Inspiratory muscle training improves exercise performance and breathing pattern during 6-min walking test in systemic...

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) significantly impacts exercise capacity and contributes to morbidity and mortality in affected individuals. Inspiratory muscle training (IMT) has demonstrated benefits in improving inspiratory muscle strength and respiratory efficiency in various cardiopulmonary conditions, including interstitial lung disease. This case-control study hypothesises that IMT can enhance inspiratory muscle strength and exercise capacity in patients with SSc-ILD, likely through improved ventilatory patterns during exercise. In this randomised, placebo-controlled trial, 24 patients with SSc-ILD (4 males, 20 females) were randomly assigned to the IMT (n=12) or sham (n=12) groups. The IMT group performed training at 60% of maximal inspiratory pressure (MIP) for 5 weeks, while the sham group received a placebo intervention at 5% MIP. Baseline and post-intervention assessments included pulmonary function tests, 6-min walk test (6MWT) with combined wearable metabolic system to measure minute ventilation (V'_E), respiratory frequency (f _R), tidal volume (V _T) and ventilatory equivalent for CO₂ (V'_E/V'_CO2 ). At rest, IMT increased MIP and prolonged expiratory time. The IMT group showed significant improvements in 6-min walking distance and oxygen uptake during the 6MWT. An increase in V'_E was observed primarily through an enhanced V _T. These improvements are likely mediated by optimised breathing patterns, potentially reducing physiological dead space thanks to increased V _T during exercise. Further studies are needed to evaluate the long-term effects of IMT on functional outcomes.