Why are there different strength tests for men and women at the FBI?

From ABC News:

A male employee of the Federal Bureau of Investigation is suing the agency for gender discrimination, claiming that a physical fitness test to become an FBI agent is biased against men. Jay Bauer, a Ph.D. graduate of Northwestern University from Mount Prospect, Ill., said he missed the fitness test by one-push up, completing only 29 push-ups instead of the minimum 30 required for male trainees, which disqualified him from becoming a special agent. The test, administered at the FBI academy in Quantico, Va., has different physical minimum requirements for female and male trainees. Bauer argues in the complaint that the FBI violated Title VII of the Civil Rights Act of 1964. He also alleges a trainee who failed to pass the female standards of the physical test was given a second chance. . . .