Abstract
Introduction:
Supramaximal accentuated eccentric loading (SAEL) is a resistance-training strategy in which the eccentric phase is performed with greater loads than the concentric phase. Although previous studies have reported beneficial effects on strength and muscle hypertrophy (Friedmann-Bette et al. 2010), evidence from short-duration, low-volume interventions remains limited. Therefore, this pilot study investigated the feasibility and short-term effects of a six-week motor-controlled SAEL squat intervention compared with traditional resistance training on strength, explosive performance, flexibility, and muscle hypertrophy.
Methods:
Nine resistance-trained participants were randomly allocated to either a SAEL group (n = 4) or a traditional resistance training group (TRAD; n = 5). Participants completed a total of six supervised squat training sessions (3 × 5 repetitions, once weekly) using a motor-controlled Smith machine. The TRAD group trained with 78% of concentric 1RM during both movement phases, whereas the SAEL group performed the concentric phase at 78% of concentric 1RM and the eccentric phase at 78% of eccentric 1RM (~112% concentric 1RM). Outcome measures included squat 1RM, eccentric 1RM, countermovement jump (CMJ), squat jump (SJ), loaded CMJ performance, passive knee range of motion (ROM), and ultrasound-derived vastus lateralis (VL) and rectus femoris (RF) cross-sectional area (CSA).
Results:
Significant improvements over time were observed for squat 1RM (p = 0.005), passive knee ROM (p = 0.044), and VL CSA (p = 0.016). No significant group or group × time interaction effects were found for any outcome. Within-group analyses showed significant increases in squat 1RM (+7.2%) and VL CSA (+5.1%) in TRAD, while SAEL demonstrated comparable but non-significant improvements in squat 1RM (+8.7%) and VL CSA (+8.2%). No significant changes were observed for RF CSA or jump performance.
Discussion:
Both training approaches produced comparable short-term adaptations following six weeks of low-volume squat training, with no evidence supporting the superiority of motor-controlled SAEL over traditional loading. The observed improvements in squat 1RM and vastus lateralis CSA are generally consistent with previous SAEL interventions reporting positive effects on strength and muscle hypertrophy (Friedmann-Bette et al. 2010; Walker et al. 2016). However, the relatively large strength gains observed within only six training sessions may also partly reflect learning effects associated with maximal testing on the motor-controlled Smith machine. Given the exploratory nature of this pilot study and its small sample size, these findings should be interpreted with caution.
Conclusion:
Motor-controlled SAEL appears to be a feasible, safe, and practical method for implementing eccentric overload within a low-volume, time-efficient squat training program. Under the present conditions, coaches may select either loading strategy based on equipment availability and practical considerations rather than expected differences in training adaptations. Future studies should include larger samples, familiarization sessions, and longer intervention periods to determine whether motor-controlled SAEL provides additional long-term benefits for strength, muscle hypertrophy, and explosive performance.
References:
Friedmann-Bette, B., Bauer, T., Kinscherf, R., Vorwald, S., Klute, K., Bischoff, D., Müller, H., Weber, M. A., & Metz, J. (2010). Effects of strength training with eccentric overload on muscle adaptation in male athletes. European Journal of Applied Physiology, 108(4), 821–836. https://doi.org/10.1007/s00421-009-1292-2
Walker, S., Blazevich, A. J., Haff, G. G., Tufano, J. J., Newton, R. U., & Häkkinen, K. (2016). Greater strength gains after training with accentuated eccentric than traditional isoinertial loads in already strength-trained men. Frontiers in Physiology, 7, Article 149. https://doi.org/10.3389/fphys.2016.00149