Relationship between Eccentric Peak Force and Loading Rate at Three Months after ACL Reconstruction in Athletes and Non Athletes: A Cross-sectional Study

Abstract

Introduction: Rehabilitation in the first three months is an expedient phase from a static load-bearing to a dynamic one. Understanding of neuromuscular recovery is crucial for preventing secondary injury and delay in return to sport. Aim: To assess the relationship between Eccentric Peak Force (EPF), Eccentric Peak Force Asymmetry (EPFA), Loading Rate (LR) and Loading Rate Asymmetry (LRA) at three months after Anterior Cruciate Ligament Reconstruction (ACLR) in athletes and non athletes. Materials and Methods: This study was a cross-sectional study conducted in the Total Healthsums Physiotherapy Centre, New Delhi, India, from January 2026 to April 2026. A total of 30 patients with primary ACLR (16 athletes and 14 non athletes) aged between 20 and 40 years were included as per eligibility criteria. They were performed with isometric squat testing on VALD ForceDecks dual force plates to evaluate EPF, EPFA, LR, and LRA at three months post-ACLR. Two different groups (athletic and non-athletic group) were analysed using an independent t-test or Mann-Whitney U test for parametric or non parametric distribution, respectively. Spearman's test was done to test correlation between EPF, EPFA, LR and LRA. Results: There was a significant difference in EPFA and LRA between the groups. A positive correlation was observed between EPF and LR across entire sample (rs=0.55, p=0.002) and non athletes (rs=0.56, p=0.035), but no linear relation in athletes. Also, there is no correlation between EPFA and LRA in any group but has linear relation across whole sample (rs=0.39, p=0.030). EPFA and LRA are independent constructs in two groups. Conclusion: With an increase in force, LR increases in non athletes as well as the entire sample population. There was no significant correlation between force and LR in athletes and between force asymmetry and LRA in both athletes and non athletes.