The Applied Exercise Science Lab at CU is currently recruiting male subjects (ages 18-44) for a study looking at physiological changes that occur during simulated space flight. We are using short term (four days) head-down tilt bed rest, a model of simulated spaceflight, to study changes in blood and fitness. Volunteers will receive monetary compensation ($600 for completion of study). Study will be ~2 weeks and will require a five-day in-lab period. If interested, E-mail Benjamin.ryan@colorado.edu