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

Gabriela Fischer,Pedro Schons,Mathieu Gruet,Francisco B De Queiroz,Danilo C Berton,Henrique B Oliveira,Leonardo A Peyré-Tartaruga,Marcelo Coertjens

doi:10.1038/s41598-021-91734-x

Abstract

This study aimed to investigate the walking economy and possible factors influencing self-selected walking speed (SSWS) in patients with fibrotic 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 first second: 56 ± 7% of predicted) and 10 healthy controls underwent resting pulmonary function tests, cardiopulmonary exercise, and submaximal treadmill walking tests at different speeds. The walking economy was assessed by calculating the cost-of-transport (CoT). Dynamic stability was assessed by stride-to-stride fluctuations using video recordings. Patients with ILD showed reduced peak oxygen uptake with a tachypneic breathing pattern and significant oxygen desaturation during exercise. The CoT did not differ 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−1p = 0.001) and did not correspond to the energetically optimal walking speed. Dynamic stability was significantly 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 affected, these factors were not associated with the slower walking speed chosen by individuals with ILD.

Highlights

This study aimed to investigate the walking economy and possible factors influencing self-selected walking speed (SSWS) in patients with fibrotic interstitial lung disease (ILD) compared to controls
ILD patients adopted a significantly lower SSWS compared to controls (2.6 ± 0.9 vs 4.2 ± 0.4 km h−1, respectively; p = 0.001)
Dyspnea was significantly higher in patients with ILD than in the controls (p = 0.005) while SpO2 was significantly lower in ILD patients (89.9 ± 2.2% vs. 96 ± 0.8%, respectively; p = 0.037)

Summary

Introduction

This study aimed to investigate the walking economy and possible factors influencing self-selected walking speed (SSWS) in patients with fibrotic interstitial lung disease (ILD) compared to controls. Patients with ILD presented a similar cost of transport compared to healthy controls; they chose lower SSWS despite higher walking energy expenditure. Patients with reduced usual walking speed have significantly worse exercise performance and health status, despite similar lung function and fibrotic tomographic e xtension[7]. Exercise test protocols assessing the energy economy profile and dynamic stability during walking speeds in daily life may provide more c larity[10]. Several studies[11,12,13] have shown that the CoT depends on walking speed and that there is an optimal walking speed (OWS) for healthy young individuals (≈4 km h−1), where the energy expenditure is minimal and corresponds to the self-selected walking speed (SSWS). The lower economic walking performance in the elderly is supposed to be due an unstable walking pattern and sarcopenia/muscle weakness associated with aging[17,18]

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