PURPOSE To characterize both the efficacy of altered restriction pressures and consequences of optimized blood flow restriction (BFR) for altering the cardiovascular and fluid regulating response in humans. METHODS This work comprised a series of related trials. Phase 1: during semi-recumbent cycling (5 min, 60 W) with BFR at 0, 50, 75, 100 and 125% of participants' lowest arterial occlusion pressure (LOP) echocardiographic images were collected alongside continuous heart rate (HR) and blood pressure (BP). In phase 2, 24 h fluid balance (intake-output) and fluid-regulating hormone responses were measured after a practical BFR exercise session (treadmill walking: 5·3 min, 1 min rest, 5 km/h, 5% incline, 100% LOP). Phase 3 examined the magnitude and effect of blood volume distribution following BFR treadmill walking using a modified CO-rebreathe technique. RESULTS Cardiac ejection fraction remained stable irrespective of cuff pressure and despite a reduction in end-diastolic volume (Δ of 11 ± 9 mL, p = 0.02). HR and BP were highest at 100% LOP (ΔHR = 18 ± 19 bpm, ΔSBP = 51 ± 30 mmHg, ΔDBP = 33 ± 15 mmHg, ΔRate Pressure Product = 76 ± 32 bpm·mmHg·100-1). BFR treadmill walking stimulated a greater release of fluid-regulating hormones than normal walking (Δrenin = BFR: 25.3 ± 24.2 vs. CON: 9.1 ± 11.8 ng/L; Δcopeptin = BFR: 50.1 ± 97.9 vs. CON: 0.43 ± 0.8 pmol/L), but no difference in fluid retention was observed (p = 0.2). Approximately 27% of total blood volume was confined to the legs during BFR, but the relative volume trapped in the legs was not related to fluid-regulating hormone release (renin r = -0.04, p = 0.9; copeptin r = 0.27, p = 0.3). CONCLUSIONS BFR exercise elicits the largest cardiovascular effect using 100% LOP, with evidence of appreciable fluid regulating hormonal response during a typical BFR exercise session. The relative volume of blood sequestered in the limb does not appear to drive this response.

中文翻译：

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血流限制运动对中枢血流动力学和液体调节激素的影响。

目的 表征改变限制压力的功效和优化血流限制 (BFR) 对改变人类心血管和体液调节反应的影响。方法 这项工作包括一系列相关试验。第 1 阶段：在半卧式骑行（5 分钟，60 W）期间，BFR 为参与者最低动脉闭塞压 (LOP) 的 0%、50%、75%、100% 和 125%，同时收集超声心动图图像以及连续心率 (HR) 和血压（BP）。在第 2 阶段，在实际 BFR 锻炼后测量 24 小时液体平衡（摄入-输出）和液体调节激素反应（跑步机步行：5·3 分钟，休息 1 分钟，5 km/h，5% 坡度，100 ％LOP）。第三阶段使用改良的二氧化碳再呼吸技术检查了 BFR 跑步机行走后血容量分布的大小和影响。结果 尽管舒张末期容积减少，但无论袖带压力如何，心脏射血分数仍保持稳定（Δ 为 11 ± 9 mL，p = 0.02）。HR 和 BP 在 100% LOP 时最高（ΔHR = 18 ± 19 bpm，ΔSBP = 51 ± 30 mmHg，ΔDBP = 33 ± 15 mmHg，ΔRatePressure Product = 76 ± 32 bpm·mmHg·100-1）。BFR 跑步机步行比正常步行刺激更多的液体调节激素释放（Δ肾素 = BFR：25.3 ± 24.2 对比 CON：9.1 ± 11.8 ng/L；Δ和肽素 = BFR：50.1 ± 97.9 对比 CON：0.43 ± 0.8 pmol/ L)，但未观察到液体潴留差异 (p = 0.2)。在 BFR 期间，大约 27% 的总血量被限制在腿部，但滞留在腿部的相对血量与液体调节激素释放无关（肾素 r = -0.04，p = 0.9；和肽素 r = 0.27，p = 0.3）。结论 使用 100% LOP，BFR 运动可引发最大的心血管效应，有证据表明在典型的 BFR 运动期间有明显的液体调节激素反应。截留在肢体中的相对血液量似乎不会驱动这种反应。