NASA is committed to maintaining astronaut health during exploration missions. The maintenance of astronaut health and fitness during space missions is important to ensure the accomplishment of critical mission tasks in transit to and from the moon and Mars as well as on the lunar and Martian surfaces. Muscles and bones weaken as an adaptation to reduced gravity environments, and no exercise regimen has been effective in successfully combating these effects.

To meet these objectives, Glenn has developed the enhanced Zero-gravity Locomotion Simulator (eZLS), which is a new ground-based simulator developed to address the detrimental physiological effects of spaceflight on the musculoskeletal system through improved exercise countermeasure systems.  The eZLS has the ability to mimic the vehicle and exercise device interfaces found on the International Space Station (ISS) and other vehicles being developed for future space exploration. It is important to replicate the interface configurations seen on the ISS and future vehicles to understand how the interface may affect the resulting forces on the muscles and bones. The eZLS is also a test bed for future exploration missions and can be used to simulate locomotion in partial gravity environments including the moon and Mars. 

In an effort to develop improved exercise routines and equipment for astronauts, the eZLS allows scientists and engineers to conduct research with human participants in the following areas:

• Understanding the metabolic cost of locomotion in partial gravity
• Improving crew comfort during exercise
• Developing exercise prescriptions
• Optimizing hardware
• Developing and characterizing advanced exercise device concepts for exploration missions

Aside from space applications, experiments conducted using the eZLS may help medical researchers improve their understanding of the role of exercise in the prevention of osteoporosis on Earth. The deterioration of bone and muscle during osteoporosis is similar to what occurs in an astronaut’s body, although the process is greatly accelerated in space.

Glenn’s Exercise Countermeasures Project is also performing simulations of locomotion in lunar gravity to assess the physiological demands of performing critical mission tasks such as carrying equipment and recovering from a fall on the moon. Since the critical mission task assessments will require the cooperation of different laboratories in other locations, Glenn is developing a database to store, process, and archive the physiological data collected from these assessments.

The project is designing a new exercise harness for astronauts to wear while they run on the ISS treadmill. In space, the treadmill includes a harness that is attached to a load device. The harness and load device tether the crewmember to the treadmill and allow them to run against the treadmill belt in microgravity. Greater loads increase the forces applied to the musculoskeletal system, which is thought to increase the effectiveness of the exercise in combating bone and muscle loss. Previous harness designs have caused discomfort to crewmembers (such as concentrated pressure at the shoulders and hips, tenderness, and impeded breathing), which prevents them from exercising comfortably at the optimal load conditions.

With a NASA grant, the Cleveland Clinic developed a new prototype harness incorporating technology from the backpack industry. The Cleveland Clinic’s prototype harness includes the following features:

• “S”-shaped padded shoulder straps that avoid sensitive regions of the neck and shoulder while minimizing chest compression

• Waist belt with cupped regions to apply load more evenly to the hips

• Moldable waist belt for customized fit and improved comfort

• Multiple load attachment points and a semi-rigid waist belt shell for better load distribution

Efforts are now being made to convert the prototype harness into a harness appropriate for use in space that allows exercise to be completed comfortably and at greater loads.

The Orion crew exploration vehicle, lunar lander, and/or lunar habitats may also have exercise equipment to keep crewmembers healthy and fit for duty. Glenn’s Exercise Countermeasures Project is developing advanced exercise device concepts to meet the requirements for exploration missions. There are special challenges posed by providing equipment with adequate capability while meeting volume, mass and power limitations imposed by the vehicle or habitat.