Effects of Covid-19 pneumonia on submaximal exercise tolerance

Abstract

<b>Introduction:</b> After Covid-19 pneumonia, regular respiratory function assessment is necessary for the subsequent management of patients, including resting respiratory function tests and assessment of submaximal exercise tolerance by six-minute walk (6MW) test. <b>Methods:</b> Six-minute walk test was undergone for 326 patients about 3 months after Covid-19 pneumonia. Physiological cost of walking (PCW) defined as the difference between maximum heart rate reached at the 6MWT and resting heart rate divided by walking speed was calculated. <b>Results:</b> Median age and BMI were respectively 61 [18–95] years-old and 30,4 [18,5–65,2] kg/m2 with a sex-ratio at 1.26. Smoking was reported in 52.8% of cases (12,45 PY). Median 6MW distance was 528 meters [48-832], corresponding of 80% [7-113] of theoric. Median PCW was 0,379 beats/meter [-1.38-5.38]. Low 6MW distance and low saturation&nbsp;during the test were found respectively in 33.1% and 15.2% of cases and were both correlated with DLCO (r=-0.258;p&lt;10-3 and r=-0.423;p&lt;10-3). Chronotropic insufficiency and chronotropic intolerance were found in 13.8% and 7% of cases. PCW was correlated with BMI&nbsp;(r=0.463;p&lt;10-3), FEV1 (r=-0.175;p=0.001), FVC (r=-0.167;p=0.002) and DLCO (r=-0.161;p=0.004). <b>Conclusion:</b> Six-minute walk test is an inexpensive, easy and reliable tool that tells us about the global response to submaximal exercise, especially after Covid-19 pneumonia. It is an interesting alternative for patients follow-up, especially when rehabilitation is considered.