Acute effects of chest binding on respiratory mechanics and cervicothoracic kinematics in healthy females: a randomized crossover study

Introduction: Chest binding is widely used for gender affirmation, yet its acute biomechanical impacts remain unclear. Objective: This study aims to investigate the immediate effects of a commercial chest binder on respiratory mechanics and cervicothoracic kinematics. Methodology: Thirty-two healthy females completed a randomized crossover study comparing a control condition (no bra) to a chest binder. Outcome measures included pulmonary function (spirometry), regional chest expansion, thoracic kyphosis, and cervical range of motion (CROM). Results: Chest binding significantly reduced FEV1 (p < 0.001) and the FEV1/FVC ratio (p = 0.038). Chest expansion was severely restricted at the middle (-3.87 cm, p < 0.001) and lower lobes (-2.35 cm, p < 0.001). Additionally, the anterior compression significantly increased thoracic kyphosis from 34.52 degrees to 36.54 degrees (p = 0.032), which subsequently reduced CROM across all six anatomical planes (all p < 0.05). Conclusion: The acute application of a chest binder significantly limits regional chest wall excursion and dynamic pulmonary function. Concurrently, it induces a hyper-kyphotic posture that restricts cervical mobility, highlighting the need for safe binding guidelines and targeted postural rehabilitation.