In 2003, the Air Force Chief of Staff (the top general in the Air Force) got tired of the Air Force being known as the "wimp" service, when it came to fitness requirements, and he decided to toughen up the standards. He began with Air Force Basic Military Training (AFBMT).
Recruits now undergo an initial physical fitness assessment when they arrive at Air Force basic and must pass a final fitness test before they can graduate. In between, recruits exercise --a lot. When the top guy made the change, Air Force basic training fitness (now called PRT, or physical readiness training) went from three or four days per week to six days per week.
The six-day-a-week PRT regimen includes three days of aerobic running and three days of muscular endurance training. All PRT sessions begin with 15 or 20 minutes of stretching.
The runs consist of 40-minute sessions of group-paced running, self-paced running, and six 30-second sprint interval runs separated by brisk walking. Each week, trainees are timed on a two-mile run (the two-mile run isn't a pass or fail, but if you don't do well, you can expect some individual attention from your T.I., and that's never a good thing).
The muscular endurance training takes up to 48 minutes on a circuit of crunches, leg lifts, push-ups, flutter kicks and pull-ups. These are designed to improve upper body and abdominal strength quickly.