Wein, Jens (2004) Effects of ambient parameters on exercise on the human diving response. (Diploma thesis), Christian-Albrechts-Universität zu Kiel, Kiel, 76 pp.

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Abstract

The effects of posture, immersion, depth and exercise on the human diving response were investigated in 12 trained breath-hold divers. They performed maximum-duration apneas with face immersion (26°C) under rest (lying prone and sitting upright), during steadystate exercise (SSapnea; 40, 80, and 120 W) and with exercise initiated at the same time as the apnea (Eapnea; 40, 80, and 120 W) on a cycle ergometer in the laboratory. In addition, they performed maximum-duration apneas under rest (at the surface and at 5 m depth), during steady-state fin swimming, and fin swims initiated simultaneously with the apnea in a 25 m pool (27°C). Mean arterial pressure increased after an initial drop and arterial oxygen saturation and oxygen uptake decreased for all apneas in the laboratory compared to control levels. After an initial rise, heart rate declined to end-apnea values below control values for resting apneas, SSapnea, and Eapnea on 40 W in the laboratory. Higher workloads increased the initial rise in heart rate and delayed the onset of bradycardic responses for Eapnea· End-apnea values for prone and sitting upright did not differ, although mid-apnea values for sitting upright were higher. The same general pattem seen for resting and exercise apneas in the lab also applied for the apneas in the pool. No effects of immersion and depth were observed. lt was concluded that time course and magnitude of heart rate response for Eapnea depended on exercise intensity, presumably due to increased sympathetic activity during higher workloads. Also, Eapnea have an oxygen-conserving effect as SSapnea and resting apneas. Under comparable conditions, laboratory data can be applied to real-life apnea-diving situations.

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