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 39(12): 1244–1253, 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: AEL 6 group (120%/75% 1 repetition maximum (1RM), eccentric overload in every repetition, n = 11), AEL 2 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). AEL 6 showed statistically greater improvements than TL across all variables. In addition, AEL 6 showed statistically greater improvements in RFCSA, 1RM, PT, and iEMG compared with AEL 2 ( p < 0.05–0.01), but no significant differences were observed in CMJH and RPP ( p > 0.05). AEL 2 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 AEL 2 appears to have a better dose-response effect for improving jump performance.