RESUMO
Objective: The study objectives were to identify the prevalence of upper crossed syndrome (UCS) and its associated factors in a population of Spanish adolescents, and to explore these associations through focus groups. Methods: The study used a sequential explanatory mixed method design. The quantitative phase consisted of a cross-sectional study in which 45 students underwent photogrammetry measurements and evaluations with the Kiddo-KINDL and VISA-TEEN questionnaires. Subsequently, several focus groups were conducted to discuss the quantitative results. Results: The results indicated a 37.8% prevalence of UCS, a 48.9% prevalence of forward head posture (FHP) and an 80% prevalence of forward shoulder posture (FSP). A positive FSP was indicated by an angle represented by the intersection of the line between the midpoint of the humerus and the spinous process of C7 of <52°. FSP was significantly higher in boys (mean [M] = 43.59, standard deviation [SD] = 6.9) than in girls (M = 47.98, SD = 6.33; p < 0.05). Boys showed significant moderate associations of FSP with body mass index (BMI) (r = -0.48, p < 0.05) and hygiene habits (r = -0.46, p < 0.05), and of FHP with worse use of technology (r = 0.53, p < 0.05). Those with UCS showed significant differences in school performance (M = 47.22, SD = 8.33, p < 0.05). Analysis of the qualitative results led to the identification of 33 codes and five categories. Conclusions: UCS was associated with factors such as BMI, school performance, use of technology and physical activity. Correcting posture in adolescence was generally believed to be necessary. Physical exercise and postural health were considered highly important among adolescents.