The lying cable curl is a good exercise for isolating the biceps.
- Set up for the exercise by attaching a straight bar to a low pulley cable and selecting the weight you want to use.
- Sit on the floor in front of the cable machine with your feet resting against it.
- Grip the bar with an underhand grip at around shoulder width and lay back on the floor. Your body should be flat on the floor.
- Keeping your upper arms on the floor, slowly curl the bar up as far as possible.
- Squeeze the biceps, and then slowly lower the bar back to the starting position.
- Repeat for desired reps.