Exercise intolerance associated with impaired oxygen extraction in patients with long COVID.

Most subjects did not meet normative criteria for a maximal test, consistent with suboptimal effort and early exercise termination. Mean O pulse peak % predicted (of 79 ± 12.9) was reduced, supporting impaired energy metabolism as a mechanism of exercise intolerance in long COVID, n = 59. We further identified blunted rise in heart rate peak during maximal CPET. Our preliminary analyses support therapies that optimize bioenergetics and improve oxygen utilization for treating long COVID-19.