Biceps leg concentration curl

Sit on a bench with your legs spread apart and your feet flat on the ground. Hold a dumbbell in one hand and place your elbow on the inside of your thigh, just above the knee. With your palm facing up, curl the dumbbell towards your shoulder while keeping your upper arm stationary. Squeeze your biceps at the top of the movement, then slowly lower the dumbbell back to the starting position. Repeat for the desired number of repetitions, then switch arms.