Muscle Response to Different Amounts of Dietary Protein During Leg Immobilization

NCT ID: NCT07069426

Last Updated: 2025-09-11

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

NA

Total Enrollment

28 participants

Study Classification

INTERVENTIONAL

Study Start Date

2025-09-01

Study Completion Date

2026-09-30

Brief Summary

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Individuals who sustain musculoskeletal injuries (MSKI) can experience a rapid loss of muscle mass due to declines in muscle loading and activation that occur post-injury (i.e., disuse atrophy). Loss of muscle under these conditions is attributed to a persistent negative net muscle protein balance (muscle protein synthesis \[MPS\] \< muscle protein breakdown) that results, in part, from declines in postprandial MPS (i.e., anabolic resistance). Nutritional interventions that enhance postprandial MPS may be used to overcome disuse-induced anabolic resistance and preserve muscle mass to accelerate recovery and improve recovery outcomes. While supplemental protein has been explored as a potential countermeasure to disuse-induce anabolic resistance, the observed efficacy of such interventions has been mixed. Equivocal findings across studies may be attributed, in part, to an insufficient understanding of what constitutes an effective protein-based intervention. Importantly, no study to date has determined an optimal protein dose for overcoming disuse-induce anabolic resistance, or if there is a threshold for maximally stimulating postprandial MPS under disuse conditions. Therefore, the objective of this work is to determine rates of MPS at rest and in response to standard (20 g) or high (40 g) doses of whey protein during knee immobilization (DISUSE) compared with standard activity (ACTIVE)

Detailed Description

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Healthy, recreationally active men and women will complete this randomized, double-blind, parallel study. Muscle disuse will be implemented for five days using a unilateral leg immobilization model with one leg assigned to immobilization (DISUSE) and the contralateral leg used as a control (ACTIVE). Immobilization will be implemented with a rigid knee brace fixed at \~60° of flexion and participants will ambulate using crutches. Diets will be standardized during the immobilization phase. Participants will complete a protein feeding study at the end of immobilization consisting of primed, continuous stable isotope infusions, serial blood draws, and muscle biopsies. MPS will be assessed in both the DISUSE and ACTIVE legs in response to standard (20 g) or high (40 g) doses of whey protein. Findings from this work will directly inform the development of targeted nutritional countermeasures for overcoming disuse-induced anabolic resistance and preserving muscle mass after MSKI to optimize physical performance recovery.

Conditions

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Muscle Disuse Muscle Disuse Atrophy

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

DOUBLE

Participants Investigators

Study Groups

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Standard Protein Dose

Participants will consume 20 g of whey protein after 5 days of muscle disuse

Group Type ACTIVE_COMPARATOR

20 grams protein

Intervention Type DIETARY_SUPPLEMENT

20 grams of whey protein provided as beverage

High Protein Dose

Participants will consume 40 g of whey protein after 5 days of muscle disuse

Group Type ACTIVE_COMPARATOR

40 grams protein

Intervention Type DIETARY_SUPPLEMENT

40 grams of whey protein provided as beverage

Interventions

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20 grams protein

20 grams of whey protein provided as beverage

Intervention Type DIETARY_SUPPLEMENT

40 grams protein

40 grams of whey protein provided as beverage

Intervention Type DIETARY_SUPPLEMENT

Eligibility Criteria

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Inclusion Criteria

* Men and women aged 18-39 years (17-39 years if military personnel)
* Body mass index (BMI) between 18.5-32 kg/m2
* Routinely participate in aerobic and/or resistance exercise at least 2 days per week.
* Willing to refrain from alcohol, smoking, smokeless nicotine products (includes e-cigarettes, vaping, chewing tobacco), and dietary supplements (i.e., vitamin D, probiotics) 24 hours before and during immobilization and final testing day.
* Willing to only consume caffeine products provided by study staff during the study.
* Supervisor approval for federal civilian employees and non-SRV active-duty military personnel stationed at NSSC.
* Biological females must have normal menstrual cycles between 26-32 days in duration; 5 menstrual cycles within the past 6 months; or on continuous hormonal contraception (i.e., IUD or oral contraceptives without placebo).

Exclusion Criteria

* Musculoskeletal injuries that may interfere with the safe use of crutches.
* Personal or family history of thrombosis, or prior diagnosis of deep vein thrombosis (DVT) or pulmonary embolism (PE).
* Metabolic or cardiovascular abnormalities, gastrointestinal disorders, neuromuscular disorders, lower-limb amputation, or muscle/bone wasting disorders (e.g., diabetes, cardiovascular disease, Crohn's disease, etc.).
* Taking medication that affects macronutrient utilization (i.e., statins, corticosteroids, weight loss medications such as Ozempic, etc.).
* Significantly abnormal blood clotting as determined by USARIEM Office of Medical Oversight (OMSO) or home duty station medical support (HMS).
* Allergy to lidocaine (or similar local anesthetic).
* Present condition of alcoholism, anabolic steroid use, or other substance abuse issues as determined by OMSO or HMS.
* Blood donation within 8-wk of beginning the study.
* Pregnant, trying to become pregnant, and/or breastfeeding (results of urine pregnancy test and self-report for breastfeeding will be obtained before body composition testing).
* Unwilling or unable to consume study diets or foods provided due to personal preference and/or food allergies.
* Unwilling or unable to adhere to study physical restrictions (i.e., no structured physical activity or recreational activity beyond activities of daily living) 24 hours before and during immobilization, and the final testing day.
* Unwilling or unable to keep the knee brace on and walk with crutches during the immobilization phase.
Minimum Eligible Age

17 Years

Maximum Eligible Age

39 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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United States Army Research Institute of Environmental Medicine

FED

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Locations

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US Army Research Institute of Environmental Medicine

Natick, Massachusetts, United States

Site Status RECRUITING

Countries

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United States

Central Contacts

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Emily E Howard, PhD

Role: CONTACT

508-206-2309

Facility Contacts

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Emily Howard, PhD

Role: primary

508-206-2309

Other Identifiers

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MO240092

Identifier Type: OTHER_GRANT

Identifier Source: secondary_id

25-04H

Identifier Type: -

Identifier Source: org_study_id

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