REF-681 · Zabaleta-Korta, Fernández-Peña & Santos-Concejero, 2020 · Strength and Conditioning Journal, · Paper
Muscle growth is non-uniform: 13 of 14 studies found some regions of a muscle grew more than others (quadriceps, triceps, biceps)
Key Findings
Search of PubMed and Scopus (May 2019); 14 studies included.
13 of the 14 found that the anatomical cross-sectional area of some regions of a muscle increased more than others.
Which region grew most was inconsistent: some studies found the distal region, others the middle region, and some reported regional differences without saying which grew most.
Hypertrophy between and within muscle heads was not homogeneous in the quadriceps femoris, triceps brachii and biceps brachii.
Practical Application
A systematic review of 14 training studies found uneven, region-specific growth within the same muscle in 13 of them (quadriceps, triceps, biceps) — one exercise should not be assumed to grow a whole muscle evenly.
Inference, not tested here: varying exercises, joint angles and positions per muscle is the plausible way to load different regions; the abstract does not identify which exercise or angle grows which region.
Limitations
14 studies, no pooled effect sizes; the direction of regional growth was inconsistent across studies.
The review shows that regional hypertrophy happens, not what causes it; practical magnitude of "region targeting" is unquantified.
How this entry was checked and changed
Content correction 2026-09-27
Title "exercise selection, variation and joint angle drive region-specific hypertrophy" and "no single exercise develops an entire muscle optimally" -> the abstract only establishes that regional hypertrophy occurs (13 of 14 studies); drivers moved to a labelled inference.
"Mostly short cross-sectional/MRI evidence" -> not stated in the abstract; limitation rewritten. Added study count and muscles.