Tehran University of Medical Sciences Journal of Modern Rehabilitation 2538-385X 15 1 2020 12 23 1 6 EN Elie Hajouj Department of Physiotherapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Reza Hadian Department of Physiotherapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran. AND Brain and Spinal Cord Injury Research Center, Institute of Neuroscience., Tehran University of Medical Sciences, Tehran, Iran. Seyed Mohsen Mir Department of Physiotherapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran. Saeed Talebian Department of Physiotherapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran. Farzin Halabchi Department of Sports and Exercise Medicine, Tehran University of Medical Sciences, Tehran, Iran. Salah Ghazi Department of Physiotherapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran. 2020 07 27 2020 08 31 Introduction: Voluntary Response Index (VRI) is used as a measure of motor control to study abnormalities of voluntary movements. This study aimed to evaluate the reliability of voluntary response index analysis in subjects with Anterior Cruciate Ligament Reconstruction (ACLR). Materials and Methods: Using surface electromyography, the VRI components of both groups of 15 ACLR and 15 healthy controls were assessed during the functional task (sit-stand-sit). The outcome variables of VRI included the magnitude and similarity index. Results: In sit to stand phase, high reliability was found (ICC=0.80-0.89) for the magnitude and similarity index in both groups. In the standing phase, high to very high reliability was found for the magnitude and similarity index in both groups (ICC=0.75-0.91). In stand to sit phase, high to very high reliability was found (ICC=0.78-0.92) for the magnitude and similarity index in both groups. Conclusion: Surface electromyographic measurements of VRI analysis demonstrated high to very high reliability in athletes with ACLR during the functional task (sit-stand-sit). The results of the current study showed that the VRI analysis in athletes after ACLR was a reliable method and can be used to evaluate motor control before and after ligament injury in these patients. https://jmr.tums.ac.ir/index.php/jmr/article/view/296