PDF(Pubmed)
Abstract：
We have previously demonstrated that acute ingestion of inorganic nitrate (NO3-)-rich beetroot juice (BRJ), a source of nitric oxide (NO) via the NO3- → nitrite (NO2-) → NO pathway, can improve muscle speed and power in older individuals. It is not known, however, whether this effect is maintained or perhaps even enhanced with repeated ingestion, or if tolerance develops as with organic nitrates, e.g., nitroglycerin. Using a double-blind, placebo-controlled, crossover design, we therefore studied 16 community-dwelling older (age 71 ± 5 y) individuals after both acute and short-term (i.e., daily for 2 wk) BRJ supplementation. Blood samples were drawn and blood pressure was measured periodically during each ∼3 h experiment, with muscle function determined using isokinetic dynamometry. Acute ingestion of BRJ containing 18.2 ± 6.2 mmol of NO3- increased plasma NO3- and NO2- concentrations 23 ± 11 and 2.7 ± 2.1-fold over placebo, respectively. This was accompanied by 5 ± 11% and 7 ± 13% increases in maximal knee extensor speed (Vmax) and power (Pmax), respectively. After daily supplementation for 2 wk, BRJ ingestion elevated NO3- and NO2- levels 24 ± 12 and 3.3 ± 4.0-fold, respectively, whereas Vmax and Pmax were 7 ± 9% and 9 ± 11% higher than baseline. No changes were observed in blood pressure or in plasma markers of oxidative stress with either acute or short-term NO3- supplementation. We conclude that both acute and short-term dietary NO3- supplementation result in similar improvements in muscle function in older individuals. The magnitudes of these improvements are sufficient to offset the decline resulting from a decade or more of aging and are therefore likely to be clinically significant.
摘要：
我们以前已经证明，急性摄入富含有机硝酸盐（NO3-）的甜菜根汁（BRJ），一氧化氮（NO）的来源通过NO3-→亚硝酸盐（NO2-）→NO途径，可以提高老年人的肌肉速度和力量。不知道,然而,无论这种效果是维持还是甚至随着重复摄入而增强，或者如果像无机硝酸盐一样产生耐受性，例如，硝酸甘油.使用双盲，安慰剂对照,交叉设计，因此，我们研究了16名社区居住的老年人(年龄71±5岁)在急性和短期(即，每天2周）补充BRJ。在每个~3小时的实验过程中，抽取血样并定期测量血压，使用等速测力计确定肌肉功能。急性摄入含有18.2±6.2mmolNO3的BRJ，使血浆NO3-和NO2-浓度比安慰剂增加了23±11和2.7±2.1倍，分别。这伴随着最大膝关节伸肌速度(Vmax)和功率(Pmax)增加5±11%和7±13%,分别。每天补充2周后，BRJ摄入升高NO3-和NO2-水平24±12和3.3±4.0倍，分别,而Vmax和Pmax比基线高7±9%和9±11%。急性或短期补充NO3均未观察到血压或血浆氧化应激标志物的变化。我们得出的结论是，急性和短期饮食补充NO3-均可导致老年人肌肉功能的改善。这些改善的幅度足以抵消由十年或更长时间的老化导致的下降，因此可能具有临床意义。
