Health Education Research Advance Access published online on October 20, 2008
Health Education Research, doi:10.1093/her/cyn051
Application of a social cognitive model in explaining physical activity in Iranian female adolescents
1 Department of Public Health, School of Health, Kurdistan Medical University, Pasdaran Street, PO Box 66177-13391, Sanandaj, Iran
2 School Of Exercise Science, Physical & Health Education, University of Victoria, Faculty of Education, University of Victoria, PO Box 3010, STN CSC, Victoria, British Columbia V8W 3N4, Canada
3 Faculty of Physical Education and Recreation, University of Alberta, E4-88 Van Vliet Centre, Edmonton, Alberta T6G 2H9, Canada
Correspondence to: * Correspondence to: P. Taymoori. E-mail: parvaneh_tay{at}yahoo.com
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Abstract |
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Adolescent Iranian girls are at high risk for physical inactivity due to cultural barriers such as restrictions regarding exercising in public and research is needed to explore ethnic and gender-related factors associated with physical activity (PA) participation. Using social cognitive theory as the guiding model, the purpose of this study was to test the fit and strength of barriers self-efficacy, outcome expectations, self-regulation and social support in explaining PA in female Iranian adolescents (n = 558). Using path analysis, social support was modeled as an antecedent of self-efficacy and outcome expectations, while self-efficacy was modeled as an antecedent of outcome expectations, self-regulatory planning and PA. Outcome expectations and self-regulatory planning were subsequently modeled as additional antecedents of PA. The model explained 52% of the variance in PA. The two significant (P < 0.05) direct effects were from self-efficacy and outcome expectations. Social support from mothers, fathers and friends had significant indirect effects on PA through self-efficacy. These results will allow for future research and interventions not only for female Iranian adolescents but also for similar cultural and immigrant groups that have been neglected to date in the PA literature.
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Introduction |
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TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionConflict of interest statementAcknowledgementsReferences |
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Regular physical activity (PA) has favorable effects on weight maintenance and/or loss, improved psychological well-being and cardiovascular fitness in adolescents [1]. Conversely, physical inactivity in youth is a risk factor for overweight and obesity, higher triglyceride levels, anxiety and depression [2] as well as for elevated blood pressure [2, 3] and type II diabetes [4]. The youth obesity epidemic has heightened interest in PA, which is recommended as a part of obesity control and health promotion in general [1, 5]. Recent recommendations state that school age youth should participate in
60 min of moderate-to-vigorous PA per day [6]. However, most adolescents do not meet these recommendations [7], and PA participation tends to decline with age [8]; this may be particularly worrisome for females as several studies have reported a decline in PA in girls [9]. Most of the research in this area has examined PA in adolescents from Western nations. However, there is some evidence that problems with physical inactivity and obesity extend to other nations with different cultural contexts. A recent study of adolescent Iranian girls found that 64% of individuals were in pre-adoption stages of PA (i.e. were not active on a regular basis) and averaged <30 min of daily PA [10]. Related to this, there has been a documented increase in the prevalence of obesity among schoolchildren in Iran and it is significantly more prevalent in girls (6.1 %) than in boys (3.3 %) [11]. These authors attribute this increase in obesity to economic development and modernization that has occurred during Iran's post-war reconstruction and it is predicted that the trend toward increased obesity will continue such that rates will be the same as in Western countries. In addition to the influence of modernization on obesity and PA, adolescent Iranian girls are at a particularly high risk for adopting sedentary behavior due to specific cultural barriers, such as restrictions regarding exercising in public. Thus, an understanding is needed of the foundation of PA participation in adolescent girls and to explore ethnic and gender-related factors associated with PA participation. In particular, more research is needed to identify the correlates of PA among girls from diverse cultures so that intervention programs can be tailored to the specific needs of Iranian girls in achieving enough PA for them to gain health benefits.
