least two possible explanations might account for the direct and moderation effects 224

of mental toughness observed in this study. First, given that perseverance is a behavioural 225

signature of mental toughness16,17, it is likely that individuals with high levels of mental 226

toughness persist longer in duration when working towards their exercise goals. Second, as a 227

resource caravan that is central to coping processes (e.g., affective self-regulatory 228

capabilities, ability to bounce back from setbacks)15, mental toughness may prove beneficial 229

in ensuring that people are able to carry out their intentions despite the presence of stressors, 230

especially when perceived behavioural control for the target behaviour is low. Nevertheless, 231

the inclusion of mental toughness as an additional predictor within the context of the TPB is 232

at odds with the principle of compatibility; that is, a new variable should be behaviour-233

specific and therefore measured at the same level of specificity as the target behaviour or 234

action29. It is therefore important that these findings are replicated in future research before 235

any definitive conclusions can be made in this regard. 236

Conclusion 237

This study is the first to test the moderating role of mental toughness on the intention-238

exercise behaviour relation. Missing from this study is an understanding of how mental 239

toughness enables people to engage in exercise rehabilitation. For example, do individuals 240

simply try harder and persevere? Are people less affected by stressors? There are other 241

limitations to the current study that open up important avenues for future research. First, all 242

study variables were measured via self-report and therefore may be influenced by common 243

method bias. Second, despite the temporal lag in the assessment of exercise behaviour over a 244

2-week period, the design is not longitudinal nor experimental in nature and therefore cannot 245

provide evidence for causality. Third, the large age range of participants in this study is both 246

a strength (e.g., ability to generalise) and weakness, as the TPB is most predictive amongst 247

young people9. Finally, it is difficult to control for motivational strategies offered by 248


physiotherapists and their influence on patients in an observational, cross-sectional study that 249

did not incorporate measures of these variables. Despite these limitations, this study offers a 250

new insight into a personal resource that may help translate good intentions into exercise 251

behaviour. 252

Practical Implications 253

• Mental toughness is an important personal resource that can enable people to make the most 254

out of good intentions 255

• Enhancing peoples’ perceptions of control over a specific behaviour can enhance the 256

likelihood that they will form strong intentions to engage in the behaviour 257

• For people with low intentions, emphasise the experiential or affective aspects (e.g., 258

enjoyable) and instrumental outcomes (e.g., individualised benefits) of engaging in exercises 259

for their knee pain 260


Acknowledgements

Gucciardi is supported by a Curtin Research Fellowship.


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Table 1. Overview of ANOVA summary statistics for attrition bias analyses (Note: normalised scores for symptoms, pain, and daily function).

Non-Responders (n=57) Responders (n=136) ANOVA (df = 1, 191)

M SD 95% CI M SD 95% CI F p η2 [90% CI]

Age 30.73 8.42 28.50, 32.97 30.81 9.80 29.15, 32.47 .003 .957 .000 [.000, .001]

BMI 24.46 5.01 23.13, 25.80 24.59 4.37 23.85, 2533 .032 .858 .000 [.000, .007]

Symptoms 71.42 16.94 66.93, 75.92 69.11 15.82 67.50, 72.09 .822 .366 .004 [.000, .033]

Pain 76.51 17.63 71.83, 81.19 75.93 15.54 73.30, 78.57 .050 .823 .000 [.000, .011]

Daily function 85.84 17.48 81.20, 90.48 81.10 18.06 78.03, 84.17 2.824 .095 .015 [.000, .054]

Attitudes 4.89 1.18 4.58, 5.20 4.98 1.18 4.78, 5.18 .245 .621 .001 [.000, .022]

Subjective norms 4.05 1.56 3.63, 4.46 3.95 1.45 3.70, 4.19 .183 .669 .001 [.000, .020]

Behavioural control 4.90 1.32 4.55, 5.25 4.54 1.39 4.31, 4.78 2.701 .102 .014 [.000, .053]

Intentions 3.20 1.67 2.75, 3.64 3.10 1.61 2.83, 3.37 .137 .712 .001 [.000, .019]

Mental toughness 5.12 1.14 4.82, 5.43 4.96 1.02 4.79, 5.14 .891 .346 .005 [.000, .034]

Exercise behaviour 1.12 2.84 .36, 1.87 .90 2.19 .53, 1.27 .331 .565 .002 [.000, .024]


Table 2. Moderated regression (Step 4) predicting exercise behaviour from TPB variables,

mental toughness, and interaction term while accounting for demographic covariates.

