Effect of Sex on Orthostatic Intolerance and Cardiovascular Response During Lunar Descent and Ascent

Phase I, Visit one Alpha (1A);

OIG (Orthostatic Intolerance Garment) Measurement:

Participants will lie supine while torso and anthropometric measurements are acquired. The investigators will utilize the same procedures developed and adopted by the Orion Program to obtain foot, leg, and torso circumference measurements at pre-determined intervals. This detailed measurement procedure has shown to be effective at providing precise compression levels at pre-determined anatomical locations. The target levels of compression will be verified by the manufacturer, using a Hosiery and Allied Trades Research Association (HATRA) test instrument that is identified in the British Standard for testing compression in elastic stockings.

Tilt Familiarization:

Participants will be instructed to lie supine without moving throughout the Familiarization tilt test. After instrumentation with brachial blood pressure, continuous blood pressure monitoring, and electrocardiogram (ECG) for heart rate, baseline measures will be obtained for at least 2 minutes while the test is explained. Participants will be tilted to 80˚ head-up and instructed to remain still and quiet. After allowing the participant to become familiar with the tilt procedure and the feeling of being upright, the bed will be lowered back to horizontal (flat) and a timer started for a 20-minute supine rest period.