As the 50th anniversary of the Apollo moon landing approaches, America’s got space travel on the brain, and a study by University of Texas Medical Branch researchers on the health of astronauts could make a big contribution to healthier space voyages in the future.

The study, published in the open source medical journal PLOS One, documents the effect on muscle mass of reduced gravity during space flight missions and the potential of customized exercise and hormone treatments to minimize muscle loss on long journeys.

Space flight-related losses in muscle mass and strength are among the prime concerns for long duration space exploration missions and involve alterations in myofibrillar protein content and metabolism, according to the medical branch study, funded by NASA.

“What we’ve shown, the real benefit of the study, is that we may be able to reduce the amount of time astronauts spend exercising to avoid losing muscle mass,” said Dr. Randall Urban, senior author of the study, professor, endocrinologist and vice president of clinical research in the medical branch’s school of medicine.

Astronauts, especially those in space for a while, have to spend as much as 2½ to 3 hours a day exercising to maintain muscle mass in low-gravity environments, such as the International Space Station and other spacecraft. Knowing this, NASA commissioned several bed rest studies, including this one at the medical branch, looking for ways to avoid muscle atrophy, Urban said.

The medical branch study took healthy subjects chosen by NASA’s Human Research Program, and put them on complete bed rest for a 70-day period. Some of the 24 subjects performed a combination of aerobic and resistance exercises while prone and received either small-dose testosterone or placebo injections, while a control group remained bedridden without any exercise training or supplements. Researchers gathered muscle biopsies throughout the study, analyzing proteins within the muscle tissue, according to a study summary.

“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 muscle atrophy,” Urban said.

The hope is that, down the line, scientists might be able to identify people more at risk to muscle atrophy and prescribe a mix of exercise and hormone therapy that will prevent muscle loss in space.

“It’s in the future and this is a first step to that,” Urban said. “As we begin to understand each individual, their genotype and the proteins they’re expressing, we can begin to identify how certain people will do in certain situations, to say yes, you’ll do well in space flight or no, you’ll need testosterone.”

The team hopes to be able to extend the results to women as well, with customized doses of testosterone, to see whether they have the same kind of response as men, Urban said.

That would require another bed rest study and, for now, the medical branch’s bed rest unit is closed while NASA has taken its bed rest studies abroad to Europe, Urban said.

But Urban and others involved in this research are looking for ways to take what they’ve learned and translate it to earthbound patient populations.

“We’re now investigating using low dose testosterone in men and women with COPD, in conjunction with pulmonary rehab and an exercise program,” Urban said. Chronic obstructive pulmonary disease is a lung disease that affects about 16 million Americans, according to the U.S. Centers for Disease Control and Prevention.

Meanwhile, NASA has recently announced it will allow private citizens to visit the International Space Station, underscoring a growing need to understand the effect of reduced gravity on the human body and how to prevent muscle atrophy in space.

Kathryn Eastburn: 409-683-5257;

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