Long expeditions to the ISS lead to a sharp deterioration in the ability of blood cells and blood vessels to deliver oxygen to the muscles, resulting in astronauts’ endurance reduced by 30-50%, say scientists in an article published in the Journal of Applied Physiology.
“This is a very serious fall, when the circulatory system begins to fail, the endurance decreases sharply, and in fact the person loses the ability to do something that requires minimal physical exertion.” Our colleagues assumed that this decrease in endurance was associated with changes in the heart, but our The data indicate the presence of problems in the capillaries, “said Carl Ade from the University of Kansas in Manhattan, USA.
Russian and American scientists have been studying for many years how life in space affects the health and work of the immune system of people and animals. For example, in 2015 they found out why many astronauts complain about vision problems in space, and also why astronauts of the Apollo program periodically fell and lost balance on the Moon.
Last year, physicians discovered even more disturbing changes in the work of the organism of humans and animals in space. In particular, it was found that a prolonged stay in weightlessness irreversibly weakens the muscles of the back and leads to a “rounding” of the heart, and a flight to Mars can lead to a significant deterioration in the intellectual abilities of astronauts due to the destructive effect of cosmic rays on the brain.
Ade and his colleagues discovered another health problem related to life in space, studying 14 astronauts who had recently returned from long-term expeditions aboard the ISS along with experts from the NASA Cosmic Flight Center Godaard.
Before and after the flight, each participant of these crews passed a series of complex medical tests for endurance, strength and other physical qualities.
During the examinations, as Ade tells, his team measured not only these parameters, but also monitored the effectiveness of the body, measuring the amount of inhaled and exhaled oxygen, carbon dioxide and the amount of energy that the astronauts’ bodies produced. In addition, scientists monitored the proportion of oxygen in the arteries and veins of their wards, observing the concentration of hemoglobin before and after the flow of blood into the muscles.
These observations showed an interesting thing – the circulatory system of all astronauts who spent more than six months aboard the ISS, much worse delivered oxygen to the muscles and vital organs after returning to Earth than before flying into space. Interestingly, the problem was not the poor performance of the heart or the deterioration in the ability of hemoglobin to carry oxygen, but in the work of the smallest vessels.
As Ada relates, for some reason, the capillaries “forgot” how the normal exchange of gases between muscles and cells of other organs and blood occurs, as a result of which the muscles constantly experienced “oxygen hunger” under severe stress. Because of this, the astronauts’ endurance decreased by 30-50%, and the peak power of their bodies dropped by about 15%.
“If we understand why the peak oxygen consumption decreases when flying into space, this will allow us to understand how we can cope with this problem, whether it requires exercises or some kind of pharmacological means.” Something similar happens to a person in old age, If we can help astronauts, then we will help elderly people with a distressed heart and blood vessels, “Ade concludes.