I know that we have both for a reason, but they both seem designed to do the same motion...
Biceps have three fonctions if you do the three you'll recruit every muscles in the biceps (include brachialis).
1) supinate the hands
2) flex the elbow
3) shoulders flexion
Any curl or chins movement will recruit all the muscles of the biceps if you do them with supinated hands.
The fonction of brachialis is to help for the elbow flexion
here is a link which may help http://www.exrx.net/Muscles/BicepsBrachii.html
Last edited by Gavan; 10-09-2003 at 10:34 AM.
Gain Muscles ? Overload !
Lose Fat ? Input < Output
Genetic determines your potential
Chins : 10x106kg Dips 10x109kg
Well, see, I know what the two muscles are... the biceps is the "main" one, and the brachialis runs underneath it and attaches a little further out. My question is really: What does the brachialis do that the biceps can't, or needs help with? exrx.net doesn't have a commentary on the motion of the brachialis except that it's used in elbow flexion, like the biceps.
You forgot about the brachioradialis, whose only fonction is also elbow flexion.
Those muscles always work as synergists.
I do not know how (would probably require a better knowledge of muscular physiology), but depending of their position, one is in a stronger position than the other and become the limiting factor of the elbow flexion (so when you train, it becomes the most fatigued one).
I can think on how the muscles can be less effective, by contracting to move in a different way than what they are attached to (the articulation) can, but why then would the contraction be less intense?
brachialis is strongest flexor in the biceps.