The effect of incorporating whole body vibration into exercise therapy on the corticomotor excitability of the quadriceps in athletes following anterior cruciate ligament reconstruction

Previous studies have shown that athletes recovering from anterior cruciate ligament (ACL) reconstruction experience a decline in motor cortex excitability and injury-related cortical reorganization, potentially leading to ongoing complications and a higher risk of subsequent injuries. Therefore, incorporating an intervention that consistently delivers sensory inputs to the central nervous system and enhances excitability at both spinal and supra-spinal levels, in addition to exercise therapy, may offer greater benefits. The purpose of this study was to explore whether combining whole body vibration (WBV) with exercise therapy enhances motor cortical excitability in athletes undergoing ACL reconstruction more effectively than exercise therapy alone. Additionally, it aimed to assess whether this combination improves quadriceps strength and reduces functional limitations in daily activities. This study is a randomized, single-blinded, controlled trial. Twenty-six participants were assigned to either the WBV plus exercise therapy group (intervention group) or the exercise therapy-only group (control group). Outcome measures, assessed before and after treatment, included motor cortex excitability [active motor threshold (AMT) and motor-evoked potential amplitude of the quadriceps], isometric peak torque of the quadriceps, and daily functional disabilities using the knee outcome survey activities of daily living scale (KOS-ADL scale). The treatment period consisted of 12 sessions (4 weeks, with 3 sessions per week). A two-way mixed ANOVA was conducted to examine the main effects of group, time and their interactions. The results showed that in the intervention group (WBV plus exercise therapy), AMT significantly decreased (F(1, 12) = 11.35, P = 0.006, η² = 0.486), while the control group (exercise therapy only) showed no significant change (F(1, 12) = 0.252, P = 0.625, η² = 0.021). In the intervention group, AMT decreased by 19.47% post-treatment. Both groups showed significant improvements in isometric peak torque and KOS-ADL scores (P < 0.001), with large effect sizes for these parameters. The study concluded that adding WBV to exercise therapy is more effective in increasing motor cortex excitability compared to exercise therapy alone. However, since both groups showed significant improvements in quadriceps peak torque and KOS-ADL scores, it suggests that the addition of WBV did not provide substantial added benefits in enhancing quadriceps strength and improving daily functional abilities. The observed improvements may primarily be attributed to exercise therapy. Nonetheless, it is important to consider the small sample size and low statistical power when interpreting these results.RCT registration: On the Iranian Registry of Clinical Trials (IRCT20220220054078N1).