Comparison Between Shoulder Flexed and Extended Positions in Elbow Flexion Resistance Training on Regional...

In the present study, the effects of resistance training on regional hypertrophy and maximum strength of the elbow flexor muscles were compared between elbow flexion exercises performed with different shoulder joint angles (∼50° of flexion vs. extension) while matched for resistance profiles. In a within-subject design, 15 young men (25.6 ± 2.1 y; 77.3 ± 6.8 kg; 175.1 ± 5.7 cm) underwent a resistance training program twice a week for 10 weeks (3-5 sets, 8-12RM), and their arms were dominant-side balanced, randomly assigned to one of the two conditions according to elbow flexion exercises: unilateral cable curl with shoulder flexed (Preacher curl; PREA) or unilateral cable curl with shoulder extended (Bayesian curl; BAYE). B-mode ultrasound imaging was used to measure changes in muscle thickness of the biceps brachii and brachialis at proximal, mid, and distal arm regions, and one-repetition maximum tests were completed in each respective trained exercise before and after training. Both conditions showed significant increases in muscle thickness (p < 0.05) with no significant differences between them (p > 0.05) across the biceps brachii proximal, mid, and distal regions (relative change [Hedges' g effect size]; PREA: 6%[0.51], 7%[0.49], 7%[0.53]; BAYE: 9%[0.73], 9%[0.62], 9%[0.62]) and brachialis (PREA: 10%[0.72]; BAYE: 8%[0.65]). Similarly, significant improvements in maximum strength were observed (p < 0.05), with equivalent results between conditions (PREA: 28%[0.85], BAYE: 37%[1.22]; equivalence testing, p-values = 0.061, 0.637). In conclusion, the shoulder joint angle does not seem to affect muscle hypertrophy and maximum strength gains after different elbow flexion exercises matched for resistance profiles.