Pedersen P K, Kiens B, Saltin B
Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense University, Denmark.
Acta Physiol Scand. 1999 Aug;166(4):309-18. doi: 10.1046/j.1365-201x.1999.00575.x.
We examined the influence of hyperoxia on peak oxygen uptake (VO2peak) and peripheral gas exchange during exercise with the quadriceps femoris muscle. Young, trained men (n=5) and women (n=3) performed single-leg knee-extension exercise at 70% and 100% of maximum while inspiring normal air (NOX) or 60% O2 (HiOX). Blood was sampled from the femoral vein of the exercising limb and from the contralateral artery. In comparison with NOX, hyperoxic arterial O2 tension (PaO2) increased from 13.5 +/- 0.3 (x +/- SE) to 41.6 +/- 0. 3 kPa, O2 saturation (SaO2) from 98 +/- 0.1 to 100 +/- 0.1%, and O2 concentration (CaO2) from 177 +/- 4 to 186 +/- 4 mL L-1 (all P < 0. 01). Peak exercise femoral venous PO2 (PvO2) was also higher in HiOX (3.68 +/- 0.06 vs. 3.39 +/- 0.7 kPa; P < 0.05), indicating a higher O2 diffusion driving pressure. HiOX femoral venous O2 saturation averaged 36.8 +/- 2.0% as opposed to 33.4 +/- 1.5% in NOX (P < 0.05) and O2 concentration 63 +/- 6 vs. 55 +/- 4 mL L-1 (P < 0.05). Peak exercise quadriceps blood flow (Qleg), measured by the thermo-dilution technique, was lower in HiOX than in NOX, 6.4 +/- 0. 5 vs. 7.3 +/- 0.9 L min-1 (P < 0.05); mean arterial blood pressure at inguinal height was similar in NOX and HiOX at 144 and 142 mmHg, respectively. O2 delivery to the limb (Qleq times CaO2) was not significantly different in HiOX and NOX. VO2peak of the exercising limb averaged 890 mL min-1 in NOX and 801 mL min-1 in HiOX (n.s.) corresponding to 365 and 330 mL min-1 per kg active muscle, respectively. The VO2peak-to-PvO2 ratio was lower (P < 0.05) in HiOX than in NOX suggesting a lower O2 conductance. We conclude that the similar VO2peak values despite higher O2 driving pressure in HiOX indicates a peripheral limitation for VO2peak. This may relate to saturation of the rate of O2 turnover in the mitochondria during exercise with a small muscle group but can also be caused by tissue diffusion limitation related to lower O2 conductance.
我们研究了高氧对股四头肌运动期间峰值摄氧量（VO₂peak）和外周气体交换的影响。年轻的受过训练的男性（n = 5）和女性（n = 3）在吸入正常空气（NOX）或60%氧气（HiOX）的情况下，以最大运动强度的70%和100%进行单腿膝关节伸展运动。从运动肢体的股静脉和对侧动脉采集血液样本。与NOX相比，高氧动脉血氧分压（PaO₂）从13.5±0.3（x±SE）kPa增加到41.6±0.3 kPa，血氧饱和度（SaO₂）从98±0.1%增加到100±0.1%，氧含量（CaO₂）从177±4 mL/L增加到186±4 mL/L（所有P < 0.01）。HiOX时运动峰值股静脉血氧分压（PvO₂）也更高（3.68±0.06 vs. 3.39±0.7 kPa；P < 0.05），表明氧扩散驱动压力更高。HiOX时股静脉血氧饱和度平均为36.8±2.0%，而NOX时为33.4±1.5%（P < 0.05），氧含量为63±6 vs. 55±4 mL/L（P < 0.05）。通过热稀释技术测量的运动峰值股四头肌血流量（Qleg），HiOX时低于NOX，分别为6.4±0.5 vs. 7.3±0.9 L/min（P < 0.05）；腹股沟高度处的平均动脉血压在NOX和HiOX时相似，分别为144和142 mmHg。HiOX和NOX时肢体的氧输送量（Qleg×CaO₂）无显著差异。运动肢体的VO₂peak在NOX时平均为890 mL/min，在HiOX时为801 mL/min（无显著差异），分别对应每千克活动肌肉365和330 mL/min。HiOX时VO₂peak与PvO₂的比值低于NOX（P < 0.05），表明氧传导率较低。我们得出结论，尽管HiOX时氧驱动压力较高，但VO₂peak值相似，这表明VO₂peak存在外周限制。这可能与小肌群运动期间线粒体中氧周转率的饱和有关，但也可能是由于与较低氧传导率相关的组织扩散限制所致。
