Wong Tak Hiong, Sim Alexiaa, Burns Stephen F
Physical Education and Sports Science, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, 637616, Singapore.
J Exerc Sci Fit. 2022 Oct;20(4):305-316. doi: 10.1016/j.jesf.2022.06.004. Epub 2022 Jul 5.
BACKGROUND/OBJECTIVE: Dietary nitrate ingestion extends endurance capacity, but data supporting endurance time-trial performance are unclear. This systematic review and meta-analysis evaluated the evidence for dietary nitrate supplementation to improve high-intensity endurance time-trial performance over 5-30 min on the premise that nitrate may alleviate peripheral fatigue over shorter durations.
A systematic literature search and data extraction was carried out following PRISMA guidelines and the PICOS framework within five databases: PubMed, ProQuest, ScienceDirect, Scopus and SPORTDiscus. Search terms used were: (nitrate OR nitrite OR beetroot) AND (high intensity OR all out) AND (time trial or total work done) AND performance.
Twenty-four studies were included. Fifteen studies applied an acute supplementation strategy (4.1 mmol-15.2 mmol serving on one day), eight chronic supplementation (4.0 mmol-13.0 mmol per day over 3-15 days), and one applied both acute and chronic supplementation (8.0 mmol on one day and over 15 days). Standardised mean difference for time-trial ranging from 5 to 30 min showed an overall trivial effect in favour of nitrate (Hedges'g = 0.15, 95% CI -0.00 to 0.31, Z = 1.95, = 0.05). Subgroup analysis revealed a small, borderline effect in favour of chronic nitrate intervention (Hedges'g = 0.30, 95% CI -0.00 to 0.59, Z = 1.94, = 0.05), and a non-significant effect for acute nitrate intervention (Hedges'g = 0.10, 95% CI -0.08 to 0.28, Z = 1.11, = 0.27).
Chronic nitrate supplementation improves time-trial performance ranging from 5 to 30 min.
背景/目的：摄入膳食硝酸盐可延长耐力，但支持耐力计时赛表现的数据尚不明确。本系统评价和荟萃分析评估了膳食硝酸盐补充剂在5至30分钟内改善高强度耐力计时赛表现的证据，前提是硝酸盐可能在较短时间内减轻外周疲劳。
按照PRISMA指南和PICOS框架，在五个数据库（PubMed、ProQuest、ScienceDirect、Scopus和SPORTDiscus）中进行了系统的文献检索和数据提取。使用的检索词为：（硝酸盐或亚硝酸盐或甜菜根）与（高强度或全力）与（计时赛或总工作量）与表现。
纳入了24项研究。15项研究采用急性补充策略（一天服用4.1毫摩尔至15.2毫摩尔），8项采用慢性补充（3至15天内每天服用4.0毫摩尔至13.0毫摩尔），1项同时采用急性和慢性补充（一天服用8.0毫摩尔，持续15天以上）。5至30分钟计时赛的标准化平均差显示，总体上对硝酸盐有微小的有利影响（Hedges'g = 0.15，95%CI -0.00至0.31，Z = 1.95，P = 0.05）。亚组分析显示，对慢性硝酸盐干预有微小的、临界显著的有利影响（Hedges'g = 0.30，95%CI -0.00至0.59，Z = 1.94，P = 0.05），而急性硝酸盐干预的影响不显著（Hedges'g = 0.10，95%CI -0.08至0.28，Z = 1.11，P = 0.27）。
慢性硝酸盐补充可改善5至30分钟的计时赛表现。
