Dexamethasone, a glucocorticoid known as “dex” in the climbing community, has been used for years to treat altitude-related symptoms in mountaineers. But there is new evidence that, taken as a preventive measure, dex can improve exercise capacity at higher altitudes. According to a recent article on Medical News Today, researchers have found that taking dex improves exercise capacity at altitude by reducing pulmonary hypertension, one of the most significant factors in limiting exercise at high altitude. The results come from a Swiss study published in the August 15th, 2009 issue of the American Journal of Respiratory and Critical Care Medicine, the journal of the American Thoracic Society.
The Swiss research team tested 23 mountaineers with a history of high altitude pulmonary edema (HAPE). They first tested the climbers’ oxygen uptake on stationary bikes at low altitude (490 meters or 1607 feet) to establish a baseline for their study. The subjects scored higher than average for their age and gender due to their increased level of fitness. The climbers then were given tadalafil, dexamethasone or a placebo. The mountaineers then climbed Capanna Regina Margherita in Italy at 4,559 meters (14,957 feet). After spending the night at the top of the mountain, the subjects were given a second set of tests. All climbers had a reduced exercise capacity, as would be expected, but the climbers who had taken tadalafil or dex showed a smaller drop in oxygen saturation over the placebo group, indicating a better uptake of oxygen, and a pulmonary artery pressure was significantly less for both the tadalafil and dexamethasone groups over placebo.
“In this study, we found that the most important limiting factor [with respect to exercise capacity at high altitude] is primarily pulmonary hypertension elevated blood pressure in the circulation of the lungs which may further reduce the oxygen uptake, particularly during exercise. Our study indicates that for HAPE-susceptible climbers, taking dexamethasone improved exercise capacity, oxygen uptake kinetics and decreased the anaerobic threshold,” said lead researcher Manuel Fischler, MD, of the University Hospital in Zurich, Switzerland. “Overall, this means that those climbers who took dex felt better, were able to do more, and probably experienced fewer altitude-related discomforts than both other groups.”
Dexamethasone did show certain advantages over tadalafil. Heart rate increased in all groups, but significantly less so in the dexamethasone group. Also, VO2max (a key measurement of how efficiently the body is able to use oxygen) was significantly higher in the dexamethasone group at high altitude compared to both placebo and tadalafil groups.
Glucocorticoids such as dexamethasone may increase exercise capacity in several ways. They lower pulmonary artery pressure, as well as stimulate clearance of sodium and water from the lungs, which may improve oxygen diffusion. They also have anti-inflammatory properties and may even improve the mental state of those who take it, giving them the drive to push harder.
But there are significant side effects to taking glucocorticoids. While short-term use is generally good, they reduce the inflammatory response to infections, increase blood glucose, may lead to long-term osteoporosis, plus reduce muscle mass and skin thickness. Also, further study is needed to determine whether these results apply to non-HAPE-susceptible climbers. We’ll be looking for more studies in the months and years to come on the effectiveness and safety of dex for climbers and other athletes as a performance-enhancing drug.
And of course, we hope you’ll follow in the high-altitude footsteps of many world-renown climbers including Ed Viesturs and Eric Meyer and check out the ColdAvenger. Ed helped design the new ColdAvenger Expedition, which just rolled out this fall for purchase. http://talusoutdoor.com/shop
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