Whole Body Vibration Improves Early Rate Of Torque Development In Individuals With ACL Reconstruction

Abstract

Quadriceps rate of torque development (RTD) is reduced following anterior cruciate ligament reconstruction (ACLR), and contributes to diminished physical function. Whole body (WBV) and local muscle vibration (LMV) improve quadriceps function and may improve RTD, but their efficacy for doing so has not been compared. It is also unclear if WBV and LMV influence early or late RTD. Early RTD is important to force attenuation during gait, which contributes to the development of knee osteoarthritis. PURPOSE: To compare the acute effects of WBV and LMV on early and late RTD in individuals with ACLR. METHODS: 20 individuals with ACLR (age=21.1 (1.2) years, mass=77.2 (17.1) kg, time since injury=50.7 (21.3) months; 14 females, 16 patellar tendon autograft, 3 hamstring autograft, 1 allograft) volunteered for this study. Interventions (WBV, LMV, control) were delivered in a randomized order during 3 separate visits separated by 1-week washout periods. Quadriceps RTD was assessed during maximal voluntary isometric (MVIC) knee extension at 60° of knee flexion prior to and immediately after the intervention. Early RTD was defined as the slope of the torque signal during the first 100ms following contraction onset (RTD100), and late RTD was defined as the slope of the torque signal from 100-200ms following contraction onset (RTD200), and were normalized to body mass for analysis. Intervention effects were assessed using 3 (condition) x 2 (time) ANOVA, and Bonferroni post hoc adjustments were used to evaluate significant ANOVA models. RESULTS: There was a significant condition x time interaction for RTD100 (p=0.008) but not RTD200 (p=0.76). Post hoc analyses indicated a significant increase in RTD100 following WBV (+2.76 Nm/sec/kg, p=0.005). No differences were observed in the LMV (-1.28 Nm/sec/kg, p=0.13) or control conditions (-1.56 Nm/sec/kg, p=0.29), and no difference was observed between conditions at pretest or posttest CONCLUSIONS: Results indicate that WBV acutely improves RTD100 in individuals with ACLR during an MVIC. The ability to rapidly produce knee extension torque is essential to force attenuation during gait. WBV may be appropriate to aid in the restoration of RTD following ACLR. Future studies are needed to determine the effects of repeated WBV exposure on quadriceps function.