目的:膳食补充硝酸盐(NO3-)可增强缺氧时的肌肉血流量和代谢效率,然而,它对神经肌肉功能的功效,特别是,对运动单位(MU)活动的影响不太清楚。我们调查了在持续3分钟的缺血性收缩后,补充NO3是否会影响MU的活性,以及在恢复期是否会受到血流限制(BFR)的影响。
方法:在随机分组中,双盲,交叉设计,14名男性(平均值±标准差,25±6年)在补充富含NO3(NIT)或富含NO3的(PLA)甜菜根汁以改变血浆亚硝酸盐(NO2-)浓度5天后完成了两项试验(482±92vs.198±48nmol·L-1,p<0.001)。肌内肌电图用于评估BFR在3分钟亚最大(25%MVC)等距收缩期间的MU电位(MUP)大小(持续时间和面积)和平均放电率(MUFR)。这些变量也在90年代的恢复期进行了评估,上半年完成了,下半场没有完成,BFR。
结果:MUP面积和MUFR的变化,条件之间没有差异(所有p>0.05),但NIT导致在短暂的等距收缩期间MUP恢复时间减少(p<0.001),以及在有(p=0.002)和没有(p=0.012)BFR的情况下回收期间。
结论:这些新的观察结果提高了对NO3-对运动后神经肌肉功能恢复的影响的理解,并可能对肌肉收缩功能的恢复具有意义。
背景:该研究于2023年8月8日在clinicaltrials.gov上注册,ID为NCT05993715。
OBJECTIVE: Dietary nitrate (NO3-) supplementation enhances muscle blood flow and metabolic efficiency in hypoxia, however, its efficacy on neuromuscular function and specifically, the effect on motor unit (MU) activity is less clear. We investigated whether NO3- supplementation affected MU activity following a 3 min sustained ischemic contraction and whether this is influenced by blood flow restriction (BFR) during the recovery period.
METHODS: In a randomized, double-blinded, cross-over design, 14 males (mean ± SD, 25 ± 6 years) completed two trials following 5 days of supplementation with NO3--rich (NIT) or NO3--depleted (PLA) beetroot juice to modify plasma nitrite (NO2-) concentration (482 ± 92 vs. 198 ± 48 nmol·L-1, p < 0.001). Intramuscular electromyography was used to assess MU potential (MUP) size (duration and area) and mean firing rates (MUFR) during a 3 min submaximal (25% MVC) isometric contraction with BFR. These variables were also assessed during a 90 s recovery period with the first half completed with, and the second half completed without, BFR.
RESULTS: The change in MUP area and MUFR, did not differ between conditions (all p > 0.05), but NIT elicited a reduction in MUP recovery time during brief isometric contractions (p < 0.001), and during recoveries with (p = 0.002) and without (p = 0.012) BFR.
CONCLUSIONS: These novel observations improve understanding of the effects of NO3- on the recovery of neuromuscular function post-exercise and might have implications for recovery of muscle contractile function.
BACKGROUND: The study was registered on clinicaltrials.gov with ID of NCT05993715 on August 08, 2023.