Comparison Between Eccentric-Concentric and Eccentric-Only Dumbbell Arm Curl Exercise Training for Their Effects on Neuromuscular Adaptations

ABSTRACT: Shibata, K, Yamaguchi, T, Takizawa, K, and Nosaka, K. Comparison between eccentric-concentric and eccentric-only dumbbell arm curl exercise training for their effects on neuromuscular adaptations. J Strength Cond Res XX(X): 000-000, 2026-Eccentric-concentric (ECC-CON), low-load (ECC-Low), and high-load eccentric-only (ECC-High) dumbbell arm-curl exercise training were compared to test the hypothesis that ECC-Low would induce similar neuromuscular adaptations to ECC-CON and ECC-High. Thirty-four male university students without regular elbow flexor resistance exercise training were placed to ECC-CON (n = 11), ECC-Low (n = 11), or ECC-High (n = 12) group, and trained twice weekly for 6 weeks. The training load was progressively increased from 30 to 90% of concentric-only one-repetition maximum (CON1-RM) for ECC-CON and ECC-Low, and of eccentric-only 1-RM (ECC1-RM) for ECC-High. Rating of perceived exertion (RPE) was recorded after each set and averaged RPE was obtained. Changes in elbow flexion CON1-RM and ECC1-RM, maximal voluntary isometric contraction (MVIC) strength at 30°, 60°, and 90° elbow flexion, concentric peak power at 30% MVIC, and biceps brachii and brachialis muscle thickness (MT) were compared between groups by split-plot analyses of variance. RPE was lower (p < 0.05) in ECC-Low (4.0 ± 0.7) and ECC-High (5.1 ± 1.1) than ECC-CON (6.2 ± 1.1). ECC1-RM, MVIC strength at all angles, and concentric peak power increased (p < 0.01) similarly between groups (e.g., ECC1-RM, ECC-CON: 9.8 ± 4.8%, ECC-Low: 10.3 ± 4.9%, ECC-High: 12.8 ± 7.1%), but increases (p < 0.01) in CON1-RM (ECC-CON: 11.8 ± 7.1%, ECC-High: 9.9 ± 5.3%) and MT (3.9 ± 3.1%, 5.4 ± 4.4%) were evident only after ECC-CON and ECC-High without a difference. These results did not fully support the hypothesis, but ECC-Low was effective for improving 6 of 8 measures similarly to ECC-High and ECC-CON with lower RPE. This suggests the efficacy of eccentric-only resistance exercise training for individuals who are novice in elbow flexor resistance exercise training.