ngly, while cardiac output and rate-pressure product at a given activity level tends to be elevated as altitude increases, the maximum attainable cardiac output and heart rate drop as altitude increases (Wahrenberger, 2003). Similarly, the maximum attainable workload increases with altitude. With acute altitude exposure there are also changes in regional blood flow, with vasoconstriction occurring in the skin, muscles, and viscera, while coronary vasodilation and increased coronary blood flow occurs. Cerebral blood flow appears to remain stable during altitude exposure.
There are also changes in the resting EKG of individuals exposed to high altitude (Wahrenberger, 2003). Recordings were made on the 1981 American Research Expedition to Mount Everest at altitudes of 17,500 ft, 20,500 ft, and 26,200 ft. Electrographic changes recorded at these heights included an increase in resting heart rate, a rightward shift in the QRS axis, and an increase in the p-wave amplitude in lead 2. The latter two changes were thought to indicate evidenc
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