European journal of applied physiology
-
Hyperventilation prior to breath-hold diving increases the risk of syncope as a result of hypoxia. Recently, a number of cases of near-drownings in which the swimmers did not hyperventilate before breath-hold diving have come to our attention. These individuals had engaged in prolonged exercise prior to breath-hold diving and it is known that such exercise enhances lipid metabolism relative to carbohydrate metabolism, resulting in a lower production of CO(2) per amount of O(2 )consumed. ⋯ A similar pattern was observed after breath-holding under resting conditions, i.e., a lower end-tidal P O(2) and P CO(2) after exercise (PPE) compared to control conditions. Our findings demonstrate that under the conditions of a relatively low RER following prolonged exercise, breath-holding is terminated at a lower P O(2) and a lower P CO(2) than under normal conditions. This suggests that elevated lipid metabolism may constitute a risk factor in connection with breath-holding during swimming and diving.