Select the appropriate weight matching your type of training and your fitness level. Sit down on a flat bench; grab one dumbbell with an underhand grip (thumb pointing outwards). Bend slightly forward and rest your elbow against the inner side of your knee. The other (free) hand rests against the other leg. Your arm should be extended and the dumbbell should be above the floor.
Curl the weight forward towards your shoulder while contracting the biceps. Your elbow is locked and resting on the inner side of your knee all the way through. Your palm is facing forward away from your thigh. Breathe in as you start the exercise and breathe out as you go up.
Maintain correct stance in the starting position without overarching your upper back (thoracic kyphosis). As you go back down to the starting position (extension), do not relax tension in your biceps.
Start with lighter resistance to master the technique well. Watch yourself in the mirror to make sure you maintain the correct technique.
Concentration curl is a biceps exercise with the elbow leaning against the thigh. Some athletes and coaches believe that this exercise will emphasize the peak of the biceps muscle.
Concentration curls can be performed while sitting or standing (bent over). It is important to do the movement slowly, with full control. The advantage is that you can use relatively high weight comparing to dumbbell curls.