The Navy SEAL Physical Fitness Guide - Uniformed Services ...

" Progressive symptoms of headache." Mental confusion or difficulty thinking." Visual disturbances." Lack of urination in excess of 8 hours." Excessive irregular breathing.Other Factors that HinderPerformance at AltitudeTemperatureIn general, temperature decreases 6.5° C for every 1,000 meter rise in elevation (or11.7°F/ 3,280 ft.). At extreme altitudes (above 5,000 meters or 16,400 ft.), the combinedeffects of hypoxia and hypothermia may make sustained aerobic activity extremelydifficult if not impossible.Dry AirRelative humidity falls as one ascends. Combined with the increased ventilatoryrate experienced at altitude, significant water loss can occur from the normally moistrespiratory passages. Cold temperatures will also cause an increase in urinary output andtogether these two sources of water loss can result in rapid dehydration. Thirst cannot beused as a “measuring stick” for hydration status and personnel must constantly replacefluids with frequent water breaks.Weight LossMost people who ascend to 13,000 feet (4,000 meters) or higher will experience aweight loss of 3% to 5% in the first 2 weeks at altitude. Some of this loss is muscle massand appears to result from a decrease in the size of individual muscle fibers. There areseveral reasons for this weight loss:" Increased energy expenditure." Decreased appetite due to a direct effect of hypoxia and a decreased sense oftaste." Loss of body water." Acute Mountain Sickness - Please refer to The Navy SEAL Nutrition Guidefor dietary recommendations at altitude.The Navy SEAL Physical Fitness Guide 195