The abdomen, lower spine, and pelvis comprise the trunk (core) of the body. This area must be stable so the limbs have a fixed base from which to create powerful movements. The abdominal and back muscles form a supportive ring around the spine. Soldiers are only as strong as their weakest link; so all these muscles must be trained in a manner that mimics their function. In reconditioning, 4C and HSD are performed daily before engaging in other PRT activities. During the toughening phase, 4C is performed after preparation and prior to strength and mobility activities. Four for the core may also be performed outside regular PRT sessions as supplemental training. Do not exceed 60 seconds for each 4C exercise. The following commands are used for 4C exercises.
Exercises 1 and 3 (bent leg raise and back bridge):
- Starting Position, MOVE.
- Ready, EXERCISE.
- Starting Position, MOVE.
- Position of Attention, MOVE.
Exercises 2 and 4 (side bridge and quadraplex) are both performed on the right and left sides. The commands for execution for this exercise and changing sides are as follows:
- Starting Position, MOVE.
- Ready, EXERCISE.
- Starting Position, MOVE.
- Change Position, Ready EXERCISE.
- Starting Position, MOVE.
- Position of Attention, MOVE.
The goal is to hold each exercise position for 60 seconds. If the Soldier is unable to do this, he will follow the instructions for each exercise to momentarily change position and return to the prescribed exercise position. Detailed descriptions of each 4C exercise follows.