# The Effects of Vibration on Quadriceps Function and Landing Biomechanics in Individuals with Anterior Cruciate Ligament Reconstruction

> **NIH NIH F32** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2022 · $70,664

## Abstract

PROJECT SUMMARY
The risk of sustaining a second anterior cruciate ligament (ACL) injury is 6 times greater following ACL
reconstruction surgery (ACLR) compared to those without a history of ACL injury and poses significant risk to
long term knee joint health (i.e., early onset osteoarthritis and poor quadriceps function). Mechanical knee
stability is restored after ACLR; however, functional deficits such as quadriceps dysfunction often persist and
result in high-risk lower extremity biomechanics and abnormal joint loading that increase the risk of a second
ACL injury. Evidence-based return to physical activity (RTPA) criteria have been developed to identify at risk
individuals after ACLR based on between limb symmetry (limb symmetry index, LSI) on single leg tasks (i.e.
hopping and landing) and quadriceps strength. Meeting RTPA criteria (>90% LSI) can reduce the secondary
injury rate by 84%; however few individuals (11-57%) with ACLR treated with standard rehabilitation meet
RTPA criteria before reengaging in unrestricted physical activity. As the primary contributor to poor landing
biomechanics, failure to meet RTPA criteria, and ultimately secondary ACL injury, there is a need to develop
interventions to alleviate persistent quadriceps dysfunction post-ACLR. Whole body vibration (WBV) and local
muscle vibration (LMV) excite the quadriceps and increase force production that potentially improves knee
stability during landing, hence mitigating risk of second ACL injury. Vibration also acutely improves voluntary
quadriceps function (i.e., peak torque, and EMG amplitude) and mitigates aberrant gait biomechanics in
individuals with ACLR. To that end, previous clinical trials indicate that vibration (WBV and LMV) embedded in
ACLR rehabilitation improves quadriceps function and somatosensory function to a greater extent than
rehabilitation alone. However, the longitudinal effects of vibration rehabilitation on quadriceps dysfunction and
subsequent reduction in high-risk biomechanics associated with second ACL injury and objective RTPA criteria
have not been evaluated. Therefore, the objective of this proposal is to assess the effects of vibration
rehabilitation (WBV and LMV) on quadriceps function, landing biomechanics, and the likelihood of meeting
RTPA criteria at 6 and 12 months post-ACLR. The central hypothesis is that 1) Vibration rehabilitation will
enhance quadriceps function during landing, 2) Vibration rehabilitation will enhance lower extremity
biomechanics during lading (i.e. peak sagittal and frontal plane angles and moments and vertical ground
reaction force), and 3) the Vibration rehabilitation groups will have greater odds of meeting RTPA criteria than
the Standard Rehabilitation group at 6 and 12 months post-ACLR. Completion of this project and the training
plan detailed in this application in conjunction with direct interaction with my sponsor and collaborators enable
me to develop new skills in clinical trial management, neuromuscular...

## Key facts

- **NIH application ID:** 10536986
- **Project number:** 1F32AR081708-01
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** Thomas B Birchmeier
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $70,664
- **Award type:** 1
- **Project period:** 2022-08-15 → 2024-08-14

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10536986

## Citation

> US National Institutes of Health, RePORTER application 10536986, The Effects of Vibration on Quadriceps Function and Landing Biomechanics in Individuals with Anterior Cruciate Ligament Reconstruction (1F32AR081708-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10536986. Licensed CC0.

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