Quadriceps Motor Unit Adaptation to Simulated Knee Injury

Status

Recruiting

Phases

Early Phase 1

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT06999057

Enrollment

Registered

2025-05-31

Start date

2026-08-01

Completion date

2027-08-01

Last updated

2026-05-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Knee Injury Simulation, Muscle Inhibition

Keywords

Quadriceps, Electromyography, Motor Unit, Knee Effusion, Lidocaine, Deafferentation, Neuromuscular Adaptation, Muscle Strength

Brief summary

This study investigates how simulated knee injury-via artificial joint effusion or deafferentation-affects quadriceps motor unit behavior in healthy young adults. Participants will complete neuromuscular testing during a single 2-hour lab session. This research seeks to improve understanding of muscle inhibition and inform interventions after real-world knee trauma.

Detailed description

Using a controlled laboratory model, the investigators will simulate knee injury through two methods: (1) intra-articular saline injection to induce effusion, and (2) intra-articular lidocaine injection to induce sensory deafferentation. Healthy participants aged 18-30 will undergo surface and decomposition EMG, isometric strength testing, and reflex measurements before and after the intervention. The primary outcome is motor unit recruitment characteristics, with secondary outcomes including quadriceps inhibition (Hoffmann reflex) and isometric peak torque. The findings will inform future neuromodulatory approaches in rehabilitation.

Interventions

DEVICEJoint Effusion via 60 mL Sterile Saline

Injection of sterile saline into the knee joint to simulate joint swelling and induce quadriceps inhibition.

DRUGIntra-articular Lidocaine

Injection of 7 mL lidocaine into the knee joint to simulate deafferentation by temporarily blocking sensory input.

OTHERSham injection

Simulated knee injection using a stage needle without skin penetration, used to blind participants and serve as control.

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

BASIC_SCIENCE

Masking

SINGLE (Subject)

Intervention model description

Parallel Assignment

Eligibility

Sex/Gender

ALL

Age

18 Years to 30 Years

Healthy volunteers

Yes

Inclusion criteria

1. Age 18-30 years 2. Physically active (Tegner ≥ 5) 3. No prior lower-limb surgery or major injury

Exclusion criteria

1. Lower limb surgery or significant injury in past 2 years 2. Cardiopulmonary, neurological, or psychiatric disorders 3. Needle/electrical stimulation anxiety 4. Medications affecting neuromuscular or psychological function 5. Pregnancy 6. Allergic to lidocaine 7. Inability to elicit Hoffmann reflex

Design outcomes

Primary

Measure	Time frame	Description
Motor Unit Recruitment (amplitude relative to recruitment threshold)	Baseline, 0, 30, and 60 minutes post-intervention	Measured via surface EMG decomposition
Motor Unit Recruitment (firing rate relative to recruitment threshold)	Baseline, 0, 30, and 60 minutes post-intervention	Measured via surface EMG decomposition

Secondary

Measure	Time frame	Description
Quadriceps Inhibition (Hoffmann Reflex)	Baseline, 0 and 60 minutes post-intervention	Measured with femoral nerve stimulation
Isometric Peak Torque (Quadriceps Strength)	Baseline and 60 minutes post-intervention	Measured with isokinetic dynamometer (Biodex)

Countries

United States

Contacts

CONTACTGrant Norte, Ph.D.

Grant.Norte@ucf.edu407-823-3188

CONTACTMeredith Chaput, Ph.D.

Meredith.Chaput@ucf.edu

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: May 2, 2026