Biceps training has always been one of my favorite training sessions, but my biceps are probably one of my weakest bodyparts--why? Improper training of course! Here's some changes I've been making that have helped, plus selected sets from today's training at 15 weeks out.
The muscle colloquially referred to as the "biceps" is actually comprised of three separate muscle heads: the outer and inner head of the biceps brachii and the brachialis. These three muscles can be isolated to a limited extent by altering angle, grip width, and form, but generally speaking they are synergistic--meaning they are assisting each other at all times. The brachialis runs under the biceps near the elbow, and assists in flexion at the elbow in addition to rotation of the lower arm. Because of its deep attachment, developing the brachialis properly can have significant effects on the look of the biceps brachii--despite the commonly held notion that it is a "forearm" muscle and therefore of lesser significance.
The biceps brachii attach at the shoulder and at the elbow, and therefore assist in movement at both joints. This allows the deltoids to assist significantly in a traditional standing curl. As you can see below in my video, I am adopting a fairly straight up-and-down movement for this exercise, eschewing the out-up-and-in "arc" movement that is so common. I'm even bending over slightly to further accommodate this limited range of motion, removing the deltoids from the equation as much as possible. This allows for a much improved biceps contraction in addition to reduced deltoid stress (they're such little guys, they don't need any more!). I'm also limiting my range of motion by completing my rep "early"--rather than curling the weight completely into my chest I stop near peak contraction. Curling into the chest only removes stress from the biceps--try it yourself, the curl becomes much easier at the top, does it not? Well, that's because your biceps is no longer working :)
In addition to shortening the range of motion, I've also emphasized the rotational aspect of biceps training--doing my best to complete the rotation early in the movement. This helps achieve an improved biceps brachii contraction and also improves elbow health. Although the brachialis is instrumental in supinating the lower arm, it should not be doing it alone. Completing the rotation sooner rather than later helps the biceps take over the majority of the stress in an optimally functional way. Forcing the brachialis to do most of the work, on the other hand, can contribute to elbow tendonitis and tendonosus, bursitis, and myriad other aches and pains--not to mention underdeveloped biceps.
And here's the video--I'm at 15 weeks out here, approximately 145 lbs--and let me tell you, I look much better in person (but you get the idea). Cheat meal tonight!