William Goins, 21st Medical Group health promotions flight commander and certified exercise physiologist, attaches a ventilation mask to 2nd Lt. Michael Horvat, 2nd Space Operations Squadron mission analyst, before a VO2 test inside Building 135 at Schriever Air Force Base, Colorado, Oct. 25, 2018. VO2 is the name for the equation which determines an individual’s maximum oxygen consumption. It is essential to knowing one’s physical endurance, as the higher the VO2, the longer a person can endure strenuous exercise. (U.S. Air Force photo by Senior Airman William Tracy)