In the next 50 years, NASA plans to send astronauts to the Moon and Mars. These astronauts will need to perform a variety of physical tasks (for example extravehicular activities, habitat assembly, etc.) to accomplish their missions. However, they may be physically unable to do these tasks if some of the health effects of space flight are not prevented.

Early medical data from International Space Station (ISS) astronauts have revealed adverse health outcomes: loss of bone density, decreased muscle strength and endurance, sensory-motor function (i.e. balance), and reductions in aerobic capacity. These deconditioning effects, caused by the absence of Earth’s gravity, over time can impair astronauts’ performance or increase their risk of injury. Exercise will play an essential role in lowering the risks from these effects, increasing the probability of mission success for objectives when landing on Moon and Mars, and ensuring optimal recovery on return to Earth.

The Exercise Countermeasures Project (ECP) is a part of the Human Research Program at NASA Johnson Space Center (JSC) in Houston, TX. The ECP is charged with developing exercise protocols and hardware to maintain astronaut health and fitness during long-duration space missions, to preserve the capability to perform mission critical tasks both in transit and while on the planetary surface. NASA engineers and scientists must consider constraints on equipment size, exercise volume, and power consumption imposed by the spacecraft and terrestrial habitats.

In addition to the personnel at JSC, the ECP is also comprised of team members from the NASA Glenn Research Center (GRC) in Cleveland, OH and collaborates with experts in various scientific subjects at the National Space Biomedical Research Institute (NSBRI) and at colleges and universities. Collaborations between these groups make the most of existing expertise and resources to develop exercise systems for astronauts to use during exploration space missions.

Project Objective

Exploration missions to the Moon and Mars will present unprecedented long-duration confinement, isolation, surface space walks, and exposure to zero and partial-gravity environments. The abrupt return to partial gravity upon arrival on the Moon or Mars, coupled with health issues related to space travel, could affect the ability of astronauts to perform their tasks and may contribute to mission- or life-threatening situations. The next generation of exercise countermeasures will be a key element in the solution to these problems.

The Exercise Countermeasure Project will identify exercise countermeasure prescriptions and systems for space exploration that are effective, optimized, validated, and meet medical, vehicle, and habitat requirements.

Project Goals

• Develop prescriptions for exercise countermeasures that efficiently reduce the negative effects of zero and partial gravity and meet the medical needs of astronauts
  
• Establish the requirements for exercise equipment that will provide the prescribed exercise countermeasures within the constraints imposed by the space exploration vehicle and the astronauts’ habitat on the Moon or Mars

Challenges

For decades, NASA has researched the benefits of using exercise in space to maintain astronaut health. When designing exercise systems for exploration missions, NASA engineers and scientists must consider constraints on equipment size, exercise volume, weight, and power consumption that are imposed by the spacecraft and surface habitats. They must also consider unique engineering factors to allow astronauts to adequately load their bodies with harnesses and restraints and comfortably complete their prescribed exercise regimens successfully. In addition, the exercise duration and frequency should be optimized to allow time for the other mission tasks.

Exercise on the International Space Station (ISS)

Resistive Exercise

Resistive exercise, or strength training, is exercise performed against a weight. During spaceflight, resistance exercise is completed by securing the astronaut to a strength device that imparts load on the body. In environments with low gravity, the resistance device simulates weight bearing on the body. Resistance is varied to provide the weight load needed for each exercise. The latest resistive exercise device, the Advanced Resistive Exercise Device (ARED), has the capabilities of load range from 0 - 600 lbs. ARED will be available to the ISS astronauts in late 2009. Resistive exercise is designed to prevent weakening of the major muscle groups and to minimize bone loss, by maintaining strength and endurance.

Cycle Ergometry

Cycle ergometer exercise in space consists of pedaling a recumbent cycle. It provides general aerobic and cardiovascular conditioning as well as improved muscular endurance. Cycle ergometry is an important aspect of physical conditioning for doing ISS tasks such as space walks, and to exercise during the pre-breathe period before a space walk. Cycle ergometry can be performed in either a manual mode, where cycling workload is controlled manually by the astronaut, or an electronic mode, where the workload is varied by an electronic controller. The workload on the device being used on the ISS can be set at a maximum of 350 watts for pedal speeds up to 120 rpm.

