Diaphragmatic Facilitation and Upper Extremity Performance in Volleyball Players

The diaphragm contributes to both respiration and trunk stabilization. Effective diaphragmatic function may support postural control, force transfer, and upper extremity performance during dynamic activities. However, evidence regarding the immediate effects of manual diaphragmatic facilitation on upper extremity performance in athletes remains limited. This study aims to investigate the immediate effects of manual diaphragmatic facilitation on upper extremity performance and respiratory function in actively participating volleyball players. Participants will receive an approximately 15-minute session of manual diaphragmatic facilitation. Pulmonary function, respiratory muscle strength, and upper extremity strength, stability, and endurance will be assessed immediately before and after the intervention. Assessments will include spirometry, maximal inspiratory and expiratory pressures, the Medicine Ball Throw Test, the Closed Kinetic Chain Upper Extremity Stability Test, and the Scapular Endurance Test.