After Paul had arranged for my first wilderness hunt, he informed me that when (not if, but when) I shot a Caribou, I had better be prepared to hike it out on my back. “Let’s get started training” he said with a grin. We worked out a schedule of weights and stairs, and topped it off with a weekly backpacking torture. By the time we were on the way to British Columbia, I was up to 100lbs in the Cabela’s Alaskan III pack (Paul was at 160lbs) for 2 ½ miles up and down the hilly dirt road. I figured that although my efforts in BC were to be at over 6500 feet (2000 meters), the 95 degree South Carolina training more than made up for any altitude issues I would encounter.
On day three of the hunt, our buddy Dr. Gregg Bonham (the third of the three stooges) spotted a monster Caribou bull and his harem way up on the mountaintop from the valley below. He deferred to me as his primary goal was a goat and off I went on horseback with my guide, Jim in pursuit. This beast was no doubt a book specimen and the excitement grew as we climbed higher and higher, broke the timberline and the herd finally came into view. Further up and across we went until my guide instructed me to dismount and the horses were tied to some brush. “About 600 yards” guessed my guide, “let’s start to sneak in closer”. We were 50 or so yards into the stalk, when the wind abruptly changed and snow started to fall. Well, not quite fall, more like howl and blow horizontal from our backs right toward the herd. “We gotta move fast and now” he whispered. Confidence welled up inside me as I knew I had trained long and hard for just this moment. We started a dead run and in 50 yards I was puffing. By 100 yards, I was nearly gasping for air as I watched the herd trot off, having pick up our scent long before I had a shot lined up. Jim just lit up a cigarette and laughed. “What about all that training I heard about” he asked? I shot back “what kind of place is this, you people don’t have any air in your air”?
Later in the hunt, I was able to catch up to a nice Caribou, Dr. Bonham to a moose and Dr. Plante to a goat but I never caught up to my guide (10 years older and a regular smoker might I add). It was an interesting hunt for all parties involved. Still I was intrigued about how my training had so little impact on my stamina. What follows are the explanations as to how altitude effects stamina, can cause illness and what can be done about it to diminish the impact of altitude on your hunt.
Essentially not having any air in the air is the actual problem that faces us when we hunt at altitude. The relationship between how much oxygen is in the air and how much reaches on blood stream is complex. Suffice to say it is not linear. That means small decreases in the amount of oxygen in the air can result in much larger decreases of oxygen in the body. At about 3300 feet (1000 meters) oxygen is reduced 11%, at around 6500 feet (2000 meters) it is reduced 21% and at 9900 feet (3000 meters) the reduction is 31%. Near the summit of Mount Everest, the oxygen is reduced 80% of sea level values. Fortunately, game animals don’t exist at truly extreme altitudes and to the best of my knowledge there are no CITES permits for a Yeti, so a discussion of the use of supplemental oxygen is beyond the hunting experience.
Our bodies can adjust or acclimatize, but this requires extended exposure to the decreased oxygen levels. Going up and down the mountain in daily pursuit presents the body with no incentive to adjust to altitude. Acclimatization requires a constant exposure to altitude and develops with great variability from one person to the next.
Decreases in the amount of oxygen we breathe impact us in many areas. Studies done in a variety of employment settings reveal decreased concentration, and diminished night vision occurring at altitudes as low as 6500 feet. Sleep also can be disturbed, but usually only fatigue and markedly diminished exercise tolerance are experienced. There are three more serious conditions that we all need to be aware of if we are contemplating hunting at altitude.
Acute Mountain Sickness is actually common when folks ascend from near sea level to altitudes of 6000 to 10,000 feet (~2000 to 3000 meters). Symptoms are gratefully self limiting but develop quickly; within 2 -3 hours of ascent. These symptoms include: headache, fatigue, breathlessness, nausea, lightheadedness, insomnia, and loss of appetite. If you develop this condition, you can be comforted by the knowledge that if you stay at altitude, the symptoms will be gone in a day or so. Descent to lower altitude briskly reverses the problems.
