PRINCIPAL INVESTIGATORS ): Edward L. Michel, John A. Rummel, Charles F. 



Sawin, Melvin C. Buderer, and John D. Lem 



EXPERIMENT TITLE/NUMBER : Metabolic Activity, M171 



PROGRAM/MISSION : Skylab 2, 3, 4 



CLASSIFICATION : Human 



DISCIPLINE(S) : Respiratory, Behavioral science 



OBJECTIVES : To determine whether man's metabolic effectiveness while 

 performing mechanical work is progressively altered by exposure to the space 

 environment and to evaluate the M171 bicycle ergometer as an inflight crew 

 personal exerciser. 



PROTOCOL : Exercise protocol on the bicycle ergometer was 5 min. rest, 5 min. 

 at 25% max. V0_, 5 min. at 50% max. V0 , 5 min. at 75% max. V0 ? , and 5 min. 

 recovery. Eight baseline tests were conducted by the crew. Inflight testing 

 occurred about every 6 days. There were eight modified tests postf light. For 

 Skylab 4, the pref light and postf light tests included both upright and supine 

 ergometry. Data was collected on ergometer work rate, ergometer RPM, oxygen 

 uptake, carbon dioxide output, minute volume, vital capacity, respiratory 

 quotient, heart rate, blood pressure, vectorcardiogram, body weight, body 

 temperature, and Skylab environmental parameters. 



EQUIPMENT : Ergometer, blood pressure measuring system, vectorcardiograph/ 

 heart rate system, metabolic analyzer consisting of a spirometer, a mass 

 spectrometer, and an analog computer. 



RESULTS : Inflight exercise was characterized by significantly reduced oxygen 

 consumption and diastolic blood pressure. Other responses were within normal 

 pref light limits. 



Postflight (R+0) tests showed significantly decreased cardiac output (-30%) 

 and increased total systemic peripheral vascular resistance. Heart rate was 

 elevated while mean stroke volume decreased 45%. Mean arterial pressure and 

 oxygen consumption were unchanged. Return to normal preflight values occurred 

 by R+26-31. 



Flight duration did not significantly influence the magnitude of changes or 

 time for return to normal. Skylab 2 reached preflight exercise response by 

 R+21, whereas Skylab 3 and 4 reached preflight exercise response by R+4-5. 



CONCLUSIONS : It appears that the observed responses were a result of a 

 decreased venous return caused by an altered fluid balance/blood volume state 

 coupled with possible reductions in vascular tone of the venous system. 

 Exercise capacity inflight was not compromised. 



PUBLICATIONS : 106, 396, 397, 398, 455, 463 



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