School of Health and Kinesiology, University of Nebraska at Omaha, Omaha, NE, USA.
Montana Center for Work Physiology and Exercise Metabolism, Department of Integrative Physiology and Athletic Training, University of Montana, 32 Campus Drive, McGill Hall, Missoula, MT, 59812, USA.
Sci Rep. 2022 Nov 15;12(1):19570. doi: 10.1038/s41598-022-23698-5.
The purpose of this study was to examine the effects of acute normobaric (NH, decreased FiO) and hypobaric (HH, 4200 m ascent) hypoxia exposures compared to sea level (normobaric normoxia, NN). Tissue oxygenation, cardiovascular, and body fluid variables measured during rest and a 3-min step-test following 90-min exposures (NH, HH, NN). Muscle oxygenated hemoglobin (OHb) decreased, and muscle deoxygenated hemoglobin (HHb) increased environmentally independent from rest to exercise (p < 0.001). During exercise, brain OHb was lower at HH compared to NN (p = 0.007), trending similarly with NH (p = 0.066), but no difference between NN and NH (p = 0.158). During exercise, HR at NH (141 ± 4 beats·min) and HH (141 ± 3 beats·min) were higher than NN (127 ± 44 beats·min, p = 0.002), but not each other (p = 0.208). During exercise, stroke volume at HH (109.6 ± 4.1 mL·beat) was higher than NH (97.8 ± 3.3 mL·beat) and NN (99.8 ± 3.9 mL·beat, p ≤ 0.010) with no difference between NH and NN (p = 0.481). During exercise, cardiac output at NH (13.8 ± 0.6 L) and HH (15.5 ± 0.7 L) were higher than NN (12.6 ± 0.5 L, p ≤ 0.006) with HH also higher than NH (p = 0.001). During acute hypoxic stimuli, skeletal muscle maintains oxygenation whereas the brain does not. These differences may be mediated by environmentally specific cardiovascular compensation. Thus, caution is advised when equating NH and HH.
本研究旨在比较急性常压低氧（NH，FiO 降低）和高空低氧（HH，海拔 4200 米上升）暴露与海平面常氧（NH，NN）暴露对组织氧合、心血管和体液变量的影响。在 90 分钟暴露后（NH、HH、NN）休息和 3 分钟台阶测试期间测量肌肉氧合血红蛋白（OHb）减少，肌肉去氧血红蛋白（HHb）增加，与休息到运动环境无关（p < 0.001）。在运动过程中，与 NN 相比，HH 时大脑 OHb 较低（p = 0.007），与 NH 相似（p = 0.066），但 NN 与 NH 之间无差异（p = 0.158）。在运动过程中，NH（141 ± 4 次·分钟）和 HH（141 ± 3 次·分钟）的 HR 高于 NN（127 ± 44 次·分钟，p = 0.002），但彼此之间无差异（p = 0.208）。在运动过程中，HH 的每搏输出量（109.6 ± 4.1 mL·beat）高于 NH（97.8 ± 3.3 mL·beat）和 NN（99.8 ± 3.9 mL·beat，p ≤ 0.010），但 NH 与 NN 之间无差异（p = 0.481）。在运动过程中，NH（13.8 ± 0.6 L）和 HH（15.5 ± 0.7 L）的心输出量高于 NN（12.6 ± 0.5 L，p ≤ 0.006），且 HH 也高于 NH（p = 0.001）。在急性低氧刺激下，骨骼肌保持氧合，而大脑则不然。这些差异可能是由环境特异性心血管代偿引起的。因此，在将 NH 和 HH 等同对待时应谨慎。
