Muscle DamageNCT07438158
Protein Distribution and Leucine Supplementation Effects on Body Composition and Performance in Tactical Athletes
A study testing L-leucine supplementation, Even Protein Distribution and Skewed Protein Distribution (16-hour Protein-Fasting Window) in people with Muscle Damage, run by Tel Aviv University.
Trial summary
This randomized controlled trial will examine the effects of within-day protein distribution and leucine supplementation on body composition, physical performance, and biomarkers of muscle damage in tactical athletes during an 8-week intensive training program. Read more about this study
- Who is it for?
- Ages 18 to 35 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Muscle Damage
- What is being tested?
- L-leucine supplementation, Even Protein Distribution and Skewed Protein Distribution (16-hour Protein-Fasting Window)
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 69 participants
- Where
- No sites listed yet
- Study dates
- Mar 2026to Dec 2028
- 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 35 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Male participants aged 18-35 years
- Enrolled in an active Ministry of Defense tactical training program
- Physically active and medically cleared to participate in intensive training
- Willing and able to comply with the dietary intervention and training protocol
- Provide written informed consent prior to participation
Who cannot join
- Musculoskeletal or neuromuscular injury or impairment limiting participation in exercise training
- Cardiopulmonary disease (including recent myocardial infarction or unstable angina)
- History of cancer, diabetes, thyroid disease, hypertension, or chronic renal failure
- Cognitive impairment affecting ability to provide informed consent
- Use of medications that may affect metabolism, muscle physiology, or exercise performance
- Known allergy or intolerance to study dietary components or leucine supplementation
- Non-compliance with study protocol requirements
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: The Effect of Protein Distribution and Leucine Supplementation on Body Composition, Physical Performance, and Myofibrillar Damage in Tactical Athletes: a Randomized Controlled Trial During 8 Weeks of Intensive Training
This randomized controlled trial will examine the effects of within-day protein distribution and leucine supplementation on body composition, physical performance, and biomarkers of muscle damage in tactical athletes during an 8-week intensive training program. Sixty-nine healthy male participants (18-35 years) enrolled in a Ministry of Defense training course will be randomly assigned to one of three iso-caloric dietary groups providing 1.6 g/kg/day of protein: (1) evenly distributed protein across three meals (EVEN), (2) a 16-hour daily protein fasting pattern with protein concentrated at lunch and dinner (FAST), or (3) the same fasting pattern with 5 g leucine supplementation at breakfast (FAST-RESCUE).
Primary outcomes include changes in lean body mass. Secondary outcomes include strength, anaerobic performance, and biochemical markers of muscle damage, including urinary titin N-terminal fragment (UTF). Assessments will be conducted at baseline, Week 5, and Week 8.
Read the detailed description
This study is an 8-week, three-arm, parallel-group randomized controlled trial conducted in healthy male tactical trainees (18-35 years) enrolled in a Ministry of Defense training program. Participants will undergo a high-volume concurrent training regimen exceeding 30 hours per week, including resistance training, load carriage, aerobic conditioning, and combat-based drills.
Participants (n=69) will be randomized in a 1:1:1 ratio to one of three iso-caloric dietary interventions providing 1.6 g/kg/day of protein:
- EVEN: Protein evenly distributed across three daily meals (08:00, 13:00, 18:00).
- FAST: Skewed protein distribution with a 16-hour protein-free window (21:00-13:00), omitting protein at breakfast and concentrating intake at lunch and dinner.
- FAST-RESCUE: Identical to FAST, with addition of 5 g free-form leucine consumed at breakfast.
Energy intake will be individualized based on measured resting metabolic rate and estimated physical activity level. Dietary adherence will be monitored daily using a mobile application and weekly dietitian supervision.
Primary Outcome:
- Change in lean body mass measured by bioelectrical impedance analysis from baseline to Week 8.
Secondary Outcomes:
- Maximal strength (isometric mid-thigh pull, maximal voluntary contraction, handgrip strength)
- Anaerobic performance (Wingate test, countermovement jump)
- Serum biomarkers (creatine kinase, urea, testosterone, inflammatory markers)
- Urinary titin N-terminal fragment to creatinine ratio (UTF/Cr) as a marker of myofibrillar damage
Assessments will be performed at baseline, Week 5, and Week 8. Data will be analyzed according to the intention-to-treat principle using linear mixed models to evaluate Group × Time interactions.
- Conditions
- Muscle Damage
- Being tested
- L-leucine supplementation, Even Protein Distribution, Skewed Protein Distribution (16-hour Protein-Fasting Window)
- Keywords
- Tactical Athletes, Protein Distribution, Leucine Supplementation, Lean Body Mass, Muscle Protein Synthesis, Resistance Training
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
L-leucine supplementationDietary supplement
Participants ingest 5 g free-form L-leucine at breakfast (~08:00) daily for 8 weeks. Leucine is provided as unflavored, pharmaceutical-grade instantized powder, reconstituted in water and consumed at the protein-free breakfast meal.
