Twelve-Week Air Stacking Training Improves Cough Effectiveness and Lung Volumes in Individuals with Spinal Cord Injury: A Single-Center Retrospective Cohort Study

Objective To determine whether daily air stacking (AS) over 12 weeks improves cough effectiveness and pulmonary volumes in individuals with spinal cord injury (SCI). Methods This retrospective study analyzed the records of individuals with SCI who received AS training at the Los Coihues Clinic in Chile. Participants performed AS exercises five days per week for 12 weeks. Pulmonary function was assessed at baseline and after the intervention, including peak cough flow (PCF) in four conditions (spontaneous, with AS, with manually assisted cough [MAC], and combined AS + MAC), vital capacity (VC), maximum insufflation capacity (MIC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP). Paired t-tests were used to compare pre and post-intervention values, with significance at p < 0.05. Results Twenty individuals (19 men; mean age 38.8 +/- 13.1 years) with cervical (85%) and thoracic (15%) SCI were included. Significant improvements were observed after 12 weeks in VC (2.41 +/- 0.91 vs. 3.01 +/- 1.06 L; p = 0.004), MIC (3.80 +/- 0.96 vs. 4.48 +/- 0.96 L; p = 0.006), MIP (71.2 +/- 26.2 vs. 88.9 +/- 26.5 cmH2O; p < 0.001), and PCF in all conditions: spontaneous (p < 0.001), with AS (p = 0.03), with MAC (p = 0.02), and with combined AS + MAC (p = 0.02). No significant change was found in MEP. Conclusions Twelve weeks of daily AS training significantly improved cough effectiveness and pulmonary function in individuals with SCI. These sustained improvements may enhance airway clearance and respiratory health in this population.