School of Health and Exercise Science, University of British Columbia Okanagan, British Columbia, Canada.
School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom.
Am J Physiol Regul Integr Comp Physiol. 2024 Oct 1;327(4):R442-R456. doi: 10.1152/ajpregu.00081.2024. Epub 2024 Aug 5.
The mammalian dive reflex, characterized by bradycardia and peripheral vasoconstriction, occurs in all mammals, including humans, in response to apnea. However, the dive reflex to a single, maximal, dry, dynamic apnea (DYN) and how it compares to a time-matched exercise control trial (EX) or dry static apnea (SA) has not been studied. We examined the hypotheses that, compared with EX and SA, the magnitude of the ) cardiovascular response and ) hematological response to DYN would be greater. Cardiovascular parameters [heart rate (HR), systolic (SBP), diastolic (DBP), and mean arterial (MAP) blood pressure] were continuously collected in 23 ( = 6 females) moderate and elite freedivers, first during a maximal DYN, then during a time-matched SA and EX on a swimming ergometer in randomized order. Venous blood draws were made before and following each trial. The change in calculated oxygen saturation (DYN: -17 ± 13%, EX: -2 ± 1%, ΔSA: -2 ± 1%; < 0.05, all comparisons) was greater during DYN compared with EX and SA. During DYN, ΔSBP (DYN: 104 ± 31 mmHg; EX: 38 ± 23 mmHg; and SA: 20 ± 11 mmHg), ΔDBP (DYN: 45 ± 12 mmHg; EX: 14 ± 10 mmHg; and SA: 15 ± 8 mmHg), and ΔMAP (DYN: 65 ± 17 mmHg; EX: 22 ± 13 mmHg; and SA: 16 ± 9 mmHg) were increased compared with EX and SA, while ΔHR was greater during EX (DYN: -24 ± 23 beats/min; EX: 33 ± 13 beats/min; and SA: -1 ± 10 beats/min) than either DYN or SA ( < 0.0001, all comparisons). Females had a greater pressor response to EX (ΔSBP: 59 ± 30 mmHg; ΔDBP: 24 ± 14 mmHg; and ΔMAP: 35 ± 8 mmHg) than males (ΔSBP: 31 ± 15 mmHg; ΔDBP: 11 ± 6 mmHg; and ΔMAP: 18 ± 8 mmHg; < 0.01, all comparisons). Together, these data indicate that DYN elicits a distinct, exaggerated cardiovascular response compared with EX or SA alone. This study performed a dry dynamic apnea with sport-specific equipment to closely mimic the physiological demands of competition diving. We found the cardiovascular and hematological responses to dynamic apnea were more robust compared with time-matched exercise and dry static apnea control trials.
哺乳动物潜水反射的特征是心率减慢和外周血管收缩，所有哺乳动物（包括人类）都会在呼吸暂停时发生这种反射。然而，单次最大、干燥、动态呼吸暂停（DYN）的潜水反射以及与时间匹配的运动对照试验（EX）或干燥静态呼吸暂停（SA）的比较尚未得到研究。我们检验了以下假设：与 EX 和 SA 相比，DYN 对心血管反应和血液反应的幅度更大。在 23 名（=6 名女性）中度和精英自由潜水员中，使用游泳测功计以随机顺序首先在最大 DYN 期间，然后在时间匹配的 SA 和 EX 期间连续采集心血管参数[心率（HR）、收缩压（SBP）、舒张压（DBP）和平均动脉（MAP）血压]。在每次试验前后进行静脉采血。与 EX 和 SA 相比，计算得出的氧饱和度变化（DYN：-17±13%；EX：-2±1%；ΔSA：-2±1%；<0.05，所有比较）在 DYN 期间更大。在 DYN 期间，与 EX 和 SA 相比，SBP 变化（DYN：104±31 mmHg；EX：38±23 mmHg；和 SA：20±11 mmHg）、DBP 变化（DYN：45±12 mmHg；EX：14±10 mmHg；和 SA：15±8 mmHg）和 MAP 变化（DYN：65±17 mmHg；EX：22±13 mmHg；和 SA：16±9 mmHg）增加，而 HR 变化在 EX 期间更大（DYN：-24±23 次/分钟；EX：33±13 次/分钟；和 SA：-1±10 次/分钟）比 DYN 或 SA 更大（<0.0001，所有比较）。女性对 EX 的升压反应大于男性（SBP 变化：59±30 mmHg；DBP 变化：24±14 mmHg；和 MAP 变化：35±8 mmHg）（SBP 变化：31±15 mmHg；DBP 变化：11±6 mmHg；和 MAP 变化：18±8 mmHg；<0.01，所有比较）。综上所述，这些数据表明，与 EX 或 SA 相比，DYN 会引起明显的、夸大的心血管反应。本研究使用特定于运动的设备进行干燥动态呼吸暂停，以紧密模拟竞争潜水的生理需求。我们发现，与时间匹配的运动和干燥静态呼吸暂停对照试验相比，动态呼吸暂停的心血管和血液反应更为强烈。
