Hemoconcentration During Maximum Exercise in Miners with Chronic Intermittent Exposure to Hypobaric Hypoxia (3800 m)

Abstract

To evaluate the effect of maximum exercise on hemoconcentration in miners with chronic intermittent hypobaric hypoxia (CIHH) at 3800 m. Sixteen miners with CIHH at high altitude (3800 m) were subjected to maximum exercise levels on a cycle ergometer, increasing exercise load by 50 W every 3 minutes at sea level and high altitude (3800 m). During exercise, arterial oxygen saturation and heart rate were measured. Blood samples were taken at each step to measure hemoglobin concentration and hematocrit. Arterial blood oxygen content was also calculated. At sea level, a decrease in arterial oxygen saturation to 92.1% ± 2.5% was observed at 150 W and the hematocrit, hemoglobin concentration and oxygen content were not altered. At high altitude, arterial oxygen saturation decreased, reaching 88.2% ± 4.9% at 50 W and remained constant during the entire exercise protocol. Hemoglobin concentration and hematocrit increased reaching 16.4 ± 0.9 g/dL and 48.8% ± 1.6%, respectively, at 100 W and were maintained until recovery. Arterial oxygen content was constant during exercise and increased in the recovery period. An increase in hemoglobin concentration during exercise compensates for the decline in arterial oxygen saturation, meanwhile arterial oxygen content remains constant.