Jaeger J J, Deal E C, Roberts D E, Ingram R H, McFadden E R
Med Sci Sports Exerc. 1980;12(5):365-9.
This study was performed to examine the dynamics and localization of respiratory heat exchange in exercising humans breathing cold air. Eight normal individuals performed 10 min of exercise at 80% of their predicted Vo2max with inspired air at 22 degrees C, saturated with water vapor; or at -40 degrees C, dry. Rectal temperature (Tre) and temperature at various locations along the length of the esophagus were measured during the exercise period. Temperature in the lower third of the esophagus was in close agreement with Tre and was unaffected by the level of respiratory heat exchange. Upper esophageal temperature decreased substantially during exercise, the magnitude of the decrease being dependent upon proximity to intrathoracic airways and the level of respiratory heat exchange (RHE). We conclude that with high levels of RHE, the capacity of the nasopharynx and upper airways to completely condition inspired air is exceeded. As a consequence, heat and water exchange occur in regions of the respiratory tract not normally involved in this function.
本研究旨在检测在呼吸冷空气的运动人体中呼吸热交换的动态变化及定位。八名正常个体在其预测最大摄氧量的80%强度下进行10分钟运动，吸入的空气温度为22℃、饱和水蒸气状态；或-40℃、干燥状态。在运动期间测量直肠温度（Tre）以及沿食管长度不同位置的温度。食管下三分之一处的温度与Tre密切相关，且不受呼吸热交换水平的影响。运动期间食管上段温度大幅下降，下降幅度取决于与胸内气道的接近程度以及呼吸热交换（RHE）水平。我们得出结论，在高水平RHE时，鼻咽部和上呼吸道完全调节吸入空气的能力被超越。因此，热和水交换发生在呼吸道中通常不参与此功能的区域。