Even Protein DistributionBehavioural
Iso-caloric diet providing 1.6 g/kg/day protein evenly distributed across three daily meals for 8 weeks.
Skewed Protein Distribution (16-hour Protein-Fasting Window)Behavioural
Iso-caloric diet providing 1.6 g/kg/day protein with protein omitted at breakfast and concentrated at lunch and dinner, creating a 16-hour daily protein-free window for 8 weeks.
| Study group | Role | What they receive |
|---|---|---|
| EVEN (Even Protein Distribution) | Other | Participants consume an iso-caloric diet providing 1.6 g/kg/day protein, distributed evenly across three daily meals at approximately 08:00, 13:00, and 18:00, with each meal providing ~one-third of daily protein. Participants follow an overnight protein fasting window of approximately 21:00-08:00. Receives: Behavioral: Even Protein Distribution |
| FAST (Protein-Fasting Morning; Protein at Lunch + Dinner) | Experimental | Participants consume an iso-caloric diet providing 1.6 g/kg/day protein using a skewed distribution that creates a 16-hour protein-free window (21:00-13:00) by omitting protein at breakfast (breakfast contains carbohydrate and fat only). Daily protein intake is concentrated at lunch and dinner to achieve the total 1.6 g/kg/day target. Receives: Behavioral: Skewed Protein Distribution (16-hour Protein-Fasting Window) |
| FAST-RESCUE (FAST + Leucine at Breakfast) | Experimental | Identical dietary pattern to FAST: iso-caloric diet with 1.6 g/kg/day protein, protein-free breakfast, and protein concentrated at lunch and dinner, creating a 16-hour protein-free window (21:00-13:00). Receives: Dietary Supplement: L-leucine supplementation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Lean Body Mass (LBM)
Lean body mass (kg) assessed by multi-frequency bioelectrical impedance analysis (BIA) using the SECA mBCA 515.
Measured: Baseline (Week 1) to Week 8
Secondary outcomes (17)
Change in Fat Mass Percentage
Fat mass percentage (%) assessed by multi-frequency bioelectrical impedance analysis (SECA mBCA 515).
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Fat-Free Mass (FFM)
Fat-free mass (kg) assessed by multi-frequency bioelectrical impedance analysis (SECA mBCA 515).
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Skeletal Muscle Mass (SMM)
Skeletal muscle mass (kg) assessed by multi-frequency bioelectrical impedance analysis (SECA mBCA 515).
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Maximal Strength - Isometric Mid-Thigh Pull (IMTP)
Maximal force during IMTP measured using a force plate system (k-Delta). Best of two trials recorded.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Maximal Voluntary Isometric Contraction (MVC)
Knee extension MVC force measured using a strain gauge system. Best of trials recorded per protocol procedures.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Handgrip Strength
Handgrip strength measured with a handgrip dynamometer; best value recorded.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Countermovement Jump (CMJ) Performance
Jump height measured via force plate system; best of two trials recorded.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Peak Power Output (Wingate Test)
Peak power output (W) during a 30-second Wingate Anaerobic Test performed on a cycle ergometer.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Mean Power Output (Wingate Test)
Mean power output (W) during a 30-second Wingate Anaerobic Test performed on a cycle ergometer.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Urinary Titin N-terminal Fragment to Creatinine Ratio (UTF/Cr)
Urinary titin N-terminal fragment (UTF) normalized to creatinine as a biomarker of myofibrillar damage, assessed from morning urine samples using ELISA methods described in the protocol.
Measured: Baseline (Week 1) and Week 5
Change in Serum Creatine Kinase (CK)
Serum CK concentration measured from blood samples as a marker of muscle damage.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Serum Urea (Blood Urea Nitrogen, BUN)
Serum urea concentration (mg/dL or mmol/L) measured from venous blood samples.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Total Testosterone
Serum total testosterone measured from blood samples.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in C-Reactive Protein (CRP)
Serum C-reactive protein concentration (mg/L) measured from venous blood samples.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Tumor Necrosis Factor-alpha (TNF-α)
Serum TNF-α concentration (pg/mL) measured from venous blood samples.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Interleukin-6 (IL-6)
Serum IL-6 concentration (pg/mL) measured from venous blood samples.
Measured: Baseline (Week 1), Week 5, and Week 8
Change in Resting Metabolic Rate (RMR)
Resting metabolic rate (kcal/day) assessed by indirect calorimetry using a metabolic cart under standardized fasting conditions.
