||This article may contain original research. (February 2012)|
Biceps curls can be done using any of the following equipment:
- E-Z bar (also known as a "Bent bar")
- Cable machine
- Biceps curling machine
- Nautilus cam equipment
- Preacher bench
- Adjustable bench
Although the exercises differ, a common factor of each is a 'curling' motion, where a weight (attached to, or used in conjunction with, an item of equipment listed above) is moved through an arc, primarily using the strength of the biceps.
The fullest range of motion is when the elbows begin in full extension, in a supine grip. The biceps contract to lift the weight upward through an arc, to a point where further movement is not possible. Some lifters also do partial reps (such as in "21s") focusing on the top or bottom position.
Some think it is important that the elbow remain next to the body during this motion to keep stress on the biceps. Others will either bring the elbows forward (to fully shorten the biceps) or bring the elbows back (a "drag curl", to avoid over-active insufficiency and keep parallel forearms) to vary the tensions placed on the biceps and other elbow flexors.
The second part of the motion has the elbow joint extending, this is called the 'eccentric' portion. The weight is lowered back to the start position.
The barbell curl specifically targets the biceps brachii which is located on the front part of the arm between the shoulder and the elbow. This muscle's primary function is elbow flexion and forearm supination. The biceps also has two heads known as the long head and the short head.
Several variations on the biceps curl transfer some of the load from the biceps to other flexors of the elbow, thus enabling a person to use bigger weights without causing an injury.
Extended shoulder 
- supine-body incline curl: With an adjustable bench positioned at a 45 degree angle, one could perform incline biceps curls . Incline biceps curls are usually performed with dumbbells in each hand, and by sitting on the incline bench, holding the dumbbells close to the body with elbows tucked in, and performing a full curl.
Flexed shoulder 
One group of variations involves postures that hold the elbows in front of the trunk, shortening the biceps and forcing the brachialis to do more work. Variations on this theme include:
- concentration curl where the elbow is braced against the inside of the knee
- preacher curl where the elbows rest upon a sloped bench
- prone-body incline curl performed lying prone on an inclined bench, where the force of gravity holds the upper arms in front of the trunk.
- spider curl which uses the preacher bench but uses the other side, so curling is done at a 90 degree angle
Grip variations 
The biceps curl is usually performed with the palms supinated (facing upwards). Turning the palms inward transfers load from the biceps to the brachioradialis. Variations on this concept include the hammer curl, performed with the palm inward, neither pronated nor supinated, and the reverse curl, with the palms pronated (facing downwards).
Another biceps curl variation is the "correct curl" where the palms are positioned further apart on a barbell, at the width they would land into once they are fully supinated. This variation heavily targets biceps with less involvement from your brachialis and brachioradialis muscles.
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