text: Exercise performance in patients with post acute sequelae of SARS CoV 2 infection compared to patients with unexplained dyspnea Dyspnea and exercise intolerance are commonly reported post acute sequelae of SARS CoV 2 infection PASC but routine diagnostic testing is often normal Cardiopulmonary exercise testing CPET offers comprehensive assessment of dyspnea to characterize pulmonary PASC We performed a retrospective cohort study of CPET performed on patients reporting dyspnea and or exercise intolerance following confirmed Covid 19 between August 1 2020 and March 1 2021 and compared them to age and sex matched patients with unexplained dyspnea referred for CPET at the same center in the pre Covid 19 era Compared to matched unexplained dyspnea comparators PASC patients shared similar medical comorbidities and subjective dyspnea at referral mMRC score 1 6 0 9 vs 1 4 0 9 i P i 0 5 Fifteen 83 3 PASC patients underwent high resolution computed tomography of the chest of which half 46 7 were normal and 17 94 4 patients had pulmonary function testing of which the majority 76 5 were normal All patients underwent CPET and 12 67 had normal findings Compared to matched comparators PASC patients had similar peak oxygen consumption oxygen consumption at ventilatory anaerobic threshold and ventilatory efficiency measured by the minute ventilation to carbon dioxide production VE VCO sub 2 sub slope Despite prominent dyspnea physiological abnormalities on CPET were mild across a range of initial Covid 19 severity and similar to matched comparators referred for dyspnea without antecedent SARS CoV 2 The project was supported by the NHLBI R01HL131029 R01HL151841 U10HL110337 T32HL116275 and a KL2 award 5KL2TR002542 02 from Harvard Catalyst 