Measured: Baseline (Week 1) and Week 8
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Feb 2026
- Study startMar 2026 (estimated)
- Primary completionDec 2028 (estimated)
- Study completionDec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Muscle DamageStudies 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
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- This is a three-arm, parallel-group randomized controlled trial. Participants will be randomly assigned in a 1:1:1 ratio to one of three dietary intervention groups (EVEN, FAST, FAST-RESCUE) for 8 weeks during an intensive tactical training program. Each group will follow a distinct protein distribution strategy while maintaining identical total daily protein intake (1.6 g/kg/day) and iso-caloric energy intake.
- Masking
- None (open label)
- Enrolment
- 69 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Tel Aviv University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Gepner Yftach, Tel Aviv University
- Investigators
- Yftach Gepner, PhD, Principal investigator, Tel Aviv University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07438158
- Sponsor's protocol ID
- 0011980-1
- Status last verified
- Feb 2026
- First submitted
- 22 Feb 2026
- Last updated
- 2 Mar 2026
- Results posted
- 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 2 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Protein Distribution and Leucine Supplementation on Body Composition, Physical Performance, and Myofibrillar Damage in Tactical Athletes: a Randomized Controlled Trial During 8 Weeks of Intensive Training
- ClinicalTrials.gov ID
- NCT07438158
- Acronym / sponsor ID
- 0011980-1
- Conditions
- Muscle Damage
- Keywords
- Tactical Athletes, Protein Distribution, Leucine Supplementation, Lean Body Mass, Muscle Protein Synthesis, Resistance Training
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 69 participants (estimated)
- Lead sponsor
- Tel Aviv UniversityUniversity, hospital or other
- Study start
- Mar 2026 (estimated)
- Primary completion
- Dec 2028 (estimated)
- Study completion
- Dec 2028 (estimated)
- First posted
- 27 Feb 2026 (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.
This randomized controlled trial will examine the effects of within-day protein distribution and leucine supplementation on body composition, physical performance, and biomarkers of muscle damage in tactical athletes during an 8-week intensive training program. Sixty-nine healthy male participants (18-35 years) enrolled in a Ministry of Defense training course will be randomly assigned to one of three iso-caloric dietary groups providing 1.6 g/kg/day of protein: (1) evenly distributed protein across three meals (EVEN), (2) a 16-hour daily protein fasting pattern with protein concentrated at lunch and dinner (FAST), or (3) the same fasting pattern with 5 g leucine supplementation at breakfast (FAST-RESCUE).
Primary outcomes include changes in lean body mass. Secondary outcomes include strength, anaerobic performance, and biochemical markers of muscle damage, including urinary titin N-terminal fragment (UTF). Assessments will be conducted at baseline, Week 5, and Week 8.
Detailed description
This study is an 8-week, three-arm, parallel-group randomized controlled trial conducted in healthy male tactical trainees (18-35 years) enrolled in a Ministry of Defense training program. Participants will undergo a high-volume concurrent training regimen exceeding 30 hours per week, including resistance training, load carriage, aerobic conditioning, and combat-based drills.
Participants (n=69) will be randomized in a 1:1:1 ratio to one of three iso-caloric dietary interventions providing 1.6 g/kg/day of protein:
- EVEN: Protein evenly distributed across three daily meals (08:00, 13:00, 18:00).
- FAST: Skewed protein distribution with a 16-hour protein-free window (21:00-13:00), omitting protein at breakfast and concentrating intake at lunch and dinner.
- FAST-RESCUE: Identical to FAST, with addition of 5 g free-form leucine consumed at breakfast.
Energy intake will be individualized based on measured resting metabolic rate and estimated physical activity level. Dietary adherence will be monitored daily using a mobile application and weekly dietitian supervision.
Primary Outcome:
- Change in lean body mass measured by bioelectrical impedance analysis from baseline to Week 8.
Secondary Outcomes:
- Maximal strength (isometric mid-thigh pull, maximal voluntary contraction, handgrip strength)
- Anaerobic performance (Wingate test, countermovement jump)
- Serum biomarkers (creatine kinase, urea, testosterone, inflammatory markers)
- Urinary titin N-terminal fragment to creatinine ratio (UTF/Cr) as a marker of myofibrillar damage
Assessments will be performed at baseline, Week 5, and Week 8. Data will be analyzed according to the intention-to-treat principle using linear mixed models to evaluate Group × Time interactions.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- This is a three-arm, parallel-group randomized controlled trial. Participants will be randomly assigned in a 1:1:1 ratio to one of three dietary intervention groups (EVEN, FAST, FAST-RESCUE) for 8 weeks during an intensive tactical training program. Each group will follow a distinct protein distribution strategy while maintaining identical total daily protein intake (1.6 g/kg/day) and iso-caloric energy intake.
