Periodic Fitness Evaluation with Oxygen Uptake Measurement (PFE-OUM) - 10.22.18

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The Periodic Fitness Evaluation with Oxygen Uptake Measurement (PFE-OUM) will demonstrate the capability of crewmembers to perform periodic fitness evaluations (PFE) with continuous oxygen consumption measurements within 14 days after arrival on ISS, and once monthly during routine PFEs. Once the capability of the pulmonary function system (PFS) to perform PFEs is verified, crewmembers will be able to integrate their monthly PFE with oxygen consumption measurements to fulfill the requirement for cardiovascular fitness evaluations during long-duration space flight.
Science Results for Everyone
Information Pending

The following content was provided by Filippo Castrucci, M.D., Sean K. Roden, M.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Filippo Castrucci, M.D., European Astronaut Centre, Cologne, Germany
Sean K. Roden, M.D., Johnson Space Center, Houston, TX, United States

Simon N. Evetts, Ph.D., European Astronaut Centre, Cologne, Germany
Frank A. McCleary, Lockheed Martin, Houston, TX, United States
Alan D. Moore Jr., Ph.D., Houston, TX, United States
Nora Petersen, European Astronaut Centre, Cologne, Germany
Ed Powers, M.D., Johnson Space Center, Houston, TX, United States

Danish Aerospace Company, Odense, Denmark

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)

Research Benefits
Information Pending

ISS Expedition Duration
April 2006 - April 2008

Expeditions Assigned

Previous Missions
ISS Expedition 13 was the first mission for the PFE-OUM.

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Experiment Description

Research Overview

  • The PFE-OUM is a collaborative effort between the European Space Agency (ESA) and National Aeronautics and Space Administration (NASA). NASA Medical Operations require an evaluation of crew aerobic capacity. Currently, the crew aerobic capacity on-board is calculated using heart rate while the crew goes through a set exercise protocol.

  • The PFS upgrade hardware developed for the Human Research Facility-2 provides the necessary hardware to directly measure oxygen consumption with the crewmember breathing through a mouthpiece in the performance of the routine PFE evaluation.

  • The project is designed to be completed in three phases. Phase I, proof of concept, was demonstrated during Increment 13. Phase II, initial implementation for crewmembers and hardware check-out, will start as soon as additional interface hardware is available on orbit, and Phase III will be the migration to PFE-OUM for crew fitness evaluation.

International Space Station (ISS) crewmembers routinely perform a ground-based exercise tests using metabolic gas analysis before and after space flight. During these tests oxygen uptake measurements (OUM) are made, and are used to determine a person's aerobic capacity. Measurement of aerobic capacity allows exercise physiologists and flight doctors to assess crew health and fitness and accurately prescribe exercise countermeasures for use onboard the ISS.

During space flight, the ISS crewmembers perform a monthly periodic fitness evaluation (PFE) starting on flight day 14, and repeated every 30 days. While performing this test, a crewmember's heart rate and blood pressure are recorded using the Blood Pressure/Electrocardiograph (BP/ECG). Heart rate data along with the prescribed Cycle Ergometer with Vibration Isolation System (CEVIS) workloads, allows ground personnel to estimate changes in crewmember aerobic capacity by comparing the heart rate response to increases in workload performed during pre-flight evaluations. There are several limitations to this approach of measuring oxygen capacity which the PFE-OUM will eliminate.

To date, OUMs have not been possible during the PFE because hardware capable of measuring oxygen uptake has not been available aboard the ISS. Now, the Pulmonary Function System (PFS) provides the ability to perform the required OUMs. The PFS is a development in the field of respiratory physiology instrumentation by the European Space Agency (ESA). The PFS consists of the Photoacoustic Analyzer Module (PAM), Pulmonary Function Module (PFM) and the Gas Delivery System (GDS) which is capable of a wide range of respiratory and cardiovascular measurements. The PFS was initially launched to the ISS aboard STS-114/LF1, followed by a hardware upgrade which was launched on a Russian Progress Cargo Module 21 in April 2006. All hardware pertaining to the OUM activity is currently stored in the HRF Rack 2 and was checked out during Expedition 12.

