Muscular AtrophyFABRICNCT07178353
Human Skeletal Muscle Response to 5 Days of Bedrest in Young Adults
A study testing Bedrest in people with Muscular Atrophy and Insulin Resistance, run by Queen's University at 1 site in Canada.
Trial summary
The goal of this intervention trial is to characterize skeletal muscle atrophy in healthy, young adults during short term bedrest. The main questions it aims to answer are: How much do skeletal muscle volume, strength, and fatigue resistance decline during bedrest? How much does whole-body insulin sensitivity change… Read more about this study
- Who is it for?
- Ages 18 to 30 yearsHealthy volunteers can take part
- Conditions the study is for
- Muscular Atrophy, Insulin Resistance, Muscle Protein Synthesis
- What is being tested?
- Bedrest
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 12 participants
- Where
- 1 siteCanada
- Study dates
- Sep 2025to Jun 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 30 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Males and females 18-30 years
- BMI between 18.5-28 kg/m2
- Weight stable (within ±2kg for 6 months)
- Generally healthy as assessed by medical and physical activity questionnaires
- recreationally active
Who cannot join
- a BMI < 18.5 and > 28 kg/m2
- the use of insulin to control blood glucose levels
- a history of any cardiovascular, respiratory, metabolic diseases, neuromuscular or bone-wasting diseases
- the use of any medication that may affect muscle protein turnover (e.g. androgen or anabolic hormone therapy, chemotherapy)
- a (family) history of thrombosis, platelet or coagulation disorders, or antiplatelet therapy and the use of anticoagulant medications
- the presence of any unremoved, or partially removed metals underneath the skin
Show all 11Show fewer
- a history of head or eye injury involving metal fragments
- have some type of implanted electrical device (such as a cardiac pacemaker or neurostimulator)
- have implanted metal objects as a result of surgery, such as artificial joints, aneurysm clips, metal staples
- are, or may be, pregnant
- are wearing metal braces on their teeth.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
Queen's Univeristy
Kingston, Ontario, K7L 3N6
Chris McGlory, PhD., 6135336000 ext. 75410, chris.mcglory@queensu.ca
About this study
Official title: Changes in Muscle Mass, Strength, and Muscle Protein Synthesis in Response to 5 Days of Bedrest in Young, Healthy Adults
The goal of this intervention trial is to characterize skeletal muscle atrophy in healthy, young adults during short term bedrest. The main questions it aims to answer are:
How much do skeletal muscle volume, strength, and fatigue resistance decline during bedrest? How much does whole-body insulin sensitivity change during bedrest? How do mitochondrial function and protein synthesis change during bedrest?
Read more
Participants will undergo the following tests before and after a free-living control period and before and after a 5 day period of strict horizontal bedrest:
- Magnetic resonance imaging of the thigh muscles
- Strength testing of the thigh muscles
- Insulin sensitivity testing in response to a mixed meal
- Exogenous glucose oxidation in response to a mixed meal
- Muscle biopsies from the thigh muscles
- Blood samples
Read the detailed description
Skeletal muscle plays a critical role in physical function and metabolic health, with its maintenance driven by the balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). During periods of disuse, such as illness or injury, MPS declines while MPB remains relatively unchanged, leading to muscle loss and atrophy. Short-term disuse, such as bedrest, is commonly experienced through hospitalization, and can result in rapid declines in muscle mass and strength, typically affecting the lower limbs to a greater extent. At the molecular level, bed rest significantly reduces MPS, with durations as little as 3 days showing drastic impairment in skeletal muscle turnover. Additionally, short-term periods of disuse have shown to blunt mitochondrial respiration, affecting the ability for skeletal muscle to produce energy for proper funcitoning and metabolic processes. Diminished skeletal muscle metabolic function directly impacts whole-body metabolic health. Periods of bedrest between 5 and 7 days have shown to decrease whole-body glucose tolerance, increase insulin resistance, and decrease insulin-stimulated leg glucose uptake. All together, these contribute to decreased skeletal muscle mass and strength, and diminished metabolic function, contributing to a decline in overall physical function, health, and well-being. Current studies on short-term bed rest (ex. 5 days) in young adults are limited, and existing research has focused on simulated microgravity models rather than horizontal bed rest, which better represents clinical scenarios. Additionally, no study to our knowledge has explored how the molecular mechanisms that drive MPS change over the course of a 5-day bedrest period. This highlights a need to explore if there are differences in the attrition of synthesis rates of the different protein pools in skeletal muscle (ex. myofibrillar, sarcoplasmic, and mitochondrial).
