Brothers Michael D, Wilber Randall L, Byrnes William C
Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA.
High Alt Med Biol. 2007 Fall;8(3):213-24. doi: 10.1089/ham.2007.8308.
While high altitude adaptations have been studied extensively, limited research has examined moderate altitude (MA: 1500 to 3000 m) adaptations and their time course, despite the fact that millions of people sojourn to or reside at MA. We retrospectively examined long-term MA acclimatization by analyzing recurring physical fitness test results and hematological data among 2147 college-age male cadets previously residing at either sea level (SL) or MA and currently attending the U.S. Air Force Academy (USAFA), a unique, regimented, and well-controlled military university located at 2210 m. Significant (p < 0.01) differences were found in aerobic and anaerobic fitness test scores between former SL and MA subjects, with MA subjects scoring 27 points (8%) higher during a 1.5-mile aerobic fitness run and 18 points (6%) higher than SL subjects in the anaerobic fitness test for 2 yr. These differences may be partly explained by the hematological differences observed. Hemoglobin concentration ([Hb]) was significantly (p < 0.001) higher (6.3%; approximately 1 g/dL) in MA subjects prior to arrival at USAFA and acutely, but the difference between altitude conditions was gone at the next retrospective blood draw (+17 months). After 2.5 yr at USAFA, former SL residents had significantly (p < 0.001) higher [Hb] by +10%, or 1.5 g/dL versus prearrival values. This study suggests that significant hematological acclimatization occurs with MA exposure and requires greater than 7 months to reach stability. The altitude-induced erythropoiesis may explain in part the improvements in aerobic performance, but altitude-related anaerobic differences still remain after hematological acclimatization.
尽管对高原适应进行了广泛研究，但针对中度海拔（MA：1500至3000米）适应及其时间进程的研究却很有限，尽管事实上有数百万人在中度海拔地区旅居或居住。我们通过分析2147名曾居住在海平面（SL）或中度海拔地区、目前就读于美国空军学院（USAFA）的大学年龄男性学员的反复体能测试结果和血液学数据，对长期的中度海拔适应情况进行了回顾性研究。美国空军学院是一所位于2210米的独特、规范且控制良好的军事大学。在前海平面和中度海拔受试者之间，有氧和无氧体能测试成绩存在显著（p < 0.01）差异，中度海拔受试者在1.5英里有氧体能跑中的得分比海平面受试者高27分（8%），在为期2年的无氧体能测试中比海平面受试者高18分（6%）。这些差异可能部分由观察到的血液学差异所解释。在到达美国空军学院之前及刚到达时，中度海拔受试者的血红蛋白浓度（[Hb]）显著（p < 0.001）更高（6.3%；约1 g/dL），但在下一次回顾性抽血时（+17个月），海拔条件之间的差异消失了。在美国空军学院待了2.5年后，前海平面居民的[Hb]比到达前的值显著（p < 0.001）高10%，即1.5 g/dL。这项研究表明，暴露于中度海拔会发生显著的血液学适应，且需要超过7个月才能达到稳定状态。海拔诱导的红细胞生成可能部分解释了有氧性能的改善，但血液学适应后，与海拔相关的无氧差异仍然存在。