This evaluation will be performed in two phases. The first phase will be used to assess the feasibility of making OUMs during the PFE. The data will give investigators and technical personnel the necessary information to determine if the PFS is able to accurately perform OUMs aboard the ISS within the current timelines designated for the PFE.

The second phase of this evaluation will be used to compare the current methods of estimating ISS crewmember's aerobic fitness with the more direct method of performing OUMs. The data collected during this phase along with data collected during phase one will be analyzed using the current method of estimating changes in aerobic fitness (i.e. workload and heart rate observations alone) and direct analysis of the heart rate data in association with OUMs.

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Space Applications
The PFE-OUM measurements will help flight surgeons to better understand the decline in cardiovascular function that occurs during long-duration stays in microgravity.

Earth Applications
Little information is currently available on the effects of long-term exposure to a closed life control system microgravity environment on aerobic capacity of humans. This information is important to maintain crew health during long-duration exploration. The data will also provide valuable insight into the aerobic capacity of teams in closed environments on Earth, such as arctic bases and submarines.

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Operational Requirements and Protocols
A minimum of six crewmembers are needed to perform the PFE-OUM on ISS. The following measurements will be examined: oxygen consumption, carbon dioxide production, respiratory exchange ratio, expiratory minute ventilation, tidal volume, respiratory rate, fraction of expired oxygen, fraction of expired carbon dioxide, heart rate, workload, estimate of aerobic capacity using heart rate and workload data (current method) and estimate of aerobic capacity using heart rate and OUM data. Each variable will be used to compare preflight, in-flight and postflight measurements.
Preflight, subjects will undergo their required tests using nominal metabolic gas analysis hardware, which includes a peak cycle test (L-270) and a submaximal cycle test (L-30 to 45). In flight, prior to the performance of the PFE-OUM, crewmembers will setup and calibrate the PFE-OUM hardware. Crewmembers will then perform the exercise protocol. During the PFE-OUM the crewmember will inhale cabin air and exhale through a mouthpiece and their nostrils will be occluded with a nose clip. The fractions of oxygen and carbon dioxide in the expired air will be measured by the PFS and used to calculate oxygen consumption, carbon dioxide production and metabolic rate. Blood pressure will be measured at designated time intervals throughout the protocol, while ECG is recorded continuously via the BP/ECG. Postflight, the crewmember will perform the nominal submaximal cycle test at R+5 to 7 and R+30 using nominal metabolic gas analysis hardware.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Analysis of data from PFE-OUM is ongoing, conclusive results will be published upon completion of data analysis.

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Results Publications

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites

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image NASA Image: ISS013E64486 - ESA astronaut Thomas Reiter, Expedition 13 flight engineer, prepares the HRF-2 rack for the scheduled upgrade of the PFS experiment in the Destiny laboratory of the ISS.
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image NASA Image: ISSE01356862 - NASA ISS Science Officer Jeff Williams assisting Flight Engineer-2, Thomas Reiter performing his PFE-OUM on the CEVIS during ISS Expedition 13.
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image NASA Image: ISS014E12532 - Expedition 14 flight Engineer and NASA Astronaut Suni Williams calibrates the PFE-OUM hardware for her upcoming session in January 2007.
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image NASA Image: ISS015E09458 - Expeditions 14 and 15 astronaut and Flight Engineer (FE-2), Sunita Williams, exercising on the Cycle Ergometer with Vibration Isolation and Stabilization (CEVIS) during the Periodic Fitness Evaluation with Oxygen Uptake Measurement (PFE-OUM) experiment in the U.S. Laboratory/Destiny. Cosmonaut and Flight Engineer (FE-1), Oleg Kotov, assists Williams.
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