Author(s): FAN, T., CHOU, P., Institution: KAOHSIUNG MEDICAL UNIVERSITY, Country: TAIWAN, Abstract-ID: 1022

INTRODUCTION:
Restoring lower-limb function and ensuring a safe return to sports remain the primary challenges following anterior cruciate ligament reconstruction (ACLR). While isokinetic peak torque is a traditional gold standard for assessment, recent evidence suggests that the ability to develop force rapidly (rate of torque development, RTD) is often more critical than maximal strength for athletic tasks. Countermovement jumps (CMJ) and drop jumps (DJ) have been widely used to assess performance in individuals with ACLR. Force plate parameters could demonstrate responsiveness to changes in neuromuscular function, and detect any functional deficits.
The Purpose of this study was to investigate the relationship between clinical strength metrics (isokinetic strength and isometric RTD) and jumping performance measured via force-plate kinetics in individuals following ACLR.
METHODS:
A total of 17 participants (8 males, 9 females) with a mean age of age: 29.09 +/- 7.85 years were enrolled in this study. The average follow-up time was 12.06 +/- 9.71 months (range 6.0~42.8 months). Isokinetic knee extension/flexion strength (60 deg/s and 180 deg/s) and RTD (100ms and 200ms) were measured; CMJ and DJ were evaluated through Hawkin Dynamics dual wireless force plates (Hawkin Dynamics, Westbrook, ME, USA), captured real-time kinetic data. Paired t-test and Wilcoxon Signed-Rank Test were employed to compare isokinetic strength and isometric RTD between limbs respectively. The relationship between strength/RTD and jump performance metrics was evaluated using Pearson correlation and Spearman's Rank Correlation. All significance levels were set at p < .05.
RESULTS:
Isokinetic peak torque for both knee extension and flexion were significantly lower in the affected limb compared to the contralateral limb across both testing velocities. All these Isokinetic strength parameters demonstrated a high positive correlation with jump height of CMJ and DJ, and also mRSI of the DJ. The Braking RFD during CMJ was significantly correlated specifically with knee extension isokinetic strength at 180 deg/s. (r = .56, p = .019) The RTD (100ms and 200ms) of the both knee flexors was significantly correlated with jump height of CMJ. The inter-limb symmetry of Peak Landing Force during the CMJ was significantly correlated with the symmetry of isokinetic knee flexion strength. (60 deg/s: r = .493, p = .044; 180 deg/s: r = .483, p = .049)
CONCLUSION:
Restoring isokinetic strength and RTD is essential for recovering jump height and propulsive symmetry post-ACLR. The correlation between high-velocity isokinetic strength and braking RFD suggests that rehabilitation should emphasize the ability to generate force rapidly. The specific link between knee flexor symmetry and landing force symmetry underscores the importance of hamstring rehabilitation for impact attenuation. Rehabilitation should target both maximal strength and rapid force production to ensure comprehensive functional recovery and safer return to sport.