The Effects of Accentuated Eccentric Loading Repetition Structures on Muscle Strength and Adaptation.

Abstract: Yue, C, Xiong, W, Zhang, C, Zhang, R, Deng, K, and Li, Z. The effects of accentuated eccentric loading repetition structures on muscle strength and adaptation. J Strength Cond Res XX(X): 000-000, 2025-The investigators aimed to compare the effects of different accentuated eccentric loading (AEL) repetition structures on lower limb muscle strength and adaptation. Thirty-five subjects were assigned to 3 groups: AEL6 group (120%/75% 1 repetition maximum (1RM), eccentric overload in every repetition, n = 11), AEL2 group (120%/75% 1RM, eccentric overload only on the first and fourth repetitions, 75%/75% 1RM on others, n = 12), and TL group (75%/75% 1RM, traditional loading, n = 12). All groups performed 6 repetitions × 4 sets, twice per week for 8 weeks. All groups showed statistically significant improvements in rectus femoris cross-sectional area (RFCSA), countermovement jump height (CMJH), countermovement jump relative peak propulsive power (RPP), back squat 1RM, eccentric peak torque (PT), and integrated electromyography (iEMG) (p < 0.01), with significant group × time interactions for all variables (p < 0.01). AEL6 showed statistically greater improvements than TL across all variables. In addition, AEL6 showed statistically greater improvements in RFCSA, 1RM, PT, and iEMG compared with AEL2 (p < 0.05-0.01), but no significant differences were observed in CMJH and RPP (p > 0.05). AEL2 had statistically greater improvements in CMJH, RPP, PT, and iEMG than TL (p < 0.05-0.01), with no significant differences in RFCSA and 1RM (p > 0.05). Therefore, we conclude that AEL is a more effective programming tactic for improving muscle strength and adaptation, whereas AEL2 appears to have a better dose-response effect for improving jump performance.