Department of Nursing and Physiotherapy, University of León, 24071 León, Spain.
Burgos Nutrition, Physiology, Nutrition and Sport, 26007 Logroño, Spain.
Nutrients. 2021 Dec 23;14(1):40. doi: 10.3390/nu14010040.
Citrulline (CIT) and nitrate-rich beetroot extract (BR) are ergogenic aids and nitric oxide (NO) precursors. In addition, both supplements seem to have other actions at the level of muscle metabolism that can benefit strength and aerobic power performance. Both supplements have been studied in numerous investigations in isolation. However, scientific evidence combining both supplements is scarce, and to the best of the authors' knowledge, there is no current study of endurance athletes. Therefore, the main purpose of this study was to determine the effect of 9 weeks of CIT plus BR supplementation on maximal and endurance-strength performance and aerobic power in male triathletes. This study was a randomized double-blind, placebo-controlled trial where participants ( = 32) were randomized into four different groups: placebo group (PLG; = 8), CIT plus BR group (CIT- BRG; 3 g/kg/day of CIT plus 3 mg/kg/day of nitrates (NO); = 8), CIT group (CITG; 3 g/kg/day; = 8) and BR group (BRG; 3 mg/kg/day of NO; = 8). Before (T1) and after 9 weeks (T2), four physical condition tests were carried out in order to assess sport performance: the horizontal jump test (HJUMP), handgrip dynamometer test, 1-min abdominal tests (1-MAT) and finally, the Cooper test. Although, no significant interactions (time × supplementation groups) were found for the strength tests ( > 0.05), the CIT- BRG supplementation presented a trend on HJUMP and 1-MAT tests confirmed by significant increase between two study moments in CIT-BRG. Likewise, CIT-BRG presented significant interactions in the aerobic power test confirmed by this group's improve estimated VO during the study with respect to the other study groups ( = 0.002; ηp = 0.418). In summary, supplementing with 3 g/day of CIT and 2.1 g/day of BR (300 mg/day of NO) for 9 weeks could increase maximal and endurance strength. Furthermore, when compared to CIT or BR supplementation alone, this combination improved performance in tests related to aerobic power.
瓜氨酸（CIT）和富含硝酸盐的甜菜根提取物（BR）是运动表现增强剂和一氧化氮（NO）前体。此外，这两种补充剂似乎在肌肉代谢水平上都有其他作用，可以提高力量和有氧能力表现。这两种补充剂都在许多单独的研究中进行了研究。然而，将这两种补充剂结合起来的科学证据很少，据作者所知，目前还没有针对耐力运动员的研究。因此，本研究的主要目的是确定 9 周 CIT 加 BR 补充对男性三项全能运动员最大和耐力力量表现以及有氧能力的影响。这是一项随机双盲、安慰剂对照试验，参与者（n=32）被随机分为四组：安慰剂组（PLG；n=8）、CIT 加 BR 组（CIT-BRG；每天 3 克/千克的 CIT 加 3 毫克/千克的硝酸盐（NO）；n=8）、CIT 组（CITG；每天 3 克；n=8）和 BR 组（BRG；每天 3 毫克的 NO；n=8）。在 9 周前（T1）和后（T2），进行了四项身体状况测试，以评估运动表现：水平跳跃测试（HJUMP）、握力测力计测试、1 分钟腹部测试（1-MAT）和最后是库珀测试。尽管在力量测试中没有发现显著的交互作用（时间×补充组）（>0.05），但 CIT-BRG 补充剂在 HJUMP 和 1-MAT 测试中呈现出一种趋势，这在 CIT-BRG 两个研究时刻之间的显著增加中得到了证实。同样，CIT-BRG 在有氧能力测试中呈现出显著的交互作用，这一结果证实了与其他研究组相比，该组在研究过程中估计 VO 的提高（=0.002；ηp=0.418）。综上所述，每天补充 3 克 CIT 和 2.1 克 BR（每天 300 毫克 NO）9 周可以提高最大和耐力力量。此外，与单独补充 CIT 或 BR 相比，这种组合提高了与有氧能力相关的测试的表现。
