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NCT Number: NCT06721026

Re-evaluation of the Muscle-full Effect During Continuously Elevated Amino Acid Availability in Healthy Young Males

Muscle tissue consists of proteins. These proteins are built up of a collection of smaller building blocks: amino acids. When protein is consumed, it gets digested and absorbed into the blood. The body can use these amino acids, by taking them up from thecirculation. By consuming sufficient protein through our diet, we ensure that the body is provided with enough amino acids to enable muscle protein building. Sufficient muscle protein synthesis is important for maintaining muscle function and strength.

Previous research has shown that when 20 to 25g of protein is eaten, muscle protein synthesis is maximized. It is therefore recommended to eat 20g of protein per meal. However, it is currently unclear what happens to muscle protein synthesis rates if multiple meals are eaten. When multiple meals are consumed, amino acids appear in the circulation for prolonged period of time.

Theoretically, when there are a high amino acid concentrations in the blood, muscle protein synthesis rates will increase. Contrary to this theory, a study more than 20 years ago showed otherwise. It was observed that muscle protein synthesis rates are only elevated for2 hours afterwhich they decrease again. This phenomenon was referred to as the "muscle-full" effect. Because this phenomenon is in contrast with more previous studies, the objective is to replicate that study. This is important so that nutritional advice for healthy, but also clinical populations in the future can be improved.

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Key information

Conditions

Muscle Protein Synthesis

Age range

18 year–35 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Maastricht University Medical Centre+

Maastricht, Limburg, 6229ER, Netherlands

Location contact

Noortje Boot, MSc

CONTACT

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Male sex
  • Aged between 18 - 35 years
  • Healthy (assessed based on routine medical questionnaire)
  • BMI between 18.5 - 30 kg/m2

Exclusion criteria

A potential subject who meets any of the following criteria will be excluded from participation in this study:

  • Smoking
  • Involved in progressive exercise training
  • A history of neuromuscular problems
  • Use of anticoagulants
  • Recent (<12 months) participation in amino acid tracer (L-[ring-13C6] phenylalanineand L-[3,5-2H2]-tyrosine) studies
  • Use of medication known to affect (muscle) protein metabolism (e.g. corticosteroids, non-steroidal anti-inflammatory drugs, acne medication)
  • Phenylketonuria
  • Diagnosed with or history of liver damage
  • Diagnosed with or history of severe kidney damage and/or malfunction
  • Diagnosed with inability to break down amino acids

Treatment and study plan

Continuous intravenous stable isotope amino acid tracer infusion

Other

During the single 12 h trial day, a primed continuous stable isotope infusion will run in order to assess muscle protein synthesis in the basal (4 h) and post-prandial (8 h) state.

Amino acid infusion

Other

In order to assess muscle protein synthesis rates during continuous elevated plasma amino acid availability, the amino acid infusion solution Vamin®14 EF will be used. Vamin® 14EF contains 85g amino acids per liter and will be administered in the post-prandial period for 8 hours to ensure a constant rate of amino acid infusion over the full assessment period of the primary outcome measure.

Primary outcomes

  1. Muscle protein synthesis during continuous elevated plasma amino acid avaialbility in healthy young males

    Time frame: 8 hours

    The primary endpoint is muscle protein synthesis rates (in %/h) over the full assessment period (8 h) as determined with contemporary stable isotope tracer methodology combined with repeated blood and muscle sampling. Muscle protein synthesis are calculated using plasma as precursor pool and the tracer enrichment in the muscle (measured with UPLC and GC-IRMS).

Secondary outcomes

  1. Basal muscle protein synthesis rates

    Time frame: 3 hours

    Basal muscle protein synthesis rates (in %/h) will be assessed over a 3h period as determined with contemporary stable isotope tracer methodology combined with repeated blood and muscle sampling. Muscle protein synthesis are calculated using plasma as precursor pool and the tracer enrichment in the muscle biopsy (measured with UPLC and GC-IRMS).

  2. Whole-body protein kinetics

    Time frame: 8 hours

    Including total rate of appearance, exogenous rate of appearance, endogenous rate of appearance, rate of disappearance based (all expressed as μmol/kg/min) on tracer plasma amino acid concentrations over time (measured with UPLC)

  3. Whole-body protein metabolism

    Time frame: 8 hours

    synthesis, breakdown, oxidation, net balance (all expressed as μmol/kg/h). Based on amino acid concentrations in plasma and breath samples (measured with UPLC and GC-IRMS).

Study contacts

Contact information is provided by the study sponsor or research team.

Luc van Loon, PhD

CONTACT

[email protected]

0031433881743

Sponsors and collaborators

Lead sponsor

Maastricht University Medical Center

Other

Registry information

Acronym: Muscle-full

Important dates

Study start
2025
Primary completion
2025
Study completion
2026
First posted
Dec 6, 2024
Registry last updated
Dec 13, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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