Shi Ya-Jun, Wang Jin-Li, Gao Ling, Wen Dong-Lin, Dan Qing, Dong Ying, Guo Ya-Tao, Zhao Cheng-Hui, Li Teng-Jing, Guo Jun, Li Zong-Bin, Chen Yun-Dai
Department of Cardiology, First Medical Center, Chinese PLA General Hospital, Beijing, China.
Front Physiol. 2021 Mar 11;12:640302. doi: 10.3389/fphys.2021.640302. eCollection 2021.
Many sea-level residents suffer from acute mountain sickness (AMS) when first visiting altitudes above 4,000 m. Exercise tolerance also decreases as altitude increases. We observed exercise capacity at sea level and under a simulated hypobaric hypoxia condition (SHHC) to explore whether the response to exercise intensity represented by physiological variables could predict AMS development in young men. Eighty young men from a military academy underwent a standard treadmill exercise test (TET) and biochemical blood test at sea level, SHHC, and 4,000-m altitude, sequentially, between December 2015 and March 2016. Exercise-related variables and 12-lead electrocardiogram parameters were obtained. Exercise intensity and AMS development were investigated. After exposure to high altitude, the count of white blood cells, alkaline phosphatase and serum albumin were increased ( < 0.05). There were no significant differences in exercise time and metabolic equivalents (METs) between SHHC and high-altitude exposures (7.05 ± 1.02 vs. 7.22 ± 0.96 min, = 0.235; 9.62 ± 1.11 vs. 9.38 ± 1.12, = 0.126, respectively). However, these variables were relatively higher at sea level (8.03 ± 0.24 min, < 0.01; 10.05 ± 0.31, < 0.01, respectively). Thus, subjects displayed an equivalent exercise tolerance upon acute exposure to high altitude and to SHHC. The trends of cardiovascular hemodynamics during exercise under the three different conditions were similar. However, both systolic blood pressure and the rate-pressure product at every TET stage were higher at high altitude and under the SHHC than at sea level. After acute exposure to high altitude, 19 (23.8%) subjects developed AMS. Multivariate logistic regression analysis showed that METs under the SHHC {odds ratio (OR) 0.355 per unit increment [95% confidence intervals (CI) 0.159-0.793], = 0.011}, diastolic blood pressure (DBP) at rest under SHHC [OR 0.893 per mmHg (95%CI 0.805-0.991), = 0.030], and recovery DBP 3 min after exercise at sea level [OR 1.179 per mmHg (95%CI 1.043-1.333), = 0.008] were independently associated with AMS. The predictive model had an area under the receiver operating characteristic curve of 0.886 (95%CI 0.803-0.969, < 0.001). Thus, young men have similar exercise tolerance in acute exposure to high altitude and to SHHC. Moreover, AMS can be predicted with superior accuracy using characteristics easily obtainable with TET.
许多海平面地区的居民首次前往海拔4000米以上的地区时会患上急性高原病（AMS）。运动耐力也会随着海拔升高而下降。我们观察了海平面和模拟低氧低压环境（SHHC）下的运动能力，以探究生理变量所代表的对运动强度的反应是否能够预测年轻男性AMS的发生。2015年12月至2016年3月期间，来自一所军事院校的80名年轻男性依次在海平面、SHHC和海拔4000米处进行了标准跑步机运动试验（TET）和血液生化检测。获取了与运动相关的变量和12导联心电图参数。对运动强度和AMS的发生情况进行了研究。暴露于高海拔环境后，白细胞计数、碱性磷酸酶和血清白蛋白均升高（<0.05）。SHHC和高海拔暴露之间的运动时间和代谢当量（METs）无显著差异（分别为7.05±1.02分钟对7.22±0.96分钟，P = 0.235；9.62±1.11对9.38±1.12，P = 0.126）。然而，这些变量在海平面时相对较高（分别为8.03±0.24分钟，P<0.01；10.05±0.31，P<0.01）。因此，受试者在急性暴露于高海拔和SHHC时表现出同等的运动耐力。三种不同条件下运动期间心血管血流动力学的趋势相似。然而，在每个TET阶段，高海拔和SHHC时的收缩压和心率-血压乘积均高于海平面。急性暴露于高海拔环境后，19名（23.8%）受试者患上了AMS。多因素逻辑回归分析显示，SHHC下的METs{每单位增量的优势比（OR）为0.355[95%置信区间（CI）0.159 - 0.793]，P = 0.011}、SHHC下静息时的舒张压（DBP）[每毫米汞柱的OR为0.893（95%CI 0.805 - 0.991），P = 0.030]以及海平面运动后3分钟的恢复DBP[每毫米汞柱的OR为1.179（95%CI 1.043 - 1.333），P = 0.008]与AMS独立相关。预测模型的受试者工作特征曲线下面积为0.886（95%CI 0.803 - 0.969，P<0.001）。因此，年轻男性在急性暴露于高海拔和SHHC时具有相似的运动耐力。此外，使用TET易于获得的特征可以以较高的准确性预测AMS。
