Date: Tue, 24 Dec 1996 18:20:10 -0500 (EST) To: Ultra@caligari.Dartmouth.EDU From: chiptrnr@mail1.nai.net (Frank R Tuthill) Subject: acclimatization Gentlemen and Ladies, There have been numerous replies to the question of acclimatization. It is my opinion that none have adequately addressed the issue.I am not a Physician . My personal experience includes ascents of slightly over twenty thousand feet. I have climbed and trekked over 12,000 feet for a total of thirty days in the past eight years. These trips were to Alaska, the Cascades, Mexico, South America and Nepal. Fortunately, and with proper precautions, I have only developed AMS, but other members of the parties did exhibit symptoms of HACE. The time proven method of acclimatization is a slow assent allowing the body time to adapt and recover from the reduction in partial pressure at altitude. The climbers adage is "climb high and sleep low" . This allows the body to recover from the stresses of hiking or running at altitude. Without the descent back to a lower altitude recovery is either limited or proceeds very slowly, if at all. The oxygen content remains the same at 20.96 % but the mechanisms to transport and utilized oxygen are compromised. This pressure gradient is also effected by blood acidity and temperature. "Pressure breathing" increases the partial pressure resulting in greater saturation of hemoglobin in the blood. The resulting greater tidal volumes can aid in performance. There is a caveat. The lowering of blood acidity from pressure breathing can cause hyperventilation syndrome. This in turn can cause faintness, dizziness, cramps and collapse. For the most part , we cannot aid in the acclimatization process. We can hinder it . Proper fluid intake is key. It is still more unfortunate that while being fit does help acclimatization, it in no way guarantees acclimatization. To that I can personally attest. Each runner must allow for his or her body to acclimatize. In my own case ( this is only for me and may or may not be appropriate for others) I will take 3-5 days and 5-7 days to acclimatize to 10,000 and 14,000 feet respectively. At arrival to a higher elevation both respiration and heart rate increase automatically. This occurs for two or three days . It is normal but can result in difficulties in sleeping. The increase blood flows felt to me as a drummer in my head. There are a number of conditions not normal that can occur to persons at altitude. AMS Acute Mountain Sickness afflicts 15-17% of people who ascend to 8,000 feet or higher too rapidly. Symptoms include headache, shortness of breath, disturbed sleep and sometimes nausea and vomiting. While death may seem preferable , it rarely requires treatment. Onset may begin slightly after arrival. HAPE High Altitude Pulmonary Edema generally occurs at elevations greater than 9,000 feet taking 36 to 72 hours to develop. Shortness of breath and bloody sputum is likely. Headache and great fatigue are common. DEATH may occur rapidly. HACE High Altitude Cerebral Edema may occur as low as 9,000 feet. Ataxia is a simple test for possible HACE. Enclose the runner with your arms. An ataxic runner will be unable to maintain equilibrium within your arms. Mental confusion and hallucinations are common. DEATH MAY OCCUR WITHIN FOUR TO SIX HOURS Unfortunately these conditions do not occur individually. They may all be present to varying degrees . They may also progress from one to another with frightening rapidity. The aggregate symptoms may mask a clear diagnosis. These are the only options where HAPE or HACE are suspected: descend Descend DESCEND Your life may be at stake. This is not meant to be alarmist, but merely to outline some medical considerations of high altitude events. While it may seen that arriving at the last minet will prevent these dangers. I do not believe that correct. Consider that for every 1,000 feet above 5,000 feet the runner will find his sea level performance reduced by 3%. At Hardrock, we can expect an average reduction of 18% . In fact most runners appear to have a much greater than 22% increase in their times. It may well be that there are no comparable sea level courses to compare. I plan on arriving two weeks early to hike the course and see the country. What a great way to acclimatize. For additional reference I recommend : Going Higher, by Charles Houston, MD Little, Brown and Co. Boston A very readable volume from which I have borrowed freely, Merry Christmas to all, and to all a good night, Chip Tuthill Chiptrnr@ct1.nai.net