Concentration curl:
Sit on a bench. Your position should be stable and comfortable. Pick up a dumbbell in your right hand and place the back of your upper right arm on the inner part of your right thigh. Your arm should be extended holding the weight off the floor. Slowly curl the weight up, only moving your forearms – the position of your upper arm on your thigh will help you keep it still during the exercise. At the top of the move, pause for a beat and squeeze your biceps, then slowly lower the weight back to the start. Do all your reps on one arm, then switch to the other.
Do not unbend the elbow to the end and do not throw the weight sharply down. Perform the required number of repetitions, take a break for 1 minute and continue.
Move only with your elbow joint and forearm. Any unnecessary movements make the exercise less effective. At the lowest point, you should not unbend and relax the arm completely, although the muscles always remain stressed. Those who have mastered the exercise well can complicate it by increasing the amplitude.

Concentration curl.