In the Mat exercise Saw, how do the opposing actions of the internal and external obliques contribute to the controlled spinal rotation and lateral flexion, emphasizing rotational stability?

In the Mat exercise Saw, the internal and external obliques work in a highly coordinated, opposing, yet synergistic manner to facilitate controlled spinal rotation, contribute to lateral flexion, and crucially, provide rotational stability. The internal obliques are deep abdominal muscles that run upwards and medially, while the external obliques are superficial and run downwards and medially, like hands in pockets. For spinal rotation, these muscles operate as a powerful pair: to rotate the trunk to the right, the right internal oblique contracts alongside the left external oblique. This contralateral pairing creates the twisting motion, with the internal oblique rotating the trunk to the same side (ipsilateral rotation) and the external oblique rotating to the opposite side (contralateral rotation). Conversely, to rotate to the left, the left internal oblique works with the right external oblique. In the Saw exercise, as the practitioner rotates the torso, for example, to the right, this specific right internal oblique and left external oblique pairing actively shortens to initiate and deepen the twist. Simultaneously, the obliques on the opposite side (left internal and right external) lengthen under tension, acting as antagonists to control the rotation, preventing excessive or uncontrolled movement. This dynamic interplay ensures the rotation is articulate and originates from the thoracic spine rather than a strained lumbar region. Regarding lateral flexion, both the internal and external obliques on the same side work together to bend the trunk towards that side. In Saw, as the upper body folds over the leg during the reach, the obliques on the side of the fold contribute to this lateral flexion component, ensuring the spine maintains its length and does not simply collapse. Rotational stability, essential in Saw, is achieved through the continuous engagement and co-contraction of all four oblique muscles. While one pair is actively rotating, the other pair is resisting and controlling that rotation. This creates a strong, circumferential corset around the torso, stabilizing the lumbar spine and pelvis. This deep core engagement prevents unwanted compensatory movements, such as a shifting of the hips or a buckling of the lower back, allowing the full power of the abdominal muscles to articulate the spine effectively and safely throughout the rotational and forward-folding elements of the exercise.