Whole-Body and Local Muscle Vibration Immediately Improve Quadriceps Function in Individuals With Anterior Cruciate Ligament Reconstruction

Abstract

ObjectiveTo determine the immediate effects of a single session of whole-body vibration (WBV) and local muscle vibration (LMV) on quadriceps function in individuals with anterior cruciate ligament reconstruction (ACLR). DesignSinge-blind, randomized crossover trial. SettingResearch laboratory. ParticipantsPopulation-based sample of individuals with ACLR (N=20; mean age ± SD, 21.1±1.2y; mean mass ± SD, 68.3±14.9kg; mean time ± SD since ACLR, 50.7±21.3mo; 14 women; 16 patellar tendon autografts, 3 hamstring autografts, 1 allograft). InterventionsParticipants performed isometric squats while being exposed to WBV, LMV, or no vibration (control). Interventions were delivered in a randomized order during separate visits separated by 1 week. Main Outcome MeasuresQuadriceps active motor threshold (AMT), motor-evoked potential (MEP) amplitude, Hoffmann reflex (H-reflex) amplitude, peak torque (PT), rate of torque development (RTD), electromyographic amplitude, and central activation ratio (CAR) were assessed before and immediately after a WBV, LMV, or control intervention. ResultsThere was an increase in CAR (+4.9%, P=.001) and electromyographic amplitude (+16.2%, P=.002), and a reduction in AMT (–3.1%, P<.001) after WBV, and an increase in CAR (+2.7%, P=.001) and a reduction in AMT (–2.9%, P<.001) after LMV. No effect was observed after WBV or LMV in H-reflex, RTD, or MEP amplitude. AMT (–3.7%, P<.001), CAR (+5.7%, P=.005), PT (+.31Nm/kg, P=.004), and electromyographic amplitude (P=.002) in the WBV condition differed from the control condition postapplication. AMT (–3.0% P=.002), CAR (+3.6%, P=.005), and PT (+.30Nm/kg, P=.002) in the LMV condition differed from the control condition postapplication. No differences were observed between WBV and LMV postapplication in any measurement. ConclusionsWBV and LMV acutely improved quadriceps function and could be useful modalities for restoring quadriceps strength in individuals with knee pathologies.