Inspiratory muscle training and trunk control exercises on respiratory strength and motor function in spinal muscular atrophy: randomized controlled trial

Spinal muscular atrophy (SMA) is a progressive neuromuscular disorder characterized by respiratory muscle weakness and impaired functional capacity. This study aimed to evaluate the effects of respiratory exercises, inspiratory muscle training (IMT), and trunk control training in children with SMA. Thirty-eight children (10.21 ± 4.56 years) with SMA were randomly assigned to two groups. Pulmonary rehabilitation group (PRG, n = 19), performed diaphragmatic, pursed-lip, and segmental breathing exercises plus IMT at 30% maximal inspiratory pressure, twice daily for 8 weeks. Trunk control group (TCG, n = 19) received the same respiratory program with additional trunk exercises, three times a week. Primary outcomes were respiratory muscle strength (MIP, MEP), pulmonary function (FVC, FEV_1, PEF), and peak cough flow (PCF). Secondary outcomes were trunk control (TCMS), upper limb function (RULM), and motor performance (HFMSE). Both groups demonstrated significant within-group improvements in respiratory strength and motor outcomes (p < 0.05). MIP increased with large effect sizes (PRG: d = 1.039; TCG: d = 1.556). Notably, TCG showed additional significant gains in static sitting balance (p < 0.05), selective movement control (p < 0.001), and RULM (p < 0.05). Although between-group differences were not statistically significant, effect sizes indicated clinically relevant advantages favoring the combined intervention. Combining IMT with trunk control training appears safe, feasible, and clinically beneficial in children with SMA.