The effect of dietary nitrate supplementation on the spatial heterogeneity of quadriceps deoxygenation during heavy-intensity cycling.
The effect of dietary nitrate supplementation on the spatial heterogeneity of quadriceps deoxygenation during heavy-intensity cycling.
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DOI：
10.14814/phy2.13340
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发表时间：
2017-07
影响因子：
2.5
通讯作者：
Koga S
中科院分区：
文献类型：
--
作者：
Breese BC;Poole DC;Okushima D;Bailey SJ;Jones AM;Kondo N;Amano T;Koga S
本研究探讨了膳食无机硝酸盐（NO3 −）补充对次极量自行车运动中肺氧摄取（O2）和肌肉脱氧血红蛋白/肌红蛋白（即脱氧[Hb + Mb]）动力学的影响。在一项随机、安慰剂对照、交叉研究中，8名健康和体力活动的男性受试者在相当于气体交换阈值和峰值O2之间差异的50%的工作率下完成了两步循环测试，分别补充富含NO 3 −（BR;每天提供8.4 mmol NO 3 −1）和NO 3 −耗尽（安慰剂; PLA）甜菜根汁。逐次呼吸测量肺部氧气，并利用时间分辨近红外光谱来量化股直肌、股外侧肌和股内侧肌内的绝对脱氧[Hb + Mb]和总[Hb + Mb]。PLA和BR试验在每个肌肉部位的初级脱氧[Hb + Mb]平均反应时间或幅度之间没有显著差异（P > 0.05）。BR显著增加了平均（三个部位）运动终末脱氧[Hb + Mb]（PLA：91 ± 9 vs. BR：95 ± 12 μmol/L，P < 0.05），并有增加总[Hb + Mb]反应的平均（三个部位）曲线下面积的趋势（PLA：3650 ± 1188 vs. BR：4467 ± 1315 μmol/L sec−1，P = 0.08）。BR补充后O2慢成分减少（PLA：0.27 ± 0.07 vs BR：0.23 ± 0.08 L min−1，P = 0.07）与三个肌肉区域中脱氧[Hb + Mb]和总[Hb + Mb]的平均增加呈负相关（r2 = 0.62和0.66，P < 0.05）。膳食NO 3 −补充增加了运动肌肉中的O2扩散传导，与高强度循环过渡期间改善的O2动力学相关。
This study investigated the influence of dietary inorganic nitrate (NO 3 −) supplementation on pulmonary O2 uptake (O2) and muscle deoxyhemoglobin/myoglobin (i.e. deoxy [Hb + Mb]) kinetics during submaximal cycling exercise. In a randomized, placebo‐controlled, cross‐over study, eight healthy and physically active male subjects completed two step cycle tests at a work rate equivalent to 50% of the difference between the gas exchange threshold and peak O2 over separate 4‐day supplementation periods with NO 3 −‐rich (BR; providing 8.4 mmol NO 3 −∙day−1) and NO 3 −‐depleted (placebo; PLA) beetroot juice. Pulmonary O2 was measured breath‐by‐breath and time‐resolved near‐infrared spectroscopy was utilized to quantify absolute deoxy [Hb + Mb] and total [Hb + Mb] within the rectus femoris, vastus lateralis, and vastus medialis. There were no significant differences (P > 0.05) in the primary deoxy [Hb + Mb] mean response time or amplitude between the PLA and BR trials at each muscle site. BR significantly increased the mean (three‐site) end‐exercise deoxy [Hb + Mb] (PLA: 91 ± 9 vs. BR: 95 ± 12 μmol/L, P < 0.05), with a tendency to increase the mean (three‐site) area under the curve for total [Hb + Mb] responses (PLA: 3650 ± 1188 vs. BR: 4467 ± 1315 μmol/L sec−1, P = 0.08). The O2 slow component reduction after BR supplementation (PLA: 0.27 ± 0.07 vs. BR: 0.23 ± 0.08 L min−1, P = 0.07) correlated inversely with the mean increases in deoxy [Hb + Mb] and total [Hb + Mb] across the three muscle regions (r 2 = 0.62 and 0.66, P < 0.05). Dietary NO 3 − supplementation increased O2 diffusive conductance across locomotor muscles in association with improved O2 dynamics during heavy‐intensity cycling transitions.