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Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response
Published on: November 12, 2014
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Cardiovascular responses during free-diving in the sea
E Marongiu1, A Crisafulli2, G Ghiani1
1Medical Sciences, University of Cagliari, Cagliari, Italy.
International Journal of Sports Medicine
|November 28, 2014
Summary
This study measured cardiac output in free divers at various depths. Results suggest that exercise and diving responses may prevent the typical reduction in cardiac output for oxygen conservation.
Area of Science:
- Physiology
- Marine Biology
- Sports Science
Background:
- Human diving response in natural marine environments remains poorly understood.
- Cardiac output data during free diving in the sea is scarce.
- Previous studies often focus on simulated or cold-water diving conditions.
Purpose of the Study:
- To assess cardiac output during free diving in the sea at different depths.
- To investigate the human diving response in a natural marine setting.
- To determine if exercise and diving responses interact to affect cardiac output during free dives.
Main Methods:
- Seven divers performed three immersions at 10m, 20m, and 30m depths.
- Each dive included descent, static apnea, and ascent phases.
- Cardiac output, stroke volume, and heart rate were measured using impedance cardiography; blood pressure, O2 saturation, and lactate were also recorded.
Main Results:
- Cardiac output increased significantly during descent and ascent at 10m, 20m, and 30m depths (p<0.01).
- Arterial O2 saturation decreased with depth, reaching 91.1±3.4% at 30m.
- Blood lactate levels rose to 4.1±1.2 mmol∙L(-1) after the 30m dive.
Conclusions:
- Simultaneous activation of exercise and diving responses may override the oxygen-conserving effect of reduced cardiac output.
- Free diving in the sea elicits a complex physiological response involving increased cardiac output.
- Further research is needed to fully elucidate the cardiovascular adjustments during marine free diving.
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