Comparing hemodynamic and cardiorespiratory responses during six-minute walk and step tests in mild acute COVID-19

The six-minute walking test (6MWT) and six-minute step test (6MST) are valuable tools for assessing functional capacity and predicting outcomes in individuals suffering from mild COVID-19. This study aims to evaluate functional capacity and oxygen uptake ($${\dot{\text {V}}}{{\text{O}}_{\text{2}}}$$) during both the 6MWT and 6MST, to examine hemodynamic and cardiorespiratory responses and identify predictive factors influencing performance and $${\dot{\text {V}}}{{\text{O}}_{\text{2}}}$$ (mL kg⁻¹ min⁻¹). This is a cross-sectional study including adults with mild COVID-19 symptoms within 6 weeks of a positive RT-PCR test. Participants were assessed for anthropometrics, handgrip strength, physical activity levels, pulmonary function, and performance on the 6MWT/6MST. Cardiorespiratory data were collected using a portable gas analyzer. Statistical analyses were conducted to compare the two tests, and regression models were used to identify predictive factors for performance and $${\dot{\text {V}}}{{\text{O}}_{\text{2}}}$$ peak (mL kg⁻¹ min⁻¹). Forty volunteers (57% female) participated, with a mean age of 35 ± 12 years and BMI of 27.55 ± 5.66 kg/m2. Mean 6MWT distance was 473 ± 97 m (82 ± 18% predicted) and mean 6MST was 144 ± 27 steps (81 ± 16% predicted). Significant differences were found in hemodynamic responses with the 6MST eliciting higher heart rate (HR; p < 0.001), systolic blood pressure (SBP; p < 0.001), and ratings of dyspnea and lower limb fatigue on the Borg scale (p < 0.001 and p = 0.015, respectively). (Regression analyses revealed factors that predicted performance and $${\dot{\text {V}}}{{\text{O}}_{\text{2}}}$$ peak (mL kg⁻¹ min⁻¹) for both tests, with models explaining 46–59% of variance for the 6MST and 12–40% for the 6MWT. The 6MST and 6MWT elicit distinct physiological responses, with the 6MST imposing greater hemodynamic and cardiorespiratory responses. Pulmonary function and body composition significantly enhance predictive models for functional performance and $${\dot{\text {V}}}{{\text{O}}_{\text{2}}}$$ peak (mL kg⁻¹ min⁻¹) in both tests.