Stand holding a dumbbell in one hand at your side; brace the back of the upper arm against the inner thigh of the same-side leg by slightly hinging forward.
With a supinated grip, curl the dumbbell upward toward your shoulder, isolating the bicep.
Squeeze at the top, then lower under full control back to full arm extension.
Complete all reps on one arm, then switch.
Dumbbell Standing One Arm Concentration Curl · Gainzz