RESPIRATORY WEIGHT LOSSES DURING EXERCISE
RESPIRATORY WEIGHT LOSSES DURING EXERCISE
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DOI：
10.1152/jappl.1972.32.4.474
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发表时间：
1972-01-01
影响因子：
3.3
通讯作者：
STOLWIJK, JA
中科院分区：
文献类型：
--
作者：
MITCHELL, JW;NADEL, ER;STOLWIJK, JA
方法在四种环境中进行稳态自行车运动期间，测定了四名受试者（表1）的呼吸水分损失。工作率约为最大耗氧量的30%、50%、65%和80%。当变量保持恒定时（运动5至20分钟之间）记录测量值。环境条件为20、26、30和37 ℃，水蒸气压在7至10 mm Hg之间。选择低湿度环境以使呼吸期间的湿度变化最大化，并强调休息和运动值之间的任何差异。在37 ℃环境中，用两种方法测量吸入和呼出空气湿度。第一个采用的标准湿球和干球热电偶放置在柯林斯阀下游0.5 m处的呼出气流中。在第二种方法中，通过电阻湿度测定电路（5）抽取500 ml/min的呼出空气，并直接测定湿度。用平衡肺量计测定通气量。在20、26和30”C环境中，环境空气温度低于呼出空气的露点，呼出空气管路中的冷凝会使通过两种方法中的任一种获得的湿度读数无效。对于这些测试，呼出的空气用高流速的环境空气稀释。测量气流的流速和湿球温度和干球温度。呼出空气的相对湿度不能单独从这些测量中确定，但总蒸发水
METHODSRespiratory water loss was determined from four subjects (Table 1) during steady-state bicycle exercise in four environments. The work rates were approximately 30, 50, 65, and 80% of maximum oxygen consumption. Measurements were recorded when the variables remained constant (between 5 and 20 min of exercise), Ambient conditions were 20, 26, 30, and 37” C with a water vapor pressure between 7 and 10 mm Hg. Low humidity environments were selected to maximize the humidity changes during breathing and to accentuate any differences between resting and exercise values. In the 37” C environment, the inspired and expired air humidities were measured by two methods. The first employed standard wet and dry bulb thermocouples placed in the expired airstream 0.5 m downstream from the Collins valve. In the second method, 500 ml/min of expired air was drawn through a resistance hygrometry circuit (5), and the humidity determined directly. Ventilatory volume was measured by a balanced spirometer. In the 20, 26, and 30” C environments, the ambient air temperature is below the dew point of the expired air, and condensation in the expired air lines would invalidate the humidity readings obtained by either of the two methods. For these tests, the expired air was diluted with a high flow rate of ambient air. Flow rate and wet and dry bulb temperatures of the air stream were measured. The relative humidity of the expired air could not be determined from these measurements alone, but the total evaporative water