Standing Single Arm Dumbbell Press

The standing single arm dumbbell press drives a dumbbell from shoulder height to full arm extension, and pressing one side at a time adds a demand the two-arm version does not have. The load sits off-centre, so the core and the obliques on the opposite side have to work throughout the set to stop the torso tipping sideways. That anti-lateral-flexion work is among the most useful trunk training there is, and here it arrives free, without adding a separate exercise. The deltoids and triceps do the pressing, with the upper back stabilising the shoulder. The most common fault is arching the lower back to gain range once the weight gets heavy: keep the ribs down, squeeze the glutes, and finish with the arm stacked over the ear rather than out in front of it.