Take hold of a suitable weight dumbbell and bend forward from the waist so that your lower back is parallel to the ground. Let your lifting arm hang down so that it is perpendicular to the ground. Your palm faces inward and the elbow points outward. The non-lifting hand is placed on the knee for support and balance. This is the starting position.
Commence the movement by curling the dumbbell up from the elbow joint and squeezing your biceps. The elbow should work like a hinge with the forearm being the only moving part and upper arm remaining stationary. Exhale through the movement. Do not use momentum to throw the dumbbells up.
When your biceps are at maximum contraction, squeeze for a second and then reverse the movement by extending the arm to the starting position, inhaling as you do.