To study space travel's effect on muscles, Dr. Robert Wolfe of the University of Texas Medical Branch at Galveston enlisted healthy subjects to stay in bed 28 days during a National Space Biomedical Research Institute study.
"One cause of muscle atrophy in space is lack of muscular activity. That's why bed rest is a good model because it minimizes activity, and like astronauts, you lose muscle mass primarily in the legs," said co-investigator Dr. Arny Ferrando, a professor of surgery at UTMB and Shriners Hospital for Children in Galveston. "When muscles are inactive, as they are in space, they don't make new proteins. If muscle breakdown rates are the same, that means you lose muscle."
Researchers are attempting to increase protein synthesis rates with supplements of amino acids, which are the raw materials of protein. Participants received the supplements three times a day, and researchers compared the protein synthesis/breakdown rates and muscle mass before and after the bed-rest study. This data was compared to results from a control group that received a placebo drink instead of the supplements.
"Early results suggest that the amino acid supplement is able to maintain synthesis rates and body mass," Ferrando said.
During the study, subjects must remain in bed and can get up only briefly to use a bedside commode. They eat and bathe from their beds, and daily activities encompass watching television, reading books and using a bedside computer.
Midway through the study, researchers determine muscle mass and function by testing the subjects' strength and body composition.
They gather the most vital data, the protein synthesis and breakdown rates, by using stable isotope analysis. With the stable isotope technique, researchers attach
Contact: Kathy Major
National Space Biomedical Research Institute