Department of Medical Sciences, School of Sport Medicine, Sport Physiology Lab., University of Cagliari, Cagliari, Italy.
Acta Physiol (Oxf). 2013 Feb;207(2):290-8. doi: 10.1111/apha.12000. Epub 2012 Sep 14.
Considering that sympathetic activation is induced by exercise, it is reasonable to assume that hemodynamic adjustments to exercise act in opposition to those elicited by the diving response. However, cardiovascular measurements have never been performed during underwater dynamic apnoea (DA), and this hypothesis remains speculative.
Data concerning heart rate (HR), stroke volume (SV) and cardiac output (CO) during static apnoea (SA) and DA were collected from 12 elite divers by means of an impedance cardiograph adapted to the underwater environment. Mean arterial pressure (MBP), systemic vascular resistance (SVR) and arterial oxygen saturation (SaO(2)) were also assessed. Five trials were performed by the divers: head-out immersion during normal breathing (test A); 3 min of SA immersed at the surface (B) and at 3 m depth (C); DA till exhaustion immersed at the surface (D) and at 3 m depth (E).
Both B and C conditions led to bradycardia (-17%) compared to A and also induced a decrement in SV (-8%) and in CO (-25%), while MBP was maintained because of an increase in SVR. A significant MBP increment (+11%) was detected only during tests D and E, when a SaO(2) drop was also present, whereas HR, SV and CO remained unchanged.
We concluded that typical diving response was present only during SA, while sympathetic activation was induced by exercise during DA, which partially obscured the effects of the diving response.
考虑到运动可引起交感神经激活，因此可以合理假设，运动引起的血流动力学调整与潜水反应引起的调整相反。然而，在水下动态呼吸暂停（DA）期间从未进行过心血管测量，并且该假设仍然是推测性的。
通过阻抗心动描记仪在水下环境中进行了调整，收集了 12 名精英潜水员在静态呼吸暂停（SA）和 DA 期间的心率（HR）、每搏量（SV）和心输出量（CO）的数据。还评估了平均动脉压（MBP）、全身血管阻力（SVR）和动脉血氧饱和度（SaO（2））。潜水员进行了五次试验：正常呼吸时头露出水面浸入（试验 A）；在水面上（B）和 3 米深处（C）进行 3 分钟的 SA；在水面上（D）和 3 米深处（E）直到疲劳的 DA。
B 和 C 条件均导致与 A 相比的心动过缓（-17％），并且还导致 SV（-8％）和 CO（-25％）下降，而由于 SVR 增加，MBP 得以维持。仅在测试 D 和 E 期间检测到显著的 MBP 升高（+11％），当时还存在 SaO（2）下降，而 HR、SV 和 CO 保持不变。
我们得出的结论是，只有在 SA 期间才存在典型的潜水反应，而在 DA 期间，运动引起了交感神经激活，这部分掩盖了潜水反应的影响。
