High Altitude and Exogenous Carbohydrate Oxidation

Inclusion Criteria: * Men aged 18 - 39 years * Born at altitudes less than 2,100 m (\~7,000 feet; Examples include Santa Fe, New Mexico; Laramie, Wyoming; Etc.) * Physically active based on assessment of physical activity history (2-4 days per week aerobic and/or resistance exercise) * Have supervisor approval (permanent party military and civilians) * Willing to refrain from alcohol, smokeless nicotine products and dietary supplement use during study periods * Refrain from taking any nonsteroidal anti-inflammatory drugs (NSAIDs; e.g. aspirin, Advil®, Aleve®, Naprosyn®, or any aspirin-containing product) for 10 days before and at least 5 days AFTER each muscle biopsy. (\*Tylenol® or acetaminophen is ok to use if needed for discomfort) Exclusion Criteria: * Born at altitudes greater than 2,100 m (\~7,000 feet; Examples include Santa Fe, New Mexico; Laramie, Wyoming; Etc.) * Living in areas that are more than 1,200 m (\~4,000 feet), or have traveled to areas that are more than 1,200 m for five days or more within the last 2 months (Examples include Ft. Huachuca, Arizona; Lima, Peru; Feldberg, Germany, Etc.) * Musculoskeletal injuries that compromise exercise capability * Metabolic or cardiovascular abnormalities (determined by resting ECG), gastrointestinal disorders (e.g., kidney disease, diabetes, cardiovascular disease, etc.) * Medication that affects macronutrient metabolism (i.e., diabetes medications, statins, corticosteroids, etc) and/or the ability to participate in …