Di Giacomo Annalisa, Ghiani Giovanna Maria, Todde Francesco, Tocco Filippo
Department of Medical Sciences and Public Health, School of Sport Medicine, University of Cagliari, Cagliari, Italy.
Front Physiol. 2021 Oct 22;12:730983. doi: 10.3389/fphys.2021.730983. eCollection 2021.
The aim of study was to assess hemodynamic changes during the simultaneous activation of muscle metaboreflex (MM) and diving reflex (DR) in a laboratory setting. We hypothesized that as long as the exercise intensity is mild DR can overwhelm the MM. Ten trained divers underwent all four phases (randomly assigned) of the following protocol. (A) Postexercise muscle ischemia session (PEMI): 3 min of resting followed by 3 min of handgrip at 30% of maximum force, followed immediately by 3 min of PEMI on the same arm induced by inflating a sphygmomanometer. Three minutes of recovery was further allowed after the cuff was deflated for a total of 6 min of recovery. (B) Control exercise recovery session: the same rest-exercise protocol used for A followed by 6 min of recovery without inflation. (C) DR session: the same rest-exercise protocol used for A followed by 1 min of breath-hold (BH) with face immersion in cold water. (D) PEMI-DR session: the same protocol used for A with 60 s of BH with face immersion in cold water during the first minute of PEMI. Stroke volume (SV), heart rate (HR), and cardiac output (CO) were collected by means of an impedance method. At the end of apnea, HR was decreased in condition C and D with respect to A (-40.8 and -40.3%, respectively vs. -9.1%; < 0.05). Since SV increase was less pronounced at the same time point (C = +32.4 and D = +21.7% vs. A = +6.0; < 0.05), CO significantly decreased during C and D with respect to A (-23 and -29.0 vs. -1.4%, respectively; < 0.05). Results addressed the hypothesis that DR overcame the MM in our setting.
本研究的目的是在实验室环境中评估肌肉代谢反射（MM）和潜水反射（DR）同时激活期间的血流动力学变化。我们假设只要运动强度较轻，DR就能压倒MM。10名训练有素的潜水员按照以下方案进行了所有四个阶段（随机分配）的实验。（A）运动后肌肉缺血期（PEMI）：休息3分钟，然后以最大力量的30%进行3分钟的握力运动，随后立即通过充气血压计在同一手臂上诱导3分钟的PEMI。袖带放气后再进行3分钟的恢复，总共恢复6分钟。（B）对照运动恢复期：采用与A相同的休息-运动方案，随后进行6分钟不充气的恢复。（C）DR期：采用与A相同的休息-运动方案，随后进行1分钟的屏气（BH），面部浸入冷水中。（D）PEMI-DR期：采用与A相同的方案，在PEMI的第一分钟面部浸入冷水中进行60秒的BH。通过阻抗法收集每搏输出量（SV）、心率（HR）和心输出量（CO）。在呼吸暂停结束时，与A相比，C组和D组的HR降低（分别为-40.8%和-40.3%，而A组为-9.1%；P<0.05）。由于在同一时间点SV的增加不太明显（C组=+32.4%，D组=+21.7%，而A组=+6.0%；P<0.05），与A相比，C组和D组的CO显著降低（分别为-23%和-29.0%，而A组为-1.4%；P<0.05）。结果证实了在我们的实验环境中DR压倒MM的假设。
