Chapter 30 

 ADAPTATION TO ENVIRONMENTAL STRESS IN SEALAB II 



Steven M. Horvath and Fred W. Kasch 



Instiute of Environmental Stress 



University of California 



Santa Barbara, California 



Responses of man to various natural environmental stresses can be evaluated by prelim- 

 inary studies in simulated environments. Although the environment of Sealab II may not be con- 

 sidered as naturally occurring yet it is obvious that it soon may well be one in which men will 

 have to live for extended periods. The combined stresses of cold water, high temperature and 

 humidity, and work present a complex of environmental stresses that may best be studied at the 

 site, but considerable insight into the effects of such a stressful situation can be obtained by 

 appropriate studies conducted prior to and immediately after the exposure. The data being pre- 

 sented represent such an evaluation based on two tests of working capacity and one of cold ex- 

 posure. The subjects were nine divers from Sealab 11, first studied before and again after their 

 15 days in Sealab II. These men also had an additional stress of 36 hours of decompression. 



Table 12 

 PHYSICAL CHARACTERISTICS OF SEALAB H SUBJECTS 



These data are preliminary in nature, but they do suggest certain alterations in capacity to 

 perform and indicate the need for additional studies of men exposed to environments such as 

 present in Sealab n. Table 12 presents certain of the physical characteristics of the nine men 

 studied. The first test was a modified maximal work-capacity test whose primary purpose was 

 to determine the maximal oxygen uptake of these divers. The data presented in Table 13 in- 

 dicated that these men have a level of maximum work capacity which was within the average 

 range (for their age) of the values obtained by Astrand and Robinson. Two of the men were 

 slightly (10 to 20 percent) below the average. No appreciable shift in maximum oxygen uptake 

 was noted as a consequence of their exposure to Sealab H, although the absolute time the men 

 could work was decreased in six subjects. A decrease in one subject was due to stoppage of 

 his own volition, and a second subject was stopped because of some questions regarding his 

 electrocardiogram. There are other evidences that these men during their post-test time had 

 some decrease in their effective responses to a maximum work load (Table 14). The oxygen 

 debt was greater and the level of blood lactates higher in the second test. Subjective evaluation 



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