Purpose

The aim was to investigate the effect of dietary nitrate supplementation (in the form of beetroot juice, BRJ) for 20 days on salivary nitrite (a potential precursor of bioactive nitric oxide), exercise performance and high altitude (HA) acclimatisation in field conditions (hypobaric hypoxia).

Methods

This was a single-blinded randomised control study of 22 healthy adult participants (12 men, 10 women, mean age 28 ± 12 years) across a HA military expedition. Participants were randomised pre-ascent to receive two 70 ml dose per day of either BRJ (~12.5 mmol nitrate per day; n = 11) or non-nitrate calorie matched control (n = 11). Participants ingested supplement doses daily, beginning 3 days prior to departure and continued until the highest sleeping altitude (4800 m) reached on day 17 of the expedition. Data were collected at baseline (44 m altitude), at 2350 m (day 9), 3400 m (day 12) and 4800 m (day 17).

Results

BRJ enhanced the salivary levels of nitrite (p = 0.007). There was a significant decrease in peripheral oxygen saturation and there were increases in heart rate, diastolic blood pressure, and rating of perceived exertion with increasing altitude (p=<0.001). Harvard Step Test fitness scores significantly declined at 4800 m in the control group (p = 0.003) compared with baseline. In contrast, there was no decline in fitness scores at 4800 m compared with baseline (p = 0.26) in the BRJ group. Heart rate recovery speed following exercise at 4800 m was significantly prolonged in the control group (p=<0.01) but was unchanged in the BRJ group (p = 0.61). BRJ did not affect the burden of HA illness (p = 1.00).

Conclusions

BRJ increases salivary nitrite levels and ameliorates the decline in fitness at altitude but does not affect the occurrence of HA illness.

中文翻译：

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向甜菜行进：膳食硝酸盐补充剂对军事徒步探险期间高海拔运动表现和适应的影响

目的

目的是研究 20 天的膳食硝酸盐补充剂（以甜菜根汁的形式，BRJ）对唾液亚硝酸盐（一种潜在的生物活性一氧化氮前体）、运动表现和田间条件下高海拔 (HA) 适应的影响。低压缺氧）。

方法

这是一项单盲随机对照研究，对 22 名健康成年参与者（12 名男性，10 名女性，平均年龄 28 ± 12 岁）进行了一次 HA 军事考察。参与者在攀登前随机接受每天两次 70 ml 剂量的 BRJ（每天约 12.5 mmol 硝酸盐；n = 11）或非硝酸盐卡路里匹配对照（n = 11）。参与者每天摄入补充剂，从出发前 3 天开始，一直持续到探险第 17 天达到最高睡眠高度（4800 米）。在基线（44 m 海拔）、2350 m（第 9 天）、3400 m（第 12 天）和 4800 m（第 17 天）收集数据。

结果

BRJ 提高了亚硝酸盐的唾液水平 (p = 0.007)。随着海拔的升高，外周血氧饱和度显着降低，心率、舒张压和感知劳累等级增加（p=<0.001）。与基线相比，对照组（p = 0.003）在 4800 米处的哈佛阶梯测试体能得分显着下降。相比之下，与 BRJ 组的基线（p = 0.26）相比，4800 m 的健身得分没有下降。对照组4800米运动后的心率恢复速度显着延长（p=<0.01），但BRJ组没有变化（p=0.61）。BRJ 不影响 HA 疾病的负担 (p = 1.00)。

结论

BRJ增加唾液亚硝酸盐水平并改善高原适应性下降，但不影响HA疾病的发生。