PRINCIPAL INVESTIGATOR (S ): James M. Waligora, and David J. Horrigan 



EXPERIMENT TITLE/NUMBER : Metabolic Cost of Extravehicular Activities 



PROGRAM/MISSION : Skylab 2, 3, 4 



CLASSIFICATION : Human 



DISCIPLINE(S) : Cardiovascular, Behavioral science 



OBJECTIVES : To measure metabolic rates during extravehicular activities. 



PROTOCOL : Using a thermoregulatory mathematical model and empirical data on 

 the liquid-cooled garment, a relationship was defined between liquid-cooled 

 garment heat removal and metabolic rate for each liquid-cooled garment inlet 

 temperature. Correlations between heart rate and metabolic rate were obtained 

 for each individual from a series of preflight exercise response tests on the 

 ergometer. The heart rate method was used only as a relative measurement 

 because of its known sensitivity to psychological and environmental factors. 



EQUIPMENT : Life support equipment. 



RESULTS : The metabolic rates were similar to those on the Apollo 1/6-g 

 extravehicular activities. The highest metabolic rate, 500 kcal/h, was 

 reached while the Commander on Skylab 2 was trying to cut a strap that was 

 keeping the solar panels from deployment. The lowest rates were resting rates 

 and these were reached several times during the extravehicular activities, 

 particularly at the times when there was not enough light to continue an 

 ongoing activity during a night pass. Crew comments during extravehicular 

 activities indicated that it was easier to maneuver themselves and their 

 equipment in zero-g than in water tank simulations, but that adequate 

 restraints were more important. 



CONCLUSIONS : With adequate life support equipment and adequate restraints, 

 the capability was demonstrated to perform varied and extensive extravehicular 

 activity tasks in zero-g with considerable real-time flexibility. 



The capability to work at relatively high levels, up to 500 kcal/h when 

 required, was demonstrated without physiologic problems provided the life 

 support capability is adequate. 



The average energy cost of long extravehicular activities was remarkably 

 consistent at about 200 to 250 kcal/h, and appeared to be a function of the 

 crew pacing its activity rather than to the effort involved in performing 

 ind iv idual tasks . 



PUBLICATIONS : 284, 552, 553, 554, 555 



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