The purpose of the present study is to investigate changes in leg muscle mass, strength, and whole-body insulin sensitivity over five days of bed rest, as well as examine the time-course changes in molecular mechanisms underlying skeletal muscle turnover. The investigators hypothesize that, compared to the control period, quadriceps muscle size (volume and cross-sectional area), strength/power/fatigue resistance, and whole-body insulin sensitivity will decrease following bedrest. The investigators hypothesize that these outcomes will be linked to decreases in mitochondrial respiratory function and impaired fractional synthetic rates of muscle proteins.
In this repeated-measures design, participants will undergo a five day baseline control period followed by five days of bed rest to compare changes from bedrest to their own free-living control period.
Findings from this study will help inform future research on the impact of short-term, clinically-relevant, bedrest in young adults and aid in the development of targeted interventions to mitigate declines in muscle mass from occurring from acute bouts of muscle disuse.
- Being tested
- Bedrest
- Keywords
- magnetic resonance imaging, muscle protein syntheis, muscle disuse atrophy, bedrest, skeletal muscle, insulin sensitivity
- Medical subject headings
- Muscular Atrophy, Insulin Resistance, Muscular Disorders, Atrophic
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
BedrestOther
Also called Horizontal Bedrest
5 days of strict bedrest. Participants are allowed to sit up in bed, but will perform any bathing or bathroom activities in a wheelchair.
| Study group | Role | What they receive |
|---|---|---|
| Experimental: Bedrest | Experimental | 19 day study period, consisting of baseline testing, 5 days of free-living (habitual daily activities) immediately followed by 5 days of strict bedrest. Diet controlled and physical activity monitored for entire study period. Receives: Other: Bedrest |
What is being measured
The primary outcome is the main question the study is designed to answer.
Quadriceps muscle volume
Quadriceps muscle volume will be assessed by magnetic resonance imaging.
Measured: Day 0, and 5
Secondary outcomes (18)
Muscle strength
Knee extensor peak torque will be assessed using dynamometry
Measured: Day -14, -9, and 5
Knee extensor power
Peak isotonic power determined at 30% maximal isometric voluntary contraction torque using a dynamometer
Measured: Day -14, -9, and 5
Muscle fatiguability
Knee extensor fatiguability will be determined by the decrease in isotonic power across 40 contractions at 30% MVC using dynamometry.
Measured: Day -14, -9, and 5
Muscle cross-sectional area
Change in quadriceps muscle cross sectional area measured by magnetic resonance imaging scan.
Measured: Day 0 and 5
Muscle protein synthesis
Muscle protein synthesis measured as fractional synthesis rate of the myofibrillar, sarcoplasmic, and mitochondrial protein pools within skeletal muscle. These 3 pools will be assessed using combined protocol of skeletal muscle biopsy, stable isotope tracing, cavity ring down spectroscopy with liquid isotope analysis, and gas-chromatography pyrolysis isotope-ratio mass spectrometry.
Measured: Day -5 to 0, day 0 to 1, day 0 to 3, day 0 to 5, day 1 to 3, day 1 to 5, and day 3 to 5.
2-hour plasma glucose incremental area under the curve
Determination of the total rise in plasma glucose during a mixed meal tolerance test, to be assessed by an enzyme-linked immunosorbent assay.
Measured: Aggregate 2-hour window on day -5, 0, and 5
2- hour plasma insulin incremental area under the curve
Determination of the total rise in plasma insulin during a mixed meal tolerance test, to be assessed by an enzyme-linked immunosorbent assay.
Measured: Aggregate 2-hours on day -5, 0, and 5
Postprandial glucose oxidation
Measurement of 13C excretion in breath samples using isotope ratio mass spectrometry.
Measured: Aggregate 3 hours during the mixed meal tolerance test on day -5, 0, and 5
Matsuda Index
Insulin sensitivity measured via the Matsuda Index during a mixed meal tolerance test. Matsuda index values <4.0 indicate insulin resistance, with higher values representing insulin sensitivity.
Measured: 2-hours on day -5, 0, and 5
Mitochondrial Respiratory Function
Mitochondrial respiration will be assessed using an Oroboros Oxygraph 2000.
Measured: Day -5, 1, 3, and 5
Expression of Translational Factors Related to Skeletal Muscle Protein Synthesis
Activation of translational factors involved in skeletal muscle protein synthesis assessed by western blotting.
Measured: Day 0, 1, 3, and 5
Plasma glucose concentration
Plasma glucose concentration measured during a mixed meal tolerance test.
Measured: 2-hour mixed meal tolerance test on day -5, 0, and 5
Serum insulin concentration
Serum insulin concentration measured during a mixed meal tolerance test
Measured: 2-hour mixed meal tolerance test on day -5, 0, and 5
Peak glucose concentration
Peak glucose concentration measured during a mixed meal tolerance test
Measured: 2-hour mixed meal tolerance test on day -5, 0, and 5
Peak insulin concentration
Peak insulin concentration measured during a mixed meal tolerance test.
