Short Term Immobilization of the Lower Limb

Study Overview
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Brief Summary
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The purpose of this study is to determine the effects of one week of knee-joint immobilization on muscle size, strength, neuromuscular function, and brain function. In addition, the effects of two different interventions (i.e., neuromuscular electrical stimulation and action observation/mental imagery) throughout immobilization will be determined. Following the immobilization period, participants that have lost strength will be rehabilitated with twice weekly resistance training sessions, and sex-based differences in rehabilitation timelines will be examined.

Detailed Description
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This study will utilize a repeated measures design in healthy adults aged 18-40 years. After a thorough familiarization visit, muscular size, strength, neuromuscular responses, and corticospinal excitability/inhibition will be measured before (PRE) and after (POST) one week of unilateral knee joint immobilization of the left leg. Four groups will be examined: 1) immobilization only, 2) immobilization + daily neuromuscular electrical stimulation, 3) immobilization + daily action observation/mental imagery training, 4) a control group. Throughout the immobilization period, participants will be in a leg brace locked at 90 degrees knee flexion. They will perform daily range of motion exercises and wear a compression sock at all times to mitigate the risk of blood clots. Following completion of the immobilization period, participants that have lost strength will complete a supervised rehabilitation program of twice weekly lower body resistance training sessions until they have returned to baseline levels of strength. Group assignment will be randomized and blocked on sex to ensure an equal number of participants within each group consisting of a relatively equal number of males and females.

Official Title
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Short-term Immobilization and Rehabilitation of the Lower Limb: Changes in Strength, Size, and Neuromuscular Function

Conditions
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Weakness, Muscle, Muscle Weakness, Muscle Loss, Muscle Atrophy, Injury, Knee

Intervention / Treatment
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* Other: Neuromuscular Electrical Stimulation
* Other: Action Observation + Mental Imagery


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy men and women between the ages of 18-40 years Body mass index >20 kg/m2 or < 35 kg/m2 Exclusion Criteria: Body mass index <20 kg/m2 or > 35 c Experience of major joint pain/discomfort of the upper or lower limbs, back, or neck within the previous six months. History of major musculoskeletal injury or surgery Neuromuscular disease (e.g., Parkinson's, MS, ALS) Metabolic disease (e.g., diabetes, thyroid disorder, metabolic syndrome) Personal or family history of blood clots Trouble using or controlling one's muscles History of cancer History of stroke History of heart attack History of arthritis Use of an assistive walking device or mobility aids within the past six months Use of anabolic steroids within the past six months History of convulsions, seizures, or syncope History of concussion as diagnosed by a physician Certain medications (e.g., muscle relaxants, benzodiazepines) Very thick hair or certain hairstyles that would impede the TMS coil from making direct contact with the scalp Allergy to rubbing alcohol Lack of transportation to and from the laboratory Implant of any kind Pregnancy Allergy to silver Diagnosis of any psychiatric condition

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Repeated measures design
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Immobilization<br>Participants in the immobilization groups will undergo one week of unilateral knee joint immobilization of the left leg. | Other: Neuromuscular Electrical Stimulation<br>* Participants in this group will perform twice daily neuromuscular electrical stimulation training sessions of the quadriceps muscles (specifically, the vastus lateralis and rectus femoris) or the immobilized left leg.<br>Other: Action Observation + Mental Imagery<br>* Participants in this group will perform daily action observation + mental imagery training via video and audio recordings.<br>|
| No Intervention: Control<br>The control group will not undergo any intervention. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Muscular strength | Changes in muscular strength will be measured via maximal voluntary contraction torque | 15 minutes | 
| Muscular size | Changes in muscular size will be measured via ultrasonography of the quadriceps | 10 minutes | 
| Corticospinal responses | Corticospinal responses will be measured with transcranial magnetic stimulation targeting the lower limbs | 30 minutes | 
| Motor unit behavior | Motor unit recruitment threshold and firing rate will be measured with surface electromyography signals detected from the quadriceps | 10 minutes | 
| Voluntary activation | Voluntary activation will be measured using the interpolated twitch technique | 15 minutes | 
| Rate of recovery | The time taken to recover strength lost will be measured via number of resistance training sessions needed after immobilization | 1.5 hours per session | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Compliance | Compliance will be measured via the use of accelerometers around both ankles. Compliance will be calculated as the number of participants that following the crutch/brace protocol as described. | one week | 
| Physical activity (Step count) | Physical activity will be assessed via step counts and compared to changes in primary outcome measures via accelerometers around both ankles | one week | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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immobilization, muscle atrophy, muscle strength, action observation, mental imagery, neuromuscular electrical stimulation, rehabilitation