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Metabolic Activity (M171)
Principal Investigator
Research Area:
Cardiovascular physiology
Pulmonary physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

The primary objective of this experiment was to determine whether man's metabolic effectiveness during mechanical work was progressively altered by exposure to the space environment. This was based on observations made during the Apollo Program, which showed a significant decrease in exercise tolerance in 20 of 27 astronauts tested. The response returned to normal within 24 to 36 hours. These observations established the need to understand the underlying physiological mechanism for the changes in metabolic activity caused by exposure to weightlessness.

A secondary objective of the experiment was to evaluate the bicycle ergometer as an inflight exercise device for long-duration missions.

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\Sawin CF, Rummel JA, and Michel EL. Instrumented personal exercise during long-duration space flight. Aviation, Space, and Environmental Medicine. 1975. April; 46(4 Sec 1):394-400. []

Buderer MC, Rummel JA, Michel EL, Mauldin OG, and Sawin CF. Exercise cardiac output following Skylab missions: the second manned Skylab mission. Aviation, Space, and Environmental Medicine. 1976. April; 47(4):365-72.[]

Johnston RS and Dietlein LF, editors. Biomedical Results of Skylab. NASA SP-377. 1977. [NTRS]

Johnston RS and Dietlein LF. The Proceedings of the Skylab Life Sciences Symposium. August 27-29, 1974. NASA Johnson Space Center; Houston, TX, United States. November 01, 1974. NASA TM X-58154. [NTRS]

Johnston RS, Skylab Medical Experiments Altitude Test (SMEAT). NASA Johnson Space Center; Houston, TX, United States. October 01, 1973. NASA TM X-58115. [NTRS]

Michel EL, Rummel JA, and Sawin CF. Skylab experiment M-171 "Metabolic Activity": results of the first manned mission, Acta Astronautica. 1975. March-April, 2(3-4): 351-365.[]

Rummel JA, Michel EL, Sawin CF, and Buderer MC. Metabolic studies during exercise: the second manned mission, Aviation, Space, and Environmental Medicine. 1976. April; 47(4):391-6. []

Sawin CF, Nicogossian AE, Rummel JA, and Michel EL. Pulmonary function evaluation during the Skylab and Apollo-Soyuz missions. Aviation, Space, and Environmental Medicine. 1976. February; 47(2):168-72. []

Spross FR. Skylab Medical Data Center and Archives. NASA Johnson Space Center; Houston, TX, United States. December 01, 1974. NASA-TM-X-58148. [NTRS]

Heart rate
Stroke volume
Oxygen consumption
Carbon dioxide (CO2)
Exercise test

Photo Gallery
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Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
Data Sets+ Request data

Aerobic capacity - VO2 max
Anthropometric measurement chest expired
Anthropometric measurement chest inspired
Anthropometric measurement hips
Anthropometric measurement left arm
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Skylab 2 05/25/1973 06/22/1973 28 days
Skylab 3 07/28/1973 09/25/1973 59.5 days
Skylab 4 11/16/1973 02/08/1974 84 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Eric Gallagher
Institutional Support
National Aeronautics and Space Administration (NASA)
Hardware Items