The unevenly distributed load of the single-arm overhead press introduces a tremendous challenge in stabilizing the spine and midsection in the frontal plane.
Single-Arm Dumbbell Overhead Press
The objective is to resist lateral flexion of the spine (side bending) and instead remain perfectly neutral while pressing the dumbbell overhead. To master this, many muscle groups will need to kick in, but expect to feel it through the obliques, upper back, and glutes.
Besides being very challenging on the hips and midsection, this exercise is often more shoulder-friendly for those with overhead limitations. Its unilateral nature allows and encourages you to better focus on upwardly rotating and elevating the independently moving scapula.
Technique and Notes
From a standing position, press a dumbbell overhead on only one side. Work to keep your spine tall and perpendicular to the ground. Don't allow the weight to pull your body toward it, and don't overcompensate by leaning away from the weight to gain leverage and stability. The shoulders and hips should stay fairly level to the ground as you press.
Increase intensity by allowing the weight to travel further away from the mid-line of your body (during the lowering phase) by narrowing your foot stance or by taking a split stance. All of these adjustments will make your body work harder to stabilize against lateral forces.
This exercise forces you to connect to the ground by creating tension through the hips and legs. Without this foundation of tension, the weight will tip you over.