One model commonly used in predicting and explaining health behavior that can be used to examine adolescent PA with this population is social cognitive theory (SCT) [12]. SCT identifies reciprocally influencing characteristics of the person (including cognitions), the environment and the behavior itself [12]. An individual's behavior is uniquely determined by the interaction of these characteristics. Important variables within this model include self-efficacy, outcome expectancies and self-regulation. Self-efficacy is a domain specific variable and within this field is the belief that an individual holds in his or her ability to achieve a given PA goal. SCT proposes that confidence in personal ability to carry out a behavior (i.e. self-efficacy) influences the direction, intensity and persistence of behavior [12, 13]. Bandura considers self-efficacy to be the central determining factor of human action. Consistent with these ideas, self-efficacy has been shown to be an important correlate of PA in adolescents [14, 15]. Further, self-efficacy is proposed to be a multidimensional construct, consisting of subdimensions (e.g. barriers, support seeking, competing activities and environmental change) related to specific aspects of being physically active which in different contexts may have different levels of influence [12]. It has been found that Iranian adolescent girls face many barriers to being active [10] and is therefore a construct that would be useful with this population.
It has also been suggested that outcome expectations and self-regulatory efforts are directly influenced by self-efficacy which is the most consistent and largest correlate of activity [16]. Outcome expectancies are beliefs about the likelihood that PA will produce benefits or undesired outcomes and can include social- or appearance-related beliefs. If an individual believes a behavior is linked to a desirable outcome, there is a greater likelihood of regular PA [17, 18]. Accordingly, girls who have high PA self-efficacy will be more likely to pursue goals on their expectations of desirable outcomes of being physically active (i.e. outcome expectancy value). Outcome expectancy has been documented as a determinant of PA among high school students [19, 20]. Further, self-efficacy might influence PA through self-management strategies such as thoughts, goals, plans and acts. Self-regulation is the use of skills such as goal setting, self-monitoring and self-reward [17, 18] that are used to reinforce a target behavior and is significant predictor of adolescents’ PA [21–23]. Dishman [24] found that self-management strategies mediated the independent associations of self-efficacy with PA in girls’ sixth and eighth grades. Further, self-efficacy and outcome expectancies may interact such that if efficacy beliefs are high but outcome expectations are low, resignation or apathy might result. If both are high, then a sense of personal satisfaction can result [12].
Another factor to consider in SCT is social support as this variable has been shown to serve as powerful influence on behavior. Family support and peer social support have been shown to directly and indirectly (via self-efficacy) be related to PA in adolescent North American girls [25]. Family support has been a consistently reported correlate of PA in adolescents [26, 27]. Parents may support PA by providing transportation and encouragement [28–30] as well as by participating in PA with their children [27, 31]. Family support was a strong predictor of team sport participation and a modest predictor of moderate-to-vigorous PA in eighth-grade girls in one study [31]. Several interventions have proven to be successful in increasing PA of youth by increasing family support [32–34].
No studies have yet applied SCT to PA in Iranian female adolescents but SCT could provide a useful framework for this understudied population. Therefore, the purpose of this study was to use ordinary least squares (OLS) path analysis to test the fit and strength of the self-efficacy, outcome expectations, self-regulation and social support constructs from SCT in explaining PA in female Iranian adolescents. Due to the importance that family plays in these girls’ lives, it is hypothesized that the findings of previous researchers [25] will be replicated and social support will prove to be a direct and indirect predictor of PA behavior. Further, because parents, friends and siblings may have qualitatively different influences on an adolescent's PA (e.g. parents may provide support through driving the girl to a sports practice whereas a friend may be active with the girl) [35], it was hypothesized that these sources of social support would have different effects on PA behavior in this sample. An additional purpose was to examine the interaction between self-efficacy and outcome expectations and the influence on PA behavior.
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Methods |
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Female adolescents (n = 570) were recruited using cluster random sampling methodology. In this way, four all-female junior high and four all-female high schools were randomly selected from 133 schools in Sanandaj, Iran, and students in these classes were invited to participate in the study. Response rate was 97.9% (n = 558). Because of the very high response rate, it was decided to simply delete cases with missing data. The mean age of participants was 14.43 years (SD = 1.60; range: 12–17). The study was approved by the educational authorities and by the institutional human participants committee. The study investigator sent a written information sheet and consent form for the parents and participants to sign.
