During Bill Clinton's 1992 presidential campaign, one of his political advisers, James Carville, was convinced that Clinton would win the election if he focused on the economy. "It's the economy, stupid" was the phrase he used to emphasize its importance. Clinton won the election and the phrase became famous. I have found it apropos in the case of post-COVID exercise limitations: "It's deconditioning, stupid."
What is deconditioning? In lay terms, it's synonymous with being out of shape. In medical terms, it's the process by which human beings lose muscle mass and aerobic capacity following inactivity. The rate at which deconditioning occurs is dependent on a number of factors. Speaking from personal and professional experience, I promise you that it occurs quickly. One hallmark of deconditioning is poor self-awareness and the tendency to attribute symptoms to organ dysfunction rather than lack of fitness.
Much like a national campaign strategy, exercise physiology and COVID-19 infection are both complicated. We're starting to get data from cardiopulmonary exercise testing (CPET) post infection, though, and lo and behold, the predominant limitation found during testing is deconditioning. Post–COVID-19 CPET studies examined inpatients within 3 months of discharge. They found that aerobic capacity was more related to hospital length of stay
