Garland was a training camp phenom two years ago, impressing the coaches with his work ethic and regularly outracing quarterback Tim Tebow in post-practice wind sprints. He was placed on the reserve/military list after training camp in 2010 and began serving his five-year military commitment.
He was serving at the Air Mobility Command, headquartered at Scott Air Force Base in Illinois east of St. Louis.
Garland told The Associated Press he was allowed to return to the NFL through a program that allows servicemen to cut short their commitment after two years for a career that would benefit the Air Force in recruiting or public affairs.
"I have saved my leave for two years so I could attend the offseason workouts," Garland said. "I am humbled to have this opportunity and love being back in Colorado."
Garland totaled 115 tackles, 11½ sacks and three forced fumbles in 39 games at the Air Force Academy.