Abstract
We compared whole-muscle and regional elbow flexor hypertrophy after incline (shoulder-extended) versus preacher (shoulder-flexed) dumbbell curl training. Twenty-one untrained adults trained one arm with incline curls and the contralateral arm with preacher curls for 12 weeks (70% one-repetition maximum; 5 sets of 10 repetitions, twice weekly). Magnetic resonance imaging quantified volumes of biceps brachii (BB), brachialis (BRC), brachioradialis (BRR), and total elbow flexors. Regional volumes were derived from cross-sectional area profiles sampled at 1% intervals along muscle length and grouped into proximal (1-33%), middle (34-66%), and distal (67-100%) regions. BB hypertrophy was greater after incline than preacher training (+22.1% vs. +18.9%, Hedges' g = 0.33), whereas BRC (+17.1% vs. +21.1%, g = 0.50) and BRR (+13.5% vs. +17.6%, g = 0.47) hypertrophy was greater after preacher training (P ≤ 0.046; incline vs. preacher). Total elbow flexor hypertrophy did not differ (+17.6% vs. +19.2%, g = 0.22, P = 0.134). Regional patterns were broadly similar between conditions: BB and BRC showed greater middle-region hypertrophy, whereas BRR showed greater proximal and middle hypertrophy. These findings indicate small-to-moderate exercise-specific differences in individual elbow flexor hypertrophy, with limited influence of exercise configuration on total elbow flexor growth and regional hypertrophy patterns. .