Effect of an H1 Receptor Antagonist on Exercise Performance in Hypoxia

This study seeks to determine whether a simple, single intervention of Cetirizine / Zyrtec® use can improve exercise performance of active individuals when acutely exposed to altitude. For this project, healthy subjects will perform steady state and progressive work rate exercise, endurance performance time trials, and repeated sprint performance time trials in the laboratory at a simulated altitude of 3000m (9900ft) after dosing with 10 mg of Cetirizine or a placebo in a repeated measures design. Non-invasive techniques (pulse oximetry, near-infrared spectroscopy [NIRS]) will be utilized to measure changes in arterial oxyhemoglobin saturation and skeletal muscle oxygenation at the level of the microvasculature during exercise. It is expected that after Cetirizine, blood and muscle microvascular oxygenation during heavy exercise will improve compared to placebo, ultimately improving exercise performance at altitude. Subjects will be asked to report to the laboratory on a three occasions, separated by a minimum of 48 hours and a maximum of 14 days. For each subject, all testing sessions will be performed at the same time of day. Prior to each testing session, subjects will be asked to abstain from caffeine consumption for 12 hours. Subjects will also be asked to avoid alcohol consumption for 24 hours before testing, be at least 3-hour post prandial and avoid high-intensity exercise during the 24 hours leading to the exercise testing. Finally, subjects will be asked to consume a similar diet the night before, and the morning of, Sessions 2 and 3.