The complete support of the prone bridge is similar to the design / structure an ‘arch bridge’. Prone Bridging is a demandingly beneficial movement for the core. It is often performed with the ‘hands clasped’ variation. There is often a preponderance of arm / upper body involvement. This (tendency) glosses over of the necessity of the feet / toes for engaging the total movement. A solid prone bridge consists of a fully engaged and responsive core. This engaged responsiveness can be attributed to the contribution of the feet
The structure of the arch bridge requires that both side of the structure contribute to the stability of the whole. The design allows both sides to press against the supporting material and (to) transfer that resultant energy up to the center, from both sides (of the structure). Thereby, the center of the bridge is held aloft by construction. The prone bridge can be supported from both sides, as well. The full engagement of the core is arrived at by anchoring the elbows / depressing the scapula onto the rib cand and anchoring the toes / pressing through the heels / engaging the femur adductors.
The prone bridge is a beneficial and Integral core movement. It is a particularly effective way of activating the Anterior Oblique System (AOS). The (AOS) consists of the external oblique and internal oblique, connecting with contralateral adductor muscles via the adductor-abdominal fascia (See image A1 – red arrows). When this group of muscles contract together, it provides stability by acting like an abdominal binder, compressing the entire pelvic girdle, resulting in force closure of the symphysis pubis.
There are several hand positions for performing prone bridge. I think the hands clasped position lends more to neglect of anchoring through the elbows and through the feet / toes. Encouraging more chest / rounding through the shoulders than is necessary. Pulling the shoulder blades onto the rib cage engages the serratus anterior. This causes the obliques to activate. By separating the hands, the scapulae are forced to engage against the rib cage, thus causing more activation to the serratus and the obliques.
The feet / legs comprise the other half of the pose. Borrowing from asana (yoga) alignment protocol, the basic standing posture provides insight into utilizing the feet / legs to engage the core. The toe ball mounts spread apart as the heels anchor press into the ground. Lengthening up through the legs, the adductors (in particular) draw upward and inward. This supports the lifting of the symphysis pubis and a pulling down of the scapulae onto the rib cage. These principles become more important in the prone position. Gravity will exert the most force at the pelvis / sacral area. Anchoring through the toes and pressing (back) into the heels will reflexively send energy into (engaging) the core. A method of training this is to let the heels press into a wall or a prop. This will directly target engaging the core
There is a method for testing prone bridge stability. By removing the limbs, one at a time. from the position and gently challenging the pelvis / core area. Especially when the arm is moved. The, the anchored *(elbow’s) shoulder blade must fully engage. the adductors must completely. Conversely, when a leg is removed from the equation, the adductor of the anchored foot must be fully activated, and the scapulae must completely depress onto the ribcage. Although the focus is mainly on the AOS, the Posterior Oblique System (POS) is also positively affected by a fully activated prone bridge. Prone Bridge can be a beneficial part of one’s exercise regimen. Actively stimulating the bodily support structures provides a solidity to everyday posture, everyday activities. The feet need not be neglected in performing this movement. They enhance overall core engagement and are just as important as the arms, if not more so.