All the instruments were translated into Persian by a bilingual researcher and then validated using the standard back translation technique by a native Persian health promotion specialist who was also fluent in English. The questionnaires were backward translated into English by a native English speaker living in Iran. Five bilingual Iranian health behavior and education, exercise psychology and instrument development experts were asked to evaluate the pilot instrument for appropriateness and relevance of the items. The instruments were then revised and modified. The questionnaire was pilot tested with a separate sample of participants (n = 115) who were students from randomly selected junior high and high schools in Sanandaj, Iran (57 females and 58 males; age range: 12–17 years). Revisions in wording and presentation were made based on empirical findings and recommendations from pilot study participants. Items that are pertinent to Iranian culture were added to the final instruments as detailed below. For the current study, questionnaires were administered to students in their classrooms. A researcher remained in the room during the questionnaire administration and answered any questions.
PA was assessed using a modified version of the Child/Adolescent Activity Log (CAAL) [36]. Minor modifications were made to the CAAL instrument based on the feedback received from the adolescents in the pilot study. The CAAL requires respondents to keep a log of their time spent in PA for six consecutive days (Saturday through Thursday). Total PA (in minutes) for the 6 days was divided by six to provide an average number of minutes spent in PA each day. The 1-week test–retest reliability of the CAAL with 115 Iranian adolescents was 0.98.
The social support measure asks respondents to indicate the quantity of support they receive from family, sibling and friends to increase their PA [37]. The 24-item measure (six items for each subscale measuring social support provided by mother, father, siblings and friends) uses a three-point scale (1 = never to 3 = often). For example, one question is ‘Exercise with me’. Participants independently rate whether their mother, father, siblings or friends do so on the three-point scale. The alpha coefficient of the separate social support subscales for mother's support was 0.85 (average variance extracted = 0.55), father's support 0.83 (average variance extracted = 0.55), sibling (average variance extracted = 0.58) and peers (average variance extracted = 0.51) ranged from 0.75 to 0.84.
A measure of perceived self-efficacy to overcome barriers for exercise was adapted from an existing exercise self-efficacy scale and asked about such things as being able to exercise if one were tired, not in the mood or sore [37]. Due to the emphasis in Iranian culture on family bonds and parents as authority figures, one item was added that asked if the girl could ‘exercise even though I have family chores to complete’. The scale then included nine items which were rated on a four-point Likert scale ranging from 1 = not at all confident to 4 = very confident. Cronbach's alpha value for the self-efficacy score was 0.86 (average variance extracted = 0.61).
Outcome expectations were measured by a modified benefits of PA scale (one item was deleted from the original scale based on recommendations from the Iranian experts) which included 18 items such as ‘A reason I might exercise is because when I exercise I have more energy’. Each item was measured on a four-point Likert scale ranging from 1 (not at all true) to 4 (very true) [37]. The mean score was used in the analyses. The Cronbach's alpha reliability coefficient for the benefits scale was 0.81 (average variance extracted = 0.43).
Self-regulation strategies were measured by an 11-item instrument that included such items as ‘I plan specific times for exercise or active sports in my weekly schedule’ and ‘I reward myself for exercising’ [38]. This scale was scored on 1 (never) to 3 (often) scale. The reliability coefficient was 0.83 (average variance extracted = 0.48).
Analysis plan
Descriptive statistics and bivariate correlations of all variables were computed. Analyses of the social cognitive model used path analysis with LISREL 8.7 [39] with maximum likelihood estimation and a covariance matrix. Specifically, in accordance with SCT [18, 40], social support was modeled as an antecedent of barriers self-efficacy and outcome expectations, while barriers self-efficacy was modeled as an antecedent of outcome expectations, self-regulatory planning and PA. Outcome expectations and self-regulatory planning were subsequently modeled as additional antecedents of PA [18, 40]. Covariances among the sources of social support were freed within the model because they may partially be determined by unmodelled common causes. Indicators of each variable were fixed to 1.0 in order to create a metric scale. Further, all variables were fixed to 0 error, which is commensurate with OLS regression analyses path models. An evaluation of the sufficiency of barrier self-efficacy and outcome expectations to account for the covariance between social support and self-regulatory planning and PA was also performed. This was achieved by comparing this nested model to a model where the direct paths of social support variables (mother, father, siblings and friends) were freed upon self-regulatory planning using a 
2 difference test between the models. An additional regression analysis was conducted to test the interaction effect of self-efficacy and outcome expectations on PA behavior. The results were subsequently graphed using simple slopes procedures [41].
