Study explains post-coital exercise intolerance
Survivors of coronavirus infection often complain of an inability to return to their previous or desired level of physical activity. A new study by American scientists has helped to explain what causes this condition. It turns out that getting back in shape simply by resuming exercise will not work.
When patients report shortness of breath and other signs of exercise intolerance, they are usually examined to see if the symptoms are related to lung or heart problems.
In some cases, CT scans, echocardiograms and pulmonary function tests do not reveal the source of the problem. People with post-Covid-19 syndrome, or as it is also called, "lingering" Covid-19, often fall into this category. Standard tests show no heart or lung limitations.
Sometimes the cause can be determined only with the help of a special examination - invasive cardiopulmonary exercise test (iCPET for short). During this test, pressure-measuring catheters are inserted into the pulmonary artery and vessels in the wrist. Then, under exercise, as in a conventional cardiopulmonary exercise test, or ergospirometry, doctors monitor how the person's heart, lungs, blood vessels, and muscles are functioning.
There are few places in the United States (as well as Russia) that perform iCPET. One such place in the United States is Yale University Medical Centers. In a study published in the journal ERJ Open Research, experts at Yale School of Medicine looked at 55 people with postcoccygeal syndrome. In 41 of them, initial examinations looking for causes of exercise intolerance did not reveal heart or lung problems.
The doctors found that although the lungs were supplying enough oxygen to the blood and the heart was pumping it normally, the patients had impaired oxygen extraction from the blood by the body tissues. This is what led to the symptoms of post-exercise exercise intolerance. The iCPET helped detect malfunctions in systemic peak oxygen extraction in about 75% of the patients studied. In the remaining 14, they found signs of central cardiopulmonary pathology.
The study showed that in patients after coronavirus infection with persistent exercise intolerance, a reduction in peak oxygen extraction should be considered.
The authors also noted that their work helps dispel some of the myths surrounding post-Covid-19 syndrome. Covid-19 survivors sometimes believe that persistent exercise intolerance after recovery is a consequence of deteriorating form due to lack of physical activity, and that resuming the latter will itself help improve the condition.
"Our results contradict this hypothesis and instead confirm that there is a clear physiologic abnormality underlying the symptoms," said Peter Kahn, lead author of the study and a pulmonology and intensive care specialist at Yale School of Medicine.
Although iCPET has helped explain what postvoid intolerance to exercise is associated with, this examination is invasive, time-consuming and rarely performed anywhere. The scientists hope their findings will spur medical professionals to create alternative, more convenient and less traumatic methods for detecting oxygen extraction disorders in the body.