A digital monitor prints out its report for a U.S. Soldier, with the 7221st Medical Support Unit, U.S. Army Reserve, based out of Newark, Del., after measuring how he processes oxygen for 15 minutes at rest, at Aberdeen Proving Ground, Md., Feb. 9, 2014. Combined with a report from 15 minutes on the treadmill, clinicians at the Army Wellness Center, Aberdeen Proving Ground, Md., then determine the Soldier's metabolism.