Individuals traveling to altitudes above 8,000 feet may suffer from impaired exercise and cognitive performance, and acute mountain sickness (AMS). Decreased barometric pressure, which leads to low blood oxygen levels, is the primary cause of these disorders. Symptoms of AMS are characterized by headache, nausea, vomiting, dizziness, fatigue, and difficulty sleeping. The goal of this research is to identify whether Respiratory Muscle Training will improve physical and cognitive performance, and reduce the symptoms of AMS, at simulated high altitude.

Inclusion Criteria:

• Healthy
• Men, ages 18-45 who are able to achieve at least 3.5 watts/kg of body weight during the peak oxygen uptake test

Exclusion Criteria:

• Less than 18 years old
• Greater than 45 years old
• Have a body mass index greater than or equal to 30
• Have been recent smokers (tobacco or e-cigarettes)
• Current recreational or medical marijuana users
• Currently taking any medication (over-the-counter or prescription) or herbal supplements
• Participants who are unable to tolerate drinking only two, 6-ounce caffeinated beverages per day of the study
• Participants who are legally blind
• Participants who have been to altitudes above Denver (1609m or 5280ft), including air travel, in the 3 weeks prior to the start of the study or with plans to do so during the study
• Participants who have suffered a significant head injury, have anemia or sickle cell trait or disease, have active peptic ulcer disease, diabetes, hypertension, heart disease, HIV/AIDS, glaucoma, kidney disease, liver disease/cirrhosis, adrenal gland failure, hyponatremia/hypokalemia, tuberculosis
• Participants who have a current herpes infection or any other current type of viral or bacterial infection
• Participants with seizure disorders or history of migraines

Participants will be masked from knowing whether they are performing the Respiratory Muscle Training or sham training.