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Researchers have discovered a way to help astronauts who spend a lot of time in space return to Earth on a more stable basis.
"One of the biggest problems since the launch of the manned space program has been the fainting of astronauts after their descent to Earth.The longer the time spent in a non-gravity environment is high, the greater the risk is." said Benjamin Levine. Professor at the Southwestern Medical Center at the University of Texas (UT) in the United States.
"This problem has been affecting the space program for a long time, but this condition is also what ordinary people often feel," said Levine, director of the Texas Health Presbyterian's Institute of Exercise and Environmental Medicine. Hospital. Orthostatic hypotension is the technical term that refers to a temporary fall in blood pressure when a person gets up after sitting or lying down because blood rushes to the feet, away from the brain.
Dizziness or fainting due to changes in blood flow may occur after a long night of rest, in people with certain health conditions or, in the case of astronauts, in a low-gravity environment.
The study, published in the journal Circulation, included 12 astronauts (eight men and four women aged 43 to 56) who had spent about six months in space.
All performed individualized endurance and strength training up to two hours per day in space flight to prevent cardiovascular, bone and muscle deconditioning. They also received an infusion of saline on their arrival.
The blood pressure of the astronauts was recorded at each heartbeat during each 24 hour period before, during and after their stay in space.
The researchers found that their blood pressure had minimal impact on all phases of measurement and that none of the astronauts participating in the study had experienced dizziness or fainting during activities. routine 24 hours after landing.
This study is the first to demonstrate that astronauts do not feel dizziness or fainting during routine activities after landing, as long as they participate in certain types of physical exercises in flight and receive fluids. intravenous when they return to Earth, said Levine.
"What surprised me the most is how well the astronauts behaved after spending six months in space, I thought the fainting episodes would be common." on their return to Earth, but they did not have any.This is convincing evidence of the effectiveness of the countermeasures – exercise program and fluid replenishment ", he said. declared.
The researchers noted that the size of the sample was small. In addition, they could not clearly distinguish whether specific readings of blood pressure in flight were made while astronauts were awake or asleep; the data were therefore combined and examined over 24-hour periods.
Since all astronauts participated in the exercise program and received a saline infusion on landing, the researchers do not know that blood pressure stabilization would have occurred without these measures.
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