A quick tutorial on the concentration curl.
By Tim Rigby
START: Sit on a bench and grasp a dumbbell using an underhand grip. Bend forward about 45 degrees from your hips, keeping a flat back. Spread your legs open to about a 90-degree angle. Rest your working arm against your inner thigh and keep your head down.
EXECUTION: Keeping your upper arm stationary against your thigh (and all other body parts motionless), flex at the elbow to curl the weight up toward your front shoulder. Pay particular attention not to pull with your back since you want to isolate the biceps. From the top position, lower the weight in a controlled manner back to the start.
TIP: Keep your arm and your thigh at a right angle to hit the peak of the biceps properly; don’t swing the weight in toward you, nor flare it outward.