Factors infuencing self-selected walking speed in fibrotic interstitial lung disease

Abstract

This study aimed to investigate the walking economy and possible factors infuencing self-selected walking speed (SSWS) in patients with fbrotic interstitial lung disease (ILD) compared to controls. In this study, 10 patients with ILD (mean age: 63.8 ± 9.2 years, forced expiratory volume in the frst second: 56 ± 7% of predicted) and 10 healthy controls underwent resting pulmonary function tests, cardiopulmonary exercise, and submaximal treadmill walking tests at diferent speeds. The walking economy was assessed by calculating the cost-of-transport (CoT). Dynamic stability was assessed by stride-to-stride fuctuations using video recordings. Patients with ILD showed reduced peak oxygen uptake with a tachypneic breathing pattern and signifcant oxygen desaturation during exercise. The CoT did not difer between the groups (p= 0.680), but dyspnea and SpO₂ were higher and lower, respectively, in patients with ILD at the same relative speeds. SSWS was reduced in ILD patients (2.6 ± 0.9 vs. 4.2 ± 0.4 km h⁻¹ p = 0.001) and did not correspond to the energetically optimal walking speed. Dynamic stability was signifcantly lower in patients with ILD than in healthy controls, mainly at lower speeds. Patients with ILD presented a similar cost of transport compared to healthy controls; however, they chose lower SSWS despite higher walking energy expenditure. Although walking stability and dyspnea were negatively afected, these factors were not associated with the slower walking speed chosen by individuals with ILD.