AEROBIC FITNESS AND SYMPATHOADRENAL RESPONSE TO SHORT-TERM PSYCHO-EMOTIONAL STRESS UNDER FIELD CONDITIONS

A possible relationship between aerobic fitness (AF), measured by maxi mal cycle ergometry (CE) and sympatho-adrenal response to acute, short lasting psyche-emotional stress was investigated by monitoring heart rate (f(c)) and excretion of catecholamines. The activation of the sym patho-adrenal system was characterised by the noradrenaline : adrenali ne ratio. A group of 11 healthy men [22.8 (SD 2.52) years] lived under identical environmental conditions; their mean maximal oxygen uptake (VO2max) was 47.1 (SD 3.9) ml . min(-1) . kg(-1). After the physiologi cal and psychological laboratory tests had been completed the f(c) of the subjects was monitored continuously during the ''guerilla slide'' and ''parachute jump by night'', two emotionally stressful military ta sks. Maximal f(c) (f(c,max)) attained during these events was 84.5% an d 83% of f(c,max) during CE (f(c,max,CE)), respectively. A significant relationship (r = - 0.92, P < 0.0002) between f(c,max) reached during the stressful tasks and VO2max was found only for the guerilla slide, which was preceded by physical strain, sleep deprivation and energy d eficit. One subject with some prior experience in parachuting showed t he lowest f(c) response and the lowest sympatho-adrenal activation in both events, independent of the degree of AF. In conclusion, AF was fo und to influence the sympatho-adrenal and f(c) response to acute, shor t-lasting emotional stress when the stressful event was aggravated by preceding physical strain, the magnitude of the stress response depend ing largely on individual experience and effective mechanisms for copi ng with specific stimuli.