Resistance Training May Help Astronauts on Long Space Flights

Newswise — Resistance training should help astronauts stay in shape during long space flights, says a new study from Ball State University.

Astronauts may be able to negate the loss of muscle strength and size caused by long durations in space with just a few regular sessions of high-intensity resistance training, according to the results of the study recently published in the Journal of Physiology.

Ball State researchers made the discovery after creating an artificial space environment, which mimics zero gravity environments, by having 12 participants confined to their beds for 84 consecutive days. During the study, six members participated in regular exercise sessions while the other six did nothing.

The non-exercise group lost 17 percent of leg muscle size and 40 percent of leg strength. Members of the exercise group performed four sets of squats every third day, allowing them to maintain muscle size and strength.

"Spaceflight is a unique environment that poses several physiological challenges to the human body," said Scott Trappe, director of Ball State's Human Performance Laboratory. "As the various space agencies around the world focus their attention on long duration stays on the International Space Station (ISS), implementation of effective exercise regimens is essential for the health and well being of the crew members."

Previous studies have found that skeletal muscle mass and strength are reduced with as few as seven days in space and continue to decline over the course of the flight, he said.

"Resistance training is the most promising candidate for providing the proper stimulus to maintain muscle function while in space," Trappe said. "Given the time and energy requirements of ISS crewmembers, the space agencies are interested in implementing effective countermeasure activities that minimize exercise time while maximizing the physiological benefits.''

In addition to leg muscle performance, a specialized laboratory technique was used in this study that allowed researchers to analyze individual slow-twitch muscle fibers, suited for endurance activities, and fast-twitch muscle fibers, for sprint and power activities, from the thigh muscles before and after bed rest. The data showed that both fiber types lose functionality with long-term bed rest.

Trappe said it was of particular interest that the resistance-training program appeared to target the fast-twitch fibers while the slow-twitch fibers still had some degree of reduced performance.

"These initial results are very promising for the physical health of the crew members in space," he said. "But the results also indicate that more research is necessary before we have an exercise countermeasure that is 100 percent effective for protecting human muscle. We are close, but there is more work to do" .

Trappe and his team are continuing their research efforts on muscles and optimizing the exercise countermeasures for human space travel in an upcoming bed rest experiment that will be conducted as a joint study between the National Aeronautics and Space Administration (NASA), European Space Agency (ESA) and the French Space Agency (CNES). This study will examine the combined effects of strength training and aerobic training for maintaining muscle performance.

Trappe and researchers from Ball State's Human Performance Laboratory have been examining the effects of space flight on the human body since the mid-1990s when they performed pre- and post-flight examinations of American astronauts on the space shuttle. As part of the project, Trappe participated in the design and development of a device that tests calf muscle strength and fatigability for space shuttle flights.

The team is currently continuing to examine the effect of prolonged space flight and bed rest on human skeletal muscles through grants from NASA.