Blood lactate accumulation and muscle deoxygenation during incremental exercise
Blood lactate accumulation and muscle deoxygenation during incremental exercise
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DOI：
10.1152/jappl.1999.87.1.348
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发表时间：
1999-07-01
影响因子：
3.3
通讯作者：
Cerretelli, P
中科院分区：
文献类型：
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作者：
Grassi, B;Quaresima, V;Cerretelli, P
近红外光谱（NIRS）可以让人们深入了解有争议的问题，有关血乳酸浓度（[La]（B））增加，在次最大的工作量（（w）超过点）。我们对5名训练有素的受试者[登山者;峰值O-2消耗量（（V）/O-2 peak），51.0 +/- 4.2（SD）ml.kg（-1）.min（-1）]在自行车测力计上进行递增运动（每4分钟增加30 W，直到自愿耗尽），通过连续波NIRS测量肺气体交换和耳垂[La]（B），并测定股外侧肌中氧合血红蛋白（Delta[O（2）Hb]）和脱氧血红蛋白（Delta[HHb]）的浓度变化。在最低[La]（b）值处任意鉴定[La]（b）相对于（w）点上的“拐点”，该最低[La]（b）值比在以下（w）点上获得的值低> 0.5mM。在感兴趣的肌肉区域中的总Hb体积（Delta[O（2）Hb + HHb]）作为点上的（w）的函数增加，达到点上O-2峰上的（V）的60-65%，之后保持不变。氧合指数（Delta[O（2）Hb-HHb]）在O-2峰上从（V）的60-65%加速下降。在总Hb体积恒定的情况下，观察到的Delta[O（2）Hb-HHb]减少表明肌肉缺氧（即，主要是毛细血管-微静脉Hb去饱和）。肌肉脱氧的开始与[La]（B）与（w）在点上的拐点显著相关（r（2）= 0.95; P < 0.01），即，随着血乳酸盐积累的开始先前的研究表明，相对恒定的股静脉P-O2水平在（w）超过点高于类似的60%的最大O-2消耗。因此，在本研究中观察到的O-2峰上60-65%（V）的肌肉脱氧可归因于在相对恒定的毛细血管-微静脉P-O2水平存在下，毛细血管-微静脉Hb去饱和，这是由乳酸酸中毒开始时确定的O（2）Hb解离曲线的快速移动的结果。
Near-infrared spectroscopy (NIRS) could allow insights into controversial issues related to blood lactate concentration ([La](b)) increases at submaximal workloads ((w) over dot). We combined, on five well-trained subjects [mountain climbers; peak O-2 consumption ((V) over dot O-2peak), 51.0 +/- 4.2 (SD) ml.kg(-1).min(-1)] performing incremental exercise on a cycle ergometer (30 W added every 4 min up to voluntary exhaustion), measurements of pulmonary gas exchange and earlobe [La](b) with determinations of concentration changes of oxygenated Hb (Delta[O(2)Hb]) and deoxygenated Hb (Delta[HHb]) in the vastus lateralis muscle, by continuous-wave NIRS. A "point of inflection" of [La](b) vs. (w) over dot was arbitrarily identified at the lowest [La](b) value which was >0.5 mM lower than that obtained at the following (w) over dot. Total Hb volume (Delta[O(2)Hb + HHb]) in the muscle region of interest increased as a function of (w) over dot up to 60-65% of (V) over dot O-2peak, after which it remained unchanged. The oxygenation index (Delta[O(2)Hb - HHb]) showed an accelerated decrease from 60-65% of (V) over dot O-2peak. In the presence of a constant total Hb volume, the observed Delta[O(2)Hb - HHb] decrease indicates muscle deoxygenation (i.e., mainly capillary-venular Hb desaturation). The onset of muscle deoxygenation was significantly correlated (r(2) = 0.95; P < 0.01) with the point of inflection of [La](b) vs. (w) over dot, i.e., with the onset of blood lactate accumulation. Previous studies showed relatively constant femoral venous P-O2 levels at (w) over dot higher than similar to 60% of maximal O-2 consumption. Thus muscle deoxygenation observed in the present study from 60-65% of (V) over dot O-2peak could be attributed to capillary-venular Hb desaturation in the presence of relatively constant capillary-venular P-O2 levels, as a consequence of a rightward shift of the O(2)Hb dissociation curve determined by the onset of lactic acidosis.