Costes F, Prieur F, Féasson L, Geyssant A, Barthélémy J C, Denis C
Laboratoire de Physiologie, GIP Exercice, Faculté de Médecine, Université J. Monnet, Saint-Etienne, France.
Med Sci Sports Exerc. 2001 Sep;33(9):1484-9. doi: 10.1097/00005768-200109000-00010.
Endurance training improves the oxygen delivery and muscle metabolism. Muscle oxygen saturation measured by near infrared spectroscopy (IR-SO(2)), which is primarily influenced by the local delivery/demand balance, should thus be modified by training. We examined this effect by determining the influence of change in blood lactate and muscle capillary density with training on IR-SO(2) in seven healthy young subjects.
Two submaximal exercise tests at 50% (Ex1) and 80% pretraining VO(2max) (Ex2) were performed before and after a 4-wk endurance-training program.
VO(2max) increased only slightly (+8%, NS) with training but the training effect was confirmed by the increased capillary density (+31%, P < 0.01) and citrate synthase activity (50%, P < 0.01), determined from muscle biopsy samples. Before training, blood lactate increased during the first 5 min of Ex1 and then remained constant (3.8 +/- 0.5 mmol x L(-1), P < 0.01), whereas it increased continuously during Ex2 (8.9 +/- 1.8 mmol x L(-1), P < 0.001). After training, lactate decreased significantly and remained constant during the two bouts of exercise (2.0 +/- 0.4 and 3.7 +/- 1.2 at the end of Ex1 and Ex2, respectively, both P < 0.001). During Ex1, IR-SO(2) dropped initially at the onset of exercise and recovered progressively without reaching the resting level. Training did not change this pattern of IR-SO(2). During Ex2, IR-SO(2) decreased progressively during the 15 min of exercise (P < 0.05); IR-SO2 kept constant after the initial drop after training. We found a significant relationship (r = 0.42, P = 0.03) between blood lactate and IR-SO(2) at the end of both bouts of exercise; this relationship was closer before training. By contrast, IR-SO(2) or IR-BV was not related to the capillary density.
The training-induced adaptation in blood lactate influences IR-SO(2) during mild- to hard-intensity exercise. Thus, NIRS could be used as a noninvasive monitoring of training-induced adaptations.
耐力训练可改善氧输送和肌肉代谢。通过近红外光谱法（IR-SO₂）测量的肌肉氧饱和度主要受局部输送/需求平衡的影响，因此应会因训练而改变。我们通过确定七名健康年轻受试者训练后血乳酸和肌肉毛细血管密度的变化对IR-SO₂的影响来研究这种效应。
在为期4周的耐力训练计划前后，进行两次次极量运动测试，运动强度分别为训练前VO₂max的50%（Ex1）和80%（Ex2）。
训练后VO₂max仅略有增加（+8%，无统计学意义），但通过肌肉活检样本测定的毛细血管密度增加（+31%，P<0.01）和柠檬酸合酶活性增加（50%，P<0.01）证实了训练效果。训练前，Ex1的前5分钟血乳酸增加，然后保持恒定（3.8±0.5 mmol·L⁻¹，P<0.01），而Ex2期间血乳酸持续增加（8.9±1.8 mmol·L⁻¹，P<0.001）。训练后，两次运动期间血乳酸均显著下降并保持恒定（Ex1和Ex2结束时分别为2.0±0.4和3.7±1.2，均P<0.001）。在Ex1期间，IR-SO₂在运动开始时最初下降，然后逐渐恢复，但未达到静息水平。训练并未改变IR-SO₂的这种模式。在Ex2期间，运动15分钟内IR-SO₂逐渐下降（P<0.05）；训练后，IR-SO₂在最初下降后保持恒定。我们发现在两次运动结束时血乳酸与IR-SO₂之间存在显著相关性（r = 0.42，P = 0.03）；训练前这种相关性更紧密。相比之下，IR-SO₂或IR-BV与毛细血管密度无关。
训练引起的血乳酸适应性变化会影响轻度至高强度运动期间的IR-SO₂。因此，近红外光谱法可用于无创监测训练引起的适应性变化。
