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Foot Reaction Forces During Space Flight (Foot)
03.13.09

Overview | Description | Applications | Operations | Results | Publications | Images

Experiment/Payload Overview

Brief Summary

Mechanical loads and joint range of motion of the lower extremities together with muscle activity in both the lower and upper extremities are compared during periods of typical daily activity on Earth and ISS. This research will provide insight into mechanical loading in the loss of bone mineral in the lower extremities that is widely viewed as a factor that could limit long term human habitation of space or planetary missions.

Principal Investigator

  • Peter R. Cavanagh, Ph.D., D.Sc., The Cleveland Clinic Foundation, Cleveland, OH

    • Co-Investigator(s)/Collaborator(s)

  • Thomas J. Beck, Sc.D., Johns Hopkins University, Baltimore, MD
  • Michael Recht, M.D., Cleveland Clinic Foundation, Cleveland, OH
  • Hakan Ilaslan, M.D., Cleveland Clinic Foundation, Cleveland, OH
  • Andrea J. Rice, Cleveland Clinic Foundation, Cleveland, OH

    • Payload Developer

    Johnson Space Center, Human Research Program, Houston, TX

    Sponsoring Agency

    National Aeronautics and Space Administration (NASA)

    Expeditions Assigned

    |6|8|11|12|

    Previous ISS Missions

    This type of research has never been conducted on the ISS. Research aboard shuttle flights and the Russian Mir studied muscle and bone, but this is the first experiment of its kind. The Foot experiment has not flown on any mission prior to Expedition 6.

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    Experiment/Payload Description

    Research Summary

    • Stress on lower extremity bones and muscles during daily life in microgravity is thought to be markedly reduced compared to Earth gravity, although no measurements have previously been made to quantify this reduction.


    • The purpose of this experiment is to measure the load applied to the feet, the muscle activation, and joint range of motion of astronauts as they conduct routine daily activities both on Earth and in the microgravity environment of the ISS.


    • Tests conducted during this study also measure the degree to which muscle volume, muscle strength, and bone mineral density change during spaceflight. The daily load, which is reduced in space because of the lack of gravity, is then correlated to muscle and bone fitness after the astronauts return to Earth.


    • The results are used to directly compare the daily load experienced with changes in bone mineral density, muscle mass and muscle strength.

    Description

    The human body is designed to bear weight. Without the stimulation caused by placing weight on lower extremities, whether due to the microgravity environment or lack of use on Earth, bone will lose mass and muscles will lose strength. The Foot experiment characterizes the load placed on lower extremities during daily activities on station and examines to what degree mechanical load stimulus, via an inflight exercise routine, could prevent the muscle atrophy and bone loss associated with space flight.

    To achieve this, Foot has several sensors mounted in a special pair of Lycra exercise pants, the lower extremity monitoring suit (LEMS). The total force-foot ground interface (TF-FGI) serves as an insole that, when placed inside a shoe, measures the amount of force placed on the bottom of the foot. Joint excursion sensors (JESs) record joint angles at the ankle, knee, and hip. Electromyography (EMG) electrodes record muscle activity, including net neural drive, along the leg (the vastus medialis, rectus femoris, biceps femorics, gastrocnemius, and tibial anterior) and in the right arm (the biceps brachii and triceps brachii). Information is collected by an ambulatory data acquisition system and downloaded into the Human Research Facility (HRF) laptop on board ISS after each session.

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    Applications

    Space Applications

    The loss of bone mineral in the lower extremities is widely viewed as one of the critical factors that may limit long-term human habitation of space (upper extremity changes in BMD appear to be minimal or to increase). Deficiencies in lower extremity muscle function as a result of prolonged exposure to microgravity also have implications for performance and safety during space missions. The information derived from this study is expected to shed new light on possible solutions to bone mineral loss and drops in muscle function of the lower extremities. These results will lay an important foundation for the further development of countermeasures for lower extremity muscle and bone loss.

    Earth Applications

    Information Pending

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    Operations

    Operational Requirements

    The Foot sensors (the TF-FGI, JES, and EMG electrodes) and the ADAS1 all operate on batteries. The information collected by the ADAS1 is downloaded into the Human Research Facility (HRF) laptop after each session. When not in use, all Foot hardware is stored in the HRF.

