Department of Exercise Physiology, Faculty of Physical Education and Sport Sciences, Tehran University, Tehran 1417935840, Iran.
Clinical Care and Health Promotion Research Center, Karaj Branch, Islamic Azad University, Karaj 3149968111, Iran.
Int J Environ Res Public Health. 2021 Sep 28;18(19):10202. doi: 10.3390/ijerph181910202.
Studies have shown that nitrate (NO)-rich beetroot juice (BJ) supplementation improves endurance and high-intensity intermittent exercise. The dose-response effects on taekwondo following BJ supplementation are yet to be determined. This study aimed to investigate two acute doses of 400 mg of NO (BJ-400) and 800 mg of NO (BJ-800) on taekwondo-specific performance and cognitive function tests compared with a placebo (PL) and control (CON) conditions. Eight trained male taekwondo athletes (age: 20 ± 4 years, height: 180 ± 2 cm, body mass: 64.8 ± 4.0 kg) completed four experimental trials using a randomized, double-blind placebo-controlled design: BJ-400, BJ-800, PL, and CON. Participants consumed two doses of BJ-400 and BJ-800 or nitrate-depleted PL at 2.5 h prior to performing the Multiple Frequency Speed of Kick Test (FSKT). Countermovement jump (CMJ) was performed before the (FSKT) and PSTT, whereas cognitive function was assessed (via the Stroop test) before and after supplementation and 10 min following PSTT. Blood lactate was collected before the CMJ tests immediately and 3 min after the FSKT and PSST; rating of perceived exertion (RPE) was recorded during and after both specific taekwondo tests. No significant differences ( > 0.05), with moderate and large effect sizes, between conditions were observed for PSTT and FSKT performances. In addition, blood lactate, RPE, heart rate, and CMJ height were not significantly different among conditions ( > 0.05). However, after the PSTT test, cognitive function was higher in BJ-400 compared to other treatments ( < 0.05). It was concluded that acute intake of 400 and 800 mg of NO rich BJ reported a moderate to large effect size in anaerobic and aerobic; however, no statistical differences were found in taekwondo-specific performance.
研究表明，富含硝酸盐（NO）的甜菜根汁（BJ）补充剂可提高耐力和高强度间歇运动。BJ 补充剂对跆拳道的剂量反应影响尚未确定。本研究旨在调查两种急性剂量 400 毫克 NO（BJ-400）和 800 毫克 NO（BJ-800）对跆拳道特定性能和认知功能测试的影响，与安慰剂（PL）和对照（CON）条件相比。8 名经过训练的男性跆拳道运动员（年龄：20±4 岁，身高：180±2cm，体重：64.8±4.0kg）完成了四项实验试验，采用随机、双盲安慰剂对照设计：BJ-400、BJ-800、PL 和 CON。参与者在进行多次频率踢速测试（FSKT）前 2.5 小时内服用两种剂量的 BJ-400 和 BJ-800 或硝酸盐耗尽的 PL。在 FSKT 和 PSTT 之前进行了下蹲跳（CMJ），而在补充前后以及 PSTT 后 10 分钟评估了认知功能（通过 Stroop 测试）。在 CMJ 测试前和 FSKT 后立即以及 PSTT 后 3 分钟采集血乳酸；在两次特定跆拳道测试期间和之后记录感觉用力等级（RPE）。PSTT 和 FSKT 表现方面，各条件之间无显著差异（>0.05），具有中到大效应量。此外，各条件之间血乳酸、RPE、心率和 CMJ 高度无显著差异（>0.05）。然而，在 PSTT 测试后，BJ-400 的认知功能高于其他治疗方法（<0.05）。结论是，急性摄入 400 和 800 毫克富含 NO 的 BJ 对无氧和有氧有中到大的效应量，但在跆拳道特定性能方面没有发现统计学差异。
