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Expert physiologist shares insights on factors affecting health of astronauts on extended missions


NASA’s Artemis program aims to land another man and the first woman on the moon by 2024, and ultimately establish sustainable space travel by 2028. The Artemis program is a stepping stone in NASA’s subsequent goal of landing on Mars, which could take a crewed mission between two and three years to complete.

Such lengthy missions could take a significant toll on the health and performance of the astronauts involved. Finding solutions to that challenge is the central question thought leaders in strength and conditioning, psychology, sport science, nutrition and related fields will explore at the Spaceflight Human Optimization and Performance Summit, to be held at University of Houston-Clear Lake April 27-29.  

Barry Spiering, lead physiologist in the New Balance Sports Research Lab, is among the summit’s expert speakers and will be sharing his insights on maintaining the health and performance of astronauts on lengthy missions.

“Being in space for a long time is like being in bed for a long time,” he said. “When you’re in space for long periods, you could see a loss of bone and muscle mass and a loss of cardiovascular function,” he said. “These and other changes in the body could disrupt health and physical performance. If someone is in space and their physical performance is jeopardized, it could affect the success of the overall mission, as well as the safety and health of the astronaut when they return to Earth.”

In the zero-gravity environment aboard the orbiting International Space Station, bones and muscles, which are built to support the body’s mass, experience loss or atrophy.

“The body is built for gravity; it’s used to dealing with forces,” Spiering said. “Over time, your muscles and bones detect forces, which tell your muscles and bones to get bigger and stronger. But in space, where there’s no gravity, those forces and signals are much less. Without them, your bones and muscles get weaker because there’s fewer forces to tell them to get stronger.”

The cardiovascular system can suffer in space as well. “Gravity pulls blood toward your feet,” explained Spiering. “Your heart adjusts to that and can maintain blood pressure and delivery on Earth. But in zero gravity, there’s nothing to pull the blood to the feet.”

The loss of gravity causes more blood to be around the heart. “Usually there isn’t that much blood around the heart, and it gets rid of plasma volume, which is the water content in the blood. Your body thinks you don’t need it,” he said. “Then, when you get back to earth, your body has trouble regulating its blood pressure. This is called orthostatic intolerance.”

Remedies for these issues are tricky, Spiering said, and although strength training is important, the problem requires more than one solution.

“Strength training is great because it maintains strength and replaces those forces that trigger the muscles and bones to get stronger,” he said. “But NASA scientists show that it’s not 100% effective in space. There are many nutritional questions as well. We aren’t sure if eating more calories helps maintain muscles size and strength. Maybe more protein? Protein helps with muscles, but not necessarily with bone loss. Diet is a huge part of the question we are considering here.”

So, what is the upper limit of an astronaut’s ability to maintain health and performance in space?

“Part of what NASA is doing, and one of the topics of this conference, is to extend how long astronauts can safely be in space,” Spiering said. “If we combine knowledge about exercise, diet, bones, muscles and the heart, we can come up with some powerful information. We want to figure out what we can do maintain astronauts’ health and performance in space for as long as possible.”

Spiering’s presentation, entitled “Training for Human Performance: From Soldiers to Spaceflight,” also draws from his insights working for the Army Research Institute of Environmental Medicine, helping soldiers reduce injury and improve performance. The presentation takes place Friday, April 28 at 9:40 a.m. To register for the conference, go online.