Comparison of the Effects of Eccentric Exercises and Traditional Rehabilitation on Muscle Strength and Single-Leg Balance in the Injured Limb of Elite Athletes after Anterior Cruciate Ligament Reconstruction

Shabanzadeh, Mahdi; Sharifnezhad, Ali; Tabatabai Ghomsheh, Farhad; Hassani, Kamran

doi:10.22089/smj.2026.18788.1843

Comparison of the Effects of Eccentric Exercises and Traditional Rehabilitation on Muscle Strength and Single-Leg Balance in the Injured Limb of Elite Athletes after Anterior Cruciate Ligament Reconstruction

Articles in Press

Document Type : Research Paper

Authors

Mahdi Shabanzadeh ¹

Ali Sharifnezhad ²

Farhad Tabatabai Ghomsheh ³

Kamran Hassani ¹

¹ Department of Biomedical Engineering, SR.C., Islamic Azad University, Tehran, Iran

² Department of Sport Biomechanics and Technology, Sport Science Research Institute, Tehran, Iran

³ Department of Pediatric Neurorehabilitation Research Center, Ergonomics Department, Faculty of Rehabilitation Sciences, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran

https://doi.org/10.22089/smj.2026.18788.1843

Abstract

Anterior cruciate ligament (ACL) injury impairs the mechanical stability and neuromuscular control of the knee, posing substantial challenges for elite athletes returning to their preinjury level of performance. Given the critical role of muscle strength and balance in successful rehabilitation after ACL reconstruction (ACLR), this study aimed to compare the effects of eccentric training and conventional rehabilitation on muscle strength and single-leg balance in the reconstructed limb of elite athletes.

In this quasi-experimental study, 30 elite athletes who were at least four months post-ACLR were randomly allocated to either an eccentric training group or a conventional rehabilitation group. Participants completed a 10-week intervention program consisting of three sessions per week. Quadriceps and hamstring muscle strength were assessed using a Biodex dynamometer, whereas single-leg balance parameters, including center-of-pressure (CoP) sway and CoP velocity, were evaluated using a force plate. Independent t-tests were used to compare baseline characteristics between groups, and repeated-measures analysis of variance (ANOVA) was applied to examine within- and between-group changes over time, with the significance level set at p < 0.05.

Both interventions significantly improved muscle strength and balance. However, the eccentric training group demonstrated greater increases in peak torque and better symmetry between the reconstructed and contralateral limbs. These findings suggest that eccentric training may provide a more effective approach than conventional rehabilitation for enhancing muscle strength and single-leg balance during rehabilitation in elite athletes following ACL reconstruction.

Keywords

Center of pressure (CoP). Isokinetic strength, Peak torque, Neuromuscular coordination, Sample entropy

Eccentric

Subjects