Academics

Researchers have extensively looked at the human dive response, where heart rate drops, and other physiological changes occur after a person immerses their face in cold water. Gooden (1994) described the mechanism that initiates bradycardia during the dive response. He claimed that the two requirements to elicit the dive response are the reflex to stop breathing and water on the face (Gooden, 1994). The input gets processed, then, since the body is no longer breathing, the brain inhibits the respiratory center and cardiac muscle activity. This process activates parasympathetic nerves, which ultimately signal the heart to slow down, and the heart rate decreases (Gooden, 1994). Other research suggests that water on the face is not needed for the diving response and that holding one’s breath can suffice (Schagatay and Anderson, 1988). 

When analyzing the dive response, researchers found that the presence of water on the face and temperature of water influenced the strength of the response (Schagatay and Holm, 1996). Specifically, cold water had a stronger effect than warm water, which had a greater effect than breath-holding (Kawakami et al., 1967). Some research suggests that the heart rate initially increases (within the first 12 seconds), then decreases based on the type of simulation (Furedy et al., 1983).  

While this research shows consistent effects of temperature on the diving response, researchers have not looked at the effects of temperature and breath-holding on college students without previous dive training. If college students without previous dive training are like other populations, then they will experience the most pronounced diving response characterized by bradycardia with a cold-water dive simulation, followed by a warm water simulation, and a breath-hold will elicit the least pronounced diving response.

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