194 Training for Specific Environments
Training at Altitude
An athlete’s performance can suffer dramatically when he rapidly ascends to
altitude. Several factors contribute to this decrement in performance but the most
significant factor is the relative hypoxia or lack of oxygen available to do work at higher
altitudes. Many changes occur during extended exposure to high altitudes; most occur after
2 to 3 weeks. The major adaptations that affect performance and ability to do work include:" Increased oxygen carrying capacity of the blood.
" Increased density of blood supply to and within muscle.
" Increased oxygen carrying capacity of muscle.
" Increased respiratory rate.
Decreased oxygen at altitude reduces the maximal aerobic capacity of an athlete by
1% to 2% for every 100 meter (328 feet) rise above 1,500 meters (4,918 feet). Therefore,
an elite endurance athlete may only be able to perform at 65% to 85% of maximal aerobic
capacity at 10,000 feet when compared to sea level. Athletes that compete in anaerobic
events, such as sprinters or weight lifters who perform brief (2-3 minutes) episodes of
maximal effort events, may notice no initial difference in performance because sustained
maximal oxygenation of muscle tissue is not necessary.Acute Mountain Sickness
Acute Mountain sickness or AMS is typically a transient mild illness resulting from
ascents to altitudes above 8,000 feet (2,440 meters) or ascents at a rate greater than 1,000
feet (305 meters) per day above 8,000 feet. Symptoms include headache, nausea, vomiting,
fatigue and poor appetite. The symptoms usually disappear within a few days. Some
individuals, however, may have to descend to gain relief. Life threatening complications of
AMS include High Altitude Pulmonary Edema (HAPE) and High Altitude Cerebral Edema
(HACE); both require immediate descent. The incidence and severity of AMS may be
reduced by taking Acetazolamide (Diamox) 24 to 48 hours prior to and during an ascent.
The dosage is 125 mg. by mouth, twice a day for two days, but this medication should only
be given under the direction of a physician.When participating in high altitude operations, you should report any of the
following symptoms to your corpsman or medical officer:" Cough or progressive shortness of breath.
" Coughing up blood or frothy spit.