RESUMEN
OBJECTIVES: To investigate the association between sitting posture during the use of school furniture and changes in the spine in adolescents. METHODS: A cross-sectional study was conducted with 240 students. The sitting position on school furniture was collected five times (3, 6, 9, 12, and 15 min). Postural alteration of the spine was identified by direct observation in front of a symmetograph. Screening for scoliosis was obtained by Adams test. RESULTS: The presence of the factor away from the table presented higher percentages at times 3, 6, 9, and 15 min (24.2, 25, 29.2, and 26.7%, respectively). At 12 min, the highest frequency was the presence of poorly positioned lower limbs (25.8%). Associations were observed between poor sitting posture with changes in head anteriorization and retroversion of the pelvis among women and with thoracic hyperkyphosis in men. CONCLUSIONS: The findings suggest that there are sex-dependent associations between poor sitting posture during use of school furniture and spinal alterations in adolescents.