Treadmill Exercise

Treadmill exercise includes walking, running, deep knee bends, and some resistive exercises. It is used to maintain bone mass, cardiovascular fitness, muscle endurance, and the neurophysiologic pathways and reflexes required for walking on Earth or other planetary surfaces. Treadmill exercise can be performed in either a motorized (active) or non-motorized (passive) mode. The motorized mode provides the astronaut with speed control adjustable from 0 to 10 miles/hour in increments of 0.1 mile/hour. Non-motorized mode allows the astronaut to drive the treadmill against variable resistenace. The astronaut is coupled to the treadmill by a subject restraint system, including a harness worn about the shoulders and hips and subject loading devices. The next generation treadmill (T2), that will be delivered to ISS in Fall of 2009, will provide NASA medical and science personnel with more physiological and biomechanical data than ever before on astronaut performance capabilities during exercise, including force plate data which records the amount of pressure exerted by the astronaut on the belt of the treadmill.

The Future: To Moon and Mars, and Beyond

The next generation of exercise countermeasures being developed by ECP will play a key role in the resolution to the deleterious effects of space exploration by building on the knowledge gained from previous space flight exercise equipment and protocols. Project personnel are working with designers of exploration vehicles and habitats to determine the requirements that an exercise device and protocol must meet for use in Lunar and Martian environments and in new transit vehicles.

Meanwhile, candidate equipment and protocols are being tested extensively with humans using Earth-based analogs of weightlessness and partial-gravity (e.g. bed rest, zero-gravity aircraft, vertical treadmill or Standalone Zero-Gravity Locomotion Simulator, sZLS), when space flight opportunities are not available for these studies. An example of one such Earth-based study is ECP’s aim to quantify the physiologic and energetic costs to astronauts in completing simulated mission critical tasks by collection and analysis of real-time aerobic and biomechanics data. Additionally, ECP will conduct functional testing on astronauts before launch and after return from Shuttle and ISS missions to better understand the impact that observed and measured physiological decrements have on the astronaut’s functional performance when completing anticipated exploration tasks. Data from testing countermeasures for extended periods on the ISS will lead to improved exercise countermeasures for extended Moon and Mars missions.

Thus, utilizing current microgravity space missions to conduct new studies, understanding what has been learned thus far from space flight history, conducting human ground-analog and flight studies, and using computer-based simulations of anticipated Exploration tasks are keys to developing more effective and efficient exercise hardware and protocols to ensure future mission success. The Exercise Countermeasures Project will play an important role in the exploration of the solar system by keeping astronauts healthy, safe, and fit for the required mission tasks.

Who is Involved

• Multiple NASA Centers
  NASA HQ, Johnson Space Center (JSC), Glenn Research Center (GRC)
• Other JSC Projects
  Crew Health Care Systems, ISS Medical, Flight Analogs, EVA Physiology, Systems and Performance Project, Non-exercise Countermeasures and others
• NASA JSC Labs
  Exercise Physiology, Nutritional Biochemistry, Pharmacotherapeutics, Cardiovascular, Neuroscience, Bone, and others
• NASA GRC Labs
  Exercise Countermeasures Lab (including the enhanced zero-g locomotion simulator or eZLS)
• National Space Biomedical Research Institute (NSBRI)
• Colleges and universities

Project Activities

• On-going review current space flight exercise data and findings
• Support ground-based simulations of anticipated exploration activities to measure physiologic cost to complete activities
• Conduct space flight studies to document pre-, in-, and post flight aerobic, muscle, and bone health and impact of exercise countermeasures
• Conduct analog studies to evaluate efficacy of candidate exercise prescriptions and hardware
• Conduct space flight studies to evaluate candidate exercise devices and prescriptions
• Assess crew performance post flight and map to physiologic systems
• Define requirements for exercise countermeasure and monitoring hardware for Moon and Mars vehicles and habitats
• Participate in integrated studies with other types of countermeasures