Scussel A; Hospital de Clinicas de Porto Alegre, Brazil
Rodrigues NG; Santos AZ; Trombin LCB; et al

European Journal of Applied Physiology. 126(8):4567-4579, 2026 Aug.

PURPOSE: Smokers with preserved ratio impaired spirometry (PRISm) present
reduced forced expiratory volume in the first second (FEV1 < 80%
predicted) but preserved FEV1/forced vital capacity (FVC) >= 0.7. Although
they do not meet diagnostic criteria for chronic obstructive pulmonary
disease (COPD), they often report respiratory symptoms and exercise
intolerance. We aimed to compare sensory and physiological responses to
exercise between smokers with PRISm and matched healthy controls. Patients
with mild-to-moderate COPD were included as a reference group.

METHODS: In this cross-sectional study, smokers (> 10 pack-years) from a
specialized outpatient clinic were evaluated. Thirteen participants (11
females; 62.4 +/- 7.7 years) with PRISm and 13 age- and sex-matched
patients with mild-to-moderate COPD (FEV1/FVC < 0.7; FEV1 > 50% predicted)
underwent incremental cardiopulmonary exercise testing on a cycle
ergometer. Data from healthy nonsmoking controls were obtained from
previous studies.

RESULTS: PRISm and COPD groups had similarly reduced FEV1 (~ 72%
predicted) compared to controls (97% predicted), whereas FVC was lower in
PRISm (73% predicted) than in COPD and controls (~ 95% predicted). Both
patient groups showed higher ventilation, reduced ventilatory reserve, and
greater dyspnoea at a given submaximal workload versus controls. Increased
tidal volume/inspiratory capacity ratios were also observed, contributing
to greater dyspnoea for a given ventilation and lower peak work rate (42
+/- 16 vs. 68 +/- 11 vs. 94 +/- 17% predicted, respectively; all P <
0.05).

CONCLUSION: Smokers with PRISm exhibit increased dyspnoea and reduced
exercise tolerance compared to healthy controls, largely driven by
excessive ventilatory demand and reduced ventilatory capacity during
submaximal exercise.