No one disagrees that prolonged hyperventilation, after minutes of vigorous breathing accompanied by dizziness and tingling in the arms and legs, is dangerous. Some diving physicians believe that any hyperventilation is deadly because of the variation in effects among individuals and on one person, from one time to another. Other physicians, studying professional freedivers such as the Ama divers of Japan, found that they routinely hyperventilated mildly and took a deep breath before descending. Hyperventilation with air should not be continued beyond three to four breaths, and the diver should start to surface as soon as he notices a definite urge to resume breathing. Learn the deadly effects of exercise underwater and plan to deal with this situation.
Most divers make minimal use of their muscles except when they fight a fish or free an anchor.
A physician writing in an Australian medical journal found a common scenario for diving deaths in Australia is the experienced diver with weight belt on, speargun fired. Medical researchers feel that many pool deaths, classified as drownings, are really the result of shallow-water blackout. Most occur in male adolescents and young adults attempting competitive endurance breath-holding, frequently on a dare. Drowning victims, especially children, have been resuscitated from long periods of immersion in cold water 30 minutes or more. The same is not true for victims blacking out in warm-water swimming pools.