Measured: 2-hour mixed meal tolerance test on day -5, 0, and 5
Transmission Electron Microscopy Analysis
Imaging of subsarcolemmal and intermyofibrillar mitochondria to assess change in mitochondrial content from bedrest.
Measured: Day 0, 1, 3, and 5
Supine to Stand Test
Orthostatic blood pressure assessment pre and post bedrest, and following recovery after bedrest
Measured: Day 0, 5
Homeostatic Model Assessment for Insulin Resistance (HOMA-IR)
Insulin resistance assessed using fasting insulin and glucose levels. Values <1.0 indicate insulin sensitivity, >1.9 and < 2.9 indicates early insulin resistance, and values >2.9 indicate significant insulin resistance
Measured: Day -5, 0, and 5
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Sep 2025
- Study startSep 2025 (estimated)
- Primary completionJun 2026 (estimated)
- Study completionJun 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Muscular AtrophyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- This study uses a within-subjects, repeated measures design. Single-arm study. Participants will complete a 5-day free-living, baseline testing period, before undergoing 5 days of strict horizontal bedrest.
- Masking
- None (open label)
- Enrolment
- 12 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Queen's University
- Sponsor type
- University, hospital or other
- Collaborators
- Canadian Institutes of Health Research (CIHR)
- Responsible party
- Principal investigator, Dr. Chris McGlory, PhD, Kingston Health Sciences Centre
- Investigators
- Chris McGlory, PhD., Principal investigator, Queen's University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07178353
- Sponsor's protocol ID
- 6043735
- Acronym
- FABRIC
- Status last verified
- Sep 2025
- First submitted
- 10 Sep 2025
- Last updated
- 22 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 22 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Changes in Muscle Mass, Strength, and Muscle Protein Synthesis in Response to 5 Days of Bedrest in Young, Healthy Adults
- ClinicalTrials.gov ID
- NCT07178353
- Acronym / sponsor ID
- FABRIC / 6043735
- Keywords
- magnetic resonance imaging, muscle protein syntheis, muscle disuse atrophy, bedrest, skeletal muscle, insulin sensitivity
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 12 participants (estimated)
- Lead sponsor
- Queen's UniversityUniversity, hospital or other
- Collaborators
- Canadian Institutes of Health Research (CIHR)
- Study start
- Sep 2025 (estimated)
- Primary completion
- Jun 2026 (estimated)
- Study completion
- Jun 2027 (estimated)
- First posted
- 17 Sep 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this intervention trial is to characterize skeletal muscle atrophy in healthy, young adults during short term bedrest. The main questions it aims to answer are:
How much do skeletal muscle volume, strength, and fatigue resistance decline during bedrest? How much does whole-body insulin sensitivity change during bedrest? How do mitochondrial function and protein synthesis change during bedrest?
Participants will undergo the following tests before and after a free-living control period and before and after a 5 day period of strict horizontal bedrest:
- Magnetic resonance imaging of the thigh muscles
- Strength testing of the thigh muscles
- Insulin sensitivity testing in response to a mixed meal
- Exogenous glucose oxidation in response to a mixed meal
- Muscle biopsies from the thigh muscles
- Blood samples
Detailed description
Skeletal muscle plays a critical role in physical function and metabolic health, with its maintenance driven by the balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). During periods of disuse, such as illness or injury, MPS declines while MPB remains relatively unchanged, leading to muscle loss and atrophy. Short-term disuse, such as bedrest, is commonly experienced through hospitalization, and can result in rapid declines in muscle mass and strength, typically affecting the lower limbs to a greater extent. At the molecular level, bed rest significantly reduces MPS, with durations as little as 3 days showing drastic impairment in skeletal muscle turnover. Additionally, short-term periods of disuse have shown to blunt mitochondrial respiration, affecting the ability for skeletal muscle to produce energy for proper funcitoning and metabolic processes. Diminished skeletal muscle metabolic function directly impacts whole-body metabolic health. Periods of bedrest between 5 and 7 days have shown to decrease whole-body glucose tolerance, increase insulin resistance, and decrease insulin-stimulated leg glucose uptake. All together, these contribute to decreased skeletal muscle mass and strength, and diminished metabolic function, contributing to a decline in overall physical function, health, and well-being. Current studies on short-term bed rest (ex. 5 days) in young adults are limited, and existing research has focused on simulated microgravity models rather than horizontal bed rest, which better represents clinical scenarios. Additionally, no study to our knowledge has explored how the molecular mechanisms that drive MPS change over the course of a 5-day bedrest period. This highlights a need to explore if there are differences in the attrition of synthesis rates of the different protein pools in skeletal muscle (ex. myofibrillar, sarcoplasmic, and mitochondrial).
