Lying Supine Dumbbell Curl
To do this curl, lie down on a flat bench face up while holding a dumbbell in each arm on top of your thighs. Lift dumbbells to the sides, arms extended and palms facing thighs. Like regular bicep curls, keep arms close to torso and elbows tucked in. Slowly lower arms as far down toward the floor as you can go.
As you exhale, slowly curl the weights while simultaneously rotating the wrists until biceps are fully contracted. Squeeze hard at the top of the position, then return back to starting position.
Upper arms and elbows should remain stationary during movement. Be sure to use a weight that you can control the movement.
Lying supine utilizes the same movement as standing, but it features a greater range of motion.
Common mistakes include lifting with the shoulders or swinging with the trunk. This puts unnecessary stress on shoulder joints, deltoid muscles and bicep tendons.
Many also make the mistake of curling weights too heavy to maintain proper form, or simply performing the exercise too much. This results in bicep tendinitis.
The preacher curl really focuses on isolating the biceps while adding fullness to the lower portion of the muscle. It requires a preacher bench in order to perform correctly.
To begin, hold the barbell with palms facing upward. Lock elbows firmly in place in an extended position on the bench. Slowly curl the barbell up, aiming to touch the shoulder of the arm being worked. Then, slowly lower to starting position, making sure arms are fully extended before beginning next curl.
Be sure your abdominal muscles are tight and back is straight. Keep elbows loose during exercise.
One Arm Dumbbell Preacher Curl
You may perform the same movement but with individual dumbbells rather than barbells. This enables you to focus on each arm separately. This is especially useful if one bicep is weaker than the other.
Machine Preacher Curl
Preacher curl machines are available that make it nearly impossible to cheat. Rather than using a barbell or dumbbell, the machine uses handles attached to adjustable weights. This forces you to keep both arms stable and locked in place.
Many athletes do not let the arms lower far enough before moving on to the next curl, allowing the arms to hang down only partially. This makes it easier to bring the weight back up again but it does not work the muscles fully. It's better to use a lighter weight which you can fully control the movement than to cheat with a heavier one.