PERSONAL TRAINER INSTRUCTION :
Sit upright on a bench or on a swiss ball with your stomach braced to prevent slouching forward. Keep your elbows tucked to your sides and exhale as you begin to curl the weight up.
Focus on consciously contracting / flexing the bicep muscle through the exercise. Slowly lower the weight back to the starting place.
This exercise can be done with both arms moving simultaneously or done alternating (unilateral). This exercise can also be done standing. Do not swing the weight forward and always be sure to keep your elbows in the same location through the entire exercise.