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Results |
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Bivariate correlations and descriptives for all variables of interest can be found in Table I. All social cognitive constructs correlated with PA and the results were in the small–large effect size range [42]. Specifically, barriers self-efficacy had the highest correlation coefficient (r = 0.62) followed by outcome expectations (r = 0.42) and self-regulation planning (r = 0.34).
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The path model resulted in a moderate fit of the data [
2 (8) = 44.80; P < 0.01; comparative fit index (CFI) = 0.97; root mean square error of approximation (RMSEA) = 0.09] using conventional cutoff criteria and considering the complexity of the model [43]. Still, freeing the direct paths for the social support variables (i.e. mother, father, siblings and friends support) on self-regulatory planning improved fit and explained an additional 2% of the variance beyond the other SCT constructs [
2 (4) = 39.43; P < 0.01). The addition of the direct paths of the social support variables on PA, however, did not add to the overall fit (P > 0.05) and thus were dropped. The final model [2 (4) = 5.27; P = 0.26; CFI = 1.00; RMSEA = 0.02] is presented in Fig. 1 (covariance results among social support constructs have been omitted for illustrative parsimony) and suggested a good fit of these data [44].
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Overall, the model explained 52% of the variance in PA. The two significant (P < 0.05) direct effects were from barriers self-efficacy (standardized effect = 0.61; unstandardized effect = 82.94, SE = 6.80) and outcome expectations (standardized effect = 0.17; unstandardized effect = 30.17, SE = 9.72); self-regulatory planning did not have an independent effect, though barrier self-efficacy (standardized effect = 0.28; unstandardized effect = 0.17, SE = 0.03) and outcome expectations (standardized effect = 0.29; unstandardized effect = 0.24, SE = 0.04) explained 40% of its variance. Further, social support had significant indirect effects on PA through barriers self-efficacy for mother [standardized effect = 0.10; unstandardized effect = 17.28, 95% confidence interval (CI) = 2.82–31.74], father (standardized effect = 0.10; unstandardized effect = 12.27, 95% CI = 3.20–21.34) and friends (standardized effect = 0.09; unstandardized effect = 10.47, 95% CI = 2.41–18.53). When considering barriers self-efficacy, it had a significant effect on outcome expectations (standardized effect = 0.49; unstandardized effect = 0.36, SE = 0.03) and explained 34% of its variance. Subsequently, barriers self-efficacy had 8% of its variance explained by social support from mother (standardized effect = 0.11; unstandardized effect = 0.15, SE = 0.08), father (standardized effect = 0.13; unstandardized effect = 0.11, SE = 0.05) and friends (standardized effect = 0.11; unstandardized effect = 0.10, SE = 0.04).
The interactive effects of self-efficacy and outcome expectations on PA were tested with a regression model which also controlled for self-regulation strategies. Prior to the analysis, SCT variables were centered before computing interaction terms as recommended by Aiken and West [41]. The regression model showed a significant interaction effect. (Because of the potential moderating effect of age, this variable was also tested within the regression model. Age did not change any values by >0.01 or change P-levels in any meaningful way. Further, there was no consistent pattern of PA, self-efficacy, outcome expectations or self-regulation across age groups. This may be related to cultural differences with female Iranian adolescents. No matter what the age, there are very few expectations within society that these girls will be physically active, but there is a big emphasis on academics. Further research should confirm these results and examine this relationship with various cultural groups.) Table II shows the results of this model and Fig. 2 highlights the differences among slopes.
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Discussion |
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TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionConflict of interest statementAcknowledgementsReferences |
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Applying SCT to the data from the cross-sectional survey of Iranian adolescent girls showed that the model fitted the data with barriers self-efficacy and outcome expectancy directly correlated with PA behavior. The results showed that the model could explain 52% of the variance. The findings regarding barriers self-efficacy are in contrast to previous studies that found that barriers self-efficacy beliefs for PA in adolescent girls were mediated by goals and intentions [45]. Further, our cross-sectional findings should be interpreted with caution as it is also possible that increased PA resulted in greater self-efficacy an idea inherent in the reciprocal nature of SCT [12]. However, other researchers have found that self-efficacy is a consistent predictor of PA behavior and the findings from this study show similar strong support for self-efficacy [16]. The finding that outcome expectancies had a direct path with PA suggests that the incentives for being physically active such as fitness or weight loss may be effective determinants for girls in this cultural context. However, the relationship found between perceived self-efficacy and outcome expectancies suggests the perception of high self-efficacy to overcome barriers may increase outcome expectancies indirectly. Further, the results of the test of the interaction between self-efficacy and outcome expectations showed that these two variables interact in their relationship to PA in this adolescent sample. This finding is similar to that of other researchers who also found this interaction in diabetes self-management in adolescents [46]. These authors also found that this interaction was more important in older than in younger youth; however, we did not find a similar relationship. This is an interesting area that has received relatively little research in the PA literature and further work should examine how these two variables interact.
An important contribution of this research was the examination of social support from four distinct sources (mother, father, siblings and friends). Contrary to our hypothesis, although three forms of social support (mother, father and friends) were related to self-regulation and self-efficacy, there was no direct effect of social support on PA behavior. This result is also contrary to the findings of others who showed both direct and indirect influences of social support on PA behavior in adolescents [25, 47]. However, social support from parents and friends in the current study were related indirectly with behavior via self-efficacy and further research should explore these findings with adolescent girls from various cultures. It has been shown longitudinally that maintenance of support from family members may reduce the decline in PA independent of girls’ self-efficacy and it has been suggested that perceived family support in the years prior to 12th grade may lay the foundation for maintaining an active lifestyle as girls move through adolescence into young adulthood [27]. Similarly, vigorous PA in 13- to 14-year olds was predicted by both direct paths from adult encouragement and indirectly through perceived competence [29]. Our findings provide support for the utility of targeting perceived social support as a means of indirectly increasing self-reported PA behavior among adolescent girls by increasing self-efficacy for overcoming barriers, which is in keeping with the findings of other research with adult populations [48]. However, future research should examine this in a longitudinal design.
Increasing perceptions of social support might be important for encouraging participation in PA among adolescent Iranian girls because the enactment of PA often requires the support of others. This is an important consideration for this population because of the unique cultural challenges that make achieving adequate levels of PA for health benefits even more difficult. Such challenges include few to no expectations that Iranian women do any exercise (even bicycling which precludes many chances for PA from transportation). It should be noted that while it is not illegal for Iranian women to do such activities, it is very much the social norm that they do not and there are definite cultural standards for activity that women can adopt or reject. Further, there is an emphasis in Iranian culture on family bonds and parents as authority figures thus targeting social support in PA interventions may be of particular benefit to these girls. Indeed, we found both direct and indirect effects of self-efficacy on PA which is consistent with SCT's concept of reciprocal determinism. Therefore, to enhance the indirect effect of social support on PA through self-efficacy, there is a need to involve parents in PA programs for females. This may be particularly important for Iranian adolescent females because of the strong emphasis on the family bond in Iranian culture. Thus, parents can enhance self-efficacy by being role models and changing family norms about PA. In this way, barriers such as low accessibly and the expenses associated with PA can be decreased. However, it should be noted that there are challenges that exist in such programs which may also highlight why social support emerged as an important variable in this study. It is very competitive for Iranian youths (female or male) to enter university and therefore it is the norm for parents and teachers place to much more value on academic success than on PA.
The only form of social support that was not a significant predictor within this model was social support from siblings. The findings from other researchers have been mixed. Saunders [31] found that family support had direct effects on vigorous PA and on team sport involvement in adolescent girls, but the source of support (e.g. mother and father) was not distinguished. Others, in qualitative work, have found relevance for sibling/cousin support with junior but not senior students [49]. The findings from our study may be because in Iran, boys have greater access to exercise facilities than girls who must exercise in a separate place from boys. Further, the gender separation in Iran results in brothers and sisters not playing together after the age of 12 or 13, especially outdoors (i.e. parks). Clearly, more research is needed to clarify the role that sibling support can play in the PA behavior of adolescent girls across cultures. Taking into account the gender, age, number of sibling and type of activities engaged may help provide further insight into this relationship.
In this study, self-regulation planning did not exhibit a direct effect on PA after controlling for self-efficacy. This is consistent with recent research on PA behavior change using SCT. Specifically, a school-based intervention that increased PA among adolescent girls also increased self-efficacy and goal setting but only self-efficacy mediated the increased PA [50]. The bivariate relationships between self-regulation, self-efficacy and PA suggest that self-regulation may be best conceived as an antecedent of self-efficacy and not as a consequence as it was modeled in our study. Still, other research has found evidence in support of the mediating role of self-regulation in self-efficacy–PA relations. For example, self-management strategies mediated the association of self-efficacy with PA in sixth- and eighth-grade girls [24]. As Bandura [18] wrote ‘People adopt personal standards and regulate their behavior by their self-evaluative reactions. They do things that give them self-satisfaction and self-worth and refrain from behaving in ways that breed self-dissatisfaction (p. 144).’ Thus, in the present study, it is possible that participants made plans to overcome the barriers they face for PA, which subsequently influence behavior. However, the mixed findings in this domain suggest the need for sustained research, yet self-regulation strategies may act as recursive motivational [51] and post-motivational [52] processes which make their precise placement in causal models difficult.
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Limitations |
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There were several limitations of the present study. First, the data were measured by self-report questionnaire that included different measurement scales including three- and four-response options. It is possible that small sets of response options lower the absolute magnitude of variability and therefore create a statistical artifact in correlation analyses (i.e. restricted range). The literature, however, has rarely tested this assumption and there is some evidence that people adjust their ‘psychological width’ valence to quickly match the scale provided (thus null differences; [53–56]). Another limitation is the cross-sectional nature of the study which makes it impossible to conclude about antecedents of successful exercise behavior change. Adolescents may make behavioral choices during this developmental period that contribute to lifelong behavioral patterns [12]; however, longitudinal studies are needed to research this area. As Bandura [12] highlights, adolescence is a time of many transformations and self-efficacy may be greatly affected. However, we tested age in our regression analysis but there was no consistent pattern. This may be related to the strong societal expectations faced by female Iranian adolescents.
Another possible limitation is that although all participants in this study did report on sibling social support (indicating that they had at least one sibling), the nature of siblings (e.g. age, gender and number) of the participants in this study was not addressed. Thus, because of the mixed findings across the literature, further research is necessary to clarify the role that siblings may play in PA behavior in adolescent girls. We focused on barriers self-efficacy and other forms of self-efficacy should also be considered with this population. Finally, further assessment of the validity of the CAAL with an objective measure in Iranian adolescents is recommended. It should be noted, however, that test–retest reliability of the CAAL in this study was 0.98. In addition, the CAAL reports only on duration and not on intensity which is an important factor for achieving adequate health. Further research should examine the intensity and types of activity with this population.
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Conclusion |
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TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionConflict of interest statementAcknowledgementsReferences |
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Iranian girls face many barriers to an active lifestyle, including lack of suitable places to be active, access to facilities and resources, cultural limitations and the low importance placed on exercising over other activities such as doing homework or home responsibilities. The findings of this study strongly support the relationship between self-efficacy and engaging in PA for female Iranian adolescents. Further, the possible influence of various sources of social support should be considered when interventions are developed to increase PA rates. For example, making school space available after classes are finished so that mothers can exercise with daughters could help develop social relationships, role modeling and allow for the opportunity for observational learning. In this way, Iranian females will have access to a suitable social and physical environment for PA which is in accord with the normative climate in Iran. These results will allow for future research and interventions for PA not only for female Iranian adolescents but also for similar cultural and immigrant groups that have been neglected to date in the PA literature.
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Conflict of interest statement |
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TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionConflict of interest statementAcknowledgementsReferences |
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None declared.
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Acknowledgements |
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Ryan E. Rhodes is supported by a new investigator award from the Canadian Institutes of Health Research and Tanya R. Berry is supported by a Population Health Investigator Award from the Alberta Heritage Foundation for Medical Research.
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References |
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Received on April 1, 2008; accepted on September 5, 2008
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