The purpose of the present study is to investigate changes in leg muscle mass, strength, and whole-body insulin sensitivity over five days of bed rest, as well as examine the time-course changes in molecular mechanisms underlying skeletal muscle turnover. The investigators hypothesize that, compared to the control period, quadriceps muscle size (volume and cross-sectional area), strength/power/fatigue resistance, and whole-body insulin sensitivity will decrease following bedrest. The investigators hypothesize that these outcomes will be linked to decreases in mitochondrial respiratory function and impaired fractional synthetic rates of muscle proteins.
In this repeated-measures design, participants will undergo a five day baseline control period followed by five days of bed rest to compare changes from bedrest to their own free-living control period.
Findings from this study will help inform future research on the impact of short-term, clinically-relevant, bedrest in young adults and aid in the development of targeted interventions to mitigate declines in muscle mass from occurring from acute bouts of muscle disuse.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- This study uses a within-subjects, repeated measures design. Single-arm study. Participants will complete a 5-day free-living, baseline testing period, before undergoing 5 days of strict horizontal bedrest.
| Arm | Type | Receives |
|---|---|---|
| Experimental: Bedrest | Experimental | Other: Bedrest19 day study period, consisting of baseline testing, 5 days of free-living (habitual daily activities) immediately followed by 5 days of strict bedrest. Diet controlled and physical activity monitored for entire study period. |
Who may qualify
- Ages
- 18 to 30 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Males and females 18-30 years
- BMI between 18.5-28 kg/m2
- Weight stable (within ±2kg for 6 months)
- Generally healthy as assessed by medical and physical activity questionnaires
- recreationally active
Key exclusion criteria (11 listed)
- a BMI < 18.5 and > 28 kg/m2
- the use of insulin to control blood glucose levels
- a history of any cardiovascular, respiratory, metabolic diseases, neuromuscular or bone-wasting diseases
- the use of any medication that may affect muscle protein turnover (e.g. androgen or anabolic hormone therapy, chemotherapy)
- a (family) history of thrombosis, platelet or coagulation disorders, or antiplatelet therapy and the use of anticoagulant medications
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| BedrestAlso: Horizontal Bedrest5 days of strict bedrest. Participants are allowed to sit up in bed, but will perform any bathing or bathroom activities in a wheelchair. | Other | Experimental: Bedrest |
Primary outcome
Quadriceps muscle volume
Time frame: Day 0, and 5
Quadriceps muscle volume will be assessed by magnetic resonance imaging.
18 secondary outcomes
Muscle strength
Time frame: Day -14, -9, and 5
Knee extensor power
Time frame: Day -14, -9, and 5
Muscle fatiguability
Time frame: Day -14, -9, and 5
Muscle cross-sectional area
Time frame: Day 0 and 5
Muscle protein synthesis
Time frame: Day -5 to 0, day 0 to 1, day 0 to 3, day 0 to 5, day 1 to 3, day 1 to 5, and day 3 to 5.
2-hour plasma glucose incremental area under the curve
Time frame: Aggregate 2-hour window on day -5, 0, and 5
2- hour plasma insulin incremental area under the curve
Time frame: Aggregate 2-hours on day -5, 0, and 5
Postprandial glucose oxidation
Time frame: Aggregate 3 hours during the mixed meal tolerance test on day -5, 0, and 5
Matsuda Index
Time frame: 2-hours on day -5, 0, and 5
Mitochondrial Respiratory Function
Time frame: Day -5, 1, 3, and 5
Expression of Translational Factors Related to Skeletal Muscle Protein Synthesis
Time frame: Day 0, 1, 3, and 5
Plasma glucose concentration
Time frame: 2-hour mixed meal tolerance test on day -5, 0, and 5
Serum insulin concentration
Time frame: 2-hour mixed meal tolerance test on day -5, 0, and 5
Peak glucose concentration
Time frame: 2-hour mixed meal tolerance test on day -5, 0, and 5
Peak insulin concentration
Time frame: 2-hour mixed meal tolerance test on day -5, 0, and 5
Transmission Electron Microscopy Analysis
Time frame: Day 0, 1, 3, and 5
Supine to Stand Test
Time frame: Day 0, 5
Homeostatic Model Assessment for Insulin Resistance (HOMA-IR)
Time frame: Day -5, 0, and 5
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Sep 2025.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Chris McGlory, PhD. principal investigator
Queen's University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Bedrest in people with Muscular Atrophy and Insulin Resistance, run by Queen's University at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 22 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Chris McGlory, PhD. (6135336000 ext. 75410, chris.mcglory@queensu.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Quadriceps muscle volume (time frame: Day 0, and 5). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Sep 2025.