# Assessment of exertional capacity using the six-minute step test in COVID-19 survivors six months after hospitalization: a prospective observational study in Paraíba, Brazil

## TL;DR

This study shows that the six-minute step test can identify reduced physical ability in people who had severe COVID-19 six months earlier.

## Contribution

The study demonstrates the 6MST's feasibility for assessing exertional capacity in post-hospitalized COVID-19 patients.

## Key findings

- 37.8% of participants performed below the predicted threshold for healthy individuals on the 6MST.
- Older age, female sex, greater dyspnea, and lower mental health scores predicted worse 6MST performance.
- The 6MST is a feasible tool for identifying exertional impairment in post-COVID-19 rehabilitation triage.

## Abstract

Survivors of Coronavirus Disease (COVID-19) frequently report persistent symptoms and reduced exercise capacity after hospital discharge. Simple, accessible methods to assess exertional performance in this population are urgently needed. We conducted a prospective observational study to evaluate exertional capacity using the six-Minute Step Test (6MST) in adults who had been hospitalized for COVID-19 at a referral center in Paraíba, Brazil. Participants were assessed six months after discharge using clinical evaluation, spirometry, standardized questionnaires (mMRC – modified Medical Research Council, SF-12 – Short Form-12), chest computed tomography and 6MST. The primary outcome was the number of steps completed on the 6MST. Performance was compared with normative values. Multivariable regression was used to identify predictors of poor exertional performance. Among 102 eligible participants, 88 (86.3%) completed the 6MST. The mean number of steps was 132.8 ± 30.9. 37.8% performed below the predicted threshold for healthy individuals; 10% fell below the 10th percentile. In the final multivariable model (R2Ajdjusted = 0.39), older age, female sex, greater post-COVID-19 dyspnea (mMRC), and lower Mental Component Scores (MCS-12) were independently associated with lower step counts. The 6MST is a feasible tool for identifying exertional impairment in COVID-19 survivors. Reduced performance was common, particularly among older women and those with residual dyspnea or poorer mental health. These findings support the use of the 6MST to triage patients for post-COVID-19 rehabilitation.