Combating muscle loss in space

Sep 16, 2019, 01:10 AM by Donna Ramirez

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A NEW UTMB STUDY has further documented how muscles are affected by reduced-gravity conditions during space flight missions and has uncovered how exercise and hormone treatments can be tailored to minimize muscle loss for individual space travelers. 

NASA’s recent announcement that it will allow private citizens to visit the International Space Station underscores the need to understand the impact of reduced gravity on the human body. 

“The study has given us the ability to identify biomarkers that predict how susceptible each individual is to muscle function decline and how effectively different exercise and hormone treatments can combat the atrophy,” said senior author Dr. Randall Urban, UTMB chief research officer and professor in the Department of Internal Medicine. 

Senior author Dr. Melinda Sheffield-Moore, professor in the Texas A&M University Department of Health and Kinesiology and UTMB’s Department of Internal Medicine, added that this new ability may allow scientists to personalize space medicine by designing specific exercise and/ or hormone intervention programs for each astronaut on Earth before they embark on a long-term mission to space. 

Space flight-related losses in muscle mass and strength are a key concern for long space exploration missions. The muscle loss during space flight largely stems from the fact that weight-bearing muscles don’t work as hard in reduced-gravity conditions. 

While in space, astronauts exercise in an effort to counter muscle loss, but the exercise doesn’t completely prevent muscle atrophy. So, researchers are looking for additional interventions that complement in-flight exercise. 

The effects of long-term muscle inactivity can be investigated with extended bed rest. In the study, 24 healthy male participants were placed on bed rest for 70 days. During the bed-rest period, some of the men followed an exercise regimen and blindly received either testosterone supplements or a placebo. A control group remained in the bed without any exercise training or supplements. 

Throughout the study, the researchers collected muscle biopsies to analyze the proteins within the muscle tissue. 

Researchers uncovered several changes to the men’s muscle proteins during the bed-rest period that were blunted or reversed with exercise, which appeared to drive a healthier protein organization within the muscle fibers. The testosterone supplements prompted further protein changes that promoted muscle growth beyond that of exercise alone. 

“The unique insights we’ve gained on muscle proteins during extended bed rest could someday be applied to predict changes to muscle mass and strength in various situations and then develop a personalized program of exercises and hormonal countermeasures,” said senior author Dr. E. Lichar Dillon, UTMB assistant professor in the Department of Internal Medicine. 

Other UTMB authors include Drs. Kizhake Soman, John Wiktorowicz, Ria Sur, Daniel Jupiter, Christopher Danesi, Kathleen Randolph, Charles Gilkison and William Durham.