Vibration on the Quadriceps after an ACL reconstruction

Quadriceps dysfunction occurs frequently after an anterior cruciate ligament reconstruction (ACLR) and might contribute to physical disability. Studies revealed activation deficits in the contralateral limb and showed impaired central influences on the quadriceps function, such as a reduced corticomotor excitability. Muscle strengthening has been shown to be often unsuccessful in restoring quadriceps function and thus novel approaches are needed.

This study investigated the novel approach of combining the squat exercise with local muscle vibration (LMV), whole body vibration (WBV) and compared the results to the squat exercise without any vibration. The group which had received the WBV, as well as the LMV group showed significant improvements of the quadriceps function compared to the group without vibration.

This study aimed to compare the immediate effects of WBV and LMV on the quadriceps function (corticiomotor excitability, spinal motorneuron excitability, strength, rate of torque development, and muscle activation) in individuals with ACLR.

To assess the alpha motorneuron pool the H-reflex and the maximal muscle response of the vastus medialis were used. In addition the isometric torque, the quadriceps peak torque, the rate of torque development (RTD), the EMG amplitude of the quadriceps and the central activation ratio (CAR) were investigated. 

20 subjects with an ACLR received 3 treatments, separated by 1-week washout period. The treatment consisted of 6 repetitions of 60 seconds in a squatting position of 60° of knee flexion. The subjects performed the squathold with (1) local vibration on the quadriceps (2) WBV by standing on a vibrating platform and (3) squatholds without vibration

Although the included participants had the reconstructive surgery nearly 4 years ago, they showed evidence of diminished quadriceps function, which highlights the need for additional quadriceps rehabilitation.

The WBV and LMV condition showed immediate improvements in peak torque, CAR, corticomotor excitability and an increased EMG amplitude. No changes were observes in the RTD, motor evoked potential or the H-reflex amplitude. The differences between WBV and LMV were not significant different.

This results emphasise that vibration may be an appropriate method to enhance quadriceps function following ACLR and may be used clinically to improve the efficacy of muscle strengthening.

> From: Pamukoff et al., Arch Phys Med Rehabil (2016) (Epub ahead of print). All rights reserved to Elsevier Ltd. Click here for the Pubmed summary.