All-male Marine units consistently performed better than units with women integrated into them, according to a new study conducted by the military branch that was released Thursday.

The Marine Corps and other branches are facing a deadline that requires them to open all specialties to women, including infantry and special operations forces, starting in 2016, USA Today reported. The services have until the end of September to request exceptions for certain jobs.

Statistics for the study were gathered over the past year when the Marines created a battalion of 100 female and 300 male volunteers, which took part in realistic combat exercises in North Carolina and California, according to National Public Radio.

The study found that, in regards to combat effectiveness, all-male squads, teams, and crews "demonstrated higher performance levels on 69 percent of tasks evaluated (93 of 134) as compared to gender-integrated squads, teams and crews. Gender-integrated teams performed better than their all-male counterparts on (two) events."

"All-male squads, regardless of infantry MOS, were faster than the gender-integrated squads in each tactical movement. The differences were more pronounced in infantry crew-served weapons specialties that carried the assault load plus the additional weight of crew-served weapons and ammunition," the study summary stated.

The study added that women suffered a higher rate of injuries as compared to men performing similar tasks and had a "comparative disadvantage in upper and lower-body strength resulted in higher fatigue levels of most women, which contributed to greater incidents of overuse injuries such as stress fractures."

The Hill reported that the Marines have opened 315 of 337 primary specialty positions to women.

"Female Marines have performed superbly in the combat environments of Iraq and Afghanistan and are fully part of the fabric of combat-hardened Marine Corps after the longest period of continuous combat operations in the Corps' history," the summary added, according to The Hill.

But Republican U.S. Rep. Duncan Hunter, a member of the House Armed Services Committee who served in the Marine Corps, has raised concerns about the challenge of opening up all military positions to women.

"If you were to turn down a request for a waiver like that I guess the political machine in the White House would be saying we don't care about the effectiveness of the ground combat units," he told USA Today.

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