The presence of a dive response in humans when the face is submerged in water was studied. A lot of mammals have shown to exhibit a dive response known as the mammalian dive reflex. During this reflex bradycardia, a slowing of the heart rate, is shown. In this study, human subjects were put through various tests to determine if humans also exhibit bradycardia. Subject's heart rates were measured while breathing normally, while holding breath and while holding breath with face submerged in water. The results showed that there was a significant decrease in heart rate while submerged in water as compared to normal breathing or holding breath out of water. Many other studies have been done that agree with the results found in this study. However, this study would have had more significant results had other factors of the dive reflex been tested for.
Mammals have shown to have a special reflex that allows them to dive to deep depths for long periods of time without coming up for air. This is known as mammalian dive reflex or MDR. This reflex has also been studied to see if it applies to humans. Professional breath-hold diving has been a common practice in several countries for many centuries, for harvesting sponges, pearls and seafood (Ferretti and Costa 2002). This practice is declining; however, in Japan and Korea there are still around 30,000 divers. Many studies have looked at the physiological aspects of these divers. Studies of diving operations and patterns, seasonal variations, diving equipment, gas compositions at the end of dives, and estimated gas exchange during diving have been done in order to better understand what the factors are effecting these dives (Ferretti and Costa 2002).
When looking at these studies, respiratory and cardiovascular changes were found. These would show a link to diving mammals and humans. One thing found to happen as a dive response was bradycardia. Bradycardia is a slowing of the
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