It originated in German sports science and is also known as double station training.
There are many strategies for structuring exercises within a training session. The two main strategies we use in YPSI are:
AB System or Single Station Workout - A, B, C, D, E - First perform the prescribed number of sets of the A exercise. Once you have completed all sets of A, move to B exercise and perform the prescribed number of sets of B exercise. Continue to follow this principle until all exercises are complete.
A1 A2 System or Dual Station Workout - A1, A2, B1, B2, C1, C2, D1, D2 - Perform 1 set of the A1 exercise followed by 1 set of the A2 exercise and repeat for the prescribed number of sets these are completed. You follow this principle until all exercise pairs and exercises are completed.
The main benefit of the A1 A2 system is that it saves time. You can train more sets per hour while only taking a full rest between exercises. For example, if you do pull-ups with 90s of rest between sets, fatigue will degrade performance very quickly. If you do sets of pull-ups with 180s of rest in between, you'll make faster progress, but you can't do too many sets in one session. If you're using a dual station that mandates 90 seconds rest between pull-ups as the A1 exercise and carb presses as the A2 exercise, and then rest 90 seconds after the A2 exercise before returning to the A1 exercise, you have a full 180s+ rest between pull-ups. This allows you to increase your training performance faster and complete more sets per workout.
Good luck with the A1 A2 system!
The A1 A2 system is also used in most programs of the YPSI Online Coaching program .
Image: A glimpse of one of the programs using the A1 A2 system.