Spc. Karen Arvizu, left, puts on her hydration pack in preparation for her role as a volunteer in a physical demands study, Tuesday, Feb. 25, 2014, in Ft. Stewart, Ga. The Army is conducting a study that will determine how all soldiers, including women, for the first time, will be deemed fit to join its fighting units from infantry platoons to tank crews. (AP Photo/Stephen B. Morton)
U.S. Army Pfc. Amy Alexanders carries a 103-pound barrel to a Bradley Fighting Vehicle during a physical demands study, Tuesday, Feb. 25, 2014, in Ft. Stewart, Ga. The Army is conducting a study that will determine how all soldiers, including women, for the first time, will be deemed fit to join its fighting units from infantry platoons to tank crews. (AP Photo/Stephen B. Morton)
U.S. Army Pfc. Amy Alexanders dresses in her Marne Standard battle gear before taking part in a physical demands study, Tuesday, Feb. 25, 2014, in Ft. Stewart, Ga. The Army is conducting a study that will determine how all soldiers, including women, for the first time, will be deemed fit to join its fighting units from infantry platoons to tank crews. (AP Photo/Stephen B. Morton)
FILE - This Sept. 18, 2012 file photo shows female soldiers training on a firing range while wearing new body armor in Fort Campbell, Ky. Only a small fraction of Army women say theyd like to move into one of the newly opening combat jobs, but those few who do, say they want a job that takes them right into the heart of battle, according to preliminary results from a survey of the services nearly 170,000 women. (AP Photo/Mark Humphrey, File)
A group of three female soldiers along with male soldiers watch a male soldier lift a 44-pound section of a 50 caliber machine gun onto a M1A2 Abrams tank during a physical demands study, Tuesday, Feb. 25, 2014, in Ft. Stewart, Ga. The Army is conducting a study that will determine how all soldiers, including women, for the first time, will be deemed fit to join its fighting units from infantry platoons to tank crews. (AP Photo/Stephen B. Morton)
U.S. Army Pfc. Amy Alexanders lifts a 65-pound T.O.W. missile through a hatch into the launcher of a Bradley Fighting Vehicle during a physical demands study, Tuesday, Feb. 25, 2014, in Ft. Stewart, Ga. The Army is conducting a study that will determine how all soldiers, including women, for the first time, will be deemed fit to join its fighting units from infantry platoons to tank crews. (AP Photo/Stephen B. Morton)
U.S. Army Corp. Jacqueline Beachum lifts a 65-pound dummy T.O.W. missile into the launcher of a Bradley Fighting Vehicle during a physical demands study, Tuesday, Feb. 25, 2014, in Ft. Stewart, Ga. The Army is conducting a study that will determine how all soldiers, including women, for the first time, will be deemed fit to join its fighting units from infantry platoons to tank crews. (AP Photo/Stephen B. Morton)
U.S. Army PFC Amy Alexanders lifts a 65-pound T.O.W. missile through a hatch into the launcher of a Bradley Fighting Vehicle during a physical demands study, Tuesday, Feb. 25, 2014, in Ft. Stewart, Ga. The Army is conducting a study that will determine how all soldiers, including women, for the first time, will be deemed fit to join its fighting units from infantry platoons to tank crews. (AP Photo/Stephen B. Morton)