Cable lying close-grip curl

Attach a straight bar to a low pulley cable machine. Lie face up on a flat bench with your feet flat on the ground. Grasp the bar with an underhand grip, hands shoulder-width apart. Extend your arms fully, keeping your elbows close to your sides. Keeping your upper arms stationary, curl the bar towards your chest by contracting your biceps. Pause for a moment at the top, squeezing your biceps. Slowly lower the bar back to the starting position, fully extending your arms. Repeat for the desired number of repetitions.