Circulatory Adjustments to Training for Apneic Diving

Twelve subjects classified into three groups, viz., experimental, control, and currently active skin divers, were studied throughout a 24-week period. The experimental group participated in an underwater swimming training program, three days a week, for four weeks. The testing procedures for all subjects each week consisted of the following: a 1-min. step test, brachial pulse wave test, a V4 ECG test, and blood pressure measurements. Radial pulse recordings were taken on those individuals who showed marked changes on the above tests when they held their breath. In no phase of the study were any of the subject's physiological responses to breath holding, as measured by the tests used, changed significantly. The changes which occurred with subjects in this study when they held their breath are discussed in relation to the findings from recent studies.