Background There are animal data suggesting green tea can enhance blood flow. However, human data are lacking. Thus, the purpose of this study was to examine the acute effects of low and high doses of a green tea-based supplement (GBS) on brachial artery blood flow before and following a resistance exercise bout. Methods In this, double-blinded placebo-controlled trial, college-aged males ( n = 18) who self-reported recreationally resistance training for the previous 6 ± 3 years were assigned to one of two studies including a low (300 mg serving) ( n = 9) or high dose (600 mg serving) ( n = 8; 1 drop) GBS study. During testing sessions, participants reported to the laboratory following an overnight fast and rested in a supine position for 15 min. Thereafter, baseline measurements for resting heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), brachial artery diameter (BAD) and blood flow (BBF) were obtained (PRE). Participants then consumed either their respective GBS dose or a similar placebo dose (microcrystalline cellulose) in a supine resting state. HR, SBP, DBP, BAD and BBF were measured 45 min after placebo or GBS ingestion (PRE2). Participants were then placed in a recumbent position and performed 4 sets of 10 arm curl repetitions using an 11 kg dumbbell. Participants returned to a supine position and HR, SBP, DBP, BAD and BBF were obtained within the first 3 min following exercise (POST), 15 min after exercise (15POST), and 45 min after exercise (45POST). Participants returned to the laboratory 24–48 h later to repeat the same protocol with either GBS or the placebo depending on randomization. Two-way (supplement x time) repeated measures ANOVAs were used to compare dependent variables between testing sessions for Study 1 (300 mg of GBS and placebo) and Study 2 (600 mg of GBS and placebo), and statistical significance was set at p < 0.05. No statistical comparisons were made between studies. Results As expected, exercise increased BAD and BBF compared to resting baseline measured irrespective of supplementation. In addition, BAD and BBF did not differ between GBS and placebo at any time point after exercise in Study 1. In study 2, however, 600 mg GBS increased baseline-normalized BBF at immediately post exercise compared to placebo (placebo = 211 ± 155% increase, GBS = 349 ± 156% increase; p = 0.012) but not BAD. Conclusions These data suggest a higher dose of GBS can enhance localized blood flow acutely following a resistance exercise bout. However, the long-term implications of these data are unclear, and more well-powered studies are needed to validate efficacy and elucidate potential mechanisms.

中文翻译：

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接受过抗阻力训练的大学生男性在进行急性抗阻运动后，更高剂量的绿茶补充剂会增加运动后的血流量

背景 有动物数据表明绿茶可以促进血液流动。然而，缺乏人类数据。因此，本研究的目的是检查低剂量和高剂量的绿茶补充剂 (GBS) 在抗阻运动前后对肱动脉血流的急性影响。方法 在这项双盲安慰剂对照试验中，自我报告过去 6 ± 3 年进行娱乐性阻力训练的大学年龄男性 (n = 18) 被分配到两项研究之一，包括一项低（300 毫克服务） (n = 9) 或高剂量（600 毫克服务）（n = 8；1 滴）GBS 研究。在测试期间，参与者在禁食过夜并仰卧休息 15 分钟后向实验室报告。此后，静息心率 (HR)、收缩压 (SBP)、获得舒张压（DBP）、肱动脉直径（BAD）和血流量（BBF）（PRE）。然后，参与者在仰卧静息状态下服用各自的 GBS 剂量或类似的安慰剂剂量（微晶纤维素）。在服用安慰剂或 GBS 后 45 分钟测量 HR、SBP、DBP、BAD 和 BBF（PRE2）。然后将参与者置于卧位，并使用 11 公斤哑铃进行 4 组 10 次手臂弯曲重复。参与者回到仰卧位，在运动后的前 3 分钟 (POST)、运动后 15 分钟 (15POST) 和运动后 45 分钟 (45POST) 内获得 HR、SBP、DBP、BAD 和 BBF。参与者在 24-48 小时后返回实验室，根据随机分组重复使用 GBS 或安慰剂的相同方案。双向（补充剂 x 时间）重复测量方差分析用于比较研究 1（300 毫克 GBS 和安慰剂）和研究 2（600 毫克 GBS 和安慰剂）的测试阶段之间的因变量，统计显着性设定为 p < 0.05。研究之间没有进行统计学比较。结果 正如预期的那样，与不考虑补充剂的静息基线相比，运动增加了 BAD 和 BBF。此外，在研究 1 中运动后任何时间点，GBS 和安慰剂之间的 BAD 和 BBF 没有差异。 然而，在研究 2 中，与安慰剂相比，600 毫克 GBS 在运动后立即增加基线标准化 BBF（安慰剂 = 211 ± 155 % 增加，GBS = 349 ± 156% 增加；p = 0.012）但不是坏的。结论 这些数据表明更高剂量的 GBS 可以在抗阻运动后迅速增强局部血流量。然而，这些数据的长期影响尚不清楚，需要更有力的研究来验证疗效并阐明潜在的机制。