An isolation exercise for the biceps. It allows you to control the range and speed of movement.
Sit down on a bench and grasp a dumbbell with one hand with underhand grip.
Press the working arms to the top of your inner thigh and straighten it keeping the elbow slightly bent.
Rest the other arm on the knee.
From the starting position, as you exhale, lift the dumbbells up slowly without moving or swinging your body.
Do not pause at the top, return to the starting position as you inhale.
Choose right dumbbell weight. If the weight is too heavy you will help yourself with your back muscles which relieves the load on the target muscles.
Find the best position for your working arm. You should feel the maximum possible work in your biceps.