    Operational Protocols

    A baseline for each participant is created preflight: a Dual Energy X-ray Absorptiometry (DEXA) image establishes bone mineral density; a muscle cross-sectional area is measured via Magnetic Resonance Imaging (MRI); and joint strength is determined using Cybex, an isokinetic dynamometer.

    During their stay on ISS, the participants wear the LEMS and accompanying armband for approximately 8 hours as they go about their daily activities, including exercise. Data is taken for four days evenly spaced throughout the Expedition. The FGI-FCU is used to calibrate the insoles; a nitrogen source keeps a neoprene bladder inflated to maintain contact with the surface of the insole. The data is transferred from the ADAS1 to the HRF laptop after each session.

    After flight, additional DEXA and MRI images and Cybex measurements are taken on each participant. The preflight, inflight, and postflight data are compared to create a complete dataset of activity, muscle strength, and bone density changes.

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    Results/More Information

    Results provide insight into the processes of loss of bone mineral density and muscle mass during long-duration stays on orbit. Knee-joint motion in space is reduced compared to that on Earth, and this has an effect on muscle action. In preliminary data analyses of the first subject, significant loss of bone mass was observed. Measurements of forces during exercise suggested that much less force was experienced than would be experienced when exercising on Earth. Detailed data were collected on loads across all exercise hardware settings during Expeditions 11 and 12. Final analysis will help in determining exercise prescriptions for station crewmembers and in the design of future exercise devices for Exploration missions.

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    Related Web Sites
  • Life Sciences Data Archive
  • Lerner Research Institute: Exercise in Microgravity
  • International Space Station Medical Project (ISSMP)

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    Publications

    Results Publications

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    Related Publications
    • Cavanagh PR, Licata AA, Rice AJ. Exercise and Pharmocological Countermeasures for Bone Loss During Long-Duration Space Flight. Gravitational and Space Biology. ;18(2):39-58. 2005

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    Images

    imageNASA Image: ISS006E11018 - Expedition Six Mission Commander Kenneth Bowersox, wearing a body harness, runs on the Treadmill Vibration Isolation System (TVIS) while conducting the Foot/Ground Reaction Forces During Spaceflight (Foot) experiment in the Zvezda/Service Module.
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    imageNASA Image: ISS006E11011 - View of the body harness for the Treadmill Vibration Isolation System (TVIS) and the Lower Extremity Monitoring Suit (LEMS) for the Foot/Ground Reaction Forces During Spaceflight (Foot) experiment in the Zvezda/Service Module. Both apparatus are being worn by Expedition Six Mission Commander Ken Bowersox.
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    imageNASA Image: ISS008E20918 - Donned in the customized Lower Extremity Monitoring Suit (LEMS), Expedition 8 Mission Commander and Science Officer Michael Foale balances on the footplate of a special track attached to the Human Research Facility (HRF) rack in the Destiny U.S. Laboratory to perform Foot/Ground Reaction Forces During Spaceflight (Foot)/ Electromyography (EMG) calibration operations.
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    imageNASA Image: ISS011E09829 - ISS Expedition 11 Science Officer, John Phillips, performing a Foot session in the U.S. Lab wearing the Foot LEMS pants.
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    imageNASA Image: ISS011E09822 - ISS Expedition 11 Science Officer, John Phillips, performing a Foot session while exercising on the Cycle Egrometer with Vibration Isolation System (CEVIS) wearing the Foot LEMS pants.
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    imageNASA Image: ISS012E18576 - Astronaut William S. (Bill) McArthur, Expedition 12 commander and NASA space station science officer, uses the Cycle Ergometer with Vibration Isolation System (CEVIS) while participating in the Foot/Ground Reaction Forces During Spaceflight (Foot) experiment in the Destiny laboratory of the International Space Station. McArthur wore the specially instrumented Lower Extremity Monitoring Suit (LEMS), cycling tights outfitted with sensors, during the experiment.
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    imageASA Image: ISS012E20120 - Astronaut William S. (Bill) McArthur, Expedition 12 commander and NASA space station science officer, equipped with a bungee harness, exercises on the Treadmill Vibration Isolation System (TVIS) while participating in the final run of the Foot experiment in the Zvezda Service Module of the International Space Station. McArthur was attired in the specially instrumented Lower Extremity Monitoring Suit (LEMS), cycling tights outfitted with sensors, during the experiment.
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    Information Provided and Updated by the ISS Program Scientist's Office
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