Effects of Covid-19 pneumonia on submaximal exercise tolerance

ABSTRACT

Introduction: 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. Method(s) 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. Result(s) 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 during the test were found respectively in 33.1% and 15.2% of cases and were both correlated with DLCO (r=-0.258;p<10-3 and r=-0.423;p<10-3). Chronotropic insufficiency and chronotropic intolerance were found in 13.8% and 7% of cases. PCW was correlated with BMI (r=0.463;p<10-3), FEV1 (r=-0.175;p=0.001), FVC (r=-0.167;p=0.002) and DLCO (r=-0.161;p=0.004). Conclusion(s) 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.