Tom McCullough, MEd
Next time you're at the newsstand pick up any one of the
popular muscle magazines you'll find 100's of different ways to build
the biceps. We are lead to believe that by attacking the biceps from
many different angles, more size and strength can actually be
developed. Each of these many different exercises promises to give you
those big guns the pros have. With all of these many different
exercises and angles of attack, biceps training can get pretty
confusing. Are all of this really necessary? To answer this question
first let's look at how the muscles in the arm work.
The Elbow Joint
The elbow joint is classified as a ginglymus or hinge-type joint. This type of joint works much the same way a door does. It simply opens and it closes. In the case of the elbow joint is specifically flexes or extends. Nothing else!
Because the radioulnar joint (forearm) is classified as a trochoid or pivot-type joint, we can add a little more variety to this movement: 1) flexion (curling) of the arm with the palms up; or 2) flexion of the arm with the palms down. In either of these two positions the biceps, brachii, the brachialis, brachioradialis, and the pronator teres are still used to perform elbow flexion. So it is starting to look like all of these different angles are NOT really necessary. The elbow still flex and the same muscles are used. Perhaps biceps training is not that difficult after all. So let's take a look at each of the muscles involved in curling a weight and see what can be done to strengthen each.
The Muscles Used In Flexion
As mentioned earlier, every time we flex (curl) the arm, four muscles are used. The muscles used in flexion of the arm are: 1) the biceps brachii; 2) the brachioradialis; 3) the brachialis; and 4) the pronator teres.
The biceps brachii (bi'seps bra'ki-i)
The biceps is a biarticular or two-joint muscle. Simply meaning it is made of the shoulder and elbow joints. The biceps is considered to be the strongest of all the elbow flexors, especially in the supinated (palm up) position. With the palms in pronation (down) position, the effectiveness of the biceps is greatly diminished because of the disadvantageous pull of the muscle in this pronated position. In any case, pronated or supinated the same muscles are used to flex the arm.
While the biceps is only one muscle, it is made up of two distinct heads-- the long head and the short head. The long head originates at the supraglenoid tubercle which is located just under the collar bone and close to the shoulder joint. It inserts or attaches to the radius (small bone or top of the forearm) just about one inch below the elbow joint. The short head originates at the coracoid process of the scapula, which is just over the shoulder joint. It inserts at the same location as the as the long head. The biceps are responsible for flexion of the elbow joint, supination of the forearm, and weak flexion of the shoulder joint.
Even though the two heads of the biceps are one muscle they both seem to have specific functions in flexion. Brown et al. (1993) using surface electromyograms (EMG) recorded from the long and short heads of biceps brachii, found that the long head produced more EMG activity at the beginning phase of the lift when the muscle was at it's longest. Furthermore, it was found that the short head seemed to produce the most EMG activity at the top phase of the lift when the muscle was at it's shortest. While both heads are used to complete a full range of flexion, partial movements may be used either at the top or bottom of the lift to further stress the two heads of the biceps.
Now, because both the long head and the short head
originate at the shoulder, rotation of the shoulder joint must have
some effect on bicep training. So by changing the grip from wide to
narrow we should be able to target different heads of the biceps.
Right? Well, we already know that the long head works best when it is
fully stretched. So obviously by rotating the shoulder laterally, the
long head is stretched even more. Brown (1993) and Kapandji (1982) both
agreed that when the shoulder is laterally rotated, activation of the
long head of the bicep is indeed increased. Furthermore, the same
researchers added that when the shoulder is rotated medially,
activation of the short head of the bicep increased. This simply means
that a wider grip will hit the long head and a narrow grip will hit the
Once again I would like to remind you that the biceps are strongest with the forearm supinated (palm up). So any curling type exercise done in this position, with a full range of movement would easily strengthen the biceps. Dumbbell curl, barbell curls, or cable curls would all be excellent exercises.
The brachioradialis (bra'ki-o-ra'di-a'lis)
The next muscle involved in flexion of the arm is the brachioradialis. The brachioradialis originates at the lower two-thirds or the humerous (upper arm) and inserts on the radius, just above the thumb and wrist. This muscle is not only responsible for flexion of the arm, but it also prontates the forearm from a supinated position to a more neutral position and also supinates the forearm from a pronated position to the neutral position. The brachioradialis acts best as a flexor or the arm when the forearm is in the mid or neutral position between pronation and supination.
Therefore, the brachioradialis is best targeted by performing curls with the forearm is in a neutral position. Dumbbell hammer curls with a full range of movement, not only strengthen the biceps, but really blast the brachioradialis. Just remember that the key is keeping the forearm in a neutral position.
The brachialis (bra'ki-a'lis)
The brachialis muscle is used in combination with the other elbow flexors everytime elbow flexion is performed. However, this muscle is the only elbow muscle that is only responsible for flexion. The brachialis originates on the top portion of the humerous under the biceps. It inserts on the ulna (large bone of the forearm) just past the bend of the arm. The brachialis performs flexion by contracting and pulling on the ulna.
The brachialis is used any time the arm flexes, however when the forearm is in the pronated (palm down) position, the biceps are less effective and the brachialis has to do much more of the work. Therefore, by doing any type of curling exercise with the forearm in a pronated position, the brachialis will be stressed even more.
The pronator teres (pro-na'tor te'rez)
The pronator teres muscle is mainly used to pronate the forearm. However, it also functions as an elbow flexor by assisting the biceps and brachialis in movement of the arm. The pronator teres originates at inside of the lower part of the arm and attaches to the upper part of the radius.
The best exercise to hit the pronator teres is any exercise that would add resistance to the action of forearm pronation and supination. A small dumbbell or large hammer can be held while you twist the forearm from the palm down position to the palm up position and back.
While all of the many different exercises and angles of attack may not really be necessary to build those big guns, a few slight variations in grip width, range of motion, and palm position may be just what it takes to really make those arms to grow.