More serious and fortunately less uncommon is High Altitude Pulmonary Edema (in lay terms, the build up of fluid in your lungs). The higher you go, the more likely you are to develop this problem. This complication is virtually unheard of at less than 10,000 feet, but altitude greater than 10,000 feet results in up to 10% developing this illness. Going up and down the mountain daily or nearly daily make developing this syndrome less probable and affords protection. Symptoms start 2 to 4 days into the high altitude stay, with a dry cough. This dry cough may progress to more serious signs including frothy, blood tinged sputum, rapid heart rate, low grade fever and severe shortness of breath. If you don’t have it after a few days, you are not likely to get it later, unless you move up hill a considerable vertical distance. If these symptoms develop, DESCEND TO LOWER ALTITUDE IMMEDIATELY. If respiratory symptoms are not resolved quickly after you descend below 6000 feet, seek medical attention. Pulmonary edema is a life threatening emergency and this is not the time for a (possibly last) macho stand against nature!
More serious yet and gratefully more rare is High Altitude Cerebral Edema (swelling of the brain). This occurs at more extreme altitude of greater than 14,500 feet. Perhaps 1 – 2% of flatlanders develop this condition with rapid ascent to these dramatic heights. Because the brain is involved this is an obvious medical emergency. Symptoms include confusion, clumsiness, agitation, and can progress to hallucination, coma and death. DESCEND AND SEEK MEDICAL ATTENTION IMMEDIATLEY!
Infrequent as these last two conditions are, their symptoms are beyond merely annoying since they can lead to death. Prevention is obviously the way to go. The most effective and easiest form of prevention of altitude related illness is a gradual ascent. This is not what we usually do when pursuing game, but is effective. An ascent of no more than 1500 to 2000 feet per day will work. Bear in mind where you started your travels from. If you are a flatlander, then the flight to base camp may be the first several thousand feet of your ascent. Overnight and then pursue your trophy up hill. If you reside at altitude then you are already acclimatized and can operate at higher altitude without concern. Remember that going from Denver (~5000 feet) up to 10,000 feet is the same change as going to 5000 feet from near sea level and prevention needs to be part of the plan.
Medications are useful for all three of these illnesses. These are not meds without any side effects and we suggest a consultation with your doctor to obtain a prescription and discuss the risks and benefits. The following medications have been found to be useful. For simple Acute Mountain Sickness, the diuretic Acetazolamide, 250mg twice daily is an effective preventative. Starting the Acetazolamide gradually prior to leaving on your Safari is the best plan. Dexamethasone, a potent steroid, can be preventative but its use can be complicated and we don’t recommend it for simple Acute Mountain Sickness prophylaxis. Simple over the counter headache meds work magic here if symptoms do develop and can be used as directed.
Pulmonary edema is a medical emergency and there are no preventative meds. The potent blood pressure medication Nifedipine is an effective treatment but again, formal medical advice from your physician is paramount here. Oxygen administration, unlikely as it may be in the field, can be life saving. Viagra (sildenafil) 50mg has been shown to be useful as treatment and prevention (tempting comments withheld here!).
Cerebral edema is too severe to recommend anything but immediate descent and medical attention. Dexamethasone is the treatment of choice but all efforts are to be directed to evacuation to a lower altitude and professional medical attention.
Novel approaches to prevention are coming from the study of nutrition and illness. These areas of research are becoming more scientific and hence dependable all the time. Ginkgo biloba is a naturally occurring herb that has some remarkable qualities. In one study, 60mg three times a day prevented Acute Mountain Sickness in a five day gradual ascent. More intriguing was a study in which subjects were treated with 60mg of Ginkgo biloba three times for only the day before a very rapid ascent. These subjects went from sea level to 4205 meters (13,670 feet) in 3 hours. Only 2 of twelve who took the Ginkgo developed Acute Mountain Sickness, whereas nine of fourteen (64%) who took placebo developed Acute Mountain Sickness.
We are not suggesting that all the physical training done prior to our B.C. hunt was not useful. Actually, the better the cardiovascular fitness, the better you fair when ascending to high altitudes as far as stamina is concerned. However fitness is not preventative for attitude sickness. A planed ascent schedule, and physical training are ideal ways to avoid altitude related illness. Secondarily, prevention with medications and or supplements (prescription or over the counter) can be a wise decision. Doctors who reside and practice at lower altitude are likely going to be unfamiliar with altitude related illness. We suggest you copy this article and take it with you to discuss this with your physician.
As always, be safe and enjoy the outdoors.