Effects of home-based inspiratory muscle training on sympatho-vagal balance, quality of life, and inflammatory profile in patients with systemic sclerosis-associated interstitial lung disease

PURPOSE: This study aimed to evaluate the effects of a home-based inspiratory muscle training (IMT) on cardiovascular autonomic control, spontaneous respiratory patterns, inflammatory profiles, health-related quality of life (HRQoL), and sleep quality in patients with systemic sclerosis (SSc) and moderate interstitial lung disease (ILD). METHODS: In a randomized, sham-controlled trial, 24 SSc-ILD patients were enrolled and evenly assigned to IMT (n = 12) or sham (n = 12) groups. IMT involved inspiratory resistive training at 50% of maximal inspiratory pressure (MIP) for five weeks, while the sham group performed training at 5% MIP. Assessments at baseline and post-intervention included: respiratory function tests, heart rate variability (HRV), baroreflex sensitivity, spontaneous respiratory patterns, the analysis of 8 inflammatory biomarkers (IFN-γ, IL-10, IL-6, TNF-α, IL-1β, TNFR1, TREM-1 and TREM-2) through ELISA technique, health-related quality of life (HRQoL), and sleep quality [Pittsburgh Sleep Quality Index (PSQI)]. RESULTS: After 5 weeks, the IMT group demonstrated significant improvements in MIP (+27 cmH₂O; p = 0.01) and spontaneous baroreflex sensitivity (+4.7 ms/mmHg; p = 0.01). Additionally, the IMT group showed increased vagal-mediated HRV (+20.5 n.u.; p = 0.02) and a prolonged expiratory time during spontaneous breathing compared to the Sham group (+0.5 s; p = 0.04). Furthermore, the IMT group exhibited an increase in the anti-inflammatory cytokine IL-10 (+0.4 pg/mL; p = 0.04). No significant changes were observed for the other inflammatory biomarkers. In patients with baseline sleep disturbances, the IMT intervention improved sleep quality (-3 PSQI points; p = 0.02). However, no significant changes in HRQoL were observed. CONCLUSION: IMT significantly enhanced cardiac autonomic regulation along with improvements in respiratory function and sleep quality in SSc-ILD patients and demonstrated slight indications of an increased anti-inflammatory effect. These findings highlight IMT as a promising non-pharmacological intervention to improve autonomic function, offering potential cardioprotective and clinical benefits for SSc patients.