| Arm | Type | Receives |
|---|---|---|
| EVEN (Even Protein Distribution) | Other | Behavioral: Even Protein DistributionParticipants consume an iso-caloric diet providing 1.6 g/kg/day protein, distributed evenly across three daily meals at approximately 08:00, 13:00, and 18:00, with each meal providing ~one-third of daily protein. Participants follow an overnight protein fasting window of approximately 21:00-08:00. |
| FAST (Protein-Fasting Morning; Protein at Lunch + Dinner) | Experimental | Behavioral: Skewed Protein Distribution (16-hour Protein-Fasting Window)Participants consume an iso-caloric diet providing 1.6 g/kg/day protein using a skewed distribution that creates a 16-hour protein-free window (21:00-13:00) by omitting protein at breakfast (breakfast contains carbohydrate and fat only). Daily protein intake is concentrated at lunch and dinner to achieve the total 1.6 g/kg/day target. |
| FAST-RESCUE (FAST + Leucine at Breakfast) | Experimental | Dietary Supplement: L-leucine supplementationIdentical dietary pattern to FAST: iso-caloric diet with 1.6 g/kg/day protein, protein-free breakfast, and protein concentrated at lunch and dinner, creating a 16-hour protein-free window (21:00-13:00). |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Male participants aged 18-35 years
- Enrolled in an active Ministry of Defense tactical training program
- Physically active and medically cleared to participate in intensive training
- Willing and able to comply with the dietary intervention and training protocol
- Provide written informed consent prior to participation
Key exclusion criteria (7 listed)
- Musculoskeletal or neuromuscular injury or impairment limiting participation in exercise training
- Cardiopulmonary disease (including recent myocardial infarction or unstable angina)
- History of cancer, diabetes, thyroid disease, hypertension, or chronic renal failure
- Cognitive impairment affecting ability to provide informed consent
- Use of medications that may affect metabolism, muscle physiology, or exercise performance
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 |
|---|---|---|
| L-leucine supplementationParticipants ingest 5 g free-form L-leucine at breakfast (~08:00) daily for 8 weeks. Leucine is provided as unflavored, pharmaceutical-grade instantized powder, reconstituted in water and consumed at the protein-free breakfast meal. | Dietary supplement | FAST-RESCUE (FAST + Leucine at Breakfast) |
| Even Protein DistributionIso-caloric diet providing 1.6 g/kg/day protein evenly distributed across three daily meals for 8 weeks. | Behavioural | EVEN (Even Protein Distribution) |
| Skewed Protein Distribution (16-hour Protein-Fasting Window)Iso-caloric diet providing 1.6 g/kg/day protein with protein omitted at breakfast and concentrated at lunch and dinner, creating a 16-hour daily protein-free window for 8 weeks. | Behavioural | FAST (Protein-Fasting Morning; Protein at Lunch + Dinner) |
Primary outcome
Change in Lean Body Mass (LBM)
Time frame: Baseline (Week 1) to Week 8
Lean body mass (kg) assessed by multi-frequency bioelectrical impedance analysis (BIA) using the SECA mBCA 515.
17 secondary outcomes
Change in Fat Mass Percentage
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Fat-Free Mass (FFM)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Skeletal Muscle Mass (SMM)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Maximal Strength - Isometric Mid-Thigh Pull (IMTP)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Maximal Voluntary Isometric Contraction (MVC)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Handgrip Strength
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Countermovement Jump (CMJ) Performance
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Peak Power Output (Wingate Test)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Mean Power Output (Wingate Test)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Urinary Titin N-terminal Fragment to Creatinine Ratio (UTF/Cr)
Time frame: Baseline (Week 1) and Week 5
Change in Serum Creatine Kinase (CK)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Serum Urea (Blood Urea Nitrogen, BUN)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Total Testosterone
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in C-Reactive Protein (CRP)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Tumor Necrosis Factor-alpha (TNF-α)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Interleukin-6 (IL-6)
Time frame: Baseline (Week 1), Week 5, and Week 8
Change in Resting Metabolic Rate (RMR)
Time frame: Baseline (Week 1) and Week 8
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 2 Mar 2026.
- 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.
Yftach Gepner, PhD principal investigator
Tel Aviv University
Questions about this trial
What is this clinical trial studying?
A study testing L-leucine supplementation, Even Protein Distribution and Skewed Protein Distribution (16-hour Protein-Fasting Window) in people with Muscle Damage, run by Tel Aviv University.
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 7 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: opening soon, as of the sponsor's last update on 2 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
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 Lien Bruck (0587487431, lien.brueck@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Lean Body Mass (LBM) (time frame: Baseline (Week 1) to Week 8). 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 2 Mar 2026.