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Psychological Stress and Sky Diving—Authors’ Response^c

University of Essen Essen, Germany

Thomas O. F. Wagner

University of Frankfurt Frankfurt, Germany 60590

We appreciate the comments of Dr. Dugué and colleagues, in the preceding letter, concerning a first-time parachute jump as a model for acute psychological stress. This model has been employed in a number of studies and has been shown to induce a pronounced neuroendocrine stress response (1, 2, 3, 4, 5). The authors argue however, that physical activity before jumping; and in particular during the jump itself, influence the psycho-neuroendocrine response. Furthermore, it is argued that anticipatory stress of the novice jumper, incurred immediately before the first jump is a superior model for analyzing the effects of purely psychological stress on neuroendocrine parameters. However, in the studies cited as examples, the prejump psychological arousal did not significantly increase cortisol plasma concentrations (6, 7). This is in accordance with previously published observations in first-time tandem parachutists where the prejump stress did not increase cortisol, prolactin, GH, or TSH levels (3, 5). Both studies however, observed increased sympathetic activity before the jump as indicated by elevated salivary -amylase (5) and plasma noradrenaline levels (3). The blunted neuroendocrine response before the jump itself was most probably due to stress coping mechanisms of novice parachutists (5). These subjects appear to cope well with the forthcoming jump. However, after boarding the aircraft and during ascent of the plane, heart rate values and endocrine parameters start to increase, and they peak during the jump itself as this potentially life threatening situation elicits an emergency (fight-flight) response with a weakening of psychological coping mechanisms (2, 3, 8).

We agree that there is some physical activity involved in performing a tandem-parachute jump. However, physical exercise, is mainly associated with the release of noradrenaline. In contrast, psychological stress, primarily elicits an increase in adrenaline plasma concentrations. The much greater jump-induced increase in adrenaline (700%) plasma concentrations when compared with a 100% increase in noradrenaline levels, demonstrates that psychological stress is predominantly responsible for the neuroendocrine changes during parachute jumping (3).

Whereas for ethical reasons it remains difficult to induce psychological stress in an experimental setting with human subjects, a first-time (tandem) parachute jump is a very good, though not perfect, model to investigate the effects of intense acute psychological stress on neuroendocrine parameters.

Footnotes

Address correspondence to: Thomas O.F. Wagner, M.D., Division of Pneumology/Allergology, University of Frankfurt, Theodor-Stern-kai 7, Frankfurt, Germany 60590.

Received January 22, 1998.

References

1. Schedlowski M, Wiechert D, Wagner TOF, Tewes U. 1992 Acute psychological stress increases plasma levels of cortisol, prolactin, and TSH. Life Sci. 50:1201–1205.[CrossRef][Medline]
2. Schedlowski M, Flüge T, Tewes U, Schmidt RE, Wagner TOF. 1995 ß-endorphin but not substance-P concentrations are increased by acute stress in man. Psychoneuroendocrinol. 20:103–110.[CrossRef][Medline]
3. Richter S, Scheurmeyer T, Schedlowski M, et al. 1996 Time kinetics of the endocrine response to acute psychological stress. J Clin Endocrinol Metab. 81:1956–1960.[Abstract]
4. Benschop RJ, Jacobs R, Sommer B, Schürmeyer T, Schmidt RE, Schedlowski M. 1996 Propranolol and alprazolam differentially affect stress-induced lymphocyte migration and function in humans. FASEB J. 10:517–524.[Abstract]
5. Chatterton RT, Vogelsong KM, Lu YC, Hudgens GA. 1997 Hormonal responses tp psychological stress in men preparing for skydiving. J Clin Endocrinol Metab. 82:2503–2509.[Abstract/Free Full Text]
6. Dugué B, Leppänen EA, Zhou HP, Gräsbeck R. 1992 Preanalytic factors and standardized specimen collection: influence of psychological stress. Scand J Clin Lab Invest. 52:43–50.[Medline]
7. Dugué B, Leppänen EA, Teppo AM, Fyhrquist F, Gräsbeck R. 1993 Effects of psychological stress on plasma interleukins-1 beta and 6, C-reactive protein, tumour necrosis factor alpha, anti-diuretic hormone and serum cortisol. Scand J Clin Lab Invest. 53:555–651.[Medline]
8. Schedlowski M, Tewes U. 1992 Physiological arousal and perception of bodily state during parachute jumping. Psychophysiology 29:95–103.

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