Unstandardised Coefficient

B 95% CI

(low, high)

SE β t p

Gender -.72 -1.84 .39 .56 -.10 -1.28 .202

Age -.18 -.74 .39 .29 -.05 -.62 .538

BMI .22 -.32 .77 .28 .06 .80 .426

Past behaviour 1.04* .43 1.66 .31 .29* 3.35 .001

Symptoms -.29 -.98 .39 .34 -.08 -.86 .394

Pain .12 -1.11 1.36 .62 .03 .20 .844

Function .11 -1.09 1.32 .61 .03 .18 .855

Intentions .50 -.22 1.22 .36 .14 1.38 .170

Attitudes .72* .07 1.36 .33 .20* 2.19 .030

Subjective norms -.09 -.72 .53 .32 -.03 -.30 .767

PBC -.44 -1.09 .21 .33 -.12 -1.34 .184

Mental toughness .82* .21 1.42 .30 .23* 2.67 .008

MTxINT .67* .14 1.20 .27 .21* 2.51 .013

Note: BMI = body mass index; PBC = perceived behavioural control; MTxINT = interaction

between mental toughness and intentions; gender (0 = female, 1 = male).


Figure 1. Visual display of simple slopes of the interaction between mental toughness and

intentions for exercise behaviour.


Supplementary Material

Appendix A – Items of the theory of planned behaviour

Items measuring attitude were preceded by the common stem, “For me, doing rehabilitative

exercise, on average, for 30 minutes about 3 times a week over the next 2 weeks would be…”

Participants’ responses are made on four 7-point semantic differential scales with the following bi-

polar adjectives: “pleasant-unpleasant”, “enjoyable-unenjoyable”, “beneficial-harmful” and “wise-

foolish”. Measures of subjective norms (two items; e.g., “People who are important to me think I

should do rehabilitative exercises for my knee, on average, for 30 minutes about 3 times a week

over the next 2 weeks”), perceived behavioural control (two items; e.g., “How much control do you

feel you have over completing rehabilitative exercises for your knee, on average, for 30 minutes

about 3 times a week over the next 2 weeks”) and intention (two items; e.g., “I intend to spend, on

average, 30 minutes doing rehabilitative exercises for my knee about 3 times a week over the next 2

weeks) were rated on 7-point Likert-type scales (e.g., 1 = strongly disagree, 7 = strongly agree).


Appendix B – Descriptive statistics and bivariate correlations among study variables for the total sample (n = 136).

1 2 3 4 5 6 7 8 9 10

1 Exercise (t1) -

2 Exercise (t2) .35** -

3 Attitudes .18* .34** (.82)

4 Subjective Norms .17 .14 .28** (.79)

5 Perceived Behavioural Control .00 .13 .34** .22** (.84)

6 Intentions .32** .40** .48** .30** .41** (.96)

7 Mental Toughness -.02 .21* .02 .09 .36** .28** (.91)

8 Symptoms -.14 -.13 -.14 -.21* .01 -.13 -.03 (.67)

9 Pain -.33** -.14 -.03 -.32** .04 -.17 -.07 .59** (.87)

10 Function -.30** -.12 -.04 -.34** .09 -.17 -.06 .58** .89** (.96)

Mean .90 1.86 4.98 3.95 4.54 3.10 4.96 50.16 75.93 81.10

Standard deviation 2.19 3.61 1.18 1.45 1.39 1.61 1.02 11.59 15.54 18.07

Range 0-16 0-28 1-7 1-7 1-7 1-7 1-7 10.71-85.71 22.22-100 25-100

Note: internal reliability estimates are presented on the diagonal in parentheses; * p < .05; ** p < .001.

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