Cadets go on athletic probation primarily by having a PE average of under a 2.0 (C). Usually, that occurs by failing to get a C (250pts) on the PFT. The PFT makes up 50% of the PE average.
When on Ath pro, cadets must go to mandatory workouts three days a week, keep records of their off-duty workouts, and are restricted to base. Each recondo workout lasts from about 1645 to 1815...they suck. They are intense workouts, but since they are designed to correct most any deficiency, they don't always focus on areas where any particular cadet needs to improve. In my case, abs workouts were mostly a pointless way to get tired, since I always max the sit-ups on the PFT. Recondo does help cadets improve their performance, but it is not very efficient and sucks up a LOT of your "free" time. Also, being restricted to base makes weekends a lot less fun.