Brain and Muscle Plasticity During Immobilization

Study Overview
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Brief Summary
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Patients in rehabilitation may undergo periods of prolonged limb immobilization in response to injury, surgery, or illness. Due to disuse, the size and strength of muscles controlling the affected limb can decrease significantly, possibly resulting in physical impairment or lower quality of life during the recovery phase. Prior immobilization studies have shown that the rate and degree of decline in muscle strength exceeds that of muscle size, indicating that determinants of muscle strength unrelated to muscle size may further contribute to functional changes during immobilization. The purpose of this study is to describe the changes in muscle strength, muscle size, corticospinal excitability, voluntary activation, M1 cortical thickness, and resting state functional connectivity following a 2-week limb immobilization period in young women.

Official Title
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Examining Changes in Muscle Size and Strength, Neuromuscular Function, and Brain Plasticity During Limb Immobilization in Women

Conditions
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Muscle Atrophy

Intervention / Treatment
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* Behavioral: Immobilization


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Biologically female Right-hand dominant Body mass index between 18.5-30 kg/m^2 (inclusive) Regular menstrual cycle Be able to maintain a habitual diet throughout the duration of the study Exclusion Criteria: Use of tobacco Pregnancy A history of brain trauma Suffers from a neurological disease or movement disorder Peripheral nerve damage Use of medications known to affect protein metabolism (i.e., corticosteroids, non-steroidal anti-inflammatory drugs, or prescription strength acne medications) Diagnosed with or suspects having a psychiatric illness Use of dietary supplements known to affect muscle size (i.e., creatine, fish oil) Past or present diagnosis of an eating disorder by a physician or registered dietician Possesses any metal implants (e.g. artificial joints, pacemakers, stents) or non-removeable medical devices that are contraindicative for magnetic resonance imaging (e.g. insulin pumps)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Female

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: Basic Science
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Immobilized arm<br>Left arm of participant | Behavioral: Immobilization<br>* Immobilization of left arm using a brace and sling.<br>|
| No Intervention: Non-immobilized arm<br>Right arm of participant | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in isometric elbow flexion and extension peak torque, both arms | Measured using an isokinetic dynamometer; peak torque during static contraction of the elbow flexors and extensors | Comparison between before and after 2 weeks of left arm immobilization | 
| Change in isokinetic elbow flexion and extension peak torque, both arms | Measured using an isokinetic dynamometer; peak torque during dynamic contraction of the elbow flexors and extensors | Comparison between before and after 2 weeks of left arm immobilization | 
| Change in cross-sectional area of the elbow flexor and extensor muscles, both arms | Obtained from magnetic resonance images of each arm | Comparison between before and after 2 weeks of left arm immobilization | 
| Change in volume of the elbow flexor and extensor muscles, both arms | Obtained from magnetic resonance images of each arm | Comparison between before and after 2 weeks of left arm immobilization | 
| Voluntary activation of biceps brachii, both arms | Measured using peripheral nerve stimulation and an isokinetic dynamometer; estimation of the capacity to voluntarily activate the force-generating elements of the biceps brachii during maximal effort elbow flexion | Comparison between before and after 2 weeks of left arm immobilization | 
| Change in corticospinal excitability of biceps brachii, both arms | Measured using transcranial magnetic stimulation; estimation of the efficacy of the corticospinal tract to relay electrical signals to the biceps brachii muscle | Comparison between before immobilization and 24 hours of left arm immobilization, and before and after 2 weeks of left arm immobilization | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in right and left primary motor cortex thickness | Obtained from magnetic resonance image of the brain | Comparison between before and after 2 weeks of left arm immobilization | 
| Change in whole brain resting state functional connectivity | Obtained from magnetic resonance image of the brain | Comparison between before and after 2 weeks of left arm immobilization |