Background
Dyspnoea and exercise intolerance are frequently reported several months after COVID-19 infection. CPET can accurately evaluate these symptoms, with variable results reported in literature.

The aim of this study was to evaluate exercise response patterns in symptomatic patients following COVID-19 disease.

Methods
A retrospective descriptive study of CPETs performed between March 2021 and February 2023 in patients with post-COVID-19 exercise intolerance was conducted. Demographic, clinical and CPET data were analysed, and patients were grouped according to World Health Organization?s COVID-19 disease severity classification.

Results
Eighteen patients were enrolled [mean age 54±12 years; 50% males]. Eleven patients had non-severe (NS), five severe (S) and two critical (C) disease (groups NS, S and C, respectively).
Elapsed time between COVID-19 diagnosis and CPET was inferior in S group [median time, 250 days (IQR 182)]. Mean peak oxygen consumption was slightly reduced in C group (18 mL/kg/min; 78,5% of predicted value), but normal in NS and S groups.
Exercise response patterns documented were normal maximal/submaximal test (n=5), muscle deconditioning (MuD) (n=5), dysfunctional breathing (DB) (n=4), obesity (n=2), alveolar hypoventilation (n=1), circulatory impairment (n=1), ventilatory impairment (n=1) and inconclusive submaximal test (n=1).

Conclusions
Our results meet those found in literature, suggesting post-COVID-19 exercise intolerance association with reduced exercise capacity and exercise response patterns of DB and MuD. There?s a need for performing more CPETs in such patients, allowing accurate diagnosis and treatment strategies.