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Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response
Published on: November 12, 2014
Cardiac alterations induced by a fish-catching diving competition.
1UMR MD2, Faculté de Médecine Nord, Université de la Méditerranée et IRBA Antenne Toulon, IMNSSA, Physiologie et Physiopathologie en Conditions d'Oxygénation Extrême, Marseille, Cedex, France.
Scandinavian Journal of Medicine & Science in Sports
|August 27, 2010
Summary
Repeated breath-hold diving in cold water caused dehydration and sympathetic hyperactivity. Left ventricular stroke volume decreased, impacting cardiac output, while right heart chambers enlarged, indicating potential strain.
Area of Science:
- Cardiovascular Physiology
- Environmental Physiology
- Sports Science
Background:
- Breath-hold diving, especially in cold water, presents physiological challenges.
- Understanding cardiac responses to repeated dives is crucial for diver safety.
- Fish-catching competitions involve prolonged exposure to cold and repeated apnea.
Purpose of the Study:
- To investigate cardiac alterations following repeated breath-hold diving during a competition.
- To assess physiological changes including dehydration, plasma volume, and autonomic function.
- To identify potential cardiac strain and adaptations to cold-water diving.
Main Methods:
- Eleven healthy subjects performed repeated breath-hold dives for 5 hours to a mean depth of 20 meters.
- Physiological parameters including body mass, temperature, blood pressure, and cardiac dimensions were measured.
- Echocardiography assessed left ventricular (LV) filling and right cavity diameters.
Main Results:
- Divers experienced body mass loss (-1.7 kg) and decreased cutaneous temperature.
- Systolic blood pressure was reduced; heart rate was unchanged, but cardiac output decreased by 20% due to reduced LV stroke volume.
- Right heart cavities enlarged, suggesting right ventricular strain, and autonomic alterations indicated sympathetic hyperactivity.
Conclusions:
- Repeated cold-water breath-hold diving can lead to dehydration, reduced plasma volume, and sympathetic hyperactivity.
- Observed cardiac changes, including decreased LV function and right heart enlargement, indicate significant physiological stress.
- Apnea and cold exposure during diving may be responsible for these observed cardiac and autonomic alterations.
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