Irving Laurence
J Appl Physiol (1985). 1963 May 1;18(3):489-491. doi: 10.1152/jappl.1963.18.3.489.
Electrocardiograms showed bradycardia developing in men and women during apnea in air and more markedly when submerged in water. Intervals between heartbeats reached 2 sec. The onset and degree of bradycardia were not reduced by vigorous swimming underwater. The bradycardia appeared with more regularity and in greater degree in practiced and capable swimmers. The rapidity of onset of this bradycardia indicates that, as in many natural diving animals, it is reflexly initiated.
心电图显示，男性和女性在空气中呼吸暂停时会出现心动过缓，而在水中时更为明显。心跳间隔达到2秒。水下剧烈游泳并不能减轻心动过缓的发作和程度。在训练有素、能力较强的游泳者中，心动过缓出现得更规律，程度也更严重。这种心动过缓发作的迅速性表明，与许多天然潜水动物一样，它是由反射引发的。
