Biceps brachialis sorness but not brachii

Question

I do push/pull days MWF, my pull days consisting of 9 sets of 4-8 reps compound back movements, and then 6-9 sets of 4-8 reps on bicep isolation. I do different arm positions for biceps (incline dumbbell curls, preacher curls, etc.). I focus a lot of the negative portion and generally go slow with around 30 seconds between sets and exercises.

I've noticed that whenever I do pull days, if my biceps get sore afterwards, it seems to always be the brachialis (sore near the joint and "outer" bicep area, not the much larger "two-headed" bicep ball), but not the long or short head of the brachii. My palms are always facing away from me for the entire movement on all biceps exercises.

I have no issue working different parts of my triceps, but for some reason, it seems as though my brachialis are always the part that gets hit and nothing else when doing biceps.

Maybe my brachialis is comparatively weak and therefore is the limiting factor? Maybe the brachialis must first be flexed before the brachii, and I'm unknowingly doing too limited of a range of motion to hit the brachii? Any other ideas?

Answer 1

If you're lifting to get stronger, progress is measured in your weights. If you're lifting to get bigger, progress is measured in the mirror and with a tape measure.

Soreness is never a good indicator of progress or the effectiveness of a workout.

Eccentric lengthening (negatives) tend to cause Delayed Onset Muscle Soreness (DOMS) much more so than concentric exercises. If negatives made you stronger and bigger, everyone would sit around doing negatives.

Different parts of a muscle have leverage and power at different angles of extension. If you look at the deadlift, there are sliding muscle recruitments occurring.

Isolation exercises in general promote imbalances; your body was never designed to be braced and for heavy loads to solely be handled by your forearm hinging on your elbow (a curl).

If you feel like you're getting the progress you want, no worries. If you want to have something more effective, look towards proven lifting programs.

Answer 2

Your seemingly excessive brachialis soreness as described is likely due to over-emphasizing your elbow flexors too far from their full-extended positions.

In other words, you should make your elbow flexors work hardest during the "initial" parts of the exercise when the arm is more fully-extended, than at the later parts when it is more flexed. Ideally, perhaps replace all your curl exercises with just a preacher bench version in which the arm(s) starts out fully extended and parallel (or just slightly below parallel) to the ground (ensuring, by physics, that the "most difficult" part of the exercise is in the beginning).