Acute Effects of Functional Inspiratory Muscle Training in Elite Male Volleyball Players

This randomized controlled trial evaluates the acute effects of a single session of functional inspiratory muscle training on muscle oxygenation, exercise capacity, dynamic balance, and agility in elite male volleyball players aged 18 to 25 years. Thirty participants will be randomly assigned in a 1:1 ratio to an intervention group or a no-intervention control group. The intervention group will perform 60 resisted breaths at 50% of maximal inspiratory pressure using a POWERbreathe device during a sport-specific fixed-ball throwing drill. Both groups will complete assessments before and immediately after the intervention period on the same day. Quadriceps muscle oxygen saturation and total hemoglobin will be measured using a Moxy near-infrared spectroscopy monitor during the Incremental Shuttle Walk Test. Exercise capacity, dynamic balance, and agility will be assessed using the Incremental Shuttle Walk Test, Star Excursion Balance Test, and T-Test, respectively.