<p><strong>Objectives</strong></p>
<p>This research aimed to construct and psychometrically test a measure of multiple sociocultural dimensions (i.e. family, peers, media) theoretically associated with exercise behaviours/attitudes in adolescents; the Sociocultural Influences on Exercise Behaviours in Adolescents Questionnaire (SIEBAQ).</p>
<p><strong>Methods and measurement</strong></p>
<p>Part 1 of this study focused on measure construction and psychometric testing, involving item generation and exploratory factor analysis (EFA) to refine the item pool, with 905 adolescents (<em>M</em>age 13.66 years (SD = 0.94); girls = 442). Part 2 sought to explore the convergent validity of the SIEBAQ (<em>n</em> = 846; <em>n</em> = 414 girls).</p>
<p><strong>Results</strong></p>
<p>EFA resulted in a 47-item measure with a nine-factor structure (including social media modelling, parent exercise expectations, peer co-participation; α = 0.72-0.92). Correlations revealed weak-moderate significant relationships between the SIEBAQ and related constructs (e.g. compulsive exercise, sociocultural attitudes towards appearance). Regression analyses with the SIEBAQ identified social media modelling of exercise as a significant predictor of compulsive exercise in boys and girls. Proving exercise ability to significant others also significantly predicted compulsive exercise outcomes.</p>
<p><strong>Conclusion</strong></p>
<p>This newly developed measure holds promise. Further psychometric testing and validation of the SIEBAQ is the recommended next step to confirm the measure’s nine-factor structure identified through EFA.</p>
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