Grasp a dumbbell in each hand and stand or sit holding the dumbbell at arm’s length at your sides with your palms facing forward. Curl your arms upward, stopping halfway when your forearms are parallel to the floor, and then lower back down to the starting position. Complete seven repetitions of this movement and without stopping, curl the weight all the way up to your shoulders, then back down, stopping halfway. Complete seven repetitions of this partial movement. Finish with seven more repetitions of dumbbell curls using a full range of motion. The full range of motion starts with your arms fully extended and finishes with the dumbbells at your shoulders and elbows fully flexed. Keep your elbows tucked into your sides throughout the entire exercise to isolate the biceps. Repeat this motion for the prescribed amount of repetitions.
See video here.