Jumping into cold water can stop your heart

5 hours ago

The first 60 seconds in cold water are the most dangerous, not due to hypothermia but due to the body's immediate physiological responses.
Two key reflexes occur: the cold shock response (causing gasping, hyperventilation, increased heart rate and blood pressure) and the diving response (slowing the heart and constricting blood vessels).
When these reflexes happen simultaneously, they create 'autonomic conflict,' which can lead to irregular heart rhythms like ventricular fibrillation, even in healthy individuals.
Most cold-water deaths occur within the first three minutes, often near edges like piers or ferry decks, not in open water.
To protect yourself: enter the water slowly by walking in, habituate with short cold-water dips, wear protective gear like wetsuits, never swim alone, and know your heart health.
Spraying athletes with cold water before a jump, as done in the Norseman race, helps blunt the cold shock response by pre-exposing the nervous system and reducing panic.
Cold water should be respected and prepared for; it can then become a valuable training tool rather than a killer.

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