Mauna Kea III: Metabolic Effects of Dietary Carbohydrate Supplementation during Exercise at 4100 m Altitude

摘要

Twenty-nine male soldiers were divided into 3 groups to study the effects of exercise and carbohydrate supplementation on physical performance and metabolism at high altitude. All groups were provided a standard military field ration (Meal, Ready-to-Eat) containing 45% carbohydrate (CHO) was consumed ad libitum during 4 consecutive days of residence at an altitude of 4100 M. Two groups (EX and EX + CHO) exercised while at high altitude by running and walking at about 75% maximum heart rate 2h/day. The third group (SED) remained sedentary while at high altitude. One exercise group One exercise group (EX + CHO) was permitted to consume carbohydrate sweetened beverages ad libitum as a supplement (250-350 g CHO/day) to the diet. The other two groups consumed similar beverages containing a non-caloric sweetner also on an ad libitum basis. Baseline measurements of food consumption, aerobic capacity, and blood and urine metabolites were recorded for all groups during 2 days of sedentary activity at sea level prior to rapid ascent to altitude (4100 M). Mean daily caloric intakes during the 4 days of exercise at altitude were 1513 kcal (SED), 1787 kcal (EX), and 2325 kcal (EX + CHO). The EC + CHO group consumed an average of 404 g CHO/day compared to 187 and 159 g CHO/day for the EX and SED groups respectively. The EX + CHO grpuos displayed a higher exercising respiratory exchanged ratio (0.81 + or - 0.01 vs 0.77 + or - 0.01), lower blood and urine beta hydroxybutyric acid and averaged 12.5% greater voluntary miles run over the course of the 4 day study. The study results confirm and extend previous studies suggesting that carbohydrate supplementation is beneficial during strenuous exercise at high altitude.