04/02/2026
A great piece about what we work when doing Side Bend Variations 😃👍
BIOMECHANICS OF THE SIDE PLANK
The side plank is a lateral-chain, anti-movement exercise that primarily challenges frontal-plane stability of the trunk and pelvis. Unlike traditional planks that resist spinal extension, the side plank resists lateral flexion and axial rotation, making it biomechanically unique and highly functional for postural control and gait-related stability.
At the lumbar spine, gravity creates a strong lateral bending moment, pulling the pelvis and trunk toward the floor. To counter this, the external and internal obliques on the weight-bearing side generate an isometric force that maintains spinal neutrality. The transversus abdominis increases intra-abdominal pressure, enhancing spinal stiffness and reducing shear stress across the lumbar segments.
Pelvic biomechanics are central to side plank efficiency. The pelvis has a natural tendency to drop toward the unsupported side due to body weight. The quadratus lumborum (deep lateral stabilizer)—although not always illustrated—plays a major role in maintaining a level pelvis, especially during prolonged holds. Failure of this control results in pelvic sag, shifting stress to the lumbar spine and reducing exercise effectiveness.
From a scapulothoracic and shoulder perspective, the side plank is also a unilateral closed-chain upper-limb exercise. The supporting shoulder must resist compressive and shear forces through the glenohumeral joint. The serratus anterior stabilizes the scapula against the thoracic wall, while the rotator cuff provides dynamic joint centering, preventing shoulder collapse or winging.
The re**us abdominis, though not the prime mover, contributes by maintaining trunk alignment and preventing excessive trunk rotation. When the top arm is elevated, the center of mass shifts superiorly, increasing the rotational torque across the trunk and further challenging the obliques and deep stabilizers.
Biomechanically, the side plank closely mirrors demands seen in single-leg stance, walking, running, and change-of-direction tasks, where the body must control lateral forces with each step. This makes it especially valuable for injury prevention, particularly in the lower back, hip, and knee, where poor frontal-plane control is a known risk factor.
Functionally, the side plank trains the body to transfer load efficiently between the upper and lower extremities through a stable lateral core, reinforcing alignment, endurance, and neuromuscular coordination rather than brute strength alone.
✨ The side plank is not just a core exercise—it’s a masterclass in lateral stability, pelvic control, and kinetic-chain integration.
