Individual differences in biophysiological toughness: sustaining working memory during physical exhaustion

Recent evidence suggests that increased dehydroepiandrosterone sulfate (DHEAS), in combination with decreased cortisol levels have been correlated with enhanced performance outcomes in stressful military environments. This study was implemented to replicate these findings in a group of active duty A...

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Bibliographic Details
Published in:	Military medicine Vol. 180; no. 2; pp. 230 - 236
Main Authors:	Shia, Regina M, Hagen, Josh A, McIntire, Lindsey K, Goodyear, Chuck D, Dykstra, Leanne N, Narayanan, Latha
Format:	Journal Article
Language:	English
Published:	England Oxford University Press 01-02-2015
Subjects:	Absorptiometry, Photon - methods Adult Biomarkers - blood Dehydroepiandrosterone Sulfate - analysis Dehydroepiandrosterone Sulfate - blood Exercise Test Humans Hydrocortisone - analysis Individuality Male Memory, Short-Term - physiology Military Personnel - psychology Physical Fitness - physiology Stress, Psychological - complications
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Summary:	Recent evidence suggests that increased dehydroepiandrosterone sulfate (DHEAS), in combination with decreased cortisol levels have been correlated with enhanced performance outcomes in stressful military environments. This study was implemented to replicate these findings in a group of active duty Air Force members to provide information on the usefulness of these biomarkers indices in the training and operational environment. Seventeen active duty males participated in the 4 sessions of this study. Sessions 1 and 2 were training days for the cognitive testing. Session 3 was a baseline measure of physical fitness, utilizing the VO2 Maximal Treadmill test. Session 4 was centered around a modified-Astrand treadmill protocol designed to induce physical exhaustion. Blood draws for biomarker analysis, cognitive testing (NovaScan), psychomotor vigilance, and physiological measures were collected before, during, and following the treadmill protocol. Results showed that prolonged increases in cortisol negatively correlate with working memory performance. DHEAS release from baseline to poststress was negatively related to the changes in cortisol for 20 minutes following stress. These results indicate that the ratio of DHEAS to cortisol buffers, the effect of cortisol increases that are related to poor working memory performance because of physical exhaustion.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0026-4075 1930-613X
DOI:	10.7205/MILMED-D-14-00363