ABSTRACT
As a feasibility study, two men were tested in a series of simulated flights which comprised a factorial experiment. Plysiologic data were collected during a 2-d baseline period, four 36-h experimental periods, and four recovery periods. The experimental conditions were as follows: a) uncomplicated simulated flight, b) flight complicated by extreme environmental dryness, c) flight complicated by mild hypoxia, and d) flight complicated by both dryness and -ypoxia. Throughout each flight the subjects alternately worked 2 h and rested 2 h, performing on psychomotor measuring devices during each work period. Five other men were studied under baseline conditions and during a 48-h simulated flight complicated by hypoxia. Urinary nitrogenous metabolites, including individual amino acids, were examined for sensitivity to the stressor complexes. Certain of the amino acids had high stressor sensitivity, tending to differentiate the effects of the single, double, and triple stressor complexes. They also differentiated the physiologic states in the experimental and recovery periods.
Subject(s)
Adaptation, Physiological , Aerospace Medicine , Amino Acids/urine , Stress, Physiological/urine , Environment, Controlled , Humans , Humidity , Male , Space FlightABSTRACT
Multifactor stress was studied, using obese men subjected to long-term (49 d) semistarvation in either a temperate or a not climate. The study was wide in scope, fiving information on endocrine-metabolic effects of a) uncomplicated obesity, b) ovesity in combination with climatic heat, c) obesity plus semistarvation, and d) ovesity combined with semistarvation plus climatic heat. The test subjects--groups of 12 to 13 obese men--remained on a diet which provided 335-400 kcal/d and contained at least 45 g protein, 14 g carbohydrate, and 11 g fat. Overnight urine specimens collected at 7-d intervals were analyzed for epinephrine, norepinephrine, 17-OHCS, ketones, urea, uric acid, creatinine, inorganic phosphate, sodium, and potassium. There was transitory hyperketonuria which related inversely to environmental thermal levels. Most of the physiologic response patterns in the triple-stressor circumstance (obesity plus climatic heat plus semistarvation) were unlike those in the double-stressor situation (obesity plus semistarvation). Thus, there was evidence of compounding of stressor effects. Evidence of diminished sensitivity to heat appeared when obesity was lessened.
