PSYCHOLOGICAL STRESS DURING EXERCISE: CARDIORESPIRATORY AND HORMONAL RESPONSES.
Webb, H.E.^{1, 2}, M.L. Weldy¹, E.C. Fabianke¹, G.R. Orndorff¹, G.H. Kamimori³, and E.O. Acevedo¹, ¹FACSM, Division of Exercise Science; ²Department of Pharmacology, University of Mississippi, University, MS; ³Walter Reed Army Research Institute, Washington, DC.

The influence of psychological states on physiological responses during exercise is of considerable importance to the soldier, pilot, firefighter, police officer, athlete, and other individuals for whom the efficiency of energy production is critical to job performance. Stress responses to physical and psychological challenges are regulated by hormones that are released following activation of the sympathoadrenal axis and the hypothalamo-pituitary-adrenocortical axis. Hormonal responses to the combination of physical and psychological stress have not been examined. PURPOSE: This study examined the cardiorespiratory responses of heart rate (HR), ventilation (V_E), respiratory rate (RR), oxygen consumption (VO₂), and respiratory exchange ratio (RER) and the hormonal responses of epinephrine (Epi), norepinephrine (NE) and cortisol (CORT) to psychological and physical stress combined. METHODS: Nine subjects performed a graded exercise test on a cycle ergometer to assess maximal oxygen consumption (VO_2max). Subsequently, each subject participated in two conditions. The treatment condition was a ride at 60% of VO_2max while participating in a computerized psychological stressor (stress condition; SC), whereas in the control condition subjects rode at the same intensity without the psychological stressor (no stress condition; NSC). The NASA Task Load Index (NTLX) was used to assess perceived physical and psychological load during each condition. These sessions were counter-balanced between subjects. RESULTS: RMANOVA’s revealed significant interactions across time for cardiorespiratory responses (HR, V_E, and RR) between the NSC nd the SC. Epi AUC was not significantly different between the two conditions; however, NE AUC was significantly elevated in the SC. Furthermore, cortisol AUC was also significantly elevated during the SC. NTLX scores demonstrated that the subjects perceived overall workload to be higher in the SC. CONCLUSION: These results demonstrate that psychological stress during exercise can elicit a stress response including the release of hormones that have been linked to negative health consequences.

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