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Stewart Green

Take Dex and Climb Better at High Altitude

By August 14, 2009

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High altitude mountaineers have long taken dexamathasone or dex for treating altitude-related illnesses like high altitude pulmonary edema (HAPE) and acute mountain sickness (AMS). Now a Swiss study reveals that taking dex can dramatically improve exercise capacity and performance at high altitude.

The study, published in the August 15th issue of the American Journal of Respiratory and Critical Care Medicine by the American Thoracic Society, used 23 mountaineers with a history of HAPE. The climbers were randomly given tadalifil, dexamethasone, or a placebo the day before a cable car ascent from 3,609 feet at Alagna, Italy to 10,499 feet, where they climbed to 11,975 feet and spent the night. The next day the climbers ascended to Capanna Regina Margherita at 14,957 feet. Exercise tests and echocardiographic exams were conducted on the summit.

"Reduced oxygen content in the air is the major limiting factor at high altitude. Reduction in exercise capacity goes in parallel to the reduction in oxygen up to an altitude of approximately 4,000 meters. At higher altitudes, there is an even further reduction in exercise capacity," says Dr. Manual Fischler, one of the lead researchers. "As expected, exercise capacity at high altitudes was diminished among all groups and key indicators of cardiopulmonary stress were elevated."

Subjects who took tadalafil and dexamethasone fared better in oxygen use than the placeo group, but the dex group had two major advantages. First, the heart rate of the dex group increased but less than the other groups. Second and more significantly, the VO2max, a measurement of how efficiently the body uses oxygen, was much higher in the dex group at high altitude. The study found that elevated blood pressure in the lungs decreases the body's ability to use oxygen during exercise. Dr. Fischler says, "Our study indicates that for HAPE-susceptible climbers, taking dexamethasone improved exercise capacity, oxygen uptake kinetics and decreased the anaerobic threshold."

What that all means is that climbers who took dex felt better at altitude, climbed better, and had "fewer altitude-related discomforts" than the other two groups.

Don't, however, run out just yet to replenish your dexamethasone stash. Dr. Fischler warns of side effects, which include "inflammatory response to infection," increased blood glucose, osteoporosis, and reduced muscle mass and skin thickness. He emphasizes that dex shouldn't be used without a prescription and a doctor's advice.

Read more about HAPE, AMS, and mountaineering:
High Altitude Illness and Acute Mountain Sickness

Tips for Exercising at High Altitude

Thin Air Kills Brain Cells

Photograph above: Bring dex next time you're climbing the Mexican volcanoes and maybe you'll be sprinting up the mountain. Photograph